sqlglot.optimizer.simplify API documentation

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# sqlglot.optimizer.simplify

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       1from __future__ import annotations
       2
       3import datetime
       4import logging
       5import functools
       6import itertools
       7import typing as t
       8from collections import deque, defaultdict
       9from functools import reduce
      10
      11import sqlglot
      12from sqlglot import Dialect, exp
      13from sqlglot.helper import first, merge_ranges, while_changing
      14from sqlglot.optimizer.scope import find_all_in_scope, walk_in_scope
      15
      16if t.TYPE_CHECKING:
      17    from sqlglot.dialects.dialect import DialectType
      18
      19    DateTruncBinaryTransform = t.Callable[
      20        [exp.Expression, datetime.date, str, Dialect, exp.DataType], t.Optional[exp.Expression]
      21    ]
      22
      23logger = logging.getLogger("sqlglot")
      24
      25# Final means that an expression should not be simplified
      26FINAL = "final"
      27
      28# Value ranges for byte-sized signed/unsigned integers
      29TINYINT_MIN = -128
      30TINYINT_MAX = 127
      31UTINYINT_MIN = 0
      32UTINYINT_MAX = 255
      33
      34
      35class UnsupportedUnit(Exception):
      36    pass
      37
      38
      39def simplify(
      40    expression: exp.Expression,
      41    constant_propagation: bool = False,
      42    coalesce_simplification: bool = False,
      43    dialect: DialectType = None,
      44):
      45    """
      46    Rewrite sqlglot AST to simplify expressions.
      47
      48    Example:
      49        >>> import sqlglot
      50        >>> expression = sqlglot.parse_one("TRUE AND TRUE")
      51        >>> simplify(expression).sql()
      52        'TRUE'
      53
      54    Args:
      55        expression: expression to simplify
      56        constant_propagation: whether the constant propagation rule should be used
      57        coalesce_simplification: whether the simplify coalesce rule should be used.
      58            This rule tries to remove coalesce functions, which can be useful in certain analyses but
      59            can leave the query more verbose.
      60    Returns:
      61        sqlglot.Expression: simplified expression
      62    """
      63
      64    dialect = Dialect.get_or_raise(dialect)
      65
      66    def _simplify(expression):
      67        pre_transformation_stack = [expression]
      68        post_transformation_stack = []
      69
      70        while pre_transformation_stack:
      71            node = pre_transformation_stack.pop()
      72
      73            if node.meta.get(FINAL):
      74                continue
      75
      76            # group by expressions cannot be simplified, for example
      77            # select x + 1 + 1 FROM y GROUP BY x + 1 + 1
      78            # the projection must exactly match the group by key
      79            group = node.args.get("group")
      80
      81            if group and hasattr(node, "selects"):
      82                groups = set(group.expressions)
      83                group.meta[FINAL] = True
      84
      85                for s in node.selects:
      86                    for n in s.walk():
      87                        if n in groups:
      88                            s.meta[FINAL] = True
      89                            break
      90
      91                having = node.args.get("having")
      92                if having:
      93                    for n in having.walk():
      94                        if n in groups:
      95                            having.meta[FINAL] = True
      96                            break
      97
      98            parent = node.parent
      99            root = node is expression
     100
     101            new_node = rewrite_between(node)
     102            new_node = uniq_sort(new_node, root)
     103            new_node = absorb_and_eliminate(new_node, root)
     104            new_node = simplify_concat(new_node)
     105            new_node = simplify_conditionals(new_node)
     106
     107            if constant_propagation:
     108                new_node = propagate_constants(new_node, root)
     109
     110            if new_node is not node:
     111                node.replace(new_node)
     112
     113            pre_transformation_stack.extend(
     114                n for n in new_node.iter_expressions(reverse=True) if not n.meta.get(FINAL)
     115            )
     116            post_transformation_stack.append((new_node, parent))
     117
     118        while post_transformation_stack:
     119            node, parent = post_transformation_stack.pop()
     120            root = node is expression
     121
     122            # Resets parent, arg_key, index pointers– this is needed because some of the
     123            # previous transformations mutate the AST, leading to an inconsistent state
     124            for k, v in tuple(node.args.items()):
     125                node.set(k, v)
     126
     127            # Post-order transformations
     128            new_node = simplify_not(node)
     129            new_node = flatten(new_node)
     130            new_node = simplify_connectors(new_node, root)
     131            new_node = remove_complements(new_node, root)
     132
     133            if coalesce_simplification:
     134                new_node = simplify_coalesce(new_node, dialect)
     135
     136            new_node.parent = parent
     137
     138            new_node = simplify_literals(new_node, root)
     139            new_node = simplify_equality(new_node)
     140            new_node = simplify_parens(new_node)
     141            new_node = simplify_datetrunc(new_node, dialect)
     142            new_node = sort_comparison(new_node)
     143            new_node = simplify_startswith(new_node)
     144
     145            if new_node is not node:
     146                node.replace(new_node)
     147
     148        return new_node
     149
     150    expression = while_changing(expression, _simplify)
     151    remove_where_true(expression)
     152    return expression
     153
     154
     155def catch(*exceptions):
     156    """Decorator that ignores a simplification function if any of `exceptions` are raised"""
     157
     158    def decorator(func):
     159        def wrapped(expression, *args, **kwargs):
     160            try:
     161                return func(expression, *args, **kwargs)
     162            except exceptions:
     163                return expression
     164
     165        return wrapped
     166
     167    return decorator
     168
     169
     170def rewrite_between(expression: exp.Expression) -> exp.Expression:
     171    """Rewrite x between y and z to x >= y AND x <= z.
     172
     173    This is done because comparison simplification is only done on lt/lte/gt/gte.
     174    """
     175    if isinstance(expression, exp.Between):
     176        negate = isinstance(expression.parent, exp.Not)
     177
     178        expression = exp.and_(
     179            exp.GTE(this=expression.this.copy(), expression=expression.args["low"]),
     180            exp.LTE(this=expression.this.copy(), expression=expression.args["high"]),
     181            copy=False,
     182        )
     183
     184        if negate:
     185            expression = exp.paren(expression, copy=False)
     186
     187    return expression
     188
     189
     190COMPLEMENT_COMPARISONS = {
     191    exp.LT: exp.GTE,
     192    exp.GT: exp.LTE,
     193    exp.LTE: exp.GT,
     194    exp.GTE: exp.LT,
     195    exp.EQ: exp.NEQ,
     196    exp.NEQ: exp.EQ,
     197}
     198
     199COMPLEMENT_SUBQUERY_PREDICATES = {
     200    exp.All: exp.Any,
     201    exp.Any: exp.All,
     202}
     203
     204
     205def simplify_not(expression):
     206    """
     207    Demorgan's Law
     208    NOT (x OR y) -> NOT x AND NOT y
     209    NOT (x AND y) -> NOT x OR NOT y
     210    """
     211    if isinstance(expression, exp.Not):
     212        this = expression.this
     213        if is_null(this):
     214            return exp.null()
     215        if this.__class__ in COMPLEMENT_COMPARISONS:
     216            right = this.expression
     217            complement_subquery_predicate = COMPLEMENT_SUBQUERY_PREDICATES.get(right.__class__)
     218            if complement_subquery_predicate:
     219                right = complement_subquery_predicate(this=right.this)
     220
     221            return COMPLEMENT_COMPARISONS[this.__class__](this=this.this, expression=right)
     222        if isinstance(this, exp.Paren):
     223            condition = this.unnest()
     224            if isinstance(condition, exp.And):
     225                return exp.paren(
     226                    exp.or_(
     227                        exp.not_(condition.left, copy=False),
     228                        exp.not_(condition.right, copy=False),
     229                        copy=False,
     230                    )
     231                )
     232            if isinstance(condition, exp.Or):
     233                return exp.paren(
     234                    exp.and_(
     235                        exp.not_(condition.left, copy=False),
     236                        exp.not_(condition.right, copy=False),
     237                        copy=False,
     238                    )
     239                )
     240            if is_null(condition):
     241                return exp.null()
     242        if always_true(this):
     243            return exp.false()
     244        if is_false(this):
     245            return exp.true()
     246        if isinstance(this, exp.Not):
     247            # double negation
     248            # NOT NOT x -> x
     249            return this.this
     250    return expression
     251
     252
     253def flatten(expression):
     254    """
     255    A AND (B AND C) -> A AND B AND C
     256    A OR (B OR C) -> A OR B OR C
     257    """
     258    if isinstance(expression, exp.Connector):
     259        for node in expression.args.values():
     260            child = node.unnest()
     261            if isinstance(child, expression.__class__):
     262                node.replace(child)
     263    return expression
     264
     265
     266def simplify_connectors(expression, root=True):
     267    def _simplify_connectors(expression, left, right):
     268        if isinstance(expression, exp.And):
     269            if is_false(left) or is_false(right):
     270                return exp.false()
     271            if is_zero(left) or is_zero(right):
     272                return exp.false()
     273            if is_null(left) or is_null(right):
     274                return exp.null()
     275            if always_true(left) and always_true(right):
     276                return exp.true()
     277            if always_true(left):
     278                return right
     279            if always_true(right):
     280                return left
     281            return _simplify_comparison(expression, left, right)
     282        elif isinstance(expression, exp.Or):
     283            if always_true(left) or always_true(right):
     284                return exp.true()
     285            if (
     286                (is_null(left) and is_null(right))
     287                or (is_null(left) and always_false(right))
     288                or (always_false(left) and is_null(right))
     289            ):
     290                return exp.null()
     291            if is_false(left):
     292                return right
     293            if is_false(right):
     294                return left
     295            return _simplify_comparison(expression, left, right, or_=True)
     296        elif isinstance(expression, exp.Xor):
     297            if left == right:
     298                return exp.false()
     299
     300    if isinstance(expression, exp.Connector):
     301        return _flat_simplify(expression, _simplify_connectors, root)
     302    return expression
     303
     304
     305LT_LTE = (exp.LT, exp.LTE)
     306GT_GTE = (exp.GT, exp.GTE)
     307
     308COMPARISONS = (
     309    *LT_LTE,
     310    *GT_GTE,
     311    exp.EQ,
     312    exp.NEQ,
     313    exp.Is,
     314)
     315
     316INVERSE_COMPARISONS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     317    exp.LT: exp.GT,
     318    exp.GT: exp.LT,
     319    exp.LTE: exp.GTE,
     320    exp.GTE: exp.LTE,
     321}
     322
     323NONDETERMINISTIC = (exp.Rand, exp.Randn)
     324AND_OR = (exp.And, exp.Or)
     325
     326
     327def _simplify_comparison(expression, left, right, or_=False):
     328    if isinstance(left, COMPARISONS) and isinstance(right, COMPARISONS):
     329        ll, lr = left.args.values()
     330        rl, rr = right.args.values()
     331
     332        largs = {ll, lr}
     333        rargs = {rl, rr}
     334
     335        matching = largs & rargs
     336        columns = {m for m in matching if not _is_constant(m) and not m.find(*NONDETERMINISTIC)}
     337
     338        if matching and columns:
     339            try:
     340                l = first(largs - columns)
     341                r = first(rargs - columns)
     342            except StopIteration:
     343                return expression
     344
     345            if l.is_number and r.is_number:
     346                l = l.to_py()
     347                r = r.to_py()
     348            elif l.is_string and r.is_string:
     349                l = l.name
     350                r = r.name
     351            else:
     352                l = extract_date(l)
     353                if not l:
     354                    return None
     355                r = extract_date(r)
     356                if not r:
     357                    return None
     358                # python won't compare date and datetime, but many engines will upcast
     359                l, r = cast_as_datetime(l), cast_as_datetime(r)
     360
     361            for (a, av), (b, bv) in itertools.permutations(((left, l), (right, r))):
     362                if isinstance(a, LT_LTE) and isinstance(b, LT_LTE):
     363                    return left if (av > bv if or_ else av <= bv) else right
     364                if isinstance(a, GT_GTE) and isinstance(b, GT_GTE):
     365                    return left if (av < bv if or_ else av >= bv) else right
     366
     367                # we can't ever shortcut to true because the column could be null
     368                if not or_:
     369                    if isinstance(a, exp.LT) and isinstance(b, GT_GTE):
     370                        if av <= bv:
     371                            return exp.false()
     372                    elif isinstance(a, exp.GT) and isinstance(b, LT_LTE):
     373                        if av >= bv:
     374                            return exp.false()
     375                    elif isinstance(a, exp.EQ):
     376                        if isinstance(b, exp.LT):
     377                            return exp.false() if av >= bv else a
     378                        if isinstance(b, exp.LTE):
     379                            return exp.false() if av > bv else a
     380                        if isinstance(b, exp.GT):
     381                            return exp.false() if av <= bv else a
     382                        if isinstance(b, exp.GTE):
     383                            return exp.false() if av < bv else a
     384                        if isinstance(b, exp.NEQ):
     385                            return exp.false() if av == bv else a
     386    return None
     387
     388
     389def remove_complements(expression, root=True):
     390    """
     391    Removing complements.
     392
     393    A AND NOT A -> FALSE
     394    A OR NOT A -> TRUE
     395    """
     396    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
     397        ops = set(expression.flatten())
     398        for op in ops:
     399            if isinstance(op, exp.Not) and op.this in ops:
     400                return exp.false() if isinstance(expression, exp.And) else exp.true()
     401
     402    return expression
     403
     404
     405def uniq_sort(expression, root=True):
     406    """
     407    Uniq and sort a connector.
     408
     409    C AND A AND B AND B -> A AND B AND C
     410    """
     411    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
     412        flattened = tuple(expression.flatten())
     413
     414        if isinstance(expression, exp.Xor):
     415            result_func = exp.xor
     416            # Do not deduplicate XOR as A XOR A != A if A == True
     417            deduped = None
     418            arr = tuple((gen(e), e) for e in flattened)
     419        else:
     420            result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
     421            deduped = {gen(e): e for e in flattened}
     422            arr = tuple(deduped.items())
     423
     424        # check if the operands are already sorted, if not sort them
     425        # A AND C AND B -> A AND B AND C
     426        for i, (sql, e) in enumerate(arr[1:]):
     427            if sql < arr[i][0]:
     428                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
     429                break
     430        else:
     431            # we didn't have to sort but maybe we need to dedup
     432            if deduped and len(deduped) < len(flattened):
     433                expression = result_func(*deduped.values(), copy=False)
     434
     435    return expression
     436
     437
     438def absorb_and_eliminate(expression, root=True):
     439    """
     440    absorption:
     441        A AND (A OR B) -> A
     442        A OR (A AND B) -> A
     443        A AND (NOT A OR B) -> A AND B
     444        A OR (NOT A AND B) -> A OR B
     445    elimination:
     446        (A AND B) OR (A AND NOT B) -> A
     447        (A OR B) AND (A OR NOT B) -> A
     448    """
     449    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
     450        kind = exp.Or if isinstance(expression, exp.And) else exp.And
     451
     452        ops = tuple(expression.flatten())
     453
     454        # Initialize lookup tables:
     455        # Set of all operands, used to find complements for absorption.
     456        op_set = set()
     457        # Sub-operands, used to find subsets for absorption.
     458        subops = defaultdict(list)
     459        # Pairs of complements, used for elimination.
     460        pairs = defaultdict(list)
     461
     462        # Populate the lookup tables
     463        for op in ops:
     464            op_set.add(op)
     465
     466            if not isinstance(op, kind):
     467                # In cases like: A OR (A AND B)
     468                # Subop will be: ^
     469                subops[op].append({op})
     470                continue
     471
     472            # In cases like: (A AND B) OR (A AND B AND C)
     473            # Subops will be: ^     ^
     474            subset = set(op.flatten())
     475            for i in subset:
     476                subops[i].append(subset)
     477
     478            a, b = op.unnest_operands()
     479            if isinstance(a, exp.Not):
     480                pairs[frozenset((a.this, b))].append((op, b))
     481            if isinstance(b, exp.Not):
     482                pairs[frozenset((a, b.this))].append((op, a))
     483
     484        for op in ops:
     485            if not isinstance(op, kind):
     486                continue
     487
     488            a, b = op.unnest_operands()
     489
     490            # Absorb
     491            if isinstance(a, exp.Not) and a.this in op_set:
     492                a.replace(exp.true() if kind == exp.And else exp.false())
     493                continue
     494            if isinstance(b, exp.Not) and b.this in op_set:
     495                b.replace(exp.true() if kind == exp.And else exp.false())
     496                continue
     497            superset = set(op.flatten())
     498            if any(any(subset < superset for subset in subops[i]) for i in superset):
     499                op.replace(exp.false() if kind == exp.And else exp.true())
     500                continue
     501
     502            # Eliminate
     503            for other, complement in pairs[frozenset((a, b))]:
     504                op.replace(complement)
     505                other.replace(complement)
     506
     507    return expression
     508
     509
     510def propagate_constants(expression, root=True):
     511    """
     512    Propagate constants for conjunctions in DNF:
     513
     514    SELECT * FROM t WHERE a = b AND b = 5 becomes
     515    SELECT * FROM t WHERE a = 5 AND b = 5
     516
     517    Reference: https://www.sqlite.org/optoverview.html
     518    """
     519
     520    if (
     521        isinstance(expression, exp.And)
     522        and (root or not expression.same_parent)
     523        and sqlglot.optimizer.normalize.normalized(expression, dnf=True)
     524    ):
     525        constant_mapping = {}
     526        for expr in walk_in_scope(expression, prune=lambda node: isinstance(node, exp.If)):
     527            if isinstance(expr, exp.EQ):
     528                l, r = expr.left, expr.right
     529
     530                # TODO: create a helper that can be used to detect nested literal expressions such
     531                # as CAST(123456 AS BIGINT), since we usually want to treat those as literals too
     532                if isinstance(l, exp.Column) and isinstance(r, exp.Literal):
     533                    constant_mapping[l] = (id(l), r)
     534
     535        if constant_mapping:
     536            for column in find_all_in_scope(expression, exp.Column):
     537                parent = column.parent
     538                column_id, constant = constant_mapping.get(column) or (None, None)
     539                if (
     540                    column_id is not None
     541                    and id(column) != column_id
     542                    and not (isinstance(parent, exp.Is) and isinstance(parent.expression, exp.Null))
     543                ):
     544                    column.replace(constant.copy())
     545
     546    return expression
     547
     548
     549INVERSE_DATE_OPS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     550    exp.DateAdd: exp.Sub,
     551    exp.DateSub: exp.Add,
     552    exp.DatetimeAdd: exp.Sub,
     553    exp.DatetimeSub: exp.Add,
     554}
     555
     556INVERSE_OPS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     557    **INVERSE_DATE_OPS,
     558    exp.Add: exp.Sub,
     559    exp.Sub: exp.Add,
     560}
     561
     562
     563def _is_number(expression: exp.Expression) -> bool:
     564    return expression.is_number
     565
     566
     567def _is_interval(expression: exp.Expression) -> bool:
     568    return isinstance(expression, exp.Interval) and extract_interval(expression) is not None
     569
     570
     571@catch(ModuleNotFoundError, UnsupportedUnit)
     572def simplify_equality(expression: exp.Expression) -> exp.Expression:
     573    """
     574    Use the subtraction and addition properties of equality to simplify expressions:
     575
     576        x + 1 = 3 becomes x = 2
     577
     578    There are two binary operations in the above expression: + and =
     579    Here's how we reference all the operands in the code below:
     580
     581          l     r
     582        x + 1 = 3
     583        a   b
     584    """
     585    if isinstance(expression, COMPARISONS):
     586        l, r = expression.left, expression.right
     587
     588        if l.__class__ not in INVERSE_OPS:
     589            return expression
     590
     591        if r.is_number:
     592            a_predicate = _is_number
     593            b_predicate = _is_number
     594        elif _is_date_literal(r):
     595            a_predicate = _is_date_literal
     596            b_predicate = _is_interval
     597        else:
     598            return expression
     599
     600        if l.__class__ in INVERSE_DATE_OPS:
     601            l = t.cast(exp.IntervalOp, l)
     602            a = l.this
     603            b = l.interval()
     604        else:
     605            l = t.cast(exp.Binary, l)
     606            a, b = l.left, l.right
     607
     608        if not a_predicate(a) and b_predicate(b):
     609            pass
     610        elif not a_predicate(b) and b_predicate(a):
     611            a, b = b, a
     612        else:
     613            return expression
     614
     615        return expression.__class__(
     616            this=a, expression=INVERSE_OPS[l.__class__](this=r, expression=b)
     617        )
     618    return expression
     619
     620
     621def simplify_literals(expression, root=True):
     622    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
     623        return _flat_simplify(expression, _simplify_binary, root)
     624
     625    if isinstance(expression, exp.Neg) and isinstance(expression.this, exp.Neg):
     626        return expression.this.this
     627
     628    if type(expression) in INVERSE_DATE_OPS:
     629        return _simplify_binary(expression, expression.this, expression.interval()) or expression
     630
     631    return expression
     632
     633
     634NULL_OK = (exp.NullSafeEQ, exp.NullSafeNEQ, exp.PropertyEQ)
     635
     636
     637def _simplify_integer_cast(expr: exp.Expression) -> exp.Expression:
     638    if isinstance(expr, exp.Cast) and isinstance(expr.this, exp.Cast):
     639        this = _simplify_integer_cast(expr.this)
     640    else:
     641        this = expr.this
     642
     643    if isinstance(expr, exp.Cast) and this.is_int:
     644        num = this.to_py()
     645
     646        # Remove the (up)cast from small (byte-sized) integers in predicates which is side-effect free. Downcasts on any
     647        # integer type might cause overflow, thus the cast cannot be eliminated and the behavior is
     648        # engine-dependent
     649        if (
     650            TINYINT_MIN <= num <= TINYINT_MAX and expr.to.this in exp.DataType.SIGNED_INTEGER_TYPES
     651        ) or (
     652            UTINYINT_MIN <= num <= UTINYINT_MAX
     653            and expr.to.this in exp.DataType.UNSIGNED_INTEGER_TYPES
     654        ):
     655            return this
     656
     657    return expr
     658
     659
     660def _simplify_binary(expression, a, b):
     661    if isinstance(expression, COMPARISONS):
     662        a = _simplify_integer_cast(a)
     663        b = _simplify_integer_cast(b)
     664
     665    if isinstance(expression, exp.Is):
     666        if isinstance(b, exp.Not):
     667            c = b.this
     668            not_ = True
     669        else:
     670            c = b
     671            not_ = False
     672
     673        if is_null(c):
     674            if isinstance(a, exp.Literal):
     675                return exp.true() if not_ else exp.false()
     676            if is_null(a):
     677                return exp.false() if not_ else exp.true()
     678    elif isinstance(expression, NULL_OK):
     679        return None
     680    elif is_null(a) or is_null(b):
     681        return exp.null()
     682
     683    if a.is_number and b.is_number:
     684        num_a = a.to_py()
     685        num_b = b.to_py()
     686
     687        if isinstance(expression, exp.Add):
     688            return exp.Literal.number(num_a + num_b)
     689        if isinstance(expression, exp.Mul):
     690            return exp.Literal.number(num_a * num_b)
     691
     692        # We only simplify Sub, Div if a and b have the same parent because they're not associative
     693        if isinstance(expression, exp.Sub):
     694            return exp.Literal.number(num_a - num_b) if a.parent is b.parent else None
     695        if isinstance(expression, exp.Div):
     696            # engines have differing int div behavior so intdiv is not safe
     697            if (isinstance(num_a, int) and isinstance(num_b, int)) or a.parent is not b.parent:
     698                return None
     699            return exp.Literal.number(num_a / num_b)
     700
     701        boolean = eval_boolean(expression, num_a, num_b)
     702
     703        if boolean:
     704            return boolean
     705    elif a.is_string and b.is_string:
     706        boolean = eval_boolean(expression, a.this, b.this)
     707
     708        if boolean:
     709            return boolean
     710    elif _is_date_literal(a) and isinstance(b, exp.Interval):
     711        date, b = extract_date(a), extract_interval(b)
     712        if date and b:
     713            if isinstance(expression, (exp.Add, exp.DateAdd, exp.DatetimeAdd)):
     714                return date_literal(date + b, extract_type(a))
     715            if isinstance(expression, (exp.Sub, exp.DateSub, exp.DatetimeSub)):
     716                return date_literal(date - b, extract_type(a))
     717    elif isinstance(a, exp.Interval) and _is_date_literal(b):
     718        a, date = extract_interval(a), extract_date(b)
     719        # you cannot subtract a date from an interval
     720        if a and b and isinstance(expression, exp.Add):
     721            return date_literal(a + date, extract_type(b))
     722    elif _is_date_literal(a) and _is_date_literal(b):
     723        if isinstance(expression, exp.Predicate):
     724            a, b = extract_date(a), extract_date(b)
     725            boolean = eval_boolean(expression, a, b)
     726            if boolean:
     727                return boolean
     728
     729    return None
     730
     731
     732def simplify_parens(expression):
     733    if not isinstance(expression, exp.Paren):
     734        return expression
     735
     736    this = expression.this
     737    parent = expression.parent
     738    parent_is_predicate = isinstance(parent, exp.Predicate)
     739
     740    if (
     741        not isinstance(this, exp.Select)
     742        and not isinstance(parent, (exp.SubqueryPredicate, exp.Bracket))
     743        and (
     744            not isinstance(parent, (exp.Condition, exp.Binary))
     745            or isinstance(parent, exp.Paren)
     746            or (
     747                not isinstance(this, exp.Binary)
     748                and not (isinstance(this, (exp.Not, exp.Is)) and parent_is_predicate)
     749            )
     750            or (isinstance(this, exp.Predicate) and not parent_is_predicate)
     751            or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
     752            or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
     753            or (isinstance(this, exp.Mul) and isinstance(parent, (exp.Add, exp.Sub)))
     754        )
     755    ):
     756        return this
     757    return expression
     758
     759
     760def _is_nonnull_constant(expression: exp.Expression) -> bool:
     761    return isinstance(expression, exp.NONNULL_CONSTANTS) or _is_date_literal(expression)
     762
     763
     764def _is_constant(expression: exp.Expression) -> bool:
     765    return isinstance(expression, exp.CONSTANTS) or _is_date_literal(expression)
     766
     767
     768def simplify_coalesce(expression: exp.Expression, dialect: DialectType) -> exp.Expression:
     769    # COALESCE(x) -> x
     770    if (
     771        isinstance(expression, exp.Coalesce)
     772        and (not expression.expressions or _is_nonnull_constant(expression.this))
     773        # COALESCE is also used as a Spark partitioning hint
     774        and not isinstance(expression.parent, exp.Hint)
     775    ):
     776        return expression.this
     777
     778    # We can't convert `COALESCE(x, 1) = 2` into `NOT x IS NULL AND x = 2` for redshift,
     779    # because they are not always equivalent. For example,  if `x` is `NULL` and it comes
     780    # from a table, then the result is `NULL`, despite `FALSE AND NULL` evaluating to `FALSE`
     781    if dialect == "redshift":
     782        return expression
     783
     784    if not isinstance(expression, COMPARISONS):
     785        return expression
     786
     787    if isinstance(expression.left, exp.Coalesce):
     788        coalesce = expression.left
     789        other = expression.right
     790    elif isinstance(expression.right, exp.Coalesce):
     791        coalesce = expression.right
     792        other = expression.left
     793    else:
     794        return expression
     795
     796    # This transformation is valid for non-constants,
     797    # but it really only does anything if they are both constants.
     798    if not _is_constant(other):
     799        return expression
     800
     801    # Find the first constant arg
     802    for arg_index, arg in enumerate(coalesce.expressions):
     803        if _is_constant(arg):
     804            break
     805    else:
     806        return expression
     807
     808    coalesce.set("expressions", coalesce.expressions[:arg_index])
     809
     810    # Remove the COALESCE function. This is an optimization, skipping a simplify iteration,
     811    # since we already remove COALESCE at the top of this function.
     812    coalesce = coalesce if coalesce.expressions else coalesce.this
     813
     814    # This expression is more complex than when we started, but it will get simplified further
     815    return exp.paren(
     816        exp.or_(
     817            exp.and_(
     818                coalesce.is_(exp.null()).not_(copy=False),
     819                expression.copy(),
     820                copy=False,
     821            ),
     822            exp.and_(
     823                coalesce.is_(exp.null()),
     824                type(expression)(this=arg.copy(), expression=other.copy()),
     825                copy=False,
     826            ),
     827            copy=False,
     828        )
     829    )
     830
     831
     832CONCATS = (exp.Concat, exp.DPipe)
     833
     834
     835def simplify_concat(expression):
     836    """Reduces all groups that contain string literals by concatenating them."""
     837    if not isinstance(expression, CONCATS) or (
     838        # We can't reduce a CONCAT_WS call if we don't statically know the separator
     839        isinstance(expression, exp.ConcatWs) and not expression.expressions[0].is_string
     840    ):
     841        return expression
     842
     843    if isinstance(expression, exp.ConcatWs):
     844        sep_expr, *expressions = expression.expressions
     845        sep = sep_expr.name
     846        concat_type = exp.ConcatWs
     847        args = {}
     848    else:
     849        expressions = expression.expressions
     850        sep = ""
     851        concat_type = exp.Concat
     852        args = {
     853            "safe": expression.args.get("safe"),
     854            "coalesce": expression.args.get("coalesce"),
     855        }
     856
     857    new_args = []
     858    for is_string_group, group in itertools.groupby(
     859        expressions or expression.flatten(), lambda e: e.is_string
     860    ):
     861        if is_string_group:
     862            new_args.append(exp.Literal.string(sep.join(string.name for string in group)))
     863        else:
     864            new_args.extend(group)
     865
     866    if len(new_args) == 1 and new_args[0].is_string:
     867        return new_args[0]
     868
     869    if concat_type is exp.ConcatWs:
     870        new_args = [sep_expr] + new_args
     871    elif isinstance(expression, exp.DPipe):
     872        return reduce(lambda x, y: exp.DPipe(this=x, expression=y), new_args)
     873
     874    return concat_type(expressions=new_args, **args)
     875
     876
     877def simplify_conditionals(expression):
     878    """Simplifies expressions like IF, CASE if their condition is statically known."""
     879    if isinstance(expression, exp.Case):
     880        this = expression.this
     881        for case in expression.args["ifs"]:
     882            cond = case.this
     883            if this:
     884                # Convert CASE x WHEN matching_value ... to CASE WHEN x = matching_value ...
     885                cond = cond.replace(this.pop().eq(cond))
     886
     887            if always_true(cond):
     888                return case.args["true"]
     889
     890            if always_false(cond):
     891                case.pop()
     892                if not expression.args["ifs"]:
     893                    return expression.args.get("default") or exp.null()
     894    elif isinstance(expression, exp.If) and not isinstance(expression.parent, exp.Case):
     895        if always_true(expression.this):
     896            return expression.args["true"]
     897        if always_false(expression.this):
     898            return expression.args.get("false") or exp.null()
     899
     900    return expression
     901
     902
     903def simplify_startswith(expression: exp.Expression) -> exp.Expression:
     904    """
     905    Reduces a prefix check to either TRUE or FALSE if both the string and the
     906    prefix are statically known.
     907
     908    Example:
     909        >>> from sqlglot import parse_one
     910        >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
     911        'TRUE'
     912    """
     913    if (
     914        isinstance(expression, exp.StartsWith)
     915        and expression.this.is_string
     916        and expression.expression.is_string
     917    ):
     918        return exp.convert(expression.name.startswith(expression.expression.name))
     919
     920    return expression
     921
     922
     923DateRange = t.Tuple[datetime.date, datetime.date]
     924
     925
     926def _datetrunc_range(date: datetime.date, unit: str, dialect: Dialect) -> t.Optional[DateRange]:
     927    """
     928    Get the date range for a DATE_TRUNC equality comparison:
     929
     930    Example:
     931        _datetrunc_range(date(2021-01-01), 'year') == (date(2021-01-01), date(2022-01-01))
     932    Returns:
     933        tuple of [min, max) or None if a value can never be equal to `date` for `unit`
     934    """
     935    floor = date_floor(date, unit, dialect)
     936
     937    if date != floor:
     938        # This will always be False, except for NULL values.
     939        return None
     940
     941    return floor, floor + interval(unit)
     942
     943
     944def _datetrunc_eq_expression(
     945    left: exp.Expression, drange: DateRange, target_type: t.Optional[exp.DataType]
     946) -> exp.Expression:
     947    """Get the logical expression for a date range"""
     948    return exp.and_(
     949        left >= date_literal(drange[0], target_type),
     950        left < date_literal(drange[1], target_type),
     951        copy=False,
     952    )
     953
     954
     955def _datetrunc_eq(
     956    left: exp.Expression,
     957    date: datetime.date,
     958    unit: str,
     959    dialect: Dialect,
     960    target_type: t.Optional[exp.DataType],
     961) -> t.Optional[exp.Expression]:
     962    drange = _datetrunc_range(date, unit, dialect)
     963    if not drange:
     964        return None
     965
     966    return _datetrunc_eq_expression(left, drange, target_type)
     967
     968
     969def _datetrunc_neq(
     970    left: exp.Expression,
     971    date: datetime.date,
     972    unit: str,
     973    dialect: Dialect,
     974    target_type: t.Optional[exp.DataType],
     975) -> t.Optional[exp.Expression]:
     976    drange = _datetrunc_range(date, unit, dialect)
     977    if not drange:
     978        return None
     979
     980    return exp.and_(
     981        left < date_literal(drange[0], target_type),
     982        left >= date_literal(drange[1], target_type),
     983        copy=False,
     984    )
     985
     986
     987DATETRUNC_BINARY_COMPARISONS: t.Dict[t.Type[exp.Expression], DateTruncBinaryTransform] = {
     988    exp.LT: lambda l, dt, u, d, t: l
     989    < date_literal(dt if dt == date_floor(dt, u, d) else date_floor(dt, u, d) + interval(u), t),
     990    exp.GT: lambda l, dt, u, d, t: l >= date_literal(date_floor(dt, u, d) + interval(u), t),
     991    exp.LTE: lambda l, dt, u, d, t: l < date_literal(date_floor(dt, u, d) + interval(u), t),
     992    exp.GTE: lambda l, dt, u, d, t: l >= date_literal(date_ceil(dt, u, d), t),
     993    exp.EQ: _datetrunc_eq,
     994    exp.NEQ: _datetrunc_neq,
     995}
     996DATETRUNC_COMPARISONS = {exp.In, *DATETRUNC_BINARY_COMPARISONS}
     997DATETRUNCS = (exp.DateTrunc, exp.TimestampTrunc)
     998
     999
    1000def _is_datetrunc_predicate(left: exp.Expression, right: exp.Expression) -> bool:
    1001    return isinstance(left, DATETRUNCS) and _is_date_literal(right)
    1002
    1003
    1004@catch(ModuleNotFoundError, UnsupportedUnit)
    1005def simplify_datetrunc(expression: exp.Expression, dialect: Dialect) -> exp.Expression:
    1006    """Simplify expressions like `DATE_TRUNC('year', x) >= CAST('2021-01-01' AS DATE)`"""
    1007    comparison = expression.__class__
    1008
    1009    if isinstance(expression, DATETRUNCS):
    1010        this = expression.this
    1011        trunc_type = extract_type(this)
    1012        date = extract_date(this)
    1013        if date and expression.unit:
    1014            return date_literal(date_floor(date, expression.unit.name.lower(), dialect), trunc_type)
    1015    elif comparison not in DATETRUNC_COMPARISONS:
    1016        return expression
    1017
    1018    if isinstance(expression, exp.Binary):
    1019        l, r = expression.left, expression.right
    1020
    1021        if not _is_datetrunc_predicate(l, r):
    1022            return expression
    1023
    1024        l = t.cast(exp.DateTrunc, l)
    1025        trunc_arg = l.this
    1026        unit = l.unit.name.lower()
    1027        date = extract_date(r)
    1028
    1029        if not date:
    1030            return expression
    1031
    1032        return (
    1033            DATETRUNC_BINARY_COMPARISONS[comparison](
    1034                trunc_arg, date, unit, dialect, extract_type(r)
    1035            )
    1036            or expression
    1037        )
    1038
    1039    if isinstance(expression, exp.In):
    1040        l = expression.this
    1041        rs = expression.expressions
    1042
    1043        if rs and all(_is_datetrunc_predicate(l, r) for r in rs):
    1044            l = t.cast(exp.DateTrunc, l)
    1045            unit = l.unit.name.lower()
    1046
    1047            ranges = []
    1048            for r in rs:
    1049                date = extract_date(r)
    1050                if not date:
    1051                    return expression
    1052                drange = _datetrunc_range(date, unit, dialect)
    1053                if drange:
    1054                    ranges.append(drange)
    1055
    1056            if not ranges:
    1057                return expression
    1058
    1059            ranges = merge_ranges(ranges)
    1060            target_type = extract_type(*rs)
    1061
    1062            return exp.or_(
    1063                *[_datetrunc_eq_expression(l, drange, target_type) for drange in ranges], copy=False
    1064            )
    1065
    1066    return expression
    1067
    1068
    1069def sort_comparison(expression: exp.Expression) -> exp.Expression:
    1070    if expression.__class__ in COMPLEMENT_COMPARISONS:
    1071        l, r = expression.this, expression.expression
    1072        l_column = isinstance(l, exp.Column)
    1073        r_column = isinstance(r, exp.Column)
    1074        l_const = _is_constant(l)
    1075        r_const = _is_constant(r)
    1076
    1077        if (
    1078            (l_column and not r_column)
    1079            or (r_const and not l_const)
    1080            or isinstance(r, exp.SubqueryPredicate)
    1081        ):
    1082            return expression
    1083        if (r_column and not l_column) or (l_const and not r_const) or (gen(l) > gen(r)):
    1084            return INVERSE_COMPARISONS.get(expression.__class__, expression.__class__)(
    1085                this=r, expression=l
    1086            )
    1087    return expression
    1088
    1089
    1090# CROSS joins result in an empty table if the right table is empty.
    1091# So we can only simplify certain types of joins to CROSS.
    1092# Or in other words, LEFT JOIN x ON TRUE != CROSS JOIN x
    1093JOINS = {
    1094    ("", ""),
    1095    ("", "INNER"),
    1096    ("RIGHT", ""),
    1097    ("RIGHT", "OUTER"),
    1098}
    1099
    1100
    1101def remove_where_true(expression):
    1102    for where in expression.find_all(exp.Where):
    1103        if always_true(where.this):
    1104            where.pop()
    1105    for join in expression.find_all(exp.Join):
    1106        if (
    1107            always_true(join.args.get("on"))
    1108            and not join.args.get("using")
    1109            and not join.args.get("method")
    1110            and (join.side, join.kind) in JOINS
    1111        ):
    1112            join.args["on"].pop()
    1113            join.set("side", None)
    1114            join.set("kind", "CROSS")
    1115
    1116
    1117def always_true(expression):
    1118    return (isinstance(expression, exp.Boolean) and expression.this) or (
    1119        isinstance(expression, exp.Literal) and not is_zero(expression)
    1120    )
    1121
    1122
    1123def always_false(expression):
    1124    return is_false(expression) or is_null(expression) or is_zero(expression)
    1125
    1126
    1127def is_zero(expression):
    1128    return isinstance(expression, exp.Literal) and expression.to_py() == 0
    1129
    1130
    1131def is_complement(a, b):
    1132    return isinstance(b, exp.Not) and b.this == a
    1133
    1134
    1135def is_false(a: exp.Expression) -> bool:
    1136    return type(a) is exp.Boolean and not a.this
    1137
    1138
    1139def is_null(a: exp.Expression) -> bool:
    1140    return type(a) is exp.Null
    1141
    1142
    1143def eval_boolean(expression, a, b):
    1144    if isinstance(expression, (exp.EQ, exp.Is)):
    1145        return boolean_literal(a == b)
    1146    if isinstance(expression, exp.NEQ):
    1147        return boolean_literal(a != b)
    1148    if isinstance(expression, exp.GT):
    1149        return boolean_literal(a > b)
    1150    if isinstance(expression, exp.GTE):
    1151        return boolean_literal(a >= b)
    1152    if isinstance(expression, exp.LT):
    1153        return boolean_literal(a < b)
    1154    if isinstance(expression, exp.LTE):
    1155        return boolean_literal(a <= b)
    1156    return None
    1157
    1158
    1159def cast_as_date(value: t.Any) -> t.Optional[datetime.date]:
    1160    if isinstance(value, datetime.datetime):
    1161        return value.date()
    1162    if isinstance(value, datetime.date):
    1163        return value
    1164    try:
    1165        return datetime.datetime.fromisoformat(value).date()
    1166    except ValueError:
    1167        return None
    1168
    1169
    1170def cast_as_datetime(value: t.Any) -> t.Optional[datetime.datetime]:
    1171    if isinstance(value, datetime.datetime):
    1172        return value
    1173    if isinstance(value, datetime.date):
    1174        return datetime.datetime(year=value.year, month=value.month, day=value.day)
    1175    try:
    1176        return datetime.datetime.fromisoformat(value)
    1177    except ValueError:
    1178        return None
    1179
    1180
    1181def cast_value(value: t.Any, to: exp.DataType) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1182    if not value:
    1183        return None
    1184    if to.is_type(exp.DataType.Type.DATE):
    1185        return cast_as_date(value)
    1186    if to.is_type(*exp.DataType.TEMPORAL_TYPES):
    1187        return cast_as_datetime(value)
    1188    return None
    1189
    1190
    1191def extract_date(cast: exp.Expression) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1192    if isinstance(cast, exp.Cast):
    1193        to = cast.to
    1194    elif isinstance(cast, exp.TsOrDsToDate) and not cast.args.get("format"):
    1195        to = exp.DataType.build(exp.DataType.Type.DATE)
    1196    else:
    1197        return None
    1198
    1199    if isinstance(cast.this, exp.Literal):
    1200        value: t.Any = cast.this.name
    1201    elif isinstance(cast.this, (exp.Cast, exp.TsOrDsToDate)):
    1202        value = extract_date(cast.this)
    1203    else:
    1204        return None
    1205    return cast_value(value, to)
    1206
    1207
    1208def _is_date_literal(expression: exp.Expression) -> bool:
    1209    return extract_date(expression) is not None
    1210
    1211
    1212def extract_interval(expression):
    1213    try:
    1214        n = int(expression.this.to_py())
    1215        unit = expression.text("unit").lower()
    1216        return interval(unit, n)
    1217    except (UnsupportedUnit, ModuleNotFoundError, ValueError):
    1218        return None
    1219
    1220
    1221def extract_type(*expressions):
    1222    target_type = None
    1223    for expression in expressions:
    1224        target_type = expression.to if isinstance(expression, exp.Cast) else expression.type
    1225        if target_type:
    1226            break
    1227
    1228    return target_type
    1229
    1230
    1231def date_literal(date, target_type=None):
    1232    if not target_type or not target_type.is_type(*exp.DataType.TEMPORAL_TYPES):
    1233        target_type = (
    1234            exp.DataType.Type.DATETIME
    1235            if isinstance(date, datetime.datetime)
    1236            else exp.DataType.Type.DATE
    1237        )
    1238
    1239    return exp.cast(exp.Literal.string(date), target_type)
    1240
    1241
    1242def interval(unit: str, n: int = 1):
    1243    from dateutil.relativedelta import relativedelta
    1244
    1245    if unit == "year":
    1246        return relativedelta(years=1 * n)
    1247    if unit == "quarter":
    1248        return relativedelta(months=3 * n)
    1249    if unit == "month":
    1250        return relativedelta(months=1 * n)
    1251    if unit == "week":
    1252        return relativedelta(weeks=1 * n)
    1253    if unit == "day":
    1254        return relativedelta(days=1 * n)
    1255    if unit == "hour":
    1256        return relativedelta(hours=1 * n)
    1257    if unit == "minute":
    1258        return relativedelta(minutes=1 * n)
    1259    if unit == "second":
    1260        return relativedelta(seconds=1 * n)
    1261
    1262    raise UnsupportedUnit(f"Unsupported unit: {unit}")
    1263
    1264
    1265def date_floor(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1266    if unit == "year":
    1267        return d.replace(month=1, day=1)
    1268    if unit == "quarter":
    1269        if d.month <= 3:
    1270            return d.replace(month=1, day=1)
    1271        elif d.month <= 6:
    1272            return d.replace(month=4, day=1)
    1273        elif d.month <= 9:
    1274            return d.replace(month=7, day=1)
    1275        else:
    1276            return d.replace(month=10, day=1)
    1277    if unit == "month":
    1278        return d.replace(month=d.month, day=1)
    1279    if unit == "week":
    1280        # Assuming week starts on Monday (0) and ends on Sunday (6)
    1281        return d - datetime.timedelta(days=d.weekday() - dialect.WEEK_OFFSET)
    1282    if unit == "day":
    1283        return d
    1284
    1285    raise UnsupportedUnit(f"Unsupported unit: {unit}")
    1286
    1287
    1288def date_ceil(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1289    floor = date_floor(d, unit, dialect)
    1290
    1291    if floor == d:
    1292        return d
    1293
    1294    return floor + interval(unit)
    1295
    1296
    1297def boolean_literal(condition):
    1298    return exp.true() if condition else exp.false()
    1299
    1300
    1301def _flat_simplify(expression, simplifier, root=True):
    1302    if root or not expression.same_parent:
    1303        operands = []
    1304        queue = deque(expression.flatten(unnest=False))
    1305        size = len(queue)
    1306
    1307        while queue:
    1308            a = queue.popleft()
    1309
    1310            for b in queue:
    1311                result = simplifier(expression, a, b)
    1312
    1313                if result and result is not expression:
    1314                    queue.remove(b)
    1315                    queue.appendleft(result)
    1316                    break
    1317            else:
    1318                operands.append(a)
    1319
    1320        if len(operands) < size:
    1321            return functools.reduce(
    1322                lambda a, b: expression.__class__(this=a, expression=b), operands
    1323            )
    1324    return expression
    1325
    1326
    1327def gen(expression: t.Any, comments: bool = False) -> str:
    1328    """Simple pseudo sql generator for quickly generating sortable and uniq strings.
    1329
    1330    Sorting and deduping sql is a necessary step for optimization. Calling the actual
    1331    generator is expensive so we have a bare minimum sql generator here.
    1332
    1333    Args:
    1334        expression: the expression to convert into a SQL string.
    1335        comments: whether to include the expression's comments.
    1336    """
    1337    return Gen().gen(expression, comments=comments)
    1338
    1339
    1340class Gen:
    1341    def __init__(self):
    1342        self.stack = []
    1343        self.sqls = []
    1344
    1345    def gen(self, expression: exp.Expression, comments: bool = False) -> str:
    1346        self.stack = [expression]
    1347        self.sqls.clear()
    1348
    1349        while self.stack:
    1350            node = self.stack.pop()
    1351
    1352            if isinstance(node, exp.Expression):
    1353                if comments and node.comments:
    1354                    self.stack.append(f" /*{','.join(node.comments)}*/")
    1355
    1356                exp_handler_name = f"{node.key}_sql"
    1357
    1358                if hasattr(self, exp_handler_name):
    1359                    getattr(self, exp_handler_name)(node)
    1360                elif isinstance(node, exp.Func):
    1361                    self._function(node)
    1362                else:
    1363                    key = node.key.upper()
    1364                    self.stack.append(f"{key} " if self._args(node) else key)
    1365            elif type(node) is list:
    1366                for n in reversed(node):
    1367                    if n is not None:
    1368                        self.stack.extend((n, ","))
    1369                if node:
    1370                    self.stack.pop()
    1371            else:
    1372                if node is not None:
    1373                    self.sqls.append(str(node))
    1374
    1375        return "".join(self.sqls)
    1376
    1377    def add_sql(self, e: exp.Add) -> None:
    1378        self._binary(e, " + ")
    1379
    1380    def alias_sql(self, e: exp.Alias) -> None:
    1381        self.stack.extend(
    1382            (
    1383                e.args.get("alias"),
    1384                " AS ",
    1385                e.args.get("this"),
    1386            )
    1387        )
    1388
    1389    def and_sql(self, e: exp.And) -> None:
    1390        self._binary(e, " AND ")
    1391
    1392    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1393        this = e.this
    1394        if isinstance(this, str):
    1395            name = this.upper()
    1396        elif isinstance(this, exp.Identifier):
    1397            name = this.this
    1398            name = f'"{name}"' if this.quoted else name.upper()
    1399        else:
    1400            raise ValueError(
    1401                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1402            )
    1403
    1404        self.stack.extend(
    1405            (
    1406                ")",
    1407                e.expressions,
    1408                "(",
    1409                name,
    1410            )
    1411        )
    1412
    1413    def between_sql(self, e: exp.Between) -> None:
    1414        self.stack.extend(
    1415            (
    1416                e.args.get("high"),
    1417                " AND ",
    1418                e.args.get("low"),
    1419                " BETWEEN ",
    1420                e.this,
    1421            )
    1422        )
    1423
    1424    def boolean_sql(self, e: exp.Boolean) -> None:
    1425        self.stack.append("TRUE" if e.this else "FALSE")
    1426
    1427    def bracket_sql(self, e: exp.Bracket) -> None:
    1428        self.stack.extend(
    1429            (
    1430                "]",
    1431                e.expressions,
    1432                "[",
    1433                e.this,
    1434            )
    1435        )
    1436
    1437    def column_sql(self, e: exp.Column) -> None:
    1438        for p in reversed(e.parts):
    1439            self.stack.extend((p, "."))
    1440        self.stack.pop()
    1441
    1442    def datatype_sql(self, e: exp.DataType) -> None:
    1443        self._args(e, 1)
    1444        self.stack.append(f"{e.this.name} ")
    1445
    1446    def div_sql(self, e: exp.Div) -> None:
    1447        self._binary(e, " / ")
    1448
    1449    def dot_sql(self, e: exp.Dot) -> None:
    1450        self._binary(e, ".")
    1451
    1452    def eq_sql(self, e: exp.EQ) -> None:
    1453        self._binary(e, " = ")
    1454
    1455    def from_sql(self, e: exp.From) -> None:
    1456        self.stack.extend((e.this, "FROM "))
    1457
    1458    def gt_sql(self, e: exp.GT) -> None:
    1459        self._binary(e, " > ")
    1460
    1461    def gte_sql(self, e: exp.GTE) -> None:
    1462        self._binary(e, " >= ")
    1463
    1464    def identifier_sql(self, e: exp.Identifier) -> None:
    1465        self.stack.append(f'"{e.this}"' if e.quoted else e.this)
    1466
    1467    def ilike_sql(self, e: exp.ILike) -> None:
    1468        self._binary(e, " ILIKE ")
    1469
    1470    def in_sql(self, e: exp.In) -> None:
    1471        self.stack.append(")")
    1472        self._args(e, 1)
    1473        self.stack.extend(
    1474            (
    1475                "(",
    1476                " IN ",
    1477                e.this,
    1478            )
    1479        )
    1480
    1481    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1482        self._binary(e, " DIV ")
    1483
    1484    def is_sql(self, e: exp.Is) -> None:
    1485        self._binary(e, " IS ")
    1486
    1487    def like_sql(self, e: exp.Like) -> None:
    1488        self._binary(e, " Like ")
    1489
    1490    def literal_sql(self, e: exp.Literal) -> None:
    1491        self.stack.append(f"'{e.this}'" if e.is_string else e.this)
    1492
    1493    def lt_sql(self, e: exp.LT) -> None:
    1494        self._binary(e, " < ")
    1495
    1496    def lte_sql(self, e: exp.LTE) -> None:
    1497        self._binary(e, " <= ")
    1498
    1499    def mod_sql(self, e: exp.Mod) -> None:
    1500        self._binary(e, " % ")
    1501
    1502    def mul_sql(self, e: exp.Mul) -> None:
    1503        self._binary(e, " * ")
    1504
    1505    def neg_sql(self, e: exp.Neg) -> None:
    1506        self._unary(e, "-")
    1507
    1508    def neq_sql(self, e: exp.NEQ) -> None:
    1509        self._binary(e, " <> ")
    1510
    1511    def not_sql(self, e: exp.Not) -> None:
    1512        self._unary(e, "NOT ")
    1513
    1514    def null_sql(self, e: exp.Null) -> None:
    1515        self.stack.append("NULL")
    1516
    1517    def or_sql(self, e: exp.Or) -> None:
    1518        self._binary(e, " OR ")
    1519
    1520    def paren_sql(self, e: exp.Paren) -> None:
    1521        self.stack.extend(
    1522            (
    1523                ")",
    1524                e.this,
    1525                "(",
    1526            )
    1527        )
    1528
    1529    def sub_sql(self, e: exp.Sub) -> None:
    1530        self._binary(e, " - ")
    1531
    1532    def subquery_sql(self, e: exp.Subquery) -> None:
    1533        self._args(e, 2)
    1534        alias = e.args.get("alias")
    1535        if alias:
    1536            self.stack.append(alias)
    1537        self.stack.extend((")", e.this, "("))
    1538
    1539    def table_sql(self, e: exp.Table) -> None:
    1540        self._args(e, 4)
    1541        alias = e.args.get("alias")
    1542        if alias:
    1543            self.stack.append(alias)
    1544        for p in reversed(e.parts):
    1545            self.stack.extend((p, "."))
    1546        self.stack.pop()
    1547
    1548    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1549        columns = e.columns
    1550
    1551        if columns:
    1552            self.stack.extend((")", columns, "("))
    1553
    1554        self.stack.extend((e.this, " AS "))
    1555
    1556    def var_sql(self, e: exp.Var) -> None:
    1557        self.stack.append(e.this)
    1558
    1559    def _binary(self, e: exp.Binary, op: str) -> None:
    1560        self.stack.extend((e.expression, op, e.this))
    1561
    1562    def _unary(self, e: exp.Unary, op: str) -> None:
    1563        self.stack.extend((e.this, op))
    1564
    1565    def _function(self, e: exp.Func) -> None:
    1566        self.stack.extend(
    1567            (
    1568                ")",
    1569                list(e.args.values()),
    1570                "(",
    1571                e.sql_name(),
    1572            )
    1573        )
    1574
    1575    def _args(self, node: exp.Expression, arg_index: int = 0) -> bool:
    1576        kvs = []
    1577        arg_types = list(node.arg_types)[arg_index:] if arg_index else node.arg_types
    1578
    1579        for k in arg_types or arg_types:
    1580            v = node.args.get(k)
    1581
    1582            if v is not None:
    1583                kvs.append([f":{k}", v])
    1584        if kvs:
    1585            self.stack.append(kvs)
    1586            return True
    1587        return False

logger = <Logger sqlglot (WARNING)>
FINAL = 'final'
TINYINT_MIN = -128
TINYINT_MAX = 127
UTINYINT_MIN = 0
UTINYINT_MAX = 255
class UnsupportedUnit(builtins.Exception): View Source

    36class UnsupportedUnit(Exception):
    37    pass

Common base class for all non-exit exceptions.

def simplify( expression: sqlglot.expressions.Expression, constant_propagation: bool = False, coalesce_simplification: bool = False, dialect: Union[str, sqlglot.dialects.Dialect, Type[sqlglot.dialects.Dialect], NoneType] = None): View Source

     40def simplify(
     41    expression: exp.Expression,
     42    constant_propagation: bool = False,
     43    coalesce_simplification: bool = False,
     44    dialect: DialectType = None,
     45):
     46    """
     47    Rewrite sqlglot AST to simplify expressions.
     48
     49    Example:
     50        >>> import sqlglot
     51        >>> expression = sqlglot.parse_one("TRUE AND TRUE")
     52        >>> simplify(expression).sql()
     53        'TRUE'
     54
     55    Args:
     56        expression: expression to simplify
     57        constant_propagation: whether the constant propagation rule should be used
     58        coalesce_simplification: whether the simplify coalesce rule should be used.
     59            This rule tries to remove coalesce functions, which can be useful in certain analyses but
     60            can leave the query more verbose.
     61    Returns:
     62        sqlglot.Expression: simplified expression
     63    """
     64
     65    dialect = Dialect.get_or_raise(dialect)
     66
     67    def _simplify(expression):
     68        pre_transformation_stack = [expression]
     69        post_transformation_stack = []
     70
     71        while pre_transformation_stack:
     72            node = pre_transformation_stack.pop()
     73
     74            if node.meta.get(FINAL):
     75                continue
     76
     77            # group by expressions cannot be simplified, for example
     78            # select x + 1 + 1 FROM y GROUP BY x + 1 + 1
     79            # the projection must exactly match the group by key
     80            group = node.args.get("group")
     81
     82            if group and hasattr(node, "selects"):
     83                groups = set(group.expressions)
     84                group.meta[FINAL] = True
     85
     86                for s in node.selects:
     87                    for n in s.walk():
     88                        if n in groups:
     89                            s.meta[FINAL] = True
     90                            break
     91
     92                having = node.args.get("having")
     93                if having:
     94                    for n in having.walk():
     95                        if n in groups:
     96                            having.meta[FINAL] = True
     97                            break
     98
     99            parent = node.parent
    100            root = node is expression
    101
    102            new_node = rewrite_between(node)
    103            new_node = uniq_sort(new_node, root)
    104            new_node = absorb_and_eliminate(new_node, root)
    105            new_node = simplify_concat(new_node)
    106            new_node = simplify_conditionals(new_node)
    107
    108            if constant_propagation:
    109                new_node = propagate_constants(new_node, root)
    110
    111            if new_node is not node:
    112                node.replace(new_node)
    113
    114            pre_transformation_stack.extend(
    115                n for n in new_node.iter_expressions(reverse=True) if not n.meta.get(FINAL)
    116            )
    117            post_transformation_stack.append((new_node, parent))
    118
    119        while post_transformation_stack:
    120            node, parent = post_transformation_stack.pop()
    121            root = node is expression
    122
    123            # Resets parent, arg_key, index pointers– this is needed because some of the
    124            # previous transformations mutate the AST, leading to an inconsistent state
    125            for k, v in tuple(node.args.items()):
    126                node.set(k, v)
    127
    128            # Post-order transformations
    129            new_node = simplify_not(node)
    130            new_node = flatten(new_node)
    131            new_node = simplify_connectors(new_node, root)
    132            new_node = remove_complements(new_node, root)
    133
    134            if coalesce_simplification:
    135                new_node = simplify_coalesce(new_node, dialect)
    136
    137            new_node.parent = parent
    138
    139            new_node = simplify_literals(new_node, root)
    140            new_node = simplify_equality(new_node)
    141            new_node = simplify_parens(new_node)
    142            new_node = simplify_datetrunc(new_node, dialect)
    143            new_node = sort_comparison(new_node)
    144            new_node = simplify_startswith(new_node)
    145
    146            if new_node is not node:
    147                node.replace(new_node)
    148
    149        return new_node
    150
    151    expression = while_changing(expression, _simplify)
    152    remove_where_true(expression)
    153    return expression

Rewrite sqlglot AST to simplify expressions.

###### Example:

>     >>> import sqlglot
>     >>> expression = sqlglot.parse_one("TRUE AND TRUE")
>     >>> simplify(expression).sql()
>     'TRUE'

###### Arguments:

- expression: expression to simplify
- constant_propagation: whether the constant propagation rule should be used
- coalesce_simplification: whether the simplify coalesce rule should be used. This rule tries to remove coalesce functions, which can be useful in certain analyses but can leave the query more verbose.

###### Returns:

> sqlglot.Expression: simplified expression

def catch(*exceptions): View Source

    156def catch(*exceptions):
    157    """Decorator that ignores a simplification function if any of `exceptions` are raised"""
    158
    159    def decorator(func):
    160        def wrapped(expression, *args, **kwargs):
    161            try:
    162                return func(expression, *args, **kwargs)
    163            except exceptions:
    164                return expression
    165
    166        return wrapped
    167
    168    return decorator

Decorator that ignores a simplification function if any of `exceptions` are raised

def rewrite_between( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression: View Source

    171def rewrite_between(expression: exp.Expression) -> exp.Expression:
    172    """Rewrite x between y and z to x >= y AND x <= z.
    173
    174    This is done because comparison simplification is only done on lt/lte/gt/gte.
    175    """
    176    if isinstance(expression, exp.Between):
    177        negate = isinstance(expression.parent, exp.Not)
    178
    179        expression = exp.and_(
    180            exp.GTE(this=expression.this.copy(), expression=expression.args["low"]),
    181            exp.LTE(this=expression.this.copy(), expression=expression.args["high"]),
    182            copy=False,
    183        )
    184
    185        if negate:
    186            expression = exp.paren(expression, copy=False)
    187
    188    return expression

Rewrite x between y and z to x >= y AND x <= z.

This is done because comparison simplification is only done on lt/lte/gt/gte.

COMPLEMENT_COMPARISONS = {<class 'sqlglot.expressions.LT'>: <class 'sqlglot.expressions.GTE'>, <class 'sqlglot.expressions.GT'>: <class 'sqlglot.expressions.LTE'>, <class 'sqlglot.expressions.LTE'>: <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.GTE'>: <class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.EQ'>: <class 'sqlglot.expressions.NEQ'>, <class 'sqlglot.expressions.NEQ'>: <class 'sqlglot.expressions.EQ'>}
COMPLEMENT_SUBQUERY_PREDICATES = {<class 'sqlglot.expressions.All'>: <class 'sqlglot.expressions.Any'>, <class 'sqlglot.expressions.Any'>: <class 'sqlglot.expressions.All'>}
def simplify_not(expression): View Source

    206def simplify_not(expression):
    207    """
    208    Demorgan's Law
    209    NOT (x OR y) -> NOT x AND NOT y
    210    NOT (x AND y) -> NOT x OR NOT y
    211    """
    212    if isinstance(expression, exp.Not):
    213        this = expression.this
    214        if is_null(this):
    215            return exp.null()
    216        if this.__class__ in COMPLEMENT_COMPARISONS:
    217            right = this.expression
    218            complement_subquery_predicate = COMPLEMENT_SUBQUERY_PREDICATES.get(right.__class__)
    219            if complement_subquery_predicate:
    220                right = complement_subquery_predicate(this=right.this)
    221
    222            return COMPLEMENT_COMPARISONS[this.__class__](this=this.this, expression=right)
    223        if isinstance(this, exp.Paren):
    224            condition = this.unnest()
    225            if isinstance(condition, exp.And):
    226                return exp.paren(
    227                    exp.or_(
    228                        exp.not_(condition.left, copy=False),
    229                        exp.not_(condition.right, copy=False),
    230                        copy=False,
    231                    )
    232                )
    233            if isinstance(condition, exp.Or):
    234                return exp.paren(
    235                    exp.and_(
    236                        exp.not_(condition.left, copy=False),
    237                        exp.not_(condition.right, copy=False),
    238                        copy=False,
    239                    )
    240                )
    241            if is_null(condition):
    242                return exp.null()
    243        if always_true(this):
    244            return exp.false()
    245        if is_false(this):
    246            return exp.true()
    247        if isinstance(this, exp.Not):
    248            # double negation
    249            # NOT NOT x -> x
    250            return this.this
    251    return expression

Demorgan's Law NOT (x OR y) -> NOT x AND NOT y NOT (x AND y) -> NOT x OR NOT y

def flatten(expression): View Source

    254def flatten(expression):
    255    """
    256    A AND (B AND C) -> A AND B AND C
    257    A OR (B OR C) -> A OR B OR C
    258    """
    259    if isinstance(expression, exp.Connector):
    260        for node in expression.args.values():
    261            child = node.unnest()
    262            if isinstance(child, expression.__class__):
    263                node.replace(child)
    264    return expression

A AND (B AND C) -> A AND B AND C A OR (B OR C) -> A OR B OR C

def simplify_connectors(expression, root=True): View Source

    267def simplify_connectors(expression, root=True):
    268    def _simplify_connectors(expression, left, right):
    269        if isinstance(expression, exp.And):
    270            if is_false(left) or is_false(right):
    271                return exp.false()
    272            if is_zero(left) or is_zero(right):
    273                return exp.false()
    274            if is_null(left) or is_null(right):
    275                return exp.null()
    276            if always_true(left) and always_true(right):
    277                return exp.true()
    278            if always_true(left):
    279                return right
    280            if always_true(right):
    281                return left
    282            return _simplify_comparison(expression, left, right)
    283        elif isinstance(expression, exp.Or):
    284            if always_true(left) or always_true(right):
    285                return exp.true()
    286            if (
    287                (is_null(left) and is_null(right))
    288                or (is_null(left) and always_false(right))
    289                or (always_false(left) and is_null(right))
    290            ):
    291                return exp.null()
    292            if is_false(left):
    293                return right
    294            if is_false(right):
    295                return left
    296            return _simplify_comparison(expression, left, right, or_=True)
    297        elif isinstance(expression, exp.Xor):
    298            if left == right:
    299                return exp.false()
    300
    301    if isinstance(expression, exp.Connector):
    302        return _flat_simplify(expression, _simplify_connectors, root)
    303    return expression

LT_LTE = (<class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.LTE'>)
GT_GTE = (<class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.GTE'>)
COMPARISONS = (<class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.LTE'>, <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.GTE'>, <class 'sqlglot.expressions.EQ'>, <class 'sqlglot.expressions.NEQ'>, <class 'sqlglot.expressions.Is'>)
INVERSE_COMPARISONS: Dict[Type[sqlglot.expressions.Expression], Type[sqlglot.expressions.Expression]] = {<class 'sqlglot.expressions.LT'>: <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.GT'>: <class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.LTE'>: <class 'sqlglot.expressions.GTE'>, <class 'sqlglot.expressions.GTE'>: <class 'sqlglot.expressions.LTE'>}
NONDETERMINISTIC = (<class 'sqlglot.expressions.Rand'>, <class 'sqlglot.expressions.Randn'>)
AND_OR = (<class 'sqlglot.expressions.And'>, <class 'sqlglot.expressions.Or'>)
def remove_complements(expression, root=True): View Source

    390def remove_complements(expression, root=True):
    391    """
    392    Removing complements.
    393
    394    A AND NOT A -> FALSE
    395    A OR NOT A -> TRUE
    396    """
    397    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
    398        ops = set(expression.flatten())
    399        for op in ops:
    400            if isinstance(op, exp.Not) and op.this in ops:
    401                return exp.false() if isinstance(expression, exp.And) else exp.true()
    402
    403    return expression

Removing complements.

A AND NOT A -> FALSE A OR NOT A -> TRUE

def uniq_sort(expression, root=True): View Source

    406def uniq_sort(expression, root=True):
    407    """
    408    Uniq and sort a connector.
    409
    410    C AND A AND B AND B -> A AND B AND C
    411    """
    412    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    413        flattened = tuple(expression.flatten())
    414
    415        if isinstance(expression, exp.Xor):
    416            result_func = exp.xor
    417            # Do not deduplicate XOR as A XOR A != A if A == True
    418            deduped = None
    419            arr = tuple((gen(e), e) for e in flattened)
    420        else:
    421            result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
    422            deduped = {gen(e): e for e in flattened}
    423            arr = tuple(deduped.items())
    424
    425        # check if the operands are already sorted, if not sort them
    426        # A AND C AND B -> A AND B AND C
    427        for i, (sql, e) in enumerate(arr[1:]):
    428            if sql < arr[i][0]:
    429                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
    430                break
    431        else:
    432            # we didn't have to sort but maybe we need to dedup
    433            if deduped and len(deduped) < len(flattened):
    434                expression = result_func(*deduped.values(), copy=False)
    435
    436    return expression

Uniq and sort a connector.

C AND A AND B AND B -> A AND B AND C

def absorb_and_eliminate(expression, root=True): View Source

    439def absorb_and_eliminate(expression, root=True):
    440    """
    441    absorption:
    442        A AND (A OR B) -> A
    443        A OR (A AND B) -> A
    444        A AND (NOT A OR B) -> A AND B
    445        A OR (NOT A AND B) -> A OR B
    446    elimination:
    447        (A AND B) OR (A AND NOT B) -> A
    448        (A OR B) AND (A OR NOT B) -> A
    449    """
    450    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
    451        kind = exp.Or if isinstance(expression, exp.And) else exp.And
    452
    453        ops = tuple(expression.flatten())
    454
    455        # Initialize lookup tables:
    456        # Set of all operands, used to find complements for absorption.
    457        op_set = set()
    458        # Sub-operands, used to find subsets for absorption.
    459        subops = defaultdict(list)
    460        # Pairs of complements, used for elimination.
    461        pairs = defaultdict(list)
    462
    463        # Populate the lookup tables
    464        for op in ops:
    465            op_set.add(op)
    466
    467            if not isinstance(op, kind):
    468                # In cases like: A OR (A AND B)
    469                # Subop will be: ^
    470                subops[op].append({op})
    471                continue
    472
    473            # In cases like: (A AND B) OR (A AND B AND C)
    474            # Subops will be: ^     ^
    475            subset = set(op.flatten())
    476            for i in subset:
    477                subops[i].append(subset)
    478
    479            a, b = op.unnest_operands()
    480            if isinstance(a, exp.Not):
    481                pairs[frozenset((a.this, b))].append((op, b))
    482            if isinstance(b, exp.Not):
    483                pairs[frozenset((a, b.this))].append((op, a))
    484
    485        for op in ops:
    486            if not isinstance(op, kind):
    487                continue
    488
    489            a, b = op.unnest_operands()
    490
    491            # Absorb
    492            if isinstance(a, exp.Not) and a.this in op_set:
    493                a.replace(exp.true() if kind == exp.And else exp.false())
    494                continue
    495            if isinstance(b, exp.Not) and b.this in op_set:
    496                b.replace(exp.true() if kind == exp.And else exp.false())
    497                continue
    498            superset = set(op.flatten())
    499            if any(any(subset < superset for subset in subops[i]) for i in superset):
    500                op.replace(exp.false() if kind == exp.And else exp.true())
    501                continue
    502
    503            # Eliminate
    504            for other, complement in pairs[frozenset((a, b))]:
    505                op.replace(complement)
    506                other.replace(complement)
    507
    508    return expression

absorption: A AND (A OR B) -> A A OR (A AND B) -> A A AND (NOT A OR B) -> A AND B A OR (NOT A AND B) -> A OR B elimination: (A AND B) OR (A AND NOT B) -> A (A OR B) AND (A OR NOT B) -> A

def propagate_constants(expression, root=True): View Source

    511def propagate_constants(expression, root=True):
    512    """
    513    Propagate constants for conjunctions in DNF:
    514
    515    SELECT * FROM t WHERE a = b AND b = 5 becomes
    516    SELECT * FROM t WHERE a = 5 AND b = 5
    517
    518    Reference: https://www.sqlite.org/optoverview.html
    519    """
    520
    521    if (
    522        isinstance(expression, exp.And)
    523        and (root or not expression.same_parent)
    524        and sqlglot.optimizer.normalize.normalized(expression, dnf=True)
    525    ):
    526        constant_mapping = {}
    527        for expr in walk_in_scope(expression, prune=lambda node: isinstance(node, exp.If)):
    528            if isinstance(expr, exp.EQ):
    529                l, r = expr.left, expr.right
    530
    531                # TODO: create a helper that can be used to detect nested literal expressions such
    532                # as CAST(123456 AS BIGINT), since we usually want to treat those as literals too
    533                if isinstance(l, exp.Column) and isinstance(r, exp.Literal):
    534                    constant_mapping[l] = (id(l), r)
    535
    536        if constant_mapping:
    537            for column in find_all_in_scope(expression, exp.Column):
    538                parent = column.parent
    539                column_id, constant = constant_mapping.get(column) or (None, None)
    540                if (
    541                    column_id is not None
    542                    and id(column) != column_id
    543                    and not (isinstance(parent, exp.Is) and isinstance(parent.expression, exp.Null))
    544                ):
    545                    column.replace(constant.copy())
    546
    547    return expression

Propagate constants for conjunctions in DNF:

SELECT * FROM t WHERE a = b AND b = 5 becomes SELECT * FROM t WHERE a = 5 AND b = 5

Reference: https://www.sqlite.org/optoverview.html

INVERSE_DATE_OPS: Dict[Type[sqlglot.expressions.Expression], Type[sqlglot.expressions.Expression]] = {<class 'sqlglot.expressions.DateAdd'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.DateSub'>: <class 'sqlglot.expressions.Add'>, <class 'sqlglot.expressions.DatetimeAdd'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.DatetimeSub'>: <class 'sqlglot.expressions.Add'>}
INVERSE_OPS: Dict[Type[sqlglot.expressions.Expression], Type[sqlglot.expressions.Expression]] = {<class 'sqlglot.expressions.DateAdd'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.DateSub'>: <class 'sqlglot.expressions.Add'>, <class 'sqlglot.expressions.DatetimeAdd'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.DatetimeSub'>: <class 'sqlglot.expressions.Add'>, <class 'sqlglot.expressions.Add'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.Sub'>: <class 'sqlglot.expressions.Add'>}
def simplify_equality(expression, *args, **kwargs): View Source

    160        def wrapped(expression, *args, **kwargs):
    161            try:
    162                return func(expression, *args, **kwargs)
    163            except exceptions:
    164                return expression

###### Use the subtraction and addition properties of equality to simplify expressions:

> x + 1 = 3 becomes x = 2

There are two binary operations in the above expression: + and = Here's how we reference all the operands in the code below:

      l     r
    x + 1 = 3
    a   b

def simplify_literals(expression, root=True): View Source

    622def simplify_literals(expression, root=True):
    623    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
    624        return _flat_simplify(expression, _simplify_binary, root)
    625
    626    if isinstance(expression, exp.Neg) and isinstance(expression.this, exp.Neg):
    627        return expression.this.this
    628
    629    if type(expression) in INVERSE_DATE_OPS:
    630        return _simplify_binary(expression, expression.this, expression.interval()) or expression
    631
    632    return expression

NULL_OK = (<class 'sqlglot.expressions.NullSafeEQ'>, <class 'sqlglot.expressions.NullSafeNEQ'>, <class 'sqlglot.expressions.PropertyEQ'>)
def simplify_parens(expression): View Source

    733def simplify_parens(expression):
    734    if not isinstance(expression, exp.Paren):
    735        return expression
    736
    737    this = expression.this
    738    parent = expression.parent
    739    parent_is_predicate = isinstance(parent, exp.Predicate)
    740
    741    if (
    742        not isinstance(this, exp.Select)
    743        and not isinstance(parent, (exp.SubqueryPredicate, exp.Bracket))
    744        and (
    745            not isinstance(parent, (exp.Condition, exp.Binary))
    746            or isinstance(parent, exp.Paren)
    747            or (
    748                not isinstance(this, exp.Binary)
    749                and not (isinstance(this, (exp.Not, exp.Is)) and parent_is_predicate)
    750            )
    751            or (isinstance(this, exp.Predicate) and not parent_is_predicate)
    752            or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
    753            or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
    754            or (isinstance(this, exp.Mul) and isinstance(parent, (exp.Add, exp.Sub)))
    755        )
    756    ):
    757        return this
    758    return expression

def simplify_coalesce( expression: sqlglot.expressions.Expression, dialect: Union[str, sqlglot.dialects.Dialect, Type[sqlglot.dialects.Dialect], NoneType]) -> sqlglot.expressions.Expression: View Source

    769def simplify_coalesce(expression: exp.Expression, dialect: DialectType) -> exp.Expression:
    770    # COALESCE(x) -> x
    771    if (
    772        isinstance(expression, exp.Coalesce)
    773        and (not expression.expressions or _is_nonnull_constant(expression.this))
    774        # COALESCE is also used as a Spark partitioning hint
    775        and not isinstance(expression.parent, exp.Hint)
    776    ):
    777        return expression.this
    778
    779    # We can't convert `COALESCE(x, 1) = 2` into `NOT x IS NULL AND x = 2` for redshift,
    780    # because they are not always equivalent. For example,  if `x` is `NULL` and it comes
    781    # from a table, then the result is `NULL`, despite `FALSE AND NULL` evaluating to `FALSE`
    782    if dialect == "redshift":
    783        return expression
    784
    785    if not isinstance(expression, COMPARISONS):
    786        return expression
    787
    788    if isinstance(expression.left, exp.Coalesce):
    789        coalesce = expression.left
    790        other = expression.right
    791    elif isinstance(expression.right, exp.Coalesce):
    792        coalesce = expression.right
    793        other = expression.left
    794    else:
    795        return expression
    796
    797    # This transformation is valid for non-constants,
    798    # but it really only does anything if they are both constants.
    799    if not _is_constant(other):
    800        return expression
    801
    802    # Find the first constant arg
    803    for arg_index, arg in enumerate(coalesce.expressions):
    804        if _is_constant(arg):
    805            break
    806    else:
    807        return expression
    808
    809    coalesce.set("expressions", coalesce.expressions[:arg_index])
    810
    811    # Remove the COALESCE function. This is an optimization, skipping a simplify iteration,
    812    # since we already remove COALESCE at the top of this function.
    813    coalesce = coalesce if coalesce.expressions else coalesce.this
    814
    815    # This expression is more complex than when we started, but it will get simplified further
    816    return exp.paren(
    817        exp.or_(
    818            exp.and_(
    819                coalesce.is_(exp.null()).not_(copy=False),
    820                expression.copy(),
    821                copy=False,
    822            ),
    823            exp.and_(
    824                coalesce.is_(exp.null()),
    825                type(expression)(this=arg.copy(), expression=other.copy()),
    826                copy=False,
    827            ),
    828            copy=False,
    829        )
    830    )

CONCATS = (<class 'sqlglot.expressions.Concat'>, <class 'sqlglot.expressions.DPipe'>)
def simplify_concat(expression): View Source

    836def simplify_concat(expression):
    837    """Reduces all groups that contain string literals by concatenating them."""
    838    if not isinstance(expression, CONCATS) or (
    839        # We can't reduce a CONCAT_WS call if we don't statically know the separator
    840        isinstance(expression, exp.ConcatWs) and not expression.expressions[0].is_string
    841    ):
    842        return expression
    843
    844    if isinstance(expression, exp.ConcatWs):
    845        sep_expr, *expressions = expression.expressions
    846        sep = sep_expr.name
    847        concat_type = exp.ConcatWs
    848        args = {}
    849    else:
    850        expressions = expression.expressions
    851        sep = ""
    852        concat_type = exp.Concat
    853        args = {
    854            "safe": expression.args.get("safe"),
    855            "coalesce": expression.args.get("coalesce"),
    856        }
    857
    858    new_args = []
    859    for is_string_group, group in itertools.groupby(
    860        expressions or expression.flatten(), lambda e: e.is_string
    861    ):
    862        if is_string_group:
    863            new_args.append(exp.Literal.string(sep.join(string.name for string in group)))
    864        else:
    865            new_args.extend(group)
    866
    867    if len(new_args) == 1 and new_args[0].is_string:
    868        return new_args[0]
    869
    870    if concat_type is exp.ConcatWs:
    871        new_args = [sep_expr] + new_args
    872    elif isinstance(expression, exp.DPipe):
    873        return reduce(lambda x, y: exp.DPipe(this=x, expression=y), new_args)
    874
    875    return concat_type(expressions=new_args, **args)

Reduces all groups that contain string literals by concatenating them.

def simplify_conditionals(expression): View Source

    878def simplify_conditionals(expression):
    879    """Simplifies expressions like IF, CASE if their condition is statically known."""
    880    if isinstance(expression, exp.Case):
    881        this = expression.this
    882        for case in expression.args["ifs"]:
    883            cond = case.this
    884            if this:
    885                # Convert CASE x WHEN matching_value ... to CASE WHEN x = matching_value ...
    886                cond = cond.replace(this.pop().eq(cond))
    887
    888            if always_true(cond):
    889                return case.args["true"]
    890
    891            if always_false(cond):
    892                case.pop()
    893                if not expression.args["ifs"]:
    894                    return expression.args.get("default") or exp.null()
    895    elif isinstance(expression, exp.If) and not isinstance(expression.parent, exp.Case):
    896        if always_true(expression.this):
    897            return expression.args["true"]
    898        if always_false(expression.this):
    899            return expression.args.get("false") or exp.null()
    900
    901    return expression

Simplifies expressions like IF, CASE if their condition is statically known.

def simplify_startswith( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression: View Source

    904def simplify_startswith(expression: exp.Expression) -> exp.Expression:
    905    """
    906    Reduces a prefix check to either TRUE or FALSE if both the string and the
    907    prefix are statically known.
    908
    909    Example:
    910        >>> from sqlglot import parse_one
    911        >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
    912        'TRUE'
    913    """
    914    if (
    915        isinstance(expression, exp.StartsWith)
    916        and expression.this.is_string
    917        and expression.expression.is_string
    918    ):
    919        return exp.convert(expression.name.startswith(expression.expression.name))
    920
    921    return expression

Reduces a prefix check to either TRUE or FALSE if both the string and the prefix are statically known.

###### Example:

>     >>> from sqlglot import parse_one
>     >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
>     'TRUE'

DateRange = typing.Tuple[datetime.date, datetime.date]
DATETRUNC_BINARY_COMPARISONS: Dict[Type[sqlglot.expressions.Expression], Callable[[sqlglot.expressions.Expression, datetime.date, str, sqlglot.dialects.Dialect, sqlglot.expressions.DataType], Optional[sqlglot.expressions.Expression]]] = {<class 'sqlglot.expressions.LT'>: <function <lambda>>, <class 'sqlglot.expressions.GT'>: <function <lambda>>, <class 'sqlglot.expressions.LTE'>: <function <lambda>>, <class 'sqlglot.expressions.GTE'>: <function <lambda>>, <class 'sqlglot.expressions.EQ'>: <function _datetrunc_eq>, <class 'sqlglot.expressions.NEQ'>: <function _datetrunc_neq>}
DATETRUNC_COMPARISONS = {<class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.In'>, <class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.NEQ'>, <class 'sqlglot.expressions.EQ'>, <class 'sqlglot.expressions.GTE'>, <class 'sqlglot.expressions.LTE'>}
DATETRUNCS = (<class 'sqlglot.expressions.DateTrunc'>, <class 'sqlglot.expressions.TimestampTrunc'>)
def simplify_datetrunc(expression, *args, **kwargs): View Source

    160        def wrapped(expression, *args, **kwargs):
    161            try:
    162                return func(expression, *args, **kwargs)
    163            except exceptions:
    164                return expression

Simplify expressions like `DATE_TRUNC('year', x) >= CAST('2021-01-01' AS DATE)`

def sort_comparison( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression: View Source

    1070def sort_comparison(expression: exp.Expression) -> exp.Expression:
    1071    if expression.__class__ in COMPLEMENT_COMPARISONS:
    1072        l, r = expression.this, expression.expression
    1073        l_column = isinstance(l, exp.Column)
    1074        r_column = isinstance(r, exp.Column)
    1075        l_const = _is_constant(l)
    1076        r_const = _is_constant(r)
    1077
    1078        if (
    1079            (l_column and not r_column)
    1080            or (r_const and not l_const)
    1081            or isinstance(r, exp.SubqueryPredicate)
    1082        ):
    1083            return expression
    1084        if (r_column and not l_column) or (l_const and not r_const) or (gen(l) > gen(r)):
    1085            return INVERSE_COMPARISONS.get(expression.__class__, expression.__class__)(
    1086                this=r, expression=l
    1087            )
    1088    return expression

JOINS = {('', 'INNER'), ('RIGHT', 'OUTER'), ('RIGHT', ''), ('', '')}
def remove_where_true(expression): View Source

    1102def remove_where_true(expression):
    1103    for where in expression.find_all(exp.Where):
    1104        if always_true(where.this):
    1105            where.pop()
    1106    for join in expression.find_all(exp.Join):
    1107        if (
    1108            always_true(join.args.get("on"))
    1109            and not join.args.get("using")
    1110            and not join.args.get("method")
    1111            and (join.side, join.kind) in JOINS
    1112        ):
    1113            join.args["on"].pop()
    1114            join.set("side", None)
    1115            join.set("kind", "CROSS")

def always_true(expression): View Source

    1118def always_true(expression):
    1119    return (isinstance(expression, exp.Boolean) and expression.this) or (
    1120        isinstance(expression, exp.Literal) and not is_zero(expression)
    1121    )

def always_false(expression): View Source

    1124def always_false(expression):
    1125    return is_false(expression) or is_null(expression) or is_zero(expression)

def is_zero(expression): View Source

    1128def is_zero(expression):
    1129    return isinstance(expression, exp.Literal) and expression.to_py() == 0

def is_complement(a, b): View Source

    1132def is_complement(a, b):
    1133    return isinstance(b, exp.Not) and b.this == a

def is_false(a: sqlglot.expressions.Expression) -> bool: View Source

    1136def is_false(a: exp.Expression) -> bool:
    1137    return type(a) is exp.Boolean and not a.this

def is_null(a: sqlglot.expressions.Expression) -> bool: View Source

    1140def is_null(a: exp.Expression) -> bool:
    1141    return type(a) is exp.Null

def eval_boolean(expression, a, b): View Source

    1144def eval_boolean(expression, a, b):
    1145    if isinstance(expression, (exp.EQ, exp.Is)):
    1146        return boolean_literal(a == b)
    1147    if isinstance(expression, exp.NEQ):
    1148        return boolean_literal(a != b)
    1149    if isinstance(expression, exp.GT):
    1150        return boolean_literal(a > b)
    1151    if isinstance(expression, exp.GTE):
    1152        return boolean_literal(a >= b)
    1153    if isinstance(expression, exp.LT):
    1154        return boolean_literal(a < b)
    1155    if isinstance(expression, exp.LTE):
    1156        return boolean_literal(a <= b)
    1157    return None

def cast_as_date(value: Any) -> Optional[datetime.date]: View Source

    1160def cast_as_date(value: t.Any) -> t.Optional[datetime.date]:
    1161    if isinstance(value, datetime.datetime):
    1162        return value.date()
    1163    if isinstance(value, datetime.date):
    1164        return value
    1165    try:
    1166        return datetime.datetime.fromisoformat(value).date()
    1167    except ValueError:
    1168        return None

def cast_as_datetime(value: Any) -> Optional[datetime.datetime]: View Source

    1171def cast_as_datetime(value: t.Any) -> t.Optional[datetime.datetime]:
    1172    if isinstance(value, datetime.datetime):
    1173        return value
    1174    if isinstance(value, datetime.date):
    1175        return datetime.datetime(year=value.year, month=value.month, day=value.day)
    1176    try:
    1177        return datetime.datetime.fromisoformat(value)
    1178    except ValueError:
    1179        return None

def cast_value(value: Any, to: sqlglot.expressions.DataType) -> Optional[datetime.date]: View Source

    1182def cast_value(value: t.Any, to: exp.DataType) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1183    if not value:
    1184        return None
    1185    if to.is_type(exp.DataType.Type.DATE):
    1186        return cast_as_date(value)
    1187    if to.is_type(*exp.DataType.TEMPORAL_TYPES):
    1188        return cast_as_datetime(value)
    1189    return None

def extract_date(cast: sqlglot.expressions.Expression) -> Optional[datetime.date]: View Source

    1192def extract_date(cast: exp.Expression) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1193    if isinstance(cast, exp.Cast):
    1194        to = cast.to
    1195    elif isinstance(cast, exp.TsOrDsToDate) and not cast.args.get("format"):
    1196        to = exp.DataType.build(exp.DataType.Type.DATE)
    1197    else:
    1198        return None
    1199
    1200    if isinstance(cast.this, exp.Literal):
    1201        value: t.Any = cast.this.name
    1202    elif isinstance(cast.this, (exp.Cast, exp.TsOrDsToDate)):
    1203        value = extract_date(cast.this)
    1204    else:
    1205        return None
    1206    return cast_value(value, to)

def extract_interval(expression): View Source

    1213def extract_interval(expression):
    1214    try:
    1215        n = int(expression.this.to_py())
    1216        unit = expression.text("unit").lower()
    1217        return interval(unit, n)
    1218    except (UnsupportedUnit, ModuleNotFoundError, ValueError):
    1219        return None

def extract_type(*expressions): View Source

    1222def extract_type(*expressions):
    1223    target_type = None
    1224    for expression in expressions:
    1225        target_type = expression.to if isinstance(expression, exp.Cast) else expression.type
    1226        if target_type:
    1227            break
    1228
    1229    return target_type

def date_literal(date, target_type=None): View Source

    1232def date_literal(date, target_type=None):
    1233    if not target_type or not target_type.is_type(*exp.DataType.TEMPORAL_TYPES):
    1234        target_type = (
    1235            exp.DataType.Type.DATETIME
    1236            if isinstance(date, datetime.datetime)
    1237            else exp.DataType.Type.DATE
    1238        )
    1239
    1240    return exp.cast(exp.Literal.string(date), target_type)

def interval(unit: str, n: int = 1): View Source

    1243def interval(unit: str, n: int = 1):
    1244    from dateutil.relativedelta import relativedelta
    1245
    1246    if unit == "year":
    1247        return relativedelta(years=1 * n)
    1248    if unit == "quarter":
    1249        return relativedelta(months=3 * n)
    1250    if unit == "month":
    1251        return relativedelta(months=1 * n)
    1252    if unit == "week":
    1253        return relativedelta(weeks=1 * n)
    1254    if unit == "day":
    1255        return relativedelta(days=1 * n)
    1256    if unit == "hour":
    1257        return relativedelta(hours=1 * n)
    1258    if unit == "minute":
    1259        return relativedelta(minutes=1 * n)
    1260    if unit == "second":
    1261        return relativedelta(seconds=1 * n)
    1262
    1263    raise UnsupportedUnit(f"Unsupported unit: {unit}")

def date_floor( d: datetime.date, unit: str, dialect: sqlglot.dialects.Dialect) -> datetime.date: View Source

    1266def date_floor(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1267    if unit == "year":
    1268        return d.replace(month=1, day=1)
    1269    if unit == "quarter":
    1270        if d.month <= 3:
    1271            return d.replace(month=1, day=1)
    1272        elif d.month <= 6:
    1273            return d.replace(month=4, day=1)
    1274        elif d.month <= 9:
    1275            return d.replace(month=7, day=1)
    1276        else:
    1277            return d.replace(month=10, day=1)
    1278    if unit == "month":
    1279        return d.replace(month=d.month, day=1)
    1280    if unit == "week":
    1281        # Assuming week starts on Monday (0) and ends on Sunday (6)
    1282        return d - datetime.timedelta(days=d.weekday() - dialect.WEEK_OFFSET)
    1283    if unit == "day":
    1284        return d
    1285
    1286    raise UnsupportedUnit(f"Unsupported unit: {unit}")

def date_ceil( d: datetime.date, unit: str, dialect: sqlglot.dialects.Dialect) -> datetime.date: View Source

    1289def date_ceil(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1290    floor = date_floor(d, unit, dialect)
    1291
    1292    if floor == d:
    1293        return d
    1294
    1295    return floor + interval(unit)

def boolean_literal(condition): View Source

    1298def boolean_literal(condition):
    1299    return exp.true() if condition else exp.false()

def gen(expression: Any, comments: bool = False) -> str: View Source

    1328def gen(expression: t.Any, comments: bool = False) -> str:
    1329    """Simple pseudo sql generator for quickly generating sortable and uniq strings.
    1330
    1331    Sorting and deduping sql is a necessary step for optimization. Calling the actual
    1332    generator is expensive so we have a bare minimum sql generator here.
    1333
    1334    Args:
    1335        expression: the expression to convert into a SQL string.
    1336        comments: whether to include the expression's comments.
    1337    """
    1338    return Gen().gen(expression, comments=comments)

Simple pseudo sql generator for quickly generating sortable and uniq strings.

Sorting and deduping sql is a necessary step for optimization. Calling the actual generator is expensive so we have a bare minimum sql generator here.

###### Arguments:

- expression: the expression to convert into a SQL string.
- comments: whether to include the expression's comments.

class Gen: View Source

    1341class Gen:
    1342    def __init__(self):
    1343        self.stack = []
    1344        self.sqls = []
    1345
    1346    def gen(self, expression: exp.Expression, comments: bool = False) -> str:
    1347        self.stack = [expression]
    1348        self.sqls.clear()
    1349
    1350        while self.stack:
    1351            node = self.stack.pop()
    1352
    1353            if isinstance(node, exp.Expression):
    1354                if comments and node.comments:
    1355                    self.stack.append(f" /*{','.join(node.comments)}*/")
    1356
    1357                exp_handler_name = f"{node.key}_sql"
    1358
    1359                if hasattr(self, exp_handler_name):
    1360                    getattr(self, exp_handler_name)(node)
    1361                elif isinstance(node, exp.Func):
    1362                    self._function(node)
    1363                else:
    1364                    key = node.key.upper()
    1365                    self.stack.append(f"{key} " if self._args(node) else key)
    1366            elif type(node) is list:
    1367                for n in reversed(node):
    1368                    if n is not None:
    1369                        self.stack.extend((n, ","))
    1370                if node:
    1371                    self.stack.pop()
    1372            else:
    1373                if node is not None:
    1374                    self.sqls.append(str(node))
    1375
    1376        return "".join(self.sqls)
    1377
    1378    def add_sql(self, e: exp.Add) -> None:
    1379        self._binary(e, " + ")
    1380
    1381    def alias_sql(self, e: exp.Alias) -> None:
    1382        self.stack.extend(
    1383            (
    1384                e.args.get("alias"),
    1385                " AS ",
    1386                e.args.get("this"),
    1387            )
    1388        )
    1389
    1390    def and_sql(self, e: exp.And) -> None:
    1391        self._binary(e, " AND ")
    1392
    1393    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1394        this = e.this
    1395        if isinstance(this, str):
    1396            name = this.upper()
    1397        elif isinstance(this, exp.Identifier):
    1398            name = this.this
    1399            name = f'"{name}"' if this.quoted else name.upper()
    1400        else:
    1401            raise ValueError(
    1402                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1403            )
    1404
    1405        self.stack.extend(
    1406            (
    1407                ")",
    1408                e.expressions,
    1409                "(",
    1410                name,
    1411            )
    1412        )
    1413
    1414    def between_sql(self, e: exp.Between) -> None:
    1415        self.stack.extend(
    1416            (
    1417                e.args.get("high"),
    1418                " AND ",
    1419                e.args.get("low"),
    1420                " BETWEEN ",
    1421                e.this,
    1422            )
    1423        )
    1424
    1425    def boolean_sql(self, e: exp.Boolean) -> None:
    1426        self.stack.append("TRUE" if e.this else "FALSE")
    1427
    1428    def bracket_sql(self, e: exp.Bracket) -> None:
    1429        self.stack.extend(
    1430            (
    1431                "]",
    1432                e.expressions,
    1433                "[",
    1434                e.this,
    1435            )
    1436        )
    1437
    1438    def column_sql(self, e: exp.Column) -> None:
    1439        for p in reversed(e.parts):
    1440            self.stack.extend((p, "."))
    1441        self.stack.pop()
    1442
    1443    def datatype_sql(self, e: exp.DataType) -> None:
    1444        self._args(e, 1)
    1445        self.stack.append(f"{e.this.name} ")
    1446
    1447    def div_sql(self, e: exp.Div) -> None:
    1448        self._binary(e, " / ")
    1449
    1450    def dot_sql(self, e: exp.Dot) -> None:
    1451        self._binary(e, ".")
    1452
    1453    def eq_sql(self, e: exp.EQ) -> None:
    1454        self._binary(e, " = ")
    1455
    1456    def from_sql(self, e: exp.From) -> None:
    1457        self.stack.extend((e.this, "FROM "))
    1458
    1459    def gt_sql(self, e: exp.GT) -> None:
    1460        self._binary(e, " > ")
    1461
    1462    def gte_sql(self, e: exp.GTE) -> None:
    1463        self._binary(e, " >= ")
    1464
    1465    def identifier_sql(self, e: exp.Identifier) -> None:
    1466        self.stack.append(f'"{e.this}"' if e.quoted else e.this)
    1467
    1468    def ilike_sql(self, e: exp.ILike) -> None:
    1469        self._binary(e, " ILIKE ")
    1470
    1471    def in_sql(self, e: exp.In) -> None:
    1472        self.stack.append(")")
    1473        self._args(e, 1)
    1474        self.stack.extend(
    1475            (
    1476                "(",
    1477                " IN ",
    1478                e.this,
    1479            )
    1480        )
    1481
    1482    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1483        self._binary(e, " DIV ")
    1484
    1485    def is_sql(self, e: exp.Is) -> None:
    1486        self._binary(e, " IS ")
    1487
    1488    def like_sql(self, e: exp.Like) -> None:
    1489        self._binary(e, " Like ")
    1490
    1491    def literal_sql(self, e: exp.Literal) -> None:
    1492        self.stack.append(f"'{e.this}'" if e.is_string else e.this)
    1493
    1494    def lt_sql(self, e: exp.LT) -> None:
    1495        self._binary(e, " < ")
    1496
    1497    def lte_sql(self, e: exp.LTE) -> None:
    1498        self._binary(e, " <= ")
    1499
    1500    def mod_sql(self, e: exp.Mod) -> None:
    1501        self._binary(e, " % ")
    1502
    1503    def mul_sql(self, e: exp.Mul) -> None:
    1504        self._binary(e, " * ")
    1505
    1506    def neg_sql(self, e: exp.Neg) -> None:
    1507        self._unary(e, "-")
    1508
    1509    def neq_sql(self, e: exp.NEQ) -> None:
    1510        self._binary(e, " <> ")
    1511
    1512    def not_sql(self, e: exp.Not) -> None:
    1513        self._unary(e, "NOT ")
    1514
    1515    def null_sql(self, e: exp.Null) -> None:
    1516        self.stack.append("NULL")
    1517
    1518    def or_sql(self, e: exp.Or) -> None:
    1519        self._binary(e, " OR ")
    1520
    1521    def paren_sql(self, e: exp.Paren) -> None:
    1522        self.stack.extend(
    1523            (
    1524                ")",
    1525                e.this,
    1526                "(",
    1527            )
    1528        )
    1529
    1530    def sub_sql(self, e: exp.Sub) -> None:
    1531        self._binary(e, " - ")
    1532
    1533    def subquery_sql(self, e: exp.Subquery) -> None:
    1534        self._args(e, 2)
    1535        alias = e.args.get("alias")
    1536        if alias:
    1537            self.stack.append(alias)
    1538        self.stack.extend((")", e.this, "("))
    1539
    1540    def table_sql(self, e: exp.Table) -> None:
    1541        self._args(e, 4)
    1542        alias = e.args.get("alias")
    1543        if alias:
    1544            self.stack.append(alias)
    1545        for p in reversed(e.parts):
    1546            self.stack.extend((p, "."))
    1547        self.stack.pop()
    1548
    1549    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1550        columns = e.columns
    1551
    1552        if columns:
    1553            self.stack.extend((")", columns, "("))
    1554
    1555        self.stack.extend((e.this, " AS "))
    1556
    1557    def var_sql(self, e: exp.Var) -> None:
    1558        self.stack.append(e.this)
    1559
    1560    def _binary(self, e: exp.Binary, op: str) -> None:
    1561        self.stack.extend((e.expression, op, e.this))
    1562
    1563    def _unary(self, e: exp.Unary, op: str) -> None:
    1564        self.stack.extend((e.this, op))
    1565
    1566    def _function(self, e: exp.Func) -> None:
    1567        self.stack.extend(
    1568            (
    1569                ")",
    1570                list(e.args.values()),
    1571                "(",
    1572                e.sql_name(),
    1573            )
    1574        )
    1575
    1576    def _args(self, node: exp.Expression, arg_index: int = 0) -> bool:
    1577        kvs = []
    1578        arg_types = list(node.arg_types)[arg_index:] if arg_index else node.arg_types
    1579
    1580        for k in arg_types or arg_types:
    1581            v = node.args.get(k)
    1582
    1583            if v is not None:
    1584                kvs.append([f":{k}", v])
    1585        if kvs:
    1586            self.stack.append(kvs)
    1587            return True
    1588        return False

stack
sqls
def gen( self, expression: sqlglot.expressions.Expression, comments: bool = False) -> str: View Source

    1346    def gen(self, expression: exp.Expression, comments: bool = False) -> str:
    1347        self.stack = [expression]
    1348        self.sqls.clear()
    1349
    1350        while self.stack:
    1351            node = self.stack.pop()
    1352
    1353            if isinstance(node, exp.Expression):
    1354                if comments and node.comments:
    1355                    self.stack.append(f" /*{','.join(node.comments)}*/")
    1356
    1357                exp_handler_name = f"{node.key}_sql"
    1358
    1359                if hasattr(self, exp_handler_name):
    1360                    getattr(self, exp_handler_name)(node)
    1361                elif isinstance(node, exp.Func):
    1362                    self._function(node)
    1363                else:
    1364                    key = node.key.upper()
    1365                    self.stack.append(f"{key} " if self._args(node) else key)
    1366            elif type(node) is list:
    1367                for n in reversed(node):
    1368                    if n is not None:
    1369                        self.stack.extend((n, ","))
    1370                if node:
    1371                    self.stack.pop()
    1372            else:
    1373                if node is not None:
    1374                    self.sqls.append(str(node))
    1375
    1376        return "".join(self.sqls)

def add_sql(self, e: sqlglot.expressions.Add) -> None: View Source

    1378    def add_sql(self, e: exp.Add) -> None:
    1379        self._binary(e, " + ")

def alias_sql(self, e: sqlglot.expressions.Alias) -> None: View Source

    1381    def alias_sql(self, e: exp.Alias) -> None:
    1382        self.stack.extend(
    1383            (
    1384                e.args.get("alias"),
    1385                " AS ",
    1386                e.args.get("this"),
    1387            )
    1388        )

def and_sql(self, e: sqlglot.expressions.And) -> None: View Source

    1390    def and_sql(self, e: exp.And) -> None:
    1391        self._binary(e, " AND ")

def anonymous_sql(self, e: sqlglot.expressions.Anonymous) -> None: View Source

    1393    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1394        this = e.this
    1395        if isinstance(this, str):
    1396            name = this.upper()
    1397        elif isinstance(this, exp.Identifier):
    1398            name = this.this
    1399            name = f'"{name}"' if this.quoted else name.upper()
    1400        else:
    1401            raise ValueError(
    1402                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1403            )
    1404
    1405        self.stack.extend(
    1406            (
    1407                ")",
    1408                e.expressions,
    1409                "(",
    1410                name,
    1411            )
    1412        )

def between_sql(self, e: sqlglot.expressions.Between) -> None: View Source

    1414    def between_sql(self, e: exp.Between) -> None:
    1415        self.stack.extend(
    1416            (
    1417                e.args.get("high"),
    1418                " AND ",
    1419                e.args.get("low"),
    1420                " BETWEEN ",
    1421                e.this,
    1422            )
    1423        )

def boolean_sql(self, e: sqlglot.expressions.Boolean) -> None: View Source

    1425    def boolean_sql(self, e: exp.Boolean) -> None:
    1426        self.stack.append("TRUE" if e.this else "FALSE")

def bracket_sql(self, e: sqlglot.expressions.Bracket) -> None: View Source

    1428    def bracket_sql(self, e: exp.Bracket) -> None:
    1429        self.stack.extend(
    1430            (
    1431                "]",
    1432                e.expressions,
    1433                "[",
    1434                e.this,
    1435            )
    1436        )

def column_sql(self, e: sqlglot.expressions.Column) -> None: View Source

    1438    def column_sql(self, e: exp.Column) -> None:
    1439        for p in reversed(e.parts):
    1440            self.stack.extend((p, "."))
    1441        self.stack.pop()

def datatype_sql(self, e: sqlglot.expressions.DataType) -> None: View Source

    1443    def datatype_sql(self, e: exp.DataType) -> None:
    1444        self._args(e, 1)
    1445        self.stack.append(f"{e.this.name} ")

def div_sql(self, e: sqlglot.expressions.Div) -> None: View Source

    1447    def div_sql(self, e: exp.Div) -> None:
    1448        self._binary(e, " / ")

def dot_sql(self, e: sqlglot.expressions.Dot) -> None: View Source

    1450    def dot_sql(self, e: exp.Dot) -> None:
    1451        self._binary(e, ".")

def eq_sql(self, e: sqlglot.expressions.EQ) -> None: View Source

    1453    def eq_sql(self, e: exp.EQ) -> None:
    1454        self._binary(e, " = ")

def from_sql(self, e: sqlglot.expressions.From) -> None: View Source

    1456    def from_sql(self, e: exp.From) -> None:
    1457        self.stack.extend((e.this, "FROM "))

def gt_sql(self, e: sqlglot.expressions.GT) -> None: View Source

    1459    def gt_sql(self, e: exp.GT) -> None:
    1460        self._binary(e, " > ")

def gte_sql(self, e: sqlglot.expressions.GTE) -> None: View Source

    1462    def gte_sql(self, e: exp.GTE) -> None:
    1463        self._binary(e, " >= ")

def identifier_sql(self, e: sqlglot.expressions.Identifier) -> None: View Source

    1465    def identifier_sql(self, e: exp.Identifier) -> None:
    1466        self.stack.append(f'"{e.this}"' if e.quoted else e.this)

def ilike_sql(self, e: sqlglot.expressions.ILike) -> None: View Source

    1468    def ilike_sql(self, e: exp.ILike) -> None:
    1469        self._binary(e, " ILIKE ")

def in_sql(self, e: sqlglot.expressions.In) -> None: View Source

    1471    def in_sql(self, e: exp.In) -> None:
    1472        self.stack.append(")")
    1473        self._args(e, 1)
    1474        self.stack.extend(
    1475            (
    1476                "(",
    1477                " IN ",
    1478                e.this,
    1479            )
    1480        )

def intdiv_sql(self, e: sqlglot.expressions.IntDiv) -> None: View Source

    1482    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1483        self._binary(e, " DIV ")

def is_sql(self, e: sqlglot.expressions.Is) -> None: View Source

    1485    def is_sql(self, e: exp.Is) -> None:
    1486        self._binary(e, " IS ")

def like_sql(self, e: sqlglot.expressions.Like) -> None: View Source

    1488    def like_sql(self, e: exp.Like) -> None:
    1489        self._binary(e, " Like ")

def literal_sql(self, e: sqlglot.expressions.Literal) -> None: View Source

    1491    def literal_sql(self, e: exp.Literal) -> None:
    1492        self.stack.append(f"'{e.this}'" if e.is_string else e.this)

def lt_sql(self, e: sqlglot.expressions.LT) -> None: View Source

    1494    def lt_sql(self, e: exp.LT) -> None:
    1495        self._binary(e, " < ")

def lte_sql(self, e: sqlglot.expressions.LTE) -> None: View Source

    1497    def lte_sql(self, e: exp.LTE) -> None:
    1498        self._binary(e, " <= ")

def mod_sql(self, e: sqlglot.expressions.Mod) -> None: View Source

    1500    def mod_sql(self, e: exp.Mod) -> None:
    1501        self._binary(e, " % ")

def mul_sql(self, e: sqlglot.expressions.Mul) -> None: View Source

    1503    def mul_sql(self, e: exp.Mul) -> None:
    1504        self._binary(e, " * ")

def neg_sql(self, e: sqlglot.expressions.Neg) -> None: View Source

    1506    def neg_sql(self, e: exp.Neg) -> None:
    1507        self._unary(e, "-")

def neq_sql(self, e: sqlglot.expressions.NEQ) -> None: View Source

    1509    def neq_sql(self, e: exp.NEQ) -> None:
    1510        self._binary(e, " <> ")

def not_sql(self, e: sqlglot.expressions.Not) -> None: View Source

    1512    def not_sql(self, e: exp.Not) -> None:
    1513        self._unary(e, "NOT ")

def null_sql(self, e: sqlglot.expressions.Null) -> None: View Source

    1515    def null_sql(self, e: exp.Null) -> None:
    1516        self.stack.append("NULL")

def or_sql(self, e: sqlglot.expressions.Or) -> None: View Source

    1518    def or_sql(self, e: exp.Or) -> None:
    1519        self._binary(e, " OR ")

def paren_sql(self, e: sqlglot.expressions.Paren) -> None: View Source

    1521    def paren_sql(self, e: exp.Paren) -> None:
    1522        self.stack.extend(
    1523            (
    1524                ")",
    1525                e.this,
    1526                "(",
    1527            )
    1528        )

def sub_sql(self, e: sqlglot.expressions.Sub) -> None: View Source

    1530    def sub_sql(self, e: exp.Sub) -> None:
    1531        self._binary(e, " - ")

def subquery_sql(self, e: sqlglot.expressions.Subquery) -> None: View Source

    1533    def subquery_sql(self, e: exp.Subquery) -> None:
    1534        self._args(e, 2)
    1535        alias = e.args.get("alias")
    1536        if alias:
    1537            self.stack.append(alias)
    1538        self.stack.extend((")", e.this, "("))

def table_sql(self, e: sqlglot.expressions.Table) -> None: View Source

    1540    def table_sql(self, e: exp.Table) -> None:
    1541        self._args(e, 4)
    1542        alias = e.args.get("alias")
    1543        if alias:
    1544            self.stack.append(alias)
    1545        for p in reversed(e.parts):
    1546            self.stack.extend((p, "."))
    1547        self.stack.pop()

def tablealias_sql(self, e: sqlglot.expressions.TableAlias) -> None: View Source

    1549    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1550        columns = e.columns
    1551
    1552        if columns:
    1553            self.stack.extend((")", columns, "("))
    1554
    1555        self.stack.extend((e.this, " AS "))

def var_sql(self, e: sqlglot.expressions.Var) -> None: View Source

    1557    def var_sql(self, e: exp.Var) -> None:
    1558        self.stack.append(e.this)