sqlglot.optimizer.simplify API documentation

Edit on GitHub

# sqlglot.optimizer.simplify

View Source

       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    dialect: DialectType = None,
      43    max_depth: t.Optional[int] = 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        max_depth: Chains of Connectors (AND, OR, etc) exceeding `max_depth` will be skipped
      58    Returns:
      59        sqlglot.Expression: simplified expression
      60    """
      61
      62    dialect = Dialect.get_or_raise(dialect)
      63
      64    def _simplify(expression, root=True):
      65        if (
      66            max_depth
      67            and isinstance(expression, exp.Connector)
      68            and not isinstance(expression.parent, exp.Connector)
      69        ):
      70            depth = connector_depth(expression)
      71            if depth > max_depth:
      72                logger.info(
      73                    f"Skipping simplification because connector depth {depth} exceeds max {max_depth}"
      74                )
      75                return expression
      76
      77        if expression.meta.get(FINAL):
      78            return expression
      79
      80        # group by expressions cannot be simplified, for example
      81        # select x + 1 + 1 FROM y GROUP BY x + 1 + 1
      82        # the projection must exactly match the group by key
      83        group = expression.args.get("group")
      84
      85        if group and hasattr(expression, "selects"):
      86            groups = set(group.expressions)
      87            group.meta[FINAL] = True
      88
      89            for e in expression.selects:
      90                for node in e.walk():
      91                    if node in groups:
      92                        e.meta[FINAL] = True
      93                        break
      94
      95            having = expression.args.get("having")
      96            if having:
      97                for node in having.walk():
      98                    if node in groups:
      99                        having.meta[FINAL] = True
     100                        break
     101
     102        # Pre-order transformations
     103        node = expression
     104        node = rewrite_between(node)
     105        node = uniq_sort(node, root)
     106        node = absorb_and_eliminate(node, root)
     107        node = simplify_concat(node)
     108        node = simplify_conditionals(node)
     109
     110        if constant_propagation:
     111            node = propagate_constants(node, root)
     112
     113        exp.replace_children(node, lambda e: _simplify(e, False))
     114
     115        # Post-order transformations
     116        node = simplify_not(node)
     117        node = flatten(node)
     118        node = simplify_connectors(node, root)
     119        node = remove_complements(node, root)
     120        node = simplify_coalesce(node)
     121        node.parent = expression.parent
     122        node = simplify_literals(node, root)
     123        node = simplify_equality(node)
     124        node = simplify_parens(node)
     125        node = simplify_datetrunc(node, dialect)
     126        node = sort_comparison(node)
     127        node = simplify_startswith(node)
     128
     129        if root:
     130            expression.replace(node)
     131        return node
     132
     133    expression = while_changing(expression, _simplify)
     134    remove_where_true(expression)
     135    return expression
     136
     137
     138def connector_depth(expression: exp.Expression) -> int:
     139    """
     140    Determine the maximum depth of a tree of Connectors.
     141
     142    For example:
     143        >>> from sqlglot import parse_one
     144        >>> connector_depth(parse_one("a AND b AND c AND d"))
     145        3
     146    """
     147    stack = deque([(expression, 0)])
     148    max_depth = 0
     149
     150    while stack:
     151        expression, depth = stack.pop()
     152
     153        if not isinstance(expression, exp.Connector):
     154            continue
     155
     156        depth += 1
     157        max_depth = max(depth, max_depth)
     158
     159        stack.append((expression.left, depth))
     160        stack.append((expression.right, depth))
     161
     162    return max_depth
     163
     164
     165def catch(*exceptions):
     166    """Decorator that ignores a simplification function if any of `exceptions` are raised"""
     167
     168    def decorator(func):
     169        def wrapped(expression, *args, **kwargs):
     170            try:
     171                return func(expression, *args, **kwargs)
     172            except exceptions:
     173                return expression
     174
     175        return wrapped
     176
     177    return decorator
     178
     179
     180def rewrite_between(expression: exp.Expression) -> exp.Expression:
     181    """Rewrite x between y and z to x >= y AND x <= z.
     182
     183    This is done because comparison simplification is only done on lt/lte/gt/gte.
     184    """
     185    if isinstance(expression, exp.Between):
     186        negate = isinstance(expression.parent, exp.Not)
     187
     188        expression = exp.and_(
     189            exp.GTE(this=expression.this.copy(), expression=expression.args["low"]),
     190            exp.LTE(this=expression.this.copy(), expression=expression.args["high"]),
     191            copy=False,
     192        )
     193
     194        if negate:
     195            expression = exp.paren(expression, copy=False)
     196
     197    return expression
     198
     199
     200COMPLEMENT_COMPARISONS = {
     201    exp.LT: exp.GTE,
     202    exp.GT: exp.LTE,
     203    exp.LTE: exp.GT,
     204    exp.GTE: exp.LT,
     205    exp.EQ: exp.NEQ,
     206    exp.NEQ: exp.EQ,
     207}
     208
     209COMPLEMENT_SUBQUERY_PREDICATES = {
     210    exp.All: exp.Any,
     211    exp.Any: exp.All,
     212}
     213
     214
     215def simplify_not(expression):
     216    """
     217    Demorgan's Law
     218    NOT (x OR y) -> NOT x AND NOT y
     219    NOT (x AND y) -> NOT x OR NOT y
     220    """
     221    if isinstance(expression, exp.Not):
     222        this = expression.this
     223        if is_null(this):
     224            return exp.null()
     225        if this.__class__ in COMPLEMENT_COMPARISONS:
     226            right = this.expression
     227            complement_subquery_predicate = COMPLEMENT_SUBQUERY_PREDICATES.get(right.__class__)
     228            if complement_subquery_predicate:
     229                right = complement_subquery_predicate(this=right.this)
     230
     231            return COMPLEMENT_COMPARISONS[this.__class__](this=this.this, expression=right)
     232        if isinstance(this, exp.Paren):
     233            condition = this.unnest()
     234            if isinstance(condition, exp.And):
     235                return exp.paren(
     236                    exp.or_(
     237                        exp.not_(condition.left, copy=False),
     238                        exp.not_(condition.right, copy=False),
     239                        copy=False,
     240                    )
     241                )
     242            if isinstance(condition, exp.Or):
     243                return exp.paren(
     244                    exp.and_(
     245                        exp.not_(condition.left, copy=False),
     246                        exp.not_(condition.right, copy=False),
     247                        copy=False,
     248                    )
     249                )
     250            if is_null(condition):
     251                return exp.null()
     252        if always_true(this):
     253            return exp.false()
     254        if is_false(this):
     255            return exp.true()
     256        if isinstance(this, exp.Not):
     257            # double negation
     258            # NOT NOT x -> x
     259            return this.this
     260    return expression
     261
     262
     263def flatten(expression):
     264    """
     265    A AND (B AND C) -> A AND B AND C
     266    A OR (B OR C) -> A OR B OR C
     267    """
     268    if isinstance(expression, exp.Connector):
     269        for node in expression.args.values():
     270            child = node.unnest()
     271            if isinstance(child, expression.__class__):
     272                node.replace(child)
     273    return expression
     274
     275
     276def simplify_connectors(expression, root=True):
     277    def _simplify_connectors(expression, left, right):
     278        if isinstance(expression, exp.And):
     279            if is_false(left) or is_false(right):
     280                return exp.false()
     281            if is_zero(left) or is_zero(right):
     282                return exp.false()
     283            if is_null(left) or is_null(right):
     284                return exp.null()
     285            if always_true(left) and always_true(right):
     286                return exp.true()
     287            if always_true(left):
     288                return right
     289            if always_true(right):
     290                return left
     291            return _simplify_comparison(expression, left, right)
     292        elif isinstance(expression, exp.Or):
     293            if always_true(left) or always_true(right):
     294                return exp.true()
     295            if (
     296                (is_null(left) and is_null(right))
     297                or (is_null(left) and always_false(right))
     298                or (always_false(left) and is_null(right))
     299            ):
     300                return exp.null()
     301            if is_false(left):
     302                return right
     303            if is_false(right):
     304                return left
     305            return _simplify_comparison(expression, left, right, or_=True)
     306        elif isinstance(expression, exp.Xor):
     307            if left == right:
     308                return exp.false()
     309
     310    if isinstance(expression, exp.Connector):
     311        return _flat_simplify(expression, _simplify_connectors, root)
     312    return expression
     313
     314
     315LT_LTE = (exp.LT, exp.LTE)
     316GT_GTE = (exp.GT, exp.GTE)
     317
     318COMPARISONS = (
     319    *LT_LTE,
     320    *GT_GTE,
     321    exp.EQ,
     322    exp.NEQ,
     323    exp.Is,
     324)
     325
     326INVERSE_COMPARISONS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     327    exp.LT: exp.GT,
     328    exp.GT: exp.LT,
     329    exp.LTE: exp.GTE,
     330    exp.GTE: exp.LTE,
     331}
     332
     333NONDETERMINISTIC = (exp.Rand, exp.Randn)
     334AND_OR = (exp.And, exp.Or)
     335
     336
     337def _simplify_comparison(expression, left, right, or_=False):
     338    if isinstance(left, COMPARISONS) and isinstance(right, COMPARISONS):
     339        ll, lr = left.args.values()
     340        rl, rr = right.args.values()
     341
     342        largs = {ll, lr}
     343        rargs = {rl, rr}
     344
     345        matching = largs & rargs
     346        columns = {m for m in matching if not _is_constant(m) and not m.find(*NONDETERMINISTIC)}
     347
     348        if matching and columns:
     349            try:
     350                l = first(largs - columns)
     351                r = first(rargs - columns)
     352            except StopIteration:
     353                return expression
     354
     355            if l.is_number and r.is_number:
     356                l = l.to_py()
     357                r = r.to_py()
     358            elif l.is_string and r.is_string:
     359                l = l.name
     360                r = r.name
     361            else:
     362                l = extract_date(l)
     363                if not l:
     364                    return None
     365                r = extract_date(r)
     366                if not r:
     367                    return None
     368                # python won't compare date and datetime, but many engines will upcast
     369                l, r = cast_as_datetime(l), cast_as_datetime(r)
     370
     371            for (a, av), (b, bv) in itertools.permutations(((left, l), (right, r))):
     372                if isinstance(a, LT_LTE) and isinstance(b, LT_LTE):
     373                    return left if (av > bv if or_ else av <= bv) else right
     374                if isinstance(a, GT_GTE) and isinstance(b, GT_GTE):
     375                    return left if (av < bv if or_ else av >= bv) else right
     376
     377                # we can't ever shortcut to true because the column could be null
     378                if not or_:
     379                    if isinstance(a, exp.LT) and isinstance(b, GT_GTE):
     380                        if av <= bv:
     381                            return exp.false()
     382                    elif isinstance(a, exp.GT) and isinstance(b, LT_LTE):
     383                        if av >= bv:
     384                            return exp.false()
     385                    elif isinstance(a, exp.EQ):
     386                        if isinstance(b, exp.LT):
     387                            return exp.false() if av >= bv else a
     388                        if isinstance(b, exp.LTE):
     389                            return exp.false() if av > bv else a
     390                        if isinstance(b, exp.GT):
     391                            return exp.false() if av <= bv else a
     392                        if isinstance(b, exp.GTE):
     393                            return exp.false() if av < bv else a
     394                        if isinstance(b, exp.NEQ):
     395                            return exp.false() if av == bv else a
     396    return None
     397
     398
     399def remove_complements(expression, root=True):
     400    """
     401    Removing complements.
     402
     403    A AND NOT A -> FALSE
     404    A OR NOT A -> TRUE
     405    """
     406    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
     407        ops = set(expression.flatten())
     408        for op in ops:
     409            if isinstance(op, exp.Not) and op.this in ops:
     410                return exp.false() if isinstance(expression, exp.And) else exp.true()
     411
     412    return expression
     413
     414
     415def uniq_sort(expression, root=True):
     416    """
     417    Uniq and sort a connector.
     418
     419    C AND A AND B AND B -> A AND B AND C
     420    """
     421    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
     422        flattened = tuple(expression.flatten())
     423
     424        if isinstance(expression, exp.Xor):
     425            result_func = exp.xor
     426            # Do not deduplicate XOR as A XOR A != A if A == True
     427            deduped = None
     428            arr = tuple((gen(e), e) for e in flattened)
     429        else:
     430            result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
     431            deduped = {gen(e): e for e in flattened}
     432            arr = tuple(deduped.items())
     433
     434        # check if the operands are already sorted, if not sort them
     435        # A AND C AND B -> A AND B AND C
     436        for i, (sql, e) in enumerate(arr[1:]):
     437            if sql < arr[i][0]:
     438                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
     439                break
     440        else:
     441            # we didn't have to sort but maybe we need to dedup
     442            if deduped and len(deduped) < len(flattened):
     443                expression = result_func(*deduped.values(), copy=False)
     444
     445    return expression
     446
     447
     448def absorb_and_eliminate(expression, root=True):
     449    """
     450    absorption:
     451        A AND (A OR B) -> A
     452        A OR (A AND B) -> A
     453        A AND (NOT A OR B) -> A AND B
     454        A OR (NOT A AND B) -> A OR B
     455    elimination:
     456        (A AND B) OR (A AND NOT B) -> A
     457        (A OR B) AND (A OR NOT B) -> A
     458    """
     459    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
     460        kind = exp.Or if isinstance(expression, exp.And) else exp.And
     461
     462        ops = tuple(expression.flatten())
     463
     464        # Initialize lookup tables:
     465        # Set of all operands, used to find complements for absorption.
     466        op_set = set()
     467        # Sub-operands, used to find subsets for absorption.
     468        subops = defaultdict(list)
     469        # Pairs of complements, used for elimination.
     470        pairs = defaultdict(list)
     471
     472        # Populate the lookup tables
     473        for op in ops:
     474            op_set.add(op)
     475
     476            if not isinstance(op, kind):
     477                # In cases like: A OR (A AND B)
     478                # Subop will be: ^
     479                subops[op].append({op})
     480                continue
     481
     482            # In cases like: (A AND B) OR (A AND B AND C)
     483            # Subops will be: ^     ^
     484            subset = set(op.flatten())
     485            for i in subset:
     486                subops[i].append(subset)
     487
     488            a, b = op.unnest_operands()
     489            if isinstance(a, exp.Not):
     490                pairs[frozenset((a.this, b))].append((op, b))
     491            if isinstance(b, exp.Not):
     492                pairs[frozenset((a, b.this))].append((op, a))
     493
     494        for op in ops:
     495            if not isinstance(op, kind):
     496                continue
     497
     498            a, b = op.unnest_operands()
     499
     500            # Absorb
     501            if isinstance(a, exp.Not) and a.this in op_set:
     502                a.replace(exp.true() if kind == exp.And else exp.false())
     503                continue
     504            if isinstance(b, exp.Not) and b.this in op_set:
     505                b.replace(exp.true() if kind == exp.And else exp.false())
     506                continue
     507            superset = set(op.flatten())
     508            if any(any(subset < superset for subset in subops[i]) for i in superset):
     509                op.replace(exp.false() if kind == exp.And else exp.true())
     510                continue
     511
     512            # Eliminate
     513            for other, complement in pairs[frozenset((a, b))]:
     514                op.replace(complement)
     515                other.replace(complement)
     516
     517    return expression
     518
     519
     520def propagate_constants(expression, root=True):
     521    """
     522    Propagate constants for conjunctions in DNF:
     523
     524    SELECT * FROM t WHERE a = b AND b = 5 becomes
     525    SELECT * FROM t WHERE a = 5 AND b = 5
     526
     527    Reference: https://www.sqlite.org/optoverview.html
     528    """
     529
     530    if (
     531        isinstance(expression, exp.And)
     532        and (root or not expression.same_parent)
     533        and sqlglot.optimizer.normalize.normalized(expression, dnf=True)
     534    ):
     535        constant_mapping = {}
     536        for expr in walk_in_scope(expression, prune=lambda node: isinstance(node, exp.If)):
     537            if isinstance(expr, exp.EQ):
     538                l, r = expr.left, expr.right
     539
     540                # TODO: create a helper that can be used to detect nested literal expressions such
     541                # as CAST(123456 AS BIGINT), since we usually want to treat those as literals too
     542                if isinstance(l, exp.Column) and isinstance(r, exp.Literal):
     543                    constant_mapping[l] = (id(l), r)
     544
     545        if constant_mapping:
     546            for column in find_all_in_scope(expression, exp.Column):
     547                parent = column.parent
     548                column_id, constant = constant_mapping.get(column) or (None, None)
     549                if (
     550                    column_id is not None
     551                    and id(column) != column_id
     552                    and not (isinstance(parent, exp.Is) and isinstance(parent.expression, exp.Null))
     553                ):
     554                    column.replace(constant.copy())
     555
     556    return expression
     557
     558
     559INVERSE_DATE_OPS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     560    exp.DateAdd: exp.Sub,
     561    exp.DateSub: exp.Add,
     562    exp.DatetimeAdd: exp.Sub,
     563    exp.DatetimeSub: exp.Add,
     564}
     565
     566INVERSE_OPS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     567    **INVERSE_DATE_OPS,
     568    exp.Add: exp.Sub,
     569    exp.Sub: exp.Add,
     570}
     571
     572
     573def _is_number(expression: exp.Expression) -> bool:
     574    return expression.is_number
     575
     576
     577def _is_interval(expression: exp.Expression) -> bool:
     578    return isinstance(expression, exp.Interval) and extract_interval(expression) is not None
     579
     580
     581@catch(ModuleNotFoundError, UnsupportedUnit)
     582def simplify_equality(expression: exp.Expression) -> exp.Expression:
     583    """
     584    Use the subtraction and addition properties of equality to simplify expressions:
     585
     586        x + 1 = 3 becomes x = 2
     587
     588    There are two binary operations in the above expression: + and =
     589    Here's how we reference all the operands in the code below:
     590
     591          l     r
     592        x + 1 = 3
     593        a   b
     594    """
     595    if isinstance(expression, COMPARISONS):
     596        l, r = expression.left, expression.right
     597
     598        if l.__class__ not in INVERSE_OPS:
     599            return expression
     600
     601        if r.is_number:
     602            a_predicate = _is_number
     603            b_predicate = _is_number
     604        elif _is_date_literal(r):
     605            a_predicate = _is_date_literal
     606            b_predicate = _is_interval
     607        else:
     608            return expression
     609
     610        if l.__class__ in INVERSE_DATE_OPS:
     611            l = t.cast(exp.IntervalOp, l)
     612            a = l.this
     613            b = l.interval()
     614        else:
     615            l = t.cast(exp.Binary, l)
     616            a, b = l.left, l.right
     617
     618        if not a_predicate(a) and b_predicate(b):
     619            pass
     620        elif not a_predicate(b) and b_predicate(a):
     621            a, b = b, a
     622        else:
     623            return expression
     624
     625        return expression.__class__(
     626            this=a, expression=INVERSE_OPS[l.__class__](this=r, expression=b)
     627        )
     628    return expression
     629
     630
     631def simplify_literals(expression, root=True):
     632    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
     633        return _flat_simplify(expression, _simplify_binary, root)
     634
     635    if isinstance(expression, exp.Neg) and isinstance(expression.this, exp.Neg):
     636        return expression.this.this
     637
     638    if type(expression) in INVERSE_DATE_OPS:
     639        return _simplify_binary(expression, expression.this, expression.interval()) or expression
     640
     641    return expression
     642
     643
     644NULL_OK = (exp.NullSafeEQ, exp.NullSafeNEQ, exp.PropertyEQ)
     645
     646
     647def _simplify_integer_cast(expr: exp.Expression) -> exp.Expression:
     648    if isinstance(expr, exp.Cast) and isinstance(expr.this, exp.Cast):
     649        this = _simplify_integer_cast(expr.this)
     650    else:
     651        this = expr.this
     652
     653    if isinstance(expr, exp.Cast) and this.is_int:
     654        num = this.to_py()
     655
     656        # Remove the (up)cast from small (byte-sized) integers in predicates which is side-effect free. Downcasts on any
     657        # integer type might cause overflow, thus the cast cannot be eliminated and the behavior is
     658        # engine-dependent
     659        if (
     660            TINYINT_MIN <= num <= TINYINT_MAX and expr.to.this in exp.DataType.SIGNED_INTEGER_TYPES
     661        ) or (
     662            UTINYINT_MIN <= num <= UTINYINT_MAX
     663            and expr.to.this in exp.DataType.UNSIGNED_INTEGER_TYPES
     664        ):
     665            return this
     666
     667    return expr
     668
     669
     670def _simplify_binary(expression, a, b):
     671    if isinstance(expression, COMPARISONS):
     672        a = _simplify_integer_cast(a)
     673        b = _simplify_integer_cast(b)
     674
     675    if isinstance(expression, exp.Is):
     676        if isinstance(b, exp.Not):
     677            c = b.this
     678            not_ = True
     679        else:
     680            c = b
     681            not_ = False
     682
     683        if is_null(c):
     684            if isinstance(a, exp.Literal):
     685                return exp.true() if not_ else exp.false()
     686            if is_null(a):
     687                return exp.false() if not_ else exp.true()
     688    elif isinstance(expression, NULL_OK):
     689        return None
     690    elif is_null(a) or is_null(b):
     691        return exp.null()
     692
     693    if a.is_number and b.is_number:
     694        num_a = a.to_py()
     695        num_b = b.to_py()
     696
     697        if isinstance(expression, exp.Add):
     698            return exp.Literal.number(num_a + num_b)
     699        if isinstance(expression, exp.Mul):
     700            return exp.Literal.number(num_a * num_b)
     701
     702        # We only simplify Sub, Div if a and b have the same parent because they're not associative
     703        if isinstance(expression, exp.Sub):
     704            return exp.Literal.number(num_a - num_b) if a.parent is b.parent else None
     705        if isinstance(expression, exp.Div):
     706            # engines have differing int div behavior so intdiv is not safe
     707            if (isinstance(num_a, int) and isinstance(num_b, int)) or a.parent is not b.parent:
     708                return None
     709            return exp.Literal.number(num_a / num_b)
     710
     711        boolean = eval_boolean(expression, num_a, num_b)
     712
     713        if boolean:
     714            return boolean
     715    elif a.is_string and b.is_string:
     716        boolean = eval_boolean(expression, a.this, b.this)
     717
     718        if boolean:
     719            return boolean
     720    elif _is_date_literal(a) and isinstance(b, exp.Interval):
     721        date, b = extract_date(a), extract_interval(b)
     722        if date and b:
     723            if isinstance(expression, (exp.Add, exp.DateAdd, exp.DatetimeAdd)):
     724                return date_literal(date + b, extract_type(a))
     725            if isinstance(expression, (exp.Sub, exp.DateSub, exp.DatetimeSub)):
     726                return date_literal(date - b, extract_type(a))
     727    elif isinstance(a, exp.Interval) and _is_date_literal(b):
     728        a, date = extract_interval(a), extract_date(b)
     729        # you cannot subtract a date from an interval
     730        if a and b and isinstance(expression, exp.Add):
     731            return date_literal(a + date, extract_type(b))
     732    elif _is_date_literal(a) and _is_date_literal(b):
     733        if isinstance(expression, exp.Predicate):
     734            a, b = extract_date(a), extract_date(b)
     735            boolean = eval_boolean(expression, a, b)
     736            if boolean:
     737                return boolean
     738
     739    return None
     740
     741
     742def simplify_parens(expression):
     743    if not isinstance(expression, exp.Paren):
     744        return expression
     745
     746    this = expression.this
     747    parent = expression.parent
     748    parent_is_predicate = isinstance(parent, exp.Predicate)
     749
     750    if (
     751        not isinstance(this, exp.Select)
     752        and not isinstance(parent, exp.SubqueryPredicate)
     753        and (
     754            not isinstance(parent, (exp.Condition, exp.Binary))
     755            or isinstance(parent, exp.Paren)
     756            or (
     757                not isinstance(this, exp.Binary)
     758                and not (isinstance(this, (exp.Not, exp.Is)) and parent_is_predicate)
     759            )
     760            or (isinstance(this, exp.Predicate) and not parent_is_predicate)
     761            or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
     762            or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
     763            or (isinstance(this, exp.Mul) and isinstance(parent, (exp.Add, exp.Sub)))
     764        )
     765    ):
     766        return this
     767    return expression
     768
     769
     770def _is_nonnull_constant(expression: exp.Expression) -> bool:
     771    return isinstance(expression, exp.NONNULL_CONSTANTS) or _is_date_literal(expression)
     772
     773
     774def _is_constant(expression: exp.Expression) -> bool:
     775    return isinstance(expression, exp.CONSTANTS) or _is_date_literal(expression)
     776
     777
     778def simplify_coalesce(expression):
     779    # COALESCE(x) -> x
     780    if (
     781        isinstance(expression, exp.Coalesce)
     782        and (not expression.expressions or _is_nonnull_constant(expression.this))
     783        # COALESCE is also used as a Spark partitioning hint
     784        and not isinstance(expression.parent, exp.Hint)
     785    ):
     786        return expression.this
     787
     788    if not isinstance(expression, COMPARISONS):
     789        return expression
     790
     791    if isinstance(expression.left, exp.Coalesce):
     792        coalesce = expression.left
     793        other = expression.right
     794    elif isinstance(expression.right, exp.Coalesce):
     795        coalesce = expression.right
     796        other = expression.left
     797    else:
     798        return expression
     799
     800    # This transformation is valid for non-constants,
     801    # but it really only does anything if they are both constants.
     802    if not _is_constant(other):
     803        return expression
     804
     805    # Find the first constant arg
     806    for arg_index, arg in enumerate(coalesce.expressions):
     807        if _is_constant(arg):
     808            break
     809    else:
     810        return expression
     811
     812    coalesce.set("expressions", coalesce.expressions[:arg_index])
     813
     814    # Remove the COALESCE function. This is an optimization, skipping a simplify iteration,
     815    # since we already remove COALESCE at the top of this function.
     816    coalesce = coalesce if coalesce.expressions else coalesce.this
     817
     818    # This expression is more complex than when we started, but it will get simplified further
     819    return exp.paren(
     820        exp.or_(
     821            exp.and_(
     822                coalesce.is_(exp.null()).not_(copy=False),
     823                expression.copy(),
     824                copy=False,
     825            ),
     826            exp.and_(
     827                coalesce.is_(exp.null()),
     828                type(expression)(this=arg.copy(), expression=other.copy()),
     829                copy=False,
     830            ),
     831            copy=False,
     832        )
     833    )
     834
     835
     836CONCATS = (exp.Concat, exp.DPipe)
     837
     838
     839def simplify_concat(expression):
     840    """Reduces all groups that contain string literals by concatenating them."""
     841    if not isinstance(expression, CONCATS) or (
     842        # We can't reduce a CONCAT_WS call if we don't statically know the separator
     843        isinstance(expression, exp.ConcatWs) and not expression.expressions[0].is_string
     844    ):
     845        return expression
     846
     847    if isinstance(expression, exp.ConcatWs):
     848        sep_expr, *expressions = expression.expressions
     849        sep = sep_expr.name
     850        concat_type = exp.ConcatWs
     851        args = {}
     852    else:
     853        expressions = expression.expressions
     854        sep = ""
     855        concat_type = exp.Concat
     856        args = {
     857            "safe": expression.args.get("safe"),
     858            "coalesce": expression.args.get("coalesce"),
     859        }
     860
     861    new_args = []
     862    for is_string_group, group in itertools.groupby(
     863        expressions or expression.flatten(), lambda e: e.is_string
     864    ):
     865        if is_string_group:
     866            new_args.append(exp.Literal.string(sep.join(string.name for string in group)))
     867        else:
     868            new_args.extend(group)
     869
     870    if len(new_args) == 1 and new_args[0].is_string:
     871        return new_args[0]
     872
     873    if concat_type is exp.ConcatWs:
     874        new_args = [sep_expr] + new_args
     875    elif isinstance(expression, exp.DPipe):
     876        return reduce(lambda x, y: exp.DPipe(this=x, expression=y), new_args)
     877
     878    return concat_type(expressions=new_args, **args)
     879
     880
     881def simplify_conditionals(expression):
     882    """Simplifies expressions like IF, CASE if their condition is statically known."""
     883    if isinstance(expression, exp.Case):
     884        this = expression.this
     885        for case in expression.args["ifs"]:
     886            cond = case.this
     887            if this:
     888                # Convert CASE x WHEN matching_value ... to CASE WHEN x = matching_value ...
     889                cond = cond.replace(this.pop().eq(cond))
     890
     891            if always_true(cond):
     892                return case.args["true"]
     893
     894            if always_false(cond):
     895                case.pop()
     896                if not expression.args["ifs"]:
     897                    return expression.args.get("default") or exp.null()
     898    elif isinstance(expression, exp.If) and not isinstance(expression.parent, exp.Case):
     899        if always_true(expression.this):
     900            return expression.args["true"]
     901        if always_false(expression.this):
     902            return expression.args.get("false") or exp.null()
     903
     904    return expression
     905
     906
     907def simplify_startswith(expression: exp.Expression) -> exp.Expression:
     908    """
     909    Reduces a prefix check to either TRUE or FALSE if both the string and the
     910    prefix are statically known.
     911
     912    Example:
     913        >>> from sqlglot import parse_one
     914        >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
     915        'TRUE'
     916    """
     917    if (
     918        isinstance(expression, exp.StartsWith)
     919        and expression.this.is_string
     920        and expression.expression.is_string
     921    ):
     922        return exp.convert(expression.name.startswith(expression.expression.name))
     923
     924    return expression
     925
     926
     927DateRange = t.Tuple[datetime.date, datetime.date]
     928
     929
     930def _datetrunc_range(date: datetime.date, unit: str, dialect: Dialect) -> t.Optional[DateRange]:
     931    """
     932    Get the date range for a DATE_TRUNC equality comparison:
     933
     934    Example:
     935        _datetrunc_range(date(2021-01-01), 'year') == (date(2021-01-01), date(2022-01-01))
     936    Returns:
     937        tuple of [min, max) or None if a value can never be equal to `date` for `unit`
     938    """
     939    floor = date_floor(date, unit, dialect)
     940
     941    if date != floor:
     942        # This will always be False, except for NULL values.
     943        return None
     944
     945    return floor, floor + interval(unit)
     946
     947
     948def _datetrunc_eq_expression(
     949    left: exp.Expression, drange: DateRange, target_type: t.Optional[exp.DataType]
     950) -> exp.Expression:
     951    """Get the logical expression for a date range"""
     952    return exp.and_(
     953        left >= date_literal(drange[0], target_type),
     954        left < date_literal(drange[1], target_type),
     955        copy=False,
     956    )
     957
     958
     959def _datetrunc_eq(
     960    left: exp.Expression,
     961    date: datetime.date,
     962    unit: str,
     963    dialect: Dialect,
     964    target_type: t.Optional[exp.DataType],
     965) -> t.Optional[exp.Expression]:
     966    drange = _datetrunc_range(date, unit, dialect)
     967    if not drange:
     968        return None
     969
     970    return _datetrunc_eq_expression(left, drange, target_type)
     971
     972
     973def _datetrunc_neq(
     974    left: exp.Expression,
     975    date: datetime.date,
     976    unit: str,
     977    dialect: Dialect,
     978    target_type: t.Optional[exp.DataType],
     979) -> t.Optional[exp.Expression]:
     980    drange = _datetrunc_range(date, unit, dialect)
     981    if not drange:
     982        return None
     983
     984    return exp.and_(
     985        left < date_literal(drange[0], target_type),
     986        left >= date_literal(drange[1], target_type),
     987        copy=False,
     988    )
     989
     990
     991DATETRUNC_BINARY_COMPARISONS: t.Dict[t.Type[exp.Expression], DateTruncBinaryTransform] = {
     992    exp.LT: lambda l, dt, u, d, t: l
     993    < date_literal(dt if dt == date_floor(dt, u, d) else date_floor(dt, u, d) + interval(u), t),
     994    exp.GT: lambda l, dt, u, d, t: l >= date_literal(date_floor(dt, u, d) + interval(u), t),
     995    exp.LTE: lambda l, dt, u, d, t: l < date_literal(date_floor(dt, u, d) + interval(u), t),
     996    exp.GTE: lambda l, dt, u, d, t: l >= date_literal(date_ceil(dt, u, d), t),
     997    exp.EQ: _datetrunc_eq,
     998    exp.NEQ: _datetrunc_neq,
     999}
    1000DATETRUNC_COMPARISONS = {exp.In, *DATETRUNC_BINARY_COMPARISONS}
    1001DATETRUNCS = (exp.DateTrunc, exp.TimestampTrunc)
    1002
    1003
    1004def _is_datetrunc_predicate(left: exp.Expression, right: exp.Expression) -> bool:
    1005    return isinstance(left, DATETRUNCS) and _is_date_literal(right)
    1006
    1007
    1008@catch(ModuleNotFoundError, UnsupportedUnit)
    1009def simplify_datetrunc(expression: exp.Expression, dialect: Dialect) -> exp.Expression:
    1010    """Simplify expressions like `DATE_TRUNC('year', x) >= CAST('2021-01-01' AS DATE)`"""
    1011    comparison = expression.__class__
    1012
    1013    if isinstance(expression, DATETRUNCS):
    1014        this = expression.this
    1015        trunc_type = extract_type(this)
    1016        date = extract_date(this)
    1017        if date and expression.unit:
    1018            return date_literal(date_floor(date, expression.unit.name.lower(), dialect), trunc_type)
    1019    elif comparison not in DATETRUNC_COMPARISONS:
    1020        return expression
    1021
    1022    if isinstance(expression, exp.Binary):
    1023        l, r = expression.left, expression.right
    1024
    1025        if not _is_datetrunc_predicate(l, r):
    1026            return expression
    1027
    1028        l = t.cast(exp.DateTrunc, l)
    1029        trunc_arg = l.this
    1030        unit = l.unit.name.lower()
    1031        date = extract_date(r)
    1032
    1033        if not date:
    1034            return expression
    1035
    1036        return (
    1037            DATETRUNC_BINARY_COMPARISONS[comparison](
    1038                trunc_arg, date, unit, dialect, extract_type(r)
    1039            )
    1040            or expression
    1041        )
    1042
    1043    if isinstance(expression, exp.In):
    1044        l = expression.this
    1045        rs = expression.expressions
    1046
    1047        if rs and all(_is_datetrunc_predicate(l, r) for r in rs):
    1048            l = t.cast(exp.DateTrunc, l)
    1049            unit = l.unit.name.lower()
    1050
    1051            ranges = []
    1052            for r in rs:
    1053                date = extract_date(r)
    1054                if not date:
    1055                    return expression
    1056                drange = _datetrunc_range(date, unit, dialect)
    1057                if drange:
    1058                    ranges.append(drange)
    1059
    1060            if not ranges:
    1061                return expression
    1062
    1063            ranges = merge_ranges(ranges)
    1064            target_type = extract_type(*rs)
    1065
    1066            return exp.or_(
    1067                *[_datetrunc_eq_expression(l, drange, target_type) for drange in ranges], copy=False
    1068            )
    1069
    1070    return expression
    1071
    1072
    1073def sort_comparison(expression: exp.Expression) -> exp.Expression:
    1074    if expression.__class__ in COMPLEMENT_COMPARISONS:
    1075        l, r = expression.this, expression.expression
    1076        l_column = isinstance(l, exp.Column)
    1077        r_column = isinstance(r, exp.Column)
    1078        l_const = _is_constant(l)
    1079        r_const = _is_constant(r)
    1080
    1081        if (
    1082            (l_column and not r_column)
    1083            or (r_const and not l_const)
    1084            or isinstance(r, exp.SubqueryPredicate)
    1085        ):
    1086            return expression
    1087        if (r_column and not l_column) or (l_const and not r_const) or (gen(l) > gen(r)):
    1088            return INVERSE_COMPARISONS.get(expression.__class__, expression.__class__)(
    1089                this=r, expression=l
    1090            )
    1091    return expression
    1092
    1093
    1094# CROSS joins result in an empty table if the right table is empty.
    1095# So we can only simplify certain types of joins to CROSS.
    1096# Or in other words, LEFT JOIN x ON TRUE != CROSS JOIN x
    1097JOINS = {
    1098    ("", ""),
    1099    ("", "INNER"),
    1100    ("RIGHT", ""),
    1101    ("RIGHT", "OUTER"),
    1102}
    1103
    1104
    1105def remove_where_true(expression):
    1106    for where in expression.find_all(exp.Where):
    1107        if always_true(where.this):
    1108            where.pop()
    1109    for join in expression.find_all(exp.Join):
    1110        if (
    1111            always_true(join.args.get("on"))
    1112            and not join.args.get("using")
    1113            and not join.args.get("method")
    1114            and (join.side, join.kind) in JOINS
    1115        ):
    1116            join.args["on"].pop()
    1117            join.set("side", None)
    1118            join.set("kind", "CROSS")
    1119
    1120
    1121def always_true(expression):
    1122    return (isinstance(expression, exp.Boolean) and expression.this) or (
    1123        isinstance(expression, exp.Literal) and not is_zero(expression)
    1124    )
    1125
    1126
    1127def always_false(expression):
    1128    return is_false(expression) or is_null(expression) or is_zero(expression)
    1129
    1130
    1131def is_zero(expression):
    1132    return isinstance(expression, exp.Literal) and expression.to_py() == 0
    1133
    1134
    1135def is_complement(a, b):
    1136    return isinstance(b, exp.Not) and b.this == a
    1137
    1138
    1139def is_false(a: exp.Expression) -> bool:
    1140    return type(a) is exp.Boolean and not a.this
    1141
    1142
    1143def is_null(a: exp.Expression) -> bool:
    1144    return type(a) is exp.Null
    1145
    1146
    1147def eval_boolean(expression, a, b):
    1148    if isinstance(expression, (exp.EQ, exp.Is)):
    1149        return boolean_literal(a == b)
    1150    if isinstance(expression, exp.NEQ):
    1151        return boolean_literal(a != b)
    1152    if isinstance(expression, exp.GT):
    1153        return boolean_literal(a > b)
    1154    if isinstance(expression, exp.GTE):
    1155        return boolean_literal(a >= b)
    1156    if isinstance(expression, exp.LT):
    1157        return boolean_literal(a < b)
    1158    if isinstance(expression, exp.LTE):
    1159        return boolean_literal(a <= b)
    1160    return None
    1161
    1162
    1163def cast_as_date(value: t.Any) -> t.Optional[datetime.date]:
    1164    if isinstance(value, datetime.datetime):
    1165        return value.date()
    1166    if isinstance(value, datetime.date):
    1167        return value
    1168    try:
    1169        return datetime.datetime.fromisoformat(value).date()
    1170    except ValueError:
    1171        return None
    1172
    1173
    1174def cast_as_datetime(value: t.Any) -> t.Optional[datetime.datetime]:
    1175    if isinstance(value, datetime.datetime):
    1176        return value
    1177    if isinstance(value, datetime.date):
    1178        return datetime.datetime(year=value.year, month=value.month, day=value.day)
    1179    try:
    1180        return datetime.datetime.fromisoformat(value)
    1181    except ValueError:
    1182        return None
    1183
    1184
    1185def cast_value(value: t.Any, to: exp.DataType) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1186    if not value:
    1187        return None
    1188    if to.is_type(exp.DataType.Type.DATE):
    1189        return cast_as_date(value)
    1190    if to.is_type(*exp.DataType.TEMPORAL_TYPES):
    1191        return cast_as_datetime(value)
    1192    return None
    1193
    1194
    1195def extract_date(cast: exp.Expression) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1196    if isinstance(cast, exp.Cast):
    1197        to = cast.to
    1198    elif isinstance(cast, exp.TsOrDsToDate) and not cast.args.get("format"):
    1199        to = exp.DataType.build(exp.DataType.Type.DATE)
    1200    else:
    1201        return None
    1202
    1203    if isinstance(cast.this, exp.Literal):
    1204        value: t.Any = cast.this.name
    1205    elif isinstance(cast.this, (exp.Cast, exp.TsOrDsToDate)):
    1206        value = extract_date(cast.this)
    1207    else:
    1208        return None
    1209    return cast_value(value, to)
    1210
    1211
    1212def _is_date_literal(expression: exp.Expression) -> bool:
    1213    return extract_date(expression) is not None
    1214
    1215
    1216def extract_interval(expression):
    1217    try:
    1218        n = int(expression.this.to_py())
    1219        unit = expression.text("unit").lower()
    1220        return interval(unit, n)
    1221    except (UnsupportedUnit, ModuleNotFoundError, ValueError):
    1222        return None
    1223
    1224
    1225def extract_type(*expressions):
    1226    target_type = None
    1227    for expression in expressions:
    1228        target_type = expression.to if isinstance(expression, exp.Cast) else expression.type
    1229        if target_type:
    1230            break
    1231
    1232    return target_type
    1233
    1234
    1235def date_literal(date, target_type=None):
    1236    if not target_type or not target_type.is_type(*exp.DataType.TEMPORAL_TYPES):
    1237        target_type = (
    1238            exp.DataType.Type.DATETIME
    1239            if isinstance(date, datetime.datetime)
    1240            else exp.DataType.Type.DATE
    1241        )
    1242
    1243    return exp.cast(exp.Literal.string(date), target_type)
    1244
    1245
    1246def interval(unit: str, n: int = 1):
    1247    from dateutil.relativedelta import relativedelta
    1248
    1249    if unit == "year":
    1250        return relativedelta(years=1 * n)
    1251    if unit == "quarter":
    1252        return relativedelta(months=3 * n)
    1253    if unit == "month":
    1254        return relativedelta(months=1 * n)
    1255    if unit == "week":
    1256        return relativedelta(weeks=1 * n)
    1257    if unit == "day":
    1258        return relativedelta(days=1 * n)
    1259    if unit == "hour":
    1260        return relativedelta(hours=1 * n)
    1261    if unit == "minute":
    1262        return relativedelta(minutes=1 * n)
    1263    if unit == "second":
    1264        return relativedelta(seconds=1 * n)
    1265
    1266    raise UnsupportedUnit(f"Unsupported unit: {unit}")
    1267
    1268
    1269def date_floor(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1270    if unit == "year":
    1271        return d.replace(month=1, day=1)
    1272    if unit == "quarter":
    1273        if d.month <= 3:
    1274            return d.replace(month=1, day=1)
    1275        elif d.month <= 6:
    1276            return d.replace(month=4, day=1)
    1277        elif d.month <= 9:
    1278            return d.replace(month=7, day=1)
    1279        else:
    1280            return d.replace(month=10, day=1)
    1281    if unit == "month":
    1282        return d.replace(month=d.month, day=1)
    1283    if unit == "week":
    1284        # Assuming week starts on Monday (0) and ends on Sunday (6)
    1285        return d - datetime.timedelta(days=d.weekday() - dialect.WEEK_OFFSET)
    1286    if unit == "day":
    1287        return d
    1288
    1289    raise UnsupportedUnit(f"Unsupported unit: {unit}")
    1290
    1291
    1292def date_ceil(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1293    floor = date_floor(d, unit, dialect)
    1294
    1295    if floor == d:
    1296        return d
    1297
    1298    return floor + interval(unit)
    1299
    1300
    1301def boolean_literal(condition):
    1302    return exp.true() if condition else exp.false()
    1303
    1304
    1305def _flat_simplify(expression, simplifier, root=True):
    1306    if root or not expression.same_parent:
    1307        operands = []
    1308        queue = deque(expression.flatten(unnest=False))
    1309        size = len(queue)
    1310
    1311        while queue:
    1312            a = queue.popleft()
    1313
    1314            for b in queue:
    1315                result = simplifier(expression, a, b)
    1316
    1317                if result and result is not expression:
    1318                    queue.remove(b)
    1319                    queue.appendleft(result)
    1320                    break
    1321            else:
    1322                operands.append(a)
    1323
    1324        if len(operands) < size:
    1325            return functools.reduce(
    1326                lambda a, b: expression.__class__(this=a, expression=b), operands
    1327            )
    1328    return expression
    1329
    1330
    1331def gen(expression: t.Any, comments: bool = False) -> str:
    1332    """Simple pseudo sql generator for quickly generating sortable and uniq strings.
    1333
    1334    Sorting and deduping sql is a necessary step for optimization. Calling the actual
    1335    generator is expensive so we have a bare minimum sql generator here.
    1336
    1337    Args:
    1338        expression: the expression to convert into a SQL string.
    1339        comments: whether to include the expression's comments.
    1340    """
    1341    return Gen().gen(expression, comments=comments)
    1342
    1343
    1344class Gen:
    1345    def __init__(self):
    1346        self.stack = []
    1347        self.sqls = []
    1348
    1349    def gen(self, expression: exp.Expression, comments: bool = False) -> str:
    1350        self.stack = [expression]
    1351        self.sqls.clear()
    1352
    1353        while self.stack:
    1354            node = self.stack.pop()
    1355
    1356            if isinstance(node, exp.Expression):
    1357                if comments and node.comments:
    1358                    self.stack.append(f" /*{','.join(node.comments)}*/")
    1359
    1360                exp_handler_name = f"{node.key}_sql"
    1361
    1362                if hasattr(self, exp_handler_name):
    1363                    getattr(self, exp_handler_name)(node)
    1364                elif isinstance(node, exp.Func):
    1365                    self._function(node)
    1366                else:
    1367                    key = node.key.upper()
    1368                    self.stack.append(f"{key} " if self._args(node) else key)
    1369            elif type(node) is list:
    1370                for n in reversed(node):
    1371                    if n is not None:
    1372                        self.stack.extend((n, ","))
    1373                if node:
    1374                    self.stack.pop()
    1375            else:
    1376                if node is not None:
    1377                    self.sqls.append(str(node))
    1378
    1379        return "".join(self.sqls)
    1380
    1381    def add_sql(self, e: exp.Add) -> None:
    1382        self._binary(e, " + ")
    1383
    1384    def alias_sql(self, e: exp.Alias) -> None:
    1385        self.stack.extend(
    1386            (
    1387                e.args.get("alias"),
    1388                " AS ",
    1389                e.args.get("this"),
    1390            )
    1391        )
    1392
    1393    def and_sql(self, e: exp.And) -> None:
    1394        self._binary(e, " AND ")
    1395
    1396    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1397        this = e.this
    1398        if isinstance(this, str):
    1399            name = this.upper()
    1400        elif isinstance(this, exp.Identifier):
    1401            name = this.this
    1402            name = f'"{name}"' if this.quoted else name.upper()
    1403        else:
    1404            raise ValueError(
    1405                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1406            )
    1407
    1408        self.stack.extend(
    1409            (
    1410                ")",
    1411                e.expressions,
    1412                "(",
    1413                name,
    1414            )
    1415        )
    1416
    1417    def between_sql(self, e: exp.Between) -> None:
    1418        self.stack.extend(
    1419            (
    1420                e.args.get("high"),
    1421                " AND ",
    1422                e.args.get("low"),
    1423                " BETWEEN ",
    1424                e.this,
    1425            )
    1426        )
    1427
    1428    def boolean_sql(self, e: exp.Boolean) -> None:
    1429        self.stack.append("TRUE" if e.this else "FALSE")
    1430
    1431    def bracket_sql(self, e: exp.Bracket) -> None:
    1432        self.stack.extend(
    1433            (
    1434                "]",
    1435                e.expressions,
    1436                "[",
    1437                e.this,
    1438            )
    1439        )
    1440
    1441    def column_sql(self, e: exp.Column) -> None:
    1442        for p in reversed(e.parts):
    1443            self.stack.extend((p, "."))
    1444        self.stack.pop()
    1445
    1446    def datatype_sql(self, e: exp.DataType) -> None:
    1447        self._args(e, 1)
    1448        self.stack.append(f"{e.this.name} ")
    1449
    1450    def div_sql(self, e: exp.Div) -> None:
    1451        self._binary(e, " / ")
    1452
    1453    def dot_sql(self, e: exp.Dot) -> None:
    1454        self._binary(e, ".")
    1455
    1456    def eq_sql(self, e: exp.EQ) -> None:
    1457        self._binary(e, " = ")
    1458
    1459    def from_sql(self, e: exp.From) -> None:
    1460        self.stack.extend((e.this, "FROM "))
    1461
    1462    def gt_sql(self, e: exp.GT) -> None:
    1463        self._binary(e, " > ")
    1464
    1465    def gte_sql(self, e: exp.GTE) -> None:
    1466        self._binary(e, " >= ")
    1467
    1468    def identifier_sql(self, e: exp.Identifier) -> None:
    1469        self.stack.append(f'"{e.this}"' if e.quoted else e.this)
    1470
    1471    def ilike_sql(self, e: exp.ILike) -> None:
    1472        self._binary(e, " ILIKE ")
    1473
    1474    def in_sql(self, e: exp.In) -> None:
    1475        self.stack.append(")")
    1476        self._args(e, 1)
    1477        self.stack.extend(
    1478            (
    1479                "(",
    1480                " IN ",
    1481                e.this,
    1482            )
    1483        )
    1484
    1485    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1486        self._binary(e, " DIV ")
    1487
    1488    def is_sql(self, e: exp.Is) -> None:
    1489        self._binary(e, " IS ")
    1490
    1491    def like_sql(self, e: exp.Like) -> None:
    1492        self._binary(e, " Like ")
    1493
    1494    def literal_sql(self, e: exp.Literal) -> None:
    1495        self.stack.append(f"'{e.this}'" if e.is_string else e.this)
    1496
    1497    def lt_sql(self, e: exp.LT) -> None:
    1498        self._binary(e, " < ")
    1499
    1500    def lte_sql(self, e: exp.LTE) -> None:
    1501        self._binary(e, " <= ")
    1502
    1503    def mod_sql(self, e: exp.Mod) -> None:
    1504        self._binary(e, " % ")
    1505
    1506    def mul_sql(self, e: exp.Mul) -> None:
    1507        self._binary(e, " * ")
    1508
    1509    def neg_sql(self, e: exp.Neg) -> None:
    1510        self._unary(e, "-")
    1511
    1512    def neq_sql(self, e: exp.NEQ) -> None:
    1513        self._binary(e, " <> ")
    1514
    1515    def not_sql(self, e: exp.Not) -> None:
    1516        self._unary(e, "NOT ")
    1517
    1518    def null_sql(self, e: exp.Null) -> None:
    1519        self.stack.append("NULL")
    1520
    1521    def or_sql(self, e: exp.Or) -> None:
    1522        self._binary(e, " OR ")
    1523
    1524    def paren_sql(self, e: exp.Paren) -> None:
    1525        self.stack.extend(
    1526            (
    1527                ")",
    1528                e.this,
    1529                "(",
    1530            )
    1531        )
    1532
    1533    def sub_sql(self, e: exp.Sub) -> None:
    1534        self._binary(e, " - ")
    1535
    1536    def subquery_sql(self, e: exp.Subquery) -> None:
    1537        self._args(e, 2)
    1538        alias = e.args.get("alias")
    1539        if alias:
    1540            self.stack.append(alias)
    1541        self.stack.extend((")", e.this, "("))
    1542
    1543    def table_sql(self, e: exp.Table) -> None:
    1544        self._args(e, 4)
    1545        alias = e.args.get("alias")
    1546        if alias:
    1547            self.stack.append(alias)
    1548        for p in reversed(e.parts):
    1549            self.stack.extend((p, "."))
    1550        self.stack.pop()
    1551
    1552    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1553        columns = e.columns
    1554
    1555        if columns:
    1556            self.stack.extend((")", columns, "("))
    1557
    1558        self.stack.extend((e.this, " AS "))
    1559
    1560    def var_sql(self, e: exp.Var) -> None:
    1561        self.stack.append(e.this)
    1562
    1563    def _binary(self, e: exp.Binary, op: str) -> None:
    1564        self.stack.extend((e.expression, op, e.this))
    1565
    1566    def _unary(self, e: exp.Unary, op: str) -> None:
    1567        self.stack.extend((e.this, op))
    1568
    1569    def _function(self, e: exp.Func) -> None:
    1570        self.stack.extend(
    1571            (
    1572                ")",
    1573                list(e.args.values()),
    1574                "(",
    1575                e.sql_name(),
    1576            )
    1577        )
    1578
    1579    def _args(self, node: exp.Expression, arg_index: int = 0) -> bool:
    1580        kvs = []
    1581        arg_types = list(node.arg_types)[arg_index:] if arg_index else node.arg_types
    1582
    1583        for k in arg_types or arg_types:
    1584            v = node.args.get(k)
    1585
    1586            if v is not None:
    1587                kvs.append([f":{k}", v])
    1588        if kvs:
    1589            self.stack.append(kvs)
    1590            return True
    1591        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, dialect: Union[str, sqlglot.dialects.dialect.Dialect, Type[sqlglot.dialects.dialect.Dialect], NoneType] = None, max_depth: Optional[int] = None): View Source

     40def simplify(
     41    expression: exp.Expression,
     42    constant_propagation: bool = False,
     43    dialect: DialectType = None,
     44    max_depth: t.Optional[int] = 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        max_depth: Chains of Connectors (AND, OR, etc) exceeding `max_depth` will be skipped
     59    Returns:
     60        sqlglot.Expression: simplified expression
     61    """
     62
     63    dialect = Dialect.get_or_raise(dialect)
     64
     65    def _simplify(expression, root=True):
     66        if (
     67            max_depth
     68            and isinstance(expression, exp.Connector)
     69            and not isinstance(expression.parent, exp.Connector)
     70        ):
     71            depth = connector_depth(expression)
     72            if depth > max_depth:
     73                logger.info(
     74                    f"Skipping simplification because connector depth {depth} exceeds max {max_depth}"
     75                )
     76                return expression
     77
     78        if expression.meta.get(FINAL):
     79            return expression
     80
     81        # group by expressions cannot be simplified, for example
     82        # select x + 1 + 1 FROM y GROUP BY x + 1 + 1
     83        # the projection must exactly match the group by key
     84        group = expression.args.get("group")
     85
     86        if group and hasattr(expression, "selects"):
     87            groups = set(group.expressions)
     88            group.meta[FINAL] = True
     89
     90            for e in expression.selects:
     91                for node in e.walk():
     92                    if node in groups:
     93                        e.meta[FINAL] = True
     94                        break
     95
     96            having = expression.args.get("having")
     97            if having:
     98                for node in having.walk():
     99                    if node in groups:
    100                        having.meta[FINAL] = True
    101                        break
    102
    103        # Pre-order transformations
    104        node = expression
    105        node = rewrite_between(node)
    106        node = uniq_sort(node, root)
    107        node = absorb_and_eliminate(node, root)
    108        node = simplify_concat(node)
    109        node = simplify_conditionals(node)
    110
    111        if constant_propagation:
    112            node = propagate_constants(node, root)
    113
    114        exp.replace_children(node, lambda e: _simplify(e, False))
    115
    116        # Post-order transformations
    117        node = simplify_not(node)
    118        node = flatten(node)
    119        node = simplify_connectors(node, root)
    120        node = remove_complements(node, root)
    121        node = simplify_coalesce(node)
    122        node.parent = expression.parent
    123        node = simplify_literals(node, root)
    124        node = simplify_equality(node)
    125        node = simplify_parens(node)
    126        node = simplify_datetrunc(node, dialect)
    127        node = sort_comparison(node)
    128        node = simplify_startswith(node)
    129
    130        if root:
    131            expression.replace(node)
    132        return node
    133
    134    expression = while_changing(expression, _simplify)
    135    remove_where_true(expression)
    136    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
- max_depth: Chains of Connectors (AND, OR, etc) exceeding `max_depth` will be skipped

###### Returns:

> sqlglot.Expression: simplified expression

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

    139def connector_depth(expression: exp.Expression) -> int:
    140    """
    141    Determine the maximum depth of a tree of Connectors.
    142
    143    For example:
    144        >>> from sqlglot import parse_one
    145        >>> connector_depth(parse_one("a AND b AND c AND d"))
    146        3
    147    """
    148    stack = deque([(expression, 0)])
    149    max_depth = 0
    150
    151    while stack:
    152        expression, depth = stack.pop()
    153
    154        if not isinstance(expression, exp.Connector):
    155            continue
    156
    157        depth += 1
    158        max_depth = max(depth, max_depth)
    159
    160        stack.append((expression.left, depth))
    161        stack.append((expression.right, depth))
    162
    163    return max_depth

Determine the maximum depth of a tree of Connectors.

###### For example:

>     >>> from sqlglot import parse_one
>     >>> connector_depth(parse_one("a AND b AND c AND d"))
>     3

def catch(*exceptions): View Source

    166def catch(*exceptions):
    167    """Decorator that ignores a simplification function if any of `exceptions` are raised"""
    168
    169    def decorator(func):
    170        def wrapped(expression, *args, **kwargs):
    171            try:
    172                return func(expression, *args, **kwargs)
    173            except exceptions:
    174                return expression
    175
    176        return wrapped
    177
    178    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

    181def rewrite_between(expression: exp.Expression) -> exp.Expression:
    182    """Rewrite x between y and z to x >= y AND x <= z.
    183
    184    This is done because comparison simplification is only done on lt/lte/gt/gte.
    185    """
    186    if isinstance(expression, exp.Between):
    187        negate = isinstance(expression.parent, exp.Not)
    188
    189        expression = exp.and_(
    190            exp.GTE(this=expression.this.copy(), expression=expression.args["low"]),
    191            exp.LTE(this=expression.this.copy(), expression=expression.args["high"]),
    192            copy=False,
    193        )
    194
    195        if negate:
    196            expression = exp.paren(expression, copy=False)
    197
    198    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

    216def simplify_not(expression):
    217    """
    218    Demorgan's Law
    219    NOT (x OR y) -> NOT x AND NOT y
    220    NOT (x AND y) -> NOT x OR NOT y
    221    """
    222    if isinstance(expression, exp.Not):
    223        this = expression.this
    224        if is_null(this):
    225            return exp.null()
    226        if this.__class__ in COMPLEMENT_COMPARISONS:
    227            right = this.expression
    228            complement_subquery_predicate = COMPLEMENT_SUBQUERY_PREDICATES.get(right.__class__)
    229            if complement_subquery_predicate:
    230                right = complement_subquery_predicate(this=right.this)
    231
    232            return COMPLEMENT_COMPARISONS[this.__class__](this=this.this, expression=right)
    233        if isinstance(this, exp.Paren):
    234            condition = this.unnest()
    235            if isinstance(condition, exp.And):
    236                return exp.paren(
    237                    exp.or_(
    238                        exp.not_(condition.left, copy=False),
    239                        exp.not_(condition.right, copy=False),
    240                        copy=False,
    241                    )
    242                )
    243            if isinstance(condition, exp.Or):
    244                return exp.paren(
    245                    exp.and_(
    246                        exp.not_(condition.left, copy=False),
    247                        exp.not_(condition.right, copy=False),
    248                        copy=False,
    249                    )
    250                )
    251            if is_null(condition):
    252                return exp.null()
    253        if always_true(this):
    254            return exp.false()
    255        if is_false(this):
    256            return exp.true()
    257        if isinstance(this, exp.Not):
    258            # double negation
    259            # NOT NOT x -> x
    260            return this.this
    261    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

    264def flatten(expression):
    265    """
    266    A AND (B AND C) -> A AND B AND C
    267    A OR (B OR C) -> A OR B OR C
    268    """
    269    if isinstance(expression, exp.Connector):
    270        for node in expression.args.values():
    271            child = node.unnest()
    272            if isinstance(child, expression.__class__):
    273                node.replace(child)
    274    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

    277def simplify_connectors(expression, root=True):
    278    def _simplify_connectors(expression, left, right):
    279        if isinstance(expression, exp.And):
    280            if is_false(left) or is_false(right):
    281                return exp.false()
    282            if is_zero(left) or is_zero(right):
    283                return exp.false()
    284            if is_null(left) or is_null(right):
    285                return exp.null()
    286            if always_true(left) and always_true(right):
    287                return exp.true()
    288            if always_true(left):
    289                return right
    290            if always_true(right):
    291                return left
    292            return _simplify_comparison(expression, left, right)
    293        elif isinstance(expression, exp.Or):
    294            if always_true(left) or always_true(right):
    295                return exp.true()
    296            if (
    297                (is_null(left) and is_null(right))
    298                or (is_null(left) and always_false(right))
    299                or (always_false(left) and is_null(right))
    300            ):
    301                return exp.null()
    302            if is_false(left):
    303                return right
    304            if is_false(right):
    305                return left
    306            return _simplify_comparison(expression, left, right, or_=True)
    307        elif isinstance(expression, exp.Xor):
    308            if left == right:
    309                return exp.false()
    310
    311    if isinstance(expression, exp.Connector):
    312        return _flat_simplify(expression, _simplify_connectors, root)
    313    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

    400def remove_complements(expression, root=True):
    401    """
    402    Removing complements.
    403
    404    A AND NOT A -> FALSE
    405    A OR NOT A -> TRUE
    406    """
    407    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
    408        ops = set(expression.flatten())
    409        for op in ops:
    410            if isinstance(op, exp.Not) and op.this in ops:
    411                return exp.false() if isinstance(expression, exp.And) else exp.true()
    412
    413    return expression

Removing complements.

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

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

    416def uniq_sort(expression, root=True):
    417    """
    418    Uniq and sort a connector.
    419
    420    C AND A AND B AND B -> A AND B AND C
    421    """
    422    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    423        flattened = tuple(expression.flatten())
    424
    425        if isinstance(expression, exp.Xor):
    426            result_func = exp.xor
    427            # Do not deduplicate XOR as A XOR A != A if A == True
    428            deduped = None
    429            arr = tuple((gen(e), e) for e in flattened)
    430        else:
    431            result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
    432            deduped = {gen(e): e for e in flattened}
    433            arr = tuple(deduped.items())
    434
    435        # check if the operands are already sorted, if not sort them
    436        # A AND C AND B -> A AND B AND C
    437        for i, (sql, e) in enumerate(arr[1:]):
    438            if sql < arr[i][0]:
    439                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
    440                break
    441        else:
    442            # we didn't have to sort but maybe we need to dedup
    443            if deduped and len(deduped) < len(flattened):
    444                expression = result_func(*deduped.values(), copy=False)
    445
    446    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

    449def absorb_and_eliminate(expression, root=True):
    450    """
    451    absorption:
    452        A AND (A OR B) -> A
    453        A OR (A AND B) -> A
    454        A AND (NOT A OR B) -> A AND B
    455        A OR (NOT A AND B) -> A OR B
    456    elimination:
    457        (A AND B) OR (A AND NOT B) -> A
    458        (A OR B) AND (A OR NOT B) -> A
    459    """
    460    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
    461        kind = exp.Or if isinstance(expression, exp.And) else exp.And
    462
    463        ops = tuple(expression.flatten())
    464
    465        # Initialize lookup tables:
    466        # Set of all operands, used to find complements for absorption.
    467        op_set = set()
    468        # Sub-operands, used to find subsets for absorption.
    469        subops = defaultdict(list)
    470        # Pairs of complements, used for elimination.
    471        pairs = defaultdict(list)
    472
    473        # Populate the lookup tables
    474        for op in ops:
    475            op_set.add(op)
    476
    477            if not isinstance(op, kind):
    478                # In cases like: A OR (A AND B)
    479                # Subop will be: ^
    480                subops[op].append({op})
    481                continue
    482
    483            # In cases like: (A AND B) OR (A AND B AND C)
    484            # Subops will be: ^     ^
    485            subset = set(op.flatten())
    486            for i in subset:
    487                subops[i].append(subset)
    488
    489            a, b = op.unnest_operands()
    490            if isinstance(a, exp.Not):
    491                pairs[frozenset((a.this, b))].append((op, b))
    492            if isinstance(b, exp.Not):
    493                pairs[frozenset((a, b.this))].append((op, a))
    494
    495        for op in ops:
    496            if not isinstance(op, kind):
    497                continue
    498
    499            a, b = op.unnest_operands()
    500
    501            # Absorb
    502            if isinstance(a, exp.Not) and a.this in op_set:
    503                a.replace(exp.true() if kind == exp.And else exp.false())
    504                continue
    505            if isinstance(b, exp.Not) and b.this in op_set:
    506                b.replace(exp.true() if kind == exp.And else exp.false())
    507                continue
    508            superset = set(op.flatten())
    509            if any(any(subset < superset for subset in subops[i]) for i in superset):
    510                op.replace(exp.false() if kind == exp.And else exp.true())
    511                continue
    512
    513            # Eliminate
    514            for other, complement in pairs[frozenset((a, b))]:
    515                op.replace(complement)
    516                other.replace(complement)
    517
    518    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

    521def propagate_constants(expression, root=True):
    522    """
    523    Propagate constants for conjunctions in DNF:
    524
    525    SELECT * FROM t WHERE a = b AND b = 5 becomes
    526    SELECT * FROM t WHERE a = 5 AND b = 5
    527
    528    Reference: https://www.sqlite.org/optoverview.html
    529    """
    530
    531    if (
    532        isinstance(expression, exp.And)
    533        and (root or not expression.same_parent)
    534        and sqlglot.optimizer.normalize.normalized(expression, dnf=True)
    535    ):
    536        constant_mapping = {}
    537        for expr in walk_in_scope(expression, prune=lambda node: isinstance(node, exp.If)):
    538            if isinstance(expr, exp.EQ):
    539                l, r = expr.left, expr.right
    540
    541                # TODO: create a helper that can be used to detect nested literal expressions such
    542                # as CAST(123456 AS BIGINT), since we usually want to treat those as literals too
    543                if isinstance(l, exp.Column) and isinstance(r, exp.Literal):
    544                    constant_mapping[l] = (id(l), r)
    545
    546        if constant_mapping:
    547            for column in find_all_in_scope(expression, exp.Column):
    548                parent = column.parent
    549                column_id, constant = constant_mapping.get(column) or (None, None)
    550                if (
    551                    column_id is not None
    552                    and id(column) != column_id
    553                    and not (isinstance(parent, exp.Is) and isinstance(parent.expression, exp.Null))
    554                ):
    555                    column.replace(constant.copy())
    556
    557    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

    170        def wrapped(expression, *args, **kwargs):
    171            try:
    172                return func(expression, *args, **kwargs)
    173            except exceptions:
    174                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

    632def simplify_literals(expression, root=True):
    633    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
    634        return _flat_simplify(expression, _simplify_binary, root)
    635
    636    if isinstance(expression, exp.Neg) and isinstance(expression.this, exp.Neg):
    637        return expression.this.this
    638
    639    if type(expression) in INVERSE_DATE_OPS:
    640        return _simplify_binary(expression, expression.this, expression.interval()) or expression
    641
    642    return expression

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

    743def simplify_parens(expression):
    744    if not isinstance(expression, exp.Paren):
    745        return expression
    746
    747    this = expression.this
    748    parent = expression.parent
    749    parent_is_predicate = isinstance(parent, exp.Predicate)
    750
    751    if (
    752        not isinstance(this, exp.Select)
    753        and not isinstance(parent, exp.SubqueryPredicate)
    754        and (
    755            not isinstance(parent, (exp.Condition, exp.Binary))
    756            or isinstance(parent, exp.Paren)
    757            or (
    758                not isinstance(this, exp.Binary)
    759                and not (isinstance(this, (exp.Not, exp.Is)) and parent_is_predicate)
    760            )
    761            or (isinstance(this, exp.Predicate) and not parent_is_predicate)
    762            or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
    763            or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
    764            or (isinstance(this, exp.Mul) and isinstance(parent, (exp.Add, exp.Sub)))
    765        )
    766    ):
    767        return this
    768    return expression

def simplify_coalesce(expression): View Source

    779def simplify_coalesce(expression):
    780    # COALESCE(x) -> x
    781    if (
    782        isinstance(expression, exp.Coalesce)
    783        and (not expression.expressions or _is_nonnull_constant(expression.this))
    784        # COALESCE is also used as a Spark partitioning hint
    785        and not isinstance(expression.parent, exp.Hint)
    786    ):
    787        return expression.this
    788
    789    if not isinstance(expression, COMPARISONS):
    790        return expression
    791
    792    if isinstance(expression.left, exp.Coalesce):
    793        coalesce = expression.left
    794        other = expression.right
    795    elif isinstance(expression.right, exp.Coalesce):
    796        coalesce = expression.right
    797        other = expression.left
    798    else:
    799        return expression
    800
    801    # This transformation is valid for non-constants,
    802    # but it really only does anything if they are both constants.
    803    if not _is_constant(other):
    804        return expression
    805
    806    # Find the first constant arg
    807    for arg_index, arg in enumerate(coalesce.expressions):
    808        if _is_constant(arg):
    809            break
    810    else:
    811        return expression
    812
    813    coalesce.set("expressions", coalesce.expressions[:arg_index])
    814
    815    # Remove the COALESCE function. This is an optimization, skipping a simplify iteration,
    816    # since we already remove COALESCE at the top of this function.
    817    coalesce = coalesce if coalesce.expressions else coalesce.this
    818
    819    # This expression is more complex than when we started, but it will get simplified further
    820    return exp.paren(
    821        exp.or_(
    822            exp.and_(
    823                coalesce.is_(exp.null()).not_(copy=False),
    824                expression.copy(),
    825                copy=False,
    826            ),
    827            exp.and_(
    828                coalesce.is_(exp.null()),
    829                type(expression)(this=arg.copy(), expression=other.copy()),
    830                copy=False,
    831            ),
    832            copy=False,
    833        )
    834    )

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

    840def simplify_concat(expression):
    841    """Reduces all groups that contain string literals by concatenating them."""
    842    if not isinstance(expression, CONCATS) or (
    843        # We can't reduce a CONCAT_WS call if we don't statically know the separator
    844        isinstance(expression, exp.ConcatWs) and not expression.expressions[0].is_string
    845    ):
    846        return expression
    847
    848    if isinstance(expression, exp.ConcatWs):
    849        sep_expr, *expressions = expression.expressions
    850        sep = sep_expr.name
    851        concat_type = exp.ConcatWs
    852        args = {}
    853    else:
    854        expressions = expression.expressions
    855        sep = ""
    856        concat_type = exp.Concat
    857        args = {
    858            "safe": expression.args.get("safe"),
    859            "coalesce": expression.args.get("coalesce"),
    860        }
    861
    862    new_args = []
    863    for is_string_group, group in itertools.groupby(
    864        expressions or expression.flatten(), lambda e: e.is_string
    865    ):
    866        if is_string_group:
    867            new_args.append(exp.Literal.string(sep.join(string.name for string in group)))
    868        else:
    869            new_args.extend(group)
    870
    871    if len(new_args) == 1 and new_args[0].is_string:
    872        return new_args[0]
    873
    874    if concat_type is exp.ConcatWs:
    875        new_args = [sep_expr] + new_args
    876    elif isinstance(expression, exp.DPipe):
    877        return reduce(lambda x, y: exp.DPipe(this=x, expression=y), new_args)
    878
    879    return concat_type(expressions=new_args, **args)

Reduces all groups that contain string literals by concatenating them.

def simplify_conditionals(expression): View Source

    882def simplify_conditionals(expression):
    883    """Simplifies expressions like IF, CASE if their condition is statically known."""
    884    if isinstance(expression, exp.Case):
    885        this = expression.this
    886        for case in expression.args["ifs"]:
    887            cond = case.this
    888            if this:
    889                # Convert CASE x WHEN matching_value ... to CASE WHEN x = matching_value ...
    890                cond = cond.replace(this.pop().eq(cond))
    891
    892            if always_true(cond):
    893                return case.args["true"]
    894
    895            if always_false(cond):
    896                case.pop()
    897                if not expression.args["ifs"]:
    898                    return expression.args.get("default") or exp.null()
    899    elif isinstance(expression, exp.If) and not isinstance(expression.parent, exp.Case):
    900        if always_true(expression.this):
    901            return expression.args["true"]
    902        if always_false(expression.this):
    903            return expression.args.get("false") or exp.null()
    904
    905    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

    908def simplify_startswith(expression: exp.Expression) -> exp.Expression:
    909    """
    910    Reduces a prefix check to either TRUE or FALSE if both the string and the
    911    prefix are statically known.
    912
    913    Example:
    914        >>> from sqlglot import parse_one
    915        >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
    916        'TRUE'
    917    """
    918    if (
    919        isinstance(expression, exp.StartsWith)
    920        and expression.this.is_string
    921        and expression.expression.is_string
    922    ):
    923        return exp.convert(expression.name.startswith(expression.expression.name))
    924
    925    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.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.LTE'>, <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.NEQ'>, <class 'sqlglot.expressions.EQ'>, <class 'sqlglot.expressions.In'>, <class 'sqlglot.expressions.GTE'>}
DATETRUNCS = (<class 'sqlglot.expressions.DateTrunc'>, <class 'sqlglot.expressions.TimestampTrunc'>)
def simplify_datetrunc(expression, *args, **kwargs): View Source

    170        def wrapped(expression, *args, **kwargs):
    171            try:
    172                return func(expression, *args, **kwargs)
    173            except exceptions:
    174                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

    1074def sort_comparison(expression: exp.Expression) -> exp.Expression:
    1075    if expression.__class__ in COMPLEMENT_COMPARISONS:
    1076        l, r = expression.this, expression.expression
    1077        l_column = isinstance(l, exp.Column)
    1078        r_column = isinstance(r, exp.Column)
    1079        l_const = _is_constant(l)
    1080        r_const = _is_constant(r)
    1081
    1082        if (
    1083            (l_column and not r_column)
    1084            or (r_const and not l_const)
    1085            or isinstance(r, exp.SubqueryPredicate)
    1086        ):
    1087            return expression
    1088        if (r_column and not l_column) or (l_const and not r_const) or (gen(l) > gen(r)):
    1089            return INVERSE_COMPARISONS.get(expression.__class__, expression.__class__)(
    1090                this=r, expression=l
    1091            )
    1092    return expression

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

    1106def remove_where_true(expression):
    1107    for where in expression.find_all(exp.Where):
    1108        if always_true(where.this):
    1109            where.pop()
    1110    for join in expression.find_all(exp.Join):
    1111        if (
    1112            always_true(join.args.get("on"))
    1113            and not join.args.get("using")
    1114            and not join.args.get("method")
    1115            and (join.side, join.kind) in JOINS
    1116        ):
    1117            join.args["on"].pop()
    1118            join.set("side", None)
    1119            join.set("kind", "CROSS")

def always_true(expression): View Source

    1122def always_true(expression):
    1123    return (isinstance(expression, exp.Boolean) and expression.this) or (
    1124        isinstance(expression, exp.Literal) and not is_zero(expression)
    1125    )

def always_false(expression): View Source

    1128def always_false(expression):
    1129    return is_false(expression) or is_null(expression) or is_zero(expression)

def is_zero(expression): View Source

    1132def is_zero(expression):
    1133    return isinstance(expression, exp.Literal) and expression.to_py() == 0

def is_complement(a, b): View Source

    1136def is_complement(a, b):
    1137    return isinstance(b, exp.Not) and b.this == a

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

    1140def is_false(a: exp.Expression) -> bool:
    1141    return type(a) is exp.Boolean and not a.this

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

    1144def is_null(a: exp.Expression) -> bool:
    1145    return type(a) is exp.Null

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

    1148def eval_boolean(expression, a, b):
    1149    if isinstance(expression, (exp.EQ, exp.Is)):
    1150        return boolean_literal(a == b)
    1151    if isinstance(expression, exp.NEQ):
    1152        return boolean_literal(a != b)
    1153    if isinstance(expression, exp.GT):
    1154        return boolean_literal(a > b)
    1155    if isinstance(expression, exp.GTE):
    1156        return boolean_literal(a >= b)
    1157    if isinstance(expression, exp.LT):
    1158        return boolean_literal(a < b)
    1159    if isinstance(expression, exp.LTE):
    1160        return boolean_literal(a <= b)
    1161    return None

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

    1164def cast_as_date(value: t.Any) -> t.Optional[datetime.date]:
    1165    if isinstance(value, datetime.datetime):
    1166        return value.date()
    1167    if isinstance(value, datetime.date):
    1168        return value
    1169    try:
    1170        return datetime.datetime.fromisoformat(value).date()
    1171    except ValueError:
    1172        return None

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

    1175def cast_as_datetime(value: t.Any) -> t.Optional[datetime.datetime]:
    1176    if isinstance(value, datetime.datetime):
    1177        return value
    1178    if isinstance(value, datetime.date):
    1179        return datetime.datetime(year=value.year, month=value.month, day=value.day)
    1180    try:
    1181        return datetime.datetime.fromisoformat(value)
    1182    except ValueError:
    1183        return None

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

    1186def cast_value(value: t.Any, to: exp.DataType) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1187    if not value:
    1188        return None
    1189    if to.is_type(exp.DataType.Type.DATE):
    1190        return cast_as_date(value)
    1191    if to.is_type(*exp.DataType.TEMPORAL_TYPES):
    1192        return cast_as_datetime(value)
    1193    return None

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

    1196def extract_date(cast: exp.Expression) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1197    if isinstance(cast, exp.Cast):
    1198        to = cast.to
    1199    elif isinstance(cast, exp.TsOrDsToDate) and not cast.args.get("format"):
    1200        to = exp.DataType.build(exp.DataType.Type.DATE)
    1201    else:
    1202        return None
    1203
    1204    if isinstance(cast.this, exp.Literal):
    1205        value: t.Any = cast.this.name
    1206    elif isinstance(cast.this, (exp.Cast, exp.TsOrDsToDate)):
    1207        value = extract_date(cast.this)
    1208    else:
    1209        return None
    1210    return cast_value(value, to)

def extract_interval(expression): View Source

    1217def extract_interval(expression):
    1218    try:
    1219        n = int(expression.this.to_py())
    1220        unit = expression.text("unit").lower()
    1221        return interval(unit, n)
    1222    except (UnsupportedUnit, ModuleNotFoundError, ValueError):
    1223        return None

def extract_type(*expressions): View Source

    1226def extract_type(*expressions):
    1227    target_type = None
    1228    for expression in expressions:
    1229        target_type = expression.to if isinstance(expression, exp.Cast) else expression.type
    1230        if target_type:
    1231            break
    1232
    1233    return target_type

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

    1236def date_literal(date, target_type=None):
    1237    if not target_type or not target_type.is_type(*exp.DataType.TEMPORAL_TYPES):
    1238        target_type = (
    1239            exp.DataType.Type.DATETIME
    1240            if isinstance(date, datetime.datetime)
    1241            else exp.DataType.Type.DATE
    1242        )
    1243
    1244    return exp.cast(exp.Literal.string(date), target_type)

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

    1247def interval(unit: str, n: int = 1):
    1248    from dateutil.relativedelta import relativedelta
    1249
    1250    if unit == "year":
    1251        return relativedelta(years=1 * n)
    1252    if unit == "quarter":
    1253        return relativedelta(months=3 * n)
    1254    if unit == "month":
    1255        return relativedelta(months=1 * n)
    1256    if unit == "week":
    1257        return relativedelta(weeks=1 * n)
    1258    if unit == "day":
    1259        return relativedelta(days=1 * n)
    1260    if unit == "hour":
    1261        return relativedelta(hours=1 * n)
    1262    if unit == "minute":
    1263        return relativedelta(minutes=1 * n)
    1264    if unit == "second":
    1265        return relativedelta(seconds=1 * n)
    1266
    1267    raise UnsupportedUnit(f"Unsupported unit: {unit}")

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

    1270def date_floor(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1271    if unit == "year":
    1272        return d.replace(month=1, day=1)
    1273    if unit == "quarter":
    1274        if d.month <= 3:
    1275            return d.replace(month=1, day=1)
    1276        elif d.month <= 6:
    1277            return d.replace(month=4, day=1)
    1278        elif d.month <= 9:
    1279            return d.replace(month=7, day=1)
    1280        else:
    1281            return d.replace(month=10, day=1)
    1282    if unit == "month":
    1283        return d.replace(month=d.month, day=1)
    1284    if unit == "week":
    1285        # Assuming week starts on Monday (0) and ends on Sunday (6)
    1286        return d - datetime.timedelta(days=d.weekday() - dialect.WEEK_OFFSET)
    1287    if unit == "day":
    1288        return d
    1289
    1290    raise UnsupportedUnit(f"Unsupported unit: {unit}")

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

    1293def date_ceil(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1294    floor = date_floor(d, unit, dialect)
    1295
    1296    if floor == d:
    1297        return d
    1298
    1299    return floor + interval(unit)

def boolean_literal(condition): View Source

    1302def boolean_literal(condition):
    1303    return exp.true() if condition else exp.false()

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

    1332def gen(expression: t.Any, comments: bool = False) -> str:
    1333    """Simple pseudo sql generator for quickly generating sortable and uniq strings.
    1334
    1335    Sorting and deduping sql is a necessary step for optimization. Calling the actual
    1336    generator is expensive so we have a bare minimum sql generator here.
    1337
    1338    Args:
    1339        expression: the expression to convert into a SQL string.
    1340        comments: whether to include the expression's comments.
    1341    """
    1342    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

    1345class Gen:
    1346    def __init__(self):
    1347        self.stack = []
    1348        self.sqls = []
    1349
    1350    def gen(self, expression: exp.Expression, comments: bool = False) -> str:
    1351        self.stack = [expression]
    1352        self.sqls.clear()
    1353
    1354        while self.stack:
    1355            node = self.stack.pop()
    1356
    1357            if isinstance(node, exp.Expression):
    1358                if comments and node.comments:
    1359                    self.stack.append(f" /*{','.join(node.comments)}*/")
    1360
    1361                exp_handler_name = f"{node.key}_sql"
    1362
    1363                if hasattr(self, exp_handler_name):
    1364                    getattr(self, exp_handler_name)(node)
    1365                elif isinstance(node, exp.Func):
    1366                    self._function(node)
    1367                else:
    1368                    key = node.key.upper()
    1369                    self.stack.append(f"{key} " if self._args(node) else key)
    1370            elif type(node) is list:
    1371                for n in reversed(node):
    1372                    if n is not None:
    1373                        self.stack.extend((n, ","))
    1374                if node:
    1375                    self.stack.pop()
    1376            else:
    1377                if node is not None:
    1378                    self.sqls.append(str(node))
    1379
    1380        return "".join(self.sqls)
    1381
    1382    def add_sql(self, e: exp.Add) -> None:
    1383        self._binary(e, " + ")
    1384
    1385    def alias_sql(self, e: exp.Alias) -> None:
    1386        self.stack.extend(
    1387            (
    1388                e.args.get("alias"),
    1389                " AS ",
    1390                e.args.get("this"),
    1391            )
    1392        )
    1393
    1394    def and_sql(self, e: exp.And) -> None:
    1395        self._binary(e, " AND ")
    1396
    1397    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1398        this = e.this
    1399        if isinstance(this, str):
    1400            name = this.upper()
    1401        elif isinstance(this, exp.Identifier):
    1402            name = this.this
    1403            name = f'"{name}"' if this.quoted else name.upper()
    1404        else:
    1405            raise ValueError(
    1406                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1407            )
    1408
    1409        self.stack.extend(
    1410            (
    1411                ")",
    1412                e.expressions,
    1413                "(",
    1414                name,
    1415            )
    1416        )
    1417
    1418    def between_sql(self, e: exp.Between) -> None:
    1419        self.stack.extend(
    1420            (
    1421                e.args.get("high"),
    1422                " AND ",
    1423                e.args.get("low"),
    1424                " BETWEEN ",
    1425                e.this,
    1426            )
    1427        )
    1428
    1429    def boolean_sql(self, e: exp.Boolean) -> None:
    1430        self.stack.append("TRUE" if e.this else "FALSE")
    1431
    1432    def bracket_sql(self, e: exp.Bracket) -> None:
    1433        self.stack.extend(
    1434            (
    1435                "]",
    1436                e.expressions,
    1437                "[",
    1438                e.this,
    1439            )
    1440        )
    1441
    1442    def column_sql(self, e: exp.Column) -> None:
    1443        for p in reversed(e.parts):
    1444            self.stack.extend((p, "."))
    1445        self.stack.pop()
    1446
    1447    def datatype_sql(self, e: exp.DataType) -> None:
    1448        self._args(e, 1)
    1449        self.stack.append(f"{e.this.name} ")
    1450
    1451    def div_sql(self, e: exp.Div) -> None:
    1452        self._binary(e, " / ")
    1453
    1454    def dot_sql(self, e: exp.Dot) -> None:
    1455        self._binary(e, ".")
    1456
    1457    def eq_sql(self, e: exp.EQ) -> None:
    1458        self._binary(e, " = ")
    1459
    1460    def from_sql(self, e: exp.From) -> None:
    1461        self.stack.extend((e.this, "FROM "))
    1462
    1463    def gt_sql(self, e: exp.GT) -> None:
    1464        self._binary(e, " > ")
    1465
    1466    def gte_sql(self, e: exp.GTE) -> None:
    1467        self._binary(e, " >= ")
    1468
    1469    def identifier_sql(self, e: exp.Identifier) -> None:
    1470        self.stack.append(f'"{e.this}"' if e.quoted else e.this)
    1471
    1472    def ilike_sql(self, e: exp.ILike) -> None:
    1473        self._binary(e, " ILIKE ")
    1474
    1475    def in_sql(self, e: exp.In) -> None:
    1476        self.stack.append(")")
    1477        self._args(e, 1)
    1478        self.stack.extend(
    1479            (
    1480                "(",
    1481                " IN ",
    1482                e.this,
    1483            )
    1484        )
    1485
    1486    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1487        self._binary(e, " DIV ")
    1488
    1489    def is_sql(self, e: exp.Is) -> None:
    1490        self._binary(e, " IS ")
    1491
    1492    def like_sql(self, e: exp.Like) -> None:
    1493        self._binary(e, " Like ")
    1494
    1495    def literal_sql(self, e: exp.Literal) -> None:
    1496        self.stack.append(f"'{e.this}'" if e.is_string else e.this)
    1497
    1498    def lt_sql(self, e: exp.LT) -> None:
    1499        self._binary(e, " < ")
    1500
    1501    def lte_sql(self, e: exp.LTE) -> None:
    1502        self._binary(e, " <= ")
    1503
    1504    def mod_sql(self, e: exp.Mod) -> None:
    1505        self._binary(e, " % ")
    1506
    1507    def mul_sql(self, e: exp.Mul) -> None:
    1508        self._binary(e, " * ")
    1509
    1510    def neg_sql(self, e: exp.Neg) -> None:
    1511        self._unary(e, "-")
    1512
    1513    def neq_sql(self, e: exp.NEQ) -> None:
    1514        self._binary(e, " <> ")
    1515
    1516    def not_sql(self, e: exp.Not) -> None:
    1517        self._unary(e, "NOT ")
    1518
    1519    def null_sql(self, e: exp.Null) -> None:
    1520        self.stack.append("NULL")
    1521
    1522    def or_sql(self, e: exp.Or) -> None:
    1523        self._binary(e, " OR ")
    1524
    1525    def paren_sql(self, e: exp.Paren) -> None:
    1526        self.stack.extend(
    1527            (
    1528                ")",
    1529                e.this,
    1530                "(",
    1531            )
    1532        )
    1533
    1534    def sub_sql(self, e: exp.Sub) -> None:
    1535        self._binary(e, " - ")
    1536
    1537    def subquery_sql(self, e: exp.Subquery) -> None:
    1538        self._args(e, 2)
    1539        alias = e.args.get("alias")
    1540        if alias:
    1541            self.stack.append(alias)
    1542        self.stack.extend((")", e.this, "("))
    1543
    1544    def table_sql(self, e: exp.Table) -> None:
    1545        self._args(e, 4)
    1546        alias = e.args.get("alias")
    1547        if alias:
    1548            self.stack.append(alias)
    1549        for p in reversed(e.parts):
    1550            self.stack.extend((p, "."))
    1551        self.stack.pop()
    1552
    1553    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1554        columns = e.columns
    1555
    1556        if columns:
    1557            self.stack.extend((")", columns, "("))
    1558
    1559        self.stack.extend((e.this, " AS "))
    1560
    1561    def var_sql(self, e: exp.Var) -> None:
    1562        self.stack.append(e.this)
    1563
    1564    def _binary(self, e: exp.Binary, op: str) -> None:
    1565        self.stack.extend((e.expression, op, e.this))
    1566
    1567    def _unary(self, e: exp.Unary, op: str) -> None:
    1568        self.stack.extend((e.this, op))
    1569
    1570    def _function(self, e: exp.Func) -> None:
    1571        self.stack.extend(
    1572            (
    1573                ")",
    1574                list(e.args.values()),
    1575                "(",
    1576                e.sql_name(),
    1577            )
    1578        )
    1579
    1580    def _args(self, node: exp.Expression, arg_index: int = 0) -> bool:
    1581        kvs = []
    1582        arg_types = list(node.arg_types)[arg_index:] if arg_index else node.arg_types
    1583
    1584        for k in arg_types or arg_types:
    1585            v = node.args.get(k)
    1586
    1587            if v is not None:
    1588                kvs.append([f":{k}", v])
    1589        if kvs:
    1590            self.stack.append(kvs)
    1591            return True
    1592        return False

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

    1350    def gen(self, expression: exp.Expression, comments: bool = False) -> str:
    1351        self.stack = [expression]
    1352        self.sqls.clear()
    1353
    1354        while self.stack:
    1355            node = self.stack.pop()
    1356
    1357            if isinstance(node, exp.Expression):
    1358                if comments and node.comments:
    1359                    self.stack.append(f" /*{','.join(node.comments)}*/")
    1360
    1361                exp_handler_name = f"{node.key}_sql"
    1362
    1363                if hasattr(self, exp_handler_name):
    1364                    getattr(self, exp_handler_name)(node)
    1365                elif isinstance(node, exp.Func):
    1366                    self._function(node)
    1367                else:
    1368                    key = node.key.upper()
    1369                    self.stack.append(f"{key} " if self._args(node) else key)
    1370            elif type(node) is list:
    1371                for n in reversed(node):
    1372                    if n is not None:
    1373                        self.stack.extend((n, ","))
    1374                if node:
    1375                    self.stack.pop()
    1376            else:
    1377                if node is not None:
    1378                    self.sqls.append(str(node))
    1379
    1380        return "".join(self.sqls)

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

    1382    def add_sql(self, e: exp.Add) -> None:
    1383        self._binary(e, " + ")

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

    1385    def alias_sql(self, e: exp.Alias) -> None:
    1386        self.stack.extend(
    1387            (
    1388                e.args.get("alias"),
    1389                " AS ",
    1390                e.args.get("this"),
    1391            )
    1392        )

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

    1394    def and_sql(self, e: exp.And) -> None:
    1395        self._binary(e, " AND ")

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

    1397    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1398        this = e.this
    1399        if isinstance(this, str):
    1400            name = this.upper()
    1401        elif isinstance(this, exp.Identifier):
    1402            name = this.this
    1403            name = f'"{name}"' if this.quoted else name.upper()
    1404        else:
    1405            raise ValueError(
    1406                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1407            )
    1408
    1409        self.stack.extend(
    1410            (
    1411                ")",
    1412                e.expressions,
    1413                "(",
    1414                name,
    1415            )
    1416        )

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

    1418    def between_sql(self, e: exp.Between) -> None:
    1419        self.stack.extend(
    1420            (
    1421                e.args.get("high"),
    1422                " AND ",
    1423                e.args.get("low"),
    1424                " BETWEEN ",
    1425                e.this,
    1426            )
    1427        )

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

    1429    def boolean_sql(self, e: exp.Boolean) -> None:
    1430        self.stack.append("TRUE" if e.this else "FALSE")

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

    1432    def bracket_sql(self, e: exp.Bracket) -> None:
    1433        self.stack.extend(
    1434            (
    1435                "]",
    1436                e.expressions,
    1437                "[",
    1438                e.this,
    1439            )
    1440        )

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

    1442    def column_sql(self, e: exp.Column) -> None:
    1443        for p in reversed(e.parts):
    1444            self.stack.extend((p, "."))
    1445        self.stack.pop()

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

    1447    def datatype_sql(self, e: exp.DataType) -> None:
    1448        self._args(e, 1)
    1449        self.stack.append(f"{e.this.name} ")

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

    1451    def div_sql(self, e: exp.Div) -> None:
    1452        self._binary(e, " / ")

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

    1454    def dot_sql(self, e: exp.Dot) -> None:
    1455        self._binary(e, ".")

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

    1457    def eq_sql(self, e: exp.EQ) -> None:
    1458        self._binary(e, " = ")

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

    1460    def from_sql(self, e: exp.From) -> None:
    1461        self.stack.extend((e.this, "FROM "))

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

    1463    def gt_sql(self, e: exp.GT) -> None:
    1464        self._binary(e, " > ")

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

    1466    def gte_sql(self, e: exp.GTE) -> None:
    1467        self._binary(e, " >= ")

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

    1469    def identifier_sql(self, e: exp.Identifier) -> None:
    1470        self.stack.append(f'"{e.this}"' if e.quoted else e.this)

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

    1472    def ilike_sql(self, e: exp.ILike) -> None:
    1473        self._binary(e, " ILIKE ")

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

    1475    def in_sql(self, e: exp.In) -> None:
    1476        self.stack.append(")")
    1477        self._args(e, 1)
    1478        self.stack.extend(
    1479            (
    1480                "(",
    1481                " IN ",
    1482                e.this,
    1483            )
    1484        )

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

    1486    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1487        self._binary(e, " DIV ")

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

    1489    def is_sql(self, e: exp.Is) -> None:
    1490        self._binary(e, " IS ")

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

    1492    def like_sql(self, e: exp.Like) -> None:
    1493        self._binary(e, " Like ")

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

    1495    def literal_sql(self, e: exp.Literal) -> None:
    1496        self.stack.append(f"'{e.this}'" if e.is_string else e.this)

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

    1498    def lt_sql(self, e: exp.LT) -> None:
    1499        self._binary(e, " < ")

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

    1501    def lte_sql(self, e: exp.LTE) -> None:
    1502        self._binary(e, " <= ")

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

    1504    def mod_sql(self, e: exp.Mod) -> None:
    1505        self._binary(e, " % ")

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

    1507    def mul_sql(self, e: exp.Mul) -> None:
    1508        self._binary(e, " * ")

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

    1510    def neg_sql(self, e: exp.Neg) -> None:
    1511        self._unary(e, "-")

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

    1513    def neq_sql(self, e: exp.NEQ) -> None:
    1514        self._binary(e, " <> ")

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

    1516    def not_sql(self, e: exp.Not) -> None:
    1517        self._unary(e, "NOT ")

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

    1519    def null_sql(self, e: exp.Null) -> None:
    1520        self.stack.append("NULL")

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

    1522    def or_sql(self, e: exp.Or) -> None:
    1523        self._binary(e, " OR ")

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

    1525    def paren_sql(self, e: exp.Paren) -> None:
    1526        self.stack.extend(
    1527            (
    1528                ")",
    1529                e.this,
    1530                "(",
    1531            )
    1532        )

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

    1534    def sub_sql(self, e: exp.Sub) -> None:
    1535        self._binary(e, " - ")

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

    1537    def subquery_sql(self, e: exp.Subquery) -> None:
    1538        self._args(e, 2)
    1539        alias = e.args.get("alias")
    1540        if alias:
    1541            self.stack.append(alias)
    1542        self.stack.extend((")", e.this, "("))

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

    1544    def table_sql(self, e: exp.Table) -> None:
    1545        self._args(e, 4)
    1546        alias = e.args.get("alias")
    1547        if alias:
    1548            self.stack.append(alias)
    1549        for p in reversed(e.parts):
    1550            self.stack.extend((p, "."))
    1551        self.stack.pop()

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

    1553    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1554        columns = e.columns
    1555
    1556        if columns:
    1557            self.stack.extend((")", columns, "("))
    1558
    1559        self.stack.extend((e.this, " AS "))

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

    1561    def var_sql(self, e: exp.Var) -> None:
    1562        self.stack.append(e.this)