sqlglot.optimizer.simplify API documentation

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# sqlglot.optimizer.simplify

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

##### Inherited Members

builtins.Exception
  Exception
builtins.BaseException
  with_traceback
  args

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'>}
def simplify_not(expression): View Source

    211def simplify_not(expression):
    212    """
    213    Demorgan's Law
    214    NOT (x OR y) -> NOT x AND NOT y
    215    NOT (x AND y) -> NOT x OR NOT y
    216    """
    217    if isinstance(expression, exp.Not):
    218        this = expression.this
    219        if is_null(this):
    220            return exp.null()
    221        if this.__class__ in COMPLEMENT_COMPARISONS:
    222            return COMPLEMENT_COMPARISONS[this.__class__](
    223                this=this.this, expression=this.expression
    224            )
    225        if isinstance(this, exp.Paren):
    226            condition = this.unnest()
    227            if isinstance(condition, exp.And):
    228                return exp.paren(
    229                    exp.or_(
    230                        exp.not_(condition.left, copy=False),
    231                        exp.not_(condition.right, copy=False),
    232                        copy=False,
    233                    )
    234                )
    235            if isinstance(condition, exp.Or):
    236                return exp.paren(
    237                    exp.and_(
    238                        exp.not_(condition.left, copy=False),
    239                        exp.not_(condition.right, copy=False),
    240                        copy=False,
    241                    )
    242                )
    243            if is_null(condition):
    244                return exp.null()
    245        if always_true(this):
    246            return exp.false()
    247        if is_false(this):
    248            return exp.true()
    249        if isinstance(this, exp.Not):
    250            # double negation
    251            # NOT NOT x -> x
    252            return this.this
    253    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

    256def flatten(expression):
    257    """
    258    A AND (B AND C) -> A AND B AND C
    259    A OR (B OR C) -> A OR B OR C
    260    """
    261    if isinstance(expression, exp.Connector):
    262        for node in expression.args.values():
    263            child = node.unnest()
    264            if isinstance(child, expression.__class__):
    265                node.replace(child)
    266    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

    269def simplify_connectors(expression, root=True):
    270    def _simplify_connectors(expression, left, right):
    271        if isinstance(expression, exp.And):
    272            if is_false(left) or is_false(right):
    273                return exp.false()
    274            if is_zero(left) or is_zero(right):
    275                return exp.false()
    276            if is_null(left) or is_null(right):
    277                return exp.null()
    278            if always_true(left) and always_true(right):
    279                return exp.true()
    280            if always_true(left):
    281                return right
    282            if always_true(right):
    283                return left
    284            return _simplify_comparison(expression, left, right)
    285        elif isinstance(expression, exp.Or):
    286            if always_true(left) or always_true(right):
    287                return exp.true()
    288            if (
    289                (is_null(left) and is_null(right))
    290                or (is_null(left) and always_false(right))
    291                or (always_false(left) and is_null(right))
    292            ):
    293                return exp.null()
    294            if is_false(left):
    295                return right
    296            if is_false(right):
    297                return left
    298            return _simplify_comparison(expression, left, right, or_=True)
    299        elif isinstance(expression, exp.Xor):
    300            if left == right:
    301                return exp.false()
    302
    303    if isinstance(expression, exp.Connector):
    304        return _flat_simplify(expression, _simplify_connectors, root)
    305    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

    392def remove_complements(expression, root=True):
    393    """
    394    Removing complements.
    395
    396    A AND NOT A -> FALSE
    397    A OR NOT A -> TRUE
    398    """
    399    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
    400        ops = set(expression.flatten())
    401        for op in ops:
    402            if isinstance(op, exp.Not) and op.this in ops:
    403                return exp.false() if isinstance(expression, exp.And) else exp.true()
    404
    405    return expression

Removing complements.

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

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

    408def uniq_sort(expression, root=True):
    409    """
    410    Uniq and sort a connector.
    411
    412    C AND A AND B AND B -> A AND B AND C
    413    """
    414    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    415        flattened = tuple(expression.flatten())
    416
    417        if isinstance(expression, exp.Xor):
    418            result_func = exp.xor
    419            # Do not deduplicate XOR as A XOR A != A if A == True
    420            deduped = None
    421            arr = tuple((gen(e), e) for e in flattened)
    422        else:
    423            result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
    424            deduped = {gen(e): e for e in flattened}
    425            arr = tuple(deduped.items())
    426
    427        # check if the operands are already sorted, if not sort them
    428        # A AND C AND B -> A AND B AND C
    429        for i, (sql, e) in enumerate(arr[1:]):
    430            if sql < arr[i][0]:
    431                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
    432                break
    433        else:
    434            # we didn't have to sort but maybe we need to dedup
    435            if deduped and len(deduped) < len(flattened):
    436                expression = result_func(*deduped.values(), copy=False)
    437
    438    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

    441def absorb_and_eliminate(expression, root=True):
    442    """
    443    absorption:
    444        A AND (A OR B) -> A
    445        A OR (A AND B) -> A
    446        A AND (NOT A OR B) -> A AND B
    447        A OR (NOT A AND B) -> A OR B
    448    elimination:
    449        (A AND B) OR (A AND NOT B) -> A
    450        (A OR B) AND (A OR NOT B) -> A
    451    """
    452    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
    453        kind = exp.Or if isinstance(expression, exp.And) else exp.And
    454
    455        ops = tuple(expression.flatten())
    456
    457        # Initialize lookup tables:
    458        # Set of all operands, used to find complements for absorption.
    459        op_set = set()
    460        # Sub-operands, used to find subsets for absorption.
    461        subops = defaultdict(list)
    462        # Pairs of complements, used for elimination.
    463        pairs = defaultdict(list)
    464
    465        # Populate the lookup tables
    466        for op in ops:
    467            op_set.add(op)
    468
    469            if not isinstance(op, kind):
    470                # In cases like: A OR (A AND B)
    471                # Subop will be: ^
    472                subops[op].append({op})
    473                continue
    474
    475            # In cases like: (A AND B) OR (A AND B AND C)
    476            # Subops will be: ^     ^
    477            subset = set(op.flatten())
    478            for i in subset:
    479                subops[i].append(subset)
    480
    481            a, b = op.unnest_operands()
    482            if isinstance(a, exp.Not):
    483                pairs[frozenset((a.this, b))].append((op, b))
    484            if isinstance(b, exp.Not):
    485                pairs[frozenset((a, b.this))].append((op, a))
    486
    487        for op in ops:
    488            if not isinstance(op, kind):
    489                continue
    490
    491            a, b = op.unnest_operands()
    492
    493            # Absorb
    494            if isinstance(a, exp.Not) and a.this in op_set:
    495                a.replace(exp.true() if kind == exp.And else exp.false())
    496                continue
    497            if isinstance(b, exp.Not) and b.this in op_set:
    498                b.replace(exp.true() if kind == exp.And else exp.false())
    499                continue
    500            superset = set(op.flatten())
    501            if any(any(subset < superset for subset in subops[i]) for i in superset):
    502                op.replace(exp.false() if kind == exp.And else exp.true())
    503                continue
    504
    505            # Eliminate
    506            for other, complement in pairs[frozenset((a, b))]:
    507                op.replace(complement)
    508                other.replace(complement)
    509
    510    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

    513def propagate_constants(expression, root=True):
    514    """
    515    Propagate constants for conjunctions in DNF:
    516
    517    SELECT * FROM t WHERE a = b AND b = 5 becomes
    518    SELECT * FROM t WHERE a = 5 AND b = 5
    519
    520    Reference: https://www.sqlite.org/optoverview.html
    521    """
    522
    523    if (
    524        isinstance(expression, exp.And)
    525        and (root or not expression.same_parent)
    526        and sqlglot.optimizer.normalize.normalized(expression, dnf=True)
    527    ):
    528        constant_mapping = {}
    529        for expr in walk_in_scope(expression, prune=lambda node: isinstance(node, exp.If)):
    530            if isinstance(expr, exp.EQ):
    531                l, r = expr.left, expr.right
    532
    533                # TODO: create a helper that can be used to detect nested literal expressions such
    534                # as CAST(123456 AS BIGINT), since we usually want to treat those as literals too
    535                if isinstance(l, exp.Column) and isinstance(r, exp.Literal):
    536                    constant_mapping[l] = (id(l), r)
    537
    538        if constant_mapping:
    539            for column in find_all_in_scope(expression, exp.Column):
    540                parent = column.parent
    541                column_id, constant = constant_mapping.get(column) or (None, None)
    542                if (
    543                    column_id is not None
    544                    and id(column) != column_id
    545                    and not (isinstance(parent, exp.Is) and isinstance(parent.expression, exp.Null))
    546                ):
    547                    column.replace(constant.copy())
    548
    549    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

    624def simplify_literals(expression, root=True):
    625    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
    626        return _flat_simplify(expression, _simplify_binary, root)
    627
    628    if isinstance(expression, exp.Neg) and isinstance(expression.this, exp.Neg):
    629        return expression.this.this
    630
    631    if type(expression) in INVERSE_DATE_OPS:
    632        return _simplify_binary(expression, expression.this, expression.interval()) or expression
    633
    634    return expression

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

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

def simplify_coalesce(expression): View Source

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

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

    832def simplify_concat(expression):
    833    """Reduces all groups that contain string literals by concatenating them."""
    834    if not isinstance(expression, CONCATS) or (
    835        # We can't reduce a CONCAT_WS call if we don't statically know the separator
    836        isinstance(expression, exp.ConcatWs) and not expression.expressions[0].is_string
    837    ):
    838        return expression
    839
    840    if isinstance(expression, exp.ConcatWs):
    841        sep_expr, *expressions = expression.expressions
    842        sep = sep_expr.name
    843        concat_type = exp.ConcatWs
    844        args = {}
    845    else:
    846        expressions = expression.expressions
    847        sep = ""
    848        concat_type = exp.Concat
    849        args = {
    850            "safe": expression.args.get("safe"),
    851            "coalesce": expression.args.get("coalesce"),
    852        }
    853
    854    new_args = []
    855    for is_string_group, group in itertools.groupby(
    856        expressions or expression.flatten(), lambda e: e.is_string
    857    ):
    858        if is_string_group:
    859            new_args.append(exp.Literal.string(sep.join(string.name for string in group)))
    860        else:
    861            new_args.extend(group)
    862
    863    if len(new_args) == 1 and new_args[0].is_string:
    864        return new_args[0]
    865
    866    if concat_type is exp.ConcatWs:
    867        new_args = [sep_expr] + new_args
    868    elif isinstance(expression, exp.DPipe):
    869        return reduce(lambda x, y: exp.DPipe(this=x, expression=y), new_args)
    870
    871    return concat_type(expressions=new_args, **args)

Reduces all groups that contain string literals by concatenating them.

def simplify_conditionals(expression): View Source

    874def simplify_conditionals(expression):
    875    """Simplifies expressions like IF, CASE if their condition is statically known."""
    876    if isinstance(expression, exp.Case):
    877        this = expression.this
    878        for case in expression.args["ifs"]:
    879            cond = case.this
    880            if this:
    881                # Convert CASE x WHEN matching_value ... to CASE WHEN x = matching_value ...
    882                cond = cond.replace(this.pop().eq(cond))
    883
    884            if always_true(cond):
    885                return case.args["true"]
    886
    887            if always_false(cond):
    888                case.pop()
    889                if not expression.args["ifs"]:
    890                    return expression.args.get("default") or exp.null()
    891    elif isinstance(expression, exp.If) and not isinstance(expression.parent, exp.Case):
    892        if always_true(expression.this):
    893            return expression.args["true"]
    894        if always_false(expression.this):
    895            return expression.args.get("false") or exp.null()
    896
    897    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

    900def simplify_startswith(expression: exp.Expression) -> exp.Expression:
    901    """
    902    Reduces a prefix check to either TRUE or FALSE if both the string and the
    903    prefix are statically known.
    904
    905    Example:
    906        >>> from sqlglot import parse_one
    907        >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
    908        'TRUE'
    909    """
    910    if (
    911        isinstance(expression, exp.StartsWith)
    912        and expression.this.is_string
    913        and expression.expression.is_string
    914    ):
    915        return exp.convert(expression.name.startswith(expression.expression.name))
    916
    917    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.LT'>, <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.In'>, <class 'sqlglot.expressions.LTE'>, <class 'sqlglot.expressions.NEQ'>, <class 'sqlglot.expressions.EQ'>, <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

    1066def sort_comparison(expression: exp.Expression) -> exp.Expression:
    1067    if expression.__class__ in COMPLEMENT_COMPARISONS:
    1068        l, r = expression.this, expression.expression
    1069        l_column = isinstance(l, exp.Column)
    1070        r_column = isinstance(r, exp.Column)
    1071        l_const = _is_constant(l)
    1072        r_const = _is_constant(r)
    1073
    1074        if (l_column and not r_column) or (r_const and not l_const):
    1075            return expression
    1076        if (r_column and not l_column) or (l_const and not r_const) or (gen(l) > gen(r)):
    1077            return INVERSE_COMPARISONS.get(expression.__class__, expression.__class__)(
    1078                this=r, expression=l
    1079            )
    1080    return expression

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

    1094def remove_where_true(expression):
    1095    for where in expression.find_all(exp.Where):
    1096        if always_true(where.this):
    1097            where.pop()
    1098    for join in expression.find_all(exp.Join):
    1099        if (
    1100            always_true(join.args.get("on"))
    1101            and not join.args.get("using")
    1102            and not join.args.get("method")
    1103            and (join.side, join.kind) in JOINS
    1104        ):
    1105            join.args["on"].pop()
    1106            join.set("side", None)
    1107            join.set("kind", "CROSS")

def always_true(expression): View Source

    1110def always_true(expression):
    1111    return (isinstance(expression, exp.Boolean) and expression.this) or (
    1112        isinstance(expression, exp.Literal) and not is_zero(expression)
    1113    )

def always_false(expression): View Source

    1116def always_false(expression):
    1117    return is_false(expression) or is_null(expression) or is_zero(expression)

def is_zero(expression): View Source

    1120def is_zero(expression):
    1121    return isinstance(expression, exp.Literal) and expression.to_py() == 0

def is_complement(a, b): View Source

    1124def is_complement(a, b):
    1125    return isinstance(b, exp.Not) and b.this == a

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

    1128def is_false(a: exp.Expression) -> bool:
    1129    return type(a) is exp.Boolean and not a.this

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

    1132def is_null(a: exp.Expression) -> bool:
    1133    return type(a) is exp.Null

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

    1136def eval_boolean(expression, a, b):
    1137    if isinstance(expression, (exp.EQ, exp.Is)):
    1138        return boolean_literal(a == b)
    1139    if isinstance(expression, exp.NEQ):
    1140        return boolean_literal(a != b)
    1141    if isinstance(expression, exp.GT):
    1142        return boolean_literal(a > b)
    1143    if isinstance(expression, exp.GTE):
    1144        return boolean_literal(a >= b)
    1145    if isinstance(expression, exp.LT):
    1146        return boolean_literal(a < b)
    1147    if isinstance(expression, exp.LTE):
    1148        return boolean_literal(a <= b)
    1149    return None

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

    1152def cast_as_date(value: t.Any) -> t.Optional[datetime.date]:
    1153    if isinstance(value, datetime.datetime):
    1154        return value.date()
    1155    if isinstance(value, datetime.date):
    1156        return value
    1157    try:
    1158        return datetime.datetime.fromisoformat(value).date()
    1159    except ValueError:
    1160        return None

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

    1163def cast_as_datetime(value: t.Any) -> t.Optional[datetime.datetime]:
    1164    if isinstance(value, datetime.datetime):
    1165        return value
    1166    if isinstance(value, datetime.date):
    1167        return datetime.datetime(year=value.year, month=value.month, day=value.day)
    1168    try:
    1169        return datetime.datetime.fromisoformat(value)
    1170    except ValueError:
    1171        return None

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

    1174def cast_value(value: t.Any, to: exp.DataType) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1175    if not value:
    1176        return None
    1177    if to.is_type(exp.DataType.Type.DATE):
    1178        return cast_as_date(value)
    1179    if to.is_type(*exp.DataType.TEMPORAL_TYPES):
    1180        return cast_as_datetime(value)
    1181    return None

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

    1184def extract_date(cast: exp.Expression) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1185    if isinstance(cast, exp.Cast):
    1186        to = cast.to
    1187    elif isinstance(cast, exp.TsOrDsToDate) and not cast.args.get("format"):
    1188        to = exp.DataType.build(exp.DataType.Type.DATE)
    1189    else:
    1190        return None
    1191
    1192    if isinstance(cast.this, exp.Literal):
    1193        value: t.Any = cast.this.name
    1194    elif isinstance(cast.this, (exp.Cast, exp.TsOrDsToDate)):
    1195        value = extract_date(cast.this)
    1196    else:
    1197        return None
    1198    return cast_value(value, to)

def extract_interval(expression): View Source

    1205def extract_interval(expression):
    1206    try:
    1207        n = int(expression.this.to_py())
    1208        unit = expression.text("unit").lower()
    1209        return interval(unit, n)
    1210    except (UnsupportedUnit, ModuleNotFoundError, ValueError):
    1211        return None

def extract_type(*expressions): View Source

    1214def extract_type(*expressions):
    1215    target_type = None
    1216    for expression in expressions:
    1217        target_type = expression.to if isinstance(expression, exp.Cast) else expression.type
    1218        if target_type:
    1219            break
    1220
    1221    return target_type

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

    1224def date_literal(date, target_type=None):
    1225    if not target_type or not target_type.is_type(*exp.DataType.TEMPORAL_TYPES):
    1226        target_type = (
    1227            exp.DataType.Type.DATETIME
    1228            if isinstance(date, datetime.datetime)
    1229            else exp.DataType.Type.DATE
    1230        )
    1231
    1232    return exp.cast(exp.Literal.string(date), target_type)

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

    1235def interval(unit: str, n: int = 1):
    1236    from dateutil.relativedelta import relativedelta
    1237
    1238    if unit == "year":
    1239        return relativedelta(years=1 * n)
    1240    if unit == "quarter":
    1241        return relativedelta(months=3 * n)
    1242    if unit == "month":
    1243        return relativedelta(months=1 * n)
    1244    if unit == "week":
    1245        return relativedelta(weeks=1 * n)
    1246    if unit == "day":
    1247        return relativedelta(days=1 * n)
    1248    if unit == "hour":
    1249        return relativedelta(hours=1 * n)
    1250    if unit == "minute":
    1251        return relativedelta(minutes=1 * n)
    1252    if unit == "second":
    1253        return relativedelta(seconds=1 * n)
    1254
    1255    raise UnsupportedUnit(f"Unsupported unit: {unit}")

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

    1258def date_floor(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1259    if unit == "year":
    1260        return d.replace(month=1, day=1)
    1261    if unit == "quarter":
    1262        if d.month <= 3:
    1263            return d.replace(month=1, day=1)
    1264        elif d.month <= 6:
    1265            return d.replace(month=4, day=1)
    1266        elif d.month <= 9:
    1267            return d.replace(month=7, day=1)
    1268        else:
    1269            return d.replace(month=10, day=1)
    1270    if unit == "month":
    1271        return d.replace(month=d.month, day=1)
    1272    if unit == "week":
    1273        # Assuming week starts on Monday (0) and ends on Sunday (6)
    1274        return d - datetime.timedelta(days=d.weekday() - dialect.WEEK_OFFSET)
    1275    if unit == "day":
    1276        return d
    1277
    1278    raise UnsupportedUnit(f"Unsupported unit: {unit}")

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

    1281def date_ceil(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1282    floor = date_floor(d, unit, dialect)
    1283
    1284    if floor == d:
    1285        return d
    1286
    1287    return floor + interval(unit)

def boolean_literal(condition): View Source

    1290def boolean_literal(condition):
    1291    return exp.true() if condition else exp.false()

def gen(expression: Any) -> str: View Source

    1320def gen(expression: t.Any) -> str:
    1321    """Simple pseudo sql generator for quickly generating sortable and uniq strings.
    1322
    1323    Sorting and deduping sql is a necessary step for optimization. Calling the actual
    1324    generator is expensive so we have a bare minimum sql generator here.
    1325    """
    1326    return Gen().gen(expression)

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.

class Gen: View Source

    1329class Gen:
    1330    def __init__(self):
    1331        self.stack = []
    1332        self.sqls = []
    1333
    1334    def gen(self, expression: exp.Expression) -> str:
    1335        self.stack = [expression]
    1336        self.sqls.clear()
    1337
    1338        while self.stack:
    1339            node = self.stack.pop()
    1340
    1341            if isinstance(node, exp.Expression):
    1342                exp_handler_name = f"{node.key}_sql"
    1343
    1344                if hasattr(self, exp_handler_name):
    1345                    getattr(self, exp_handler_name)(node)
    1346                elif isinstance(node, exp.Func):
    1347                    self._function(node)
    1348                else:
    1349                    key = node.key.upper()
    1350                    self.stack.append(f"{key} " if self._args(node) else key)
    1351            elif type(node) is list:
    1352                for n in reversed(node):
    1353                    if n is not None:
    1354                        self.stack.extend((n, ","))
    1355                if node:
    1356                    self.stack.pop()
    1357            else:
    1358                if node is not None:
    1359                    self.sqls.append(str(node))
    1360
    1361        return "".join(self.sqls)
    1362
    1363    def add_sql(self, e: exp.Add) -> None:
    1364        self._binary(e, " + ")
    1365
    1366    def alias_sql(self, e: exp.Alias) -> None:
    1367        self.stack.extend(
    1368            (
    1369                e.args.get("alias"),
    1370                " AS ",
    1371                e.args.get("this"),
    1372            )
    1373        )
    1374
    1375    def and_sql(self, e: exp.And) -> None:
    1376        self._binary(e, " AND ")
    1377
    1378    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1379        this = e.this
    1380        if isinstance(this, str):
    1381            name = this.upper()
    1382        elif isinstance(this, exp.Identifier):
    1383            name = this.this
    1384            name = f'"{name}"' if this.quoted else name.upper()
    1385        else:
    1386            raise ValueError(
    1387                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1388            )
    1389
    1390        self.stack.extend(
    1391            (
    1392                ")",
    1393                e.expressions,
    1394                "(",
    1395                name,
    1396            )
    1397        )
    1398
    1399    def between_sql(self, e: exp.Between) -> None:
    1400        self.stack.extend(
    1401            (
    1402                e.args.get("high"),
    1403                " AND ",
    1404                e.args.get("low"),
    1405                " BETWEEN ",
    1406                e.this,
    1407            )
    1408        )
    1409
    1410    def boolean_sql(self, e: exp.Boolean) -> None:
    1411        self.stack.append("TRUE" if e.this else "FALSE")
    1412
    1413    def bracket_sql(self, e: exp.Bracket) -> None:
    1414        self.stack.extend(
    1415            (
    1416                "]",
    1417                e.expressions,
    1418                "[",
    1419                e.this,
    1420            )
    1421        )
    1422
    1423    def column_sql(self, e: exp.Column) -> None:
    1424        for p in reversed(e.parts):
    1425            self.stack.extend((p, "."))
    1426        self.stack.pop()
    1427
    1428    def datatype_sql(self, e: exp.DataType) -> None:
    1429        self._args(e, 1)
    1430        self.stack.append(f"{e.this.name} ")
    1431
    1432    def div_sql(self, e: exp.Div) -> None:
    1433        self._binary(e, " / ")
    1434
    1435    def dot_sql(self, e: exp.Dot) -> None:
    1436        self._binary(e, ".")
    1437
    1438    def eq_sql(self, e: exp.EQ) -> None:
    1439        self._binary(e, " = ")
    1440
    1441    def from_sql(self, e: exp.From) -> None:
    1442        self.stack.extend((e.this, "FROM "))
    1443
    1444    def gt_sql(self, e: exp.GT) -> None:
    1445        self._binary(e, " > ")
    1446
    1447    def gte_sql(self, e: exp.GTE) -> None:
    1448        self._binary(e, " >= ")
    1449
    1450    def identifier_sql(self, e: exp.Identifier) -> None:
    1451        self.stack.append(f'"{e.this}"' if e.quoted else e.this)
    1452
    1453    def ilike_sql(self, e: exp.ILike) -> None:
    1454        self._binary(e, " ILIKE ")
    1455
    1456    def in_sql(self, e: exp.In) -> None:
    1457        self.stack.append(")")
    1458        self._args(e, 1)
    1459        self.stack.extend(
    1460            (
    1461                "(",
    1462                " IN ",
    1463                e.this,
    1464            )
    1465        )
    1466
    1467    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1468        self._binary(e, " DIV ")
    1469
    1470    def is_sql(self, e: exp.Is) -> None:
    1471        self._binary(e, " IS ")
    1472
    1473    def like_sql(self, e: exp.Like) -> None:
    1474        self._binary(e, " Like ")
    1475
    1476    def literal_sql(self, e: exp.Literal) -> None:
    1477        self.stack.append(f"'{e.this}'" if e.is_string else e.this)
    1478
    1479    def lt_sql(self, e: exp.LT) -> None:
    1480        self._binary(e, " < ")
    1481
    1482    def lte_sql(self, e: exp.LTE) -> None:
    1483        self._binary(e, " <= ")
    1484
    1485    def mod_sql(self, e: exp.Mod) -> None:
    1486        self._binary(e, " % ")
    1487
    1488    def mul_sql(self, e: exp.Mul) -> None:
    1489        self._binary(e, " * ")
    1490
    1491    def neg_sql(self, e: exp.Neg) -> None:
    1492        self._unary(e, "-")
    1493
    1494    def neq_sql(self, e: exp.NEQ) -> None:
    1495        self._binary(e, " <> ")
    1496
    1497    def not_sql(self, e: exp.Not) -> None:
    1498        self._unary(e, "NOT ")
    1499
    1500    def null_sql(self, e: exp.Null) -> None:
    1501        self.stack.append("NULL")
    1502
    1503    def or_sql(self, e: exp.Or) -> None:
    1504        self._binary(e, " OR ")
    1505
    1506    def paren_sql(self, e: exp.Paren) -> None:
    1507        self.stack.extend(
    1508            (
    1509                ")",
    1510                e.this,
    1511                "(",
    1512            )
    1513        )
    1514
    1515    def sub_sql(self, e: exp.Sub) -> None:
    1516        self._binary(e, " - ")
    1517
    1518    def subquery_sql(self, e: exp.Subquery) -> None:
    1519        self._args(e, 2)
    1520        alias = e.args.get("alias")
    1521        if alias:
    1522            self.stack.append(alias)
    1523        self.stack.extend((")", e.this, "("))
    1524
    1525    def table_sql(self, e: exp.Table) -> None:
    1526        self._args(e, 4)
    1527        alias = e.args.get("alias")
    1528        if alias:
    1529            self.stack.append(alias)
    1530        for p in reversed(e.parts):
    1531            self.stack.extend((p, "."))
    1532        self.stack.pop()
    1533
    1534    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1535        columns = e.columns
    1536
    1537        if columns:
    1538            self.stack.extend((")", columns, "("))
    1539
    1540        self.stack.extend((e.this, " AS "))
    1541
    1542    def var_sql(self, e: exp.Var) -> None:
    1543        self.stack.append(e.this)
    1544
    1545    def _binary(self, e: exp.Binary, op: str) -> None:
    1546        self.stack.extend((e.expression, op, e.this))
    1547
    1548    def _unary(self, e: exp.Unary, op: str) -> None:
    1549        self.stack.extend((e.this, op))
    1550
    1551    def _function(self, e: exp.Func) -> None:
    1552        self.stack.extend(
    1553            (
    1554                ")",
    1555                list(e.args.values()),
    1556                "(",
    1557                e.sql_name(),
    1558            )
    1559        )
    1560
    1561    def _args(self, node: exp.Expression, arg_index: int = 0) -> bool:
    1562        kvs = []
    1563        arg_types = list(node.arg_types)[arg_index:] if arg_index else node.arg_types
    1564
    1565        for k in arg_types or arg_types:
    1566            v = node.args.get(k)
    1567
    1568            if v is not None:
    1569                kvs.append([f":{k}", v])
    1570        if kvs:
    1571            self.stack.append(kvs)
    1572            return True
    1573        return False

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

    1334    def gen(self, expression: exp.Expression) -> str:
    1335        self.stack = [expression]
    1336        self.sqls.clear()
    1337
    1338        while self.stack:
    1339            node = self.stack.pop()
    1340
    1341            if isinstance(node, exp.Expression):
    1342                exp_handler_name = f"{node.key}_sql"
    1343
    1344                if hasattr(self, exp_handler_name):
    1345                    getattr(self, exp_handler_name)(node)
    1346                elif isinstance(node, exp.Func):
    1347                    self._function(node)
    1348                else:
    1349                    key = node.key.upper()
    1350                    self.stack.append(f"{key} " if self._args(node) else key)
    1351            elif type(node) is list:
    1352                for n in reversed(node):
    1353                    if n is not None:
    1354                        self.stack.extend((n, ","))
    1355                if node:
    1356                    self.stack.pop()
    1357            else:
    1358                if node is not None:
    1359                    self.sqls.append(str(node))
    1360
    1361        return "".join(self.sqls)

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

    1363    def add_sql(self, e: exp.Add) -> None:
    1364        self._binary(e, " + ")

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

    1366    def alias_sql(self, e: exp.Alias) -> None:
    1367        self.stack.extend(
    1368            (
    1369                e.args.get("alias"),
    1370                " AS ",
    1371                e.args.get("this"),
    1372            )
    1373        )

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

    1375    def and_sql(self, e: exp.And) -> None:
    1376        self._binary(e, " AND ")

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

    1378    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1379        this = e.this
    1380        if isinstance(this, str):
    1381            name = this.upper()
    1382        elif isinstance(this, exp.Identifier):
    1383            name = this.this
    1384            name = f'"{name}"' if this.quoted else name.upper()
    1385        else:
    1386            raise ValueError(
    1387                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1388            )
    1389
    1390        self.stack.extend(
    1391            (
    1392                ")",
    1393                e.expressions,
    1394                "(",
    1395                name,
    1396            )
    1397        )

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

    1399    def between_sql(self, e: exp.Between) -> None:
    1400        self.stack.extend(
    1401            (
    1402                e.args.get("high"),
    1403                " AND ",
    1404                e.args.get("low"),
    1405                " BETWEEN ",
    1406                e.this,
    1407            )
    1408        )

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

    1410    def boolean_sql(self, e: exp.Boolean) -> None:
    1411        self.stack.append("TRUE" if e.this else "FALSE")

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

    1413    def bracket_sql(self, e: exp.Bracket) -> None:
    1414        self.stack.extend(
    1415            (
    1416                "]",
    1417                e.expressions,
    1418                "[",
    1419                e.this,
    1420            )
    1421        )

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

    1423    def column_sql(self, e: exp.Column) -> None:
    1424        for p in reversed(e.parts):
    1425            self.stack.extend((p, "."))
    1426        self.stack.pop()

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

    1428    def datatype_sql(self, e: exp.DataType) -> None:
    1429        self._args(e, 1)
    1430        self.stack.append(f"{e.this.name} ")

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

    1432    def div_sql(self, e: exp.Div) -> None:
    1433        self._binary(e, " / ")

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

    1435    def dot_sql(self, e: exp.Dot) -> None:
    1436        self._binary(e, ".")

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

    1438    def eq_sql(self, e: exp.EQ) -> None:
    1439        self._binary(e, " = ")

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

    1441    def from_sql(self, e: exp.From) -> None:
    1442        self.stack.extend((e.this, "FROM "))

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

    1444    def gt_sql(self, e: exp.GT) -> None:
    1445        self._binary(e, " > ")

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

    1447    def gte_sql(self, e: exp.GTE) -> None:
    1448        self._binary(e, " >= ")

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

    1450    def identifier_sql(self, e: exp.Identifier) -> None:
    1451        self.stack.append(f'"{e.this}"' if e.quoted else e.this)

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

    1453    def ilike_sql(self, e: exp.ILike) -> None:
    1454        self._binary(e, " ILIKE ")

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

    1456    def in_sql(self, e: exp.In) -> None:
    1457        self.stack.append(")")
    1458        self._args(e, 1)
    1459        self.stack.extend(
    1460            (
    1461                "(",
    1462                " IN ",
    1463                e.this,
    1464            )
    1465        )

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

    1467    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1468        self._binary(e, " DIV ")

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

    1470    def is_sql(self, e: exp.Is) -> None:
    1471        self._binary(e, " IS ")

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

    1473    def like_sql(self, e: exp.Like) -> None:
    1474        self._binary(e, " Like ")

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

    1476    def literal_sql(self, e: exp.Literal) -> None:
    1477        self.stack.append(f"'{e.this}'" if e.is_string else e.this)

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

    1479    def lt_sql(self, e: exp.LT) -> None:
    1480        self._binary(e, " < ")

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

    1482    def lte_sql(self, e: exp.LTE) -> None:
    1483        self._binary(e, " <= ")

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

    1485    def mod_sql(self, e: exp.Mod) -> None:
    1486        self._binary(e, " % ")

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

    1488    def mul_sql(self, e: exp.Mul) -> None:
    1489        self._binary(e, " * ")

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

    1491    def neg_sql(self, e: exp.Neg) -> None:
    1492        self._unary(e, "-")

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

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

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

    1497    def not_sql(self, e: exp.Not) -> None:
    1498        self._unary(e, "NOT ")

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

    1500    def null_sql(self, e: exp.Null) -> None:
    1501        self.stack.append("NULL")

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

    1503    def or_sql(self, e: exp.Or) -> None:
    1504        self._binary(e, " OR ")

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

    1506    def paren_sql(self, e: exp.Paren) -> None:
    1507        self.stack.extend(
    1508            (
    1509                ")",
    1510                e.this,
    1511                "(",
    1512            )
    1513        )

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

    1515    def sub_sql(self, e: exp.Sub) -> None:
    1516        self._binary(e, " - ")

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

    1518    def subquery_sql(self, e: exp.Subquery) -> None:
    1519        self._args(e, 2)
    1520        alias = e.args.get("alias")
    1521        if alias:
    1522            self.stack.append(alias)
    1523        self.stack.extend((")", e.this, "("))

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

    1525    def table_sql(self, e: exp.Table) -> None:
    1526        self._args(e, 4)
    1527        alias = e.args.get("alias")
    1528        if alias:
    1529            self.stack.append(alias)
    1530        for p in reversed(e.parts):
    1531            self.stack.extend((p, "."))
    1532        self.stack.pop()

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

    1534    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1535        columns = e.columns
    1536
    1537        if columns:
    1538            self.stack.extend((")", columns, "("))
    1539
    1540        self.stack.extend((e.this, " AS "))

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

    1542    def var_sql(self, e: exp.Var) -> None:
    1543        self.stack.append(e.this)