sqlglot.optimizer.simplify API documentation

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# sqlglot.optimizer.simplify

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      1import datetime
      2import functools
      3import itertools
      4from collections import deque
      5from decimal import Decimal
      6
      7from sqlglot import exp
      8from sqlglot.generator import cached_generator
      9from sqlglot.helper import first, while_changing
     10
     11
     12def simplify(expression):
     13    """
     14    Rewrite sqlglot AST to simplify expressions.
     15
     16    Example:
     17        >>> import sqlglot
     18        >>> expression = sqlglot.parse_one("TRUE AND TRUE")
     19        >>> simplify(expression).sql()
     20        'TRUE'
     21
     22    Args:
     23        expression (sqlglot.Expression): expression to simplify
     24    Returns:
     25        sqlglot.Expression: simplified expression
     26    """
     27
     28    generate = cached_generator()
     29
     30    def _simplify(expression, root=True):
     31        node = expression
     32        node = rewrite_between(node)
     33        node = uniq_sort(node, generate, root)
     34        node = absorb_and_eliminate(node, root)
     35        exp.replace_children(node, lambda e: _simplify(e, False))
     36        node = simplify_not(node)
     37        node = flatten(node)
     38        node = simplify_connectors(node, root)
     39        node = remove_compliments(node, root)
     40        node.parent = expression.parent
     41        node = simplify_literals(node, root)
     42        node = simplify_parens(node)
     43        if root:
     44            expression.replace(node)
     45        return node
     46
     47    expression = while_changing(expression, _simplify)
     48    remove_where_true(expression)
     49    return expression
     50
     51
     52def rewrite_between(expression: exp.Expression) -> exp.Expression:
     53    """Rewrite x between y and z to x >= y AND x <= z.
     54
     55    This is done because comparison simplification is only done on lt/lte/gt/gte.
     56    """
     57    if isinstance(expression, exp.Between):
     58        return exp.and_(
     59            exp.GTE(this=expression.this.copy(), expression=expression.args["low"]),
     60            exp.LTE(this=expression.this.copy(), expression=expression.args["high"]),
     61            copy=False,
     62        )
     63    return expression
     64
     65
     66def simplify_not(expression):
     67    """
     68    Demorgan's Law
     69    NOT (x OR y) -> NOT x AND NOT y
     70    NOT (x AND y) -> NOT x OR NOT y
     71    """
     72    if isinstance(expression, exp.Not):
     73        if is_null(expression.this):
     74            return exp.null()
     75        if isinstance(expression.this, exp.Paren):
     76            condition = expression.this.unnest()
     77            if isinstance(condition, exp.And):
     78                return exp.or_(
     79                    exp.not_(condition.left, copy=False),
     80                    exp.not_(condition.right, copy=False),
     81                    copy=False,
     82                )
     83            if isinstance(condition, exp.Or):
     84                return exp.and_(
     85                    exp.not_(condition.left, copy=False),
     86                    exp.not_(condition.right, copy=False),
     87                    copy=False,
     88                )
     89            if is_null(condition):
     90                return exp.null()
     91        if always_true(expression.this):
     92            return exp.false()
     93        if is_false(expression.this):
     94            return exp.true()
     95        if isinstance(expression.this, exp.Not):
     96            # double negation
     97            # NOT NOT x -> x
     98            return expression.this.this
     99    return expression
    100
    101
    102def flatten(expression):
    103    """
    104    A AND (B AND C) -> A AND B AND C
    105    A OR (B OR C) -> A OR B OR C
    106    """
    107    if isinstance(expression, exp.Connector):
    108        for node in expression.args.values():
    109            child = node.unnest()
    110            if isinstance(child, expression.__class__):
    111                node.replace(child)
    112    return expression
    113
    114
    115def simplify_connectors(expression, root=True):
    116    def _simplify_connectors(expression, left, right):
    117        if left == right:
    118            return left
    119        if isinstance(expression, exp.And):
    120            if is_false(left) or is_false(right):
    121                return exp.false()
    122            if is_null(left) or is_null(right):
    123                return exp.null()
    124            if always_true(left) and always_true(right):
    125                return exp.true()
    126            if always_true(left):
    127                return right
    128            if always_true(right):
    129                return left
    130            return _simplify_comparison(expression, left, right)
    131        elif isinstance(expression, exp.Or):
    132            if always_true(left) or always_true(right):
    133                return exp.true()
    134            if is_false(left) and is_false(right):
    135                return exp.false()
    136            if (
    137                (is_null(left) and is_null(right))
    138                or (is_null(left) and is_false(right))
    139                or (is_false(left) and is_null(right))
    140            ):
    141                return exp.null()
    142            if is_false(left):
    143                return right
    144            if is_false(right):
    145                return left
    146            return _simplify_comparison(expression, left, right, or_=True)
    147
    148    if isinstance(expression, exp.Connector):
    149        return _flat_simplify(expression, _simplify_connectors, root)
    150    return expression
    151
    152
    153LT_LTE = (exp.LT, exp.LTE)
    154GT_GTE = (exp.GT, exp.GTE)
    155
    156COMPARISONS = (
    157    *LT_LTE,
    158    *GT_GTE,
    159    exp.EQ,
    160    exp.NEQ,
    161)
    162
    163INVERSE_COMPARISONS = {
    164    exp.LT: exp.GT,
    165    exp.GT: exp.LT,
    166    exp.LTE: exp.GTE,
    167    exp.GTE: exp.LTE,
    168}
    169
    170
    171def _simplify_comparison(expression, left, right, or_=False):
    172    if isinstance(left, COMPARISONS) and isinstance(right, COMPARISONS):
    173        ll, lr = left.args.values()
    174        rl, rr = right.args.values()
    175
    176        largs = {ll, lr}
    177        rargs = {rl, rr}
    178
    179        matching = largs & rargs
    180        columns = {m for m in matching if isinstance(m, exp.Column)}
    181
    182        if matching and columns:
    183            try:
    184                l = first(largs - columns)
    185                r = first(rargs - columns)
    186            except StopIteration:
    187                return expression
    188
    189            # make sure the comparison is always of the form x > 1 instead of 1 < x
    190            if left.__class__ in INVERSE_COMPARISONS and l == ll:
    191                left = INVERSE_COMPARISONS[left.__class__](this=lr, expression=ll)
    192            if right.__class__ in INVERSE_COMPARISONS and r == rl:
    193                right = INVERSE_COMPARISONS[right.__class__](this=rr, expression=rl)
    194
    195            if l.is_number and r.is_number:
    196                l = float(l.name)
    197                r = float(r.name)
    198            elif l.is_string and r.is_string:
    199                l = l.name
    200                r = r.name
    201            else:
    202                return None
    203
    204            for (a, av), (b, bv) in itertools.permutations(((left, l), (right, r))):
    205                if isinstance(a, LT_LTE) and isinstance(b, LT_LTE):
    206                    return left if (av > bv if or_ else av <= bv) else right
    207                if isinstance(a, GT_GTE) and isinstance(b, GT_GTE):
    208                    return left if (av < bv if or_ else av >= bv) else right
    209
    210                # we can't ever shortcut to true because the column could be null
    211                if not or_:
    212                    if isinstance(a, exp.LT) and isinstance(b, GT_GTE):
    213                        if av <= bv:
    214                            return exp.false()
    215                    elif isinstance(a, exp.GT) and isinstance(b, LT_LTE):
    216                        if av >= bv:
    217                            return exp.false()
    218                    elif isinstance(a, exp.EQ):
    219                        if isinstance(b, exp.LT):
    220                            return exp.false() if av >= bv else a
    221                        if isinstance(b, exp.LTE):
    222                            return exp.false() if av > bv else a
    223                        if isinstance(b, exp.GT):
    224                            return exp.false() if av <= bv else a
    225                        if isinstance(b, exp.GTE):
    226                            return exp.false() if av < bv else a
    227                        if isinstance(b, exp.NEQ):
    228                            return exp.false() if av == bv else a
    229    return None
    230
    231
    232def remove_compliments(expression, root=True):
    233    """
    234    Removing compliments.
    235
    236    A AND NOT A -> FALSE
    237    A OR NOT A -> TRUE
    238    """
    239    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    240        compliment = exp.false() if isinstance(expression, exp.And) else exp.true()
    241
    242        for a, b in itertools.permutations(expression.flatten(), 2):
    243            if is_complement(a, b):
    244                return compliment
    245    return expression
    246
    247
    248def uniq_sort(expression, generate, root=True):
    249    """
    250    Uniq and sort a connector.
    251
    252    C AND A AND B AND B -> A AND B AND C
    253    """
    254    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    255        result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
    256        flattened = tuple(expression.flatten())
    257        deduped = {generate(e): e for e in flattened}
    258        arr = tuple(deduped.items())
    259
    260        # check if the operands are already sorted, if not sort them
    261        # A AND C AND B -> A AND B AND C
    262        for i, (sql, e) in enumerate(arr[1:]):
    263            if sql < arr[i][0]:
    264                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
    265                break
    266        else:
    267            # we didn't have to sort but maybe we need to dedup
    268            if len(deduped) < len(flattened):
    269                expression = result_func(*deduped.values(), copy=False)
    270
    271    return expression
    272
    273
    274def absorb_and_eliminate(expression, root=True):
    275    """
    276    absorption:
    277        A AND (A OR B) -> A
    278        A OR (A AND B) -> A
    279        A AND (NOT A OR B) -> A AND B
    280        A OR (NOT A AND B) -> A OR B
    281    elimination:
    282        (A AND B) OR (A AND NOT B) -> A
    283        (A OR B) AND (A OR NOT B) -> A
    284    """
    285    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    286        kind = exp.Or if isinstance(expression, exp.And) else exp.And
    287
    288        for a, b in itertools.permutations(expression.flatten(), 2):
    289            if isinstance(a, kind):
    290                aa, ab = a.unnest_operands()
    291
    292                # absorb
    293                if is_complement(b, aa):
    294                    aa.replace(exp.true() if kind == exp.And else exp.false())
    295                elif is_complement(b, ab):
    296                    ab.replace(exp.true() if kind == exp.And else exp.false())
    297                elif (set(b.flatten()) if isinstance(b, kind) else {b}) < set(a.flatten()):
    298                    a.replace(exp.false() if kind == exp.And else exp.true())
    299                elif isinstance(b, kind):
    300                    # eliminate
    301                    rhs = b.unnest_operands()
    302                    ba, bb = rhs
    303
    304                    if aa in rhs and (is_complement(ab, ba) or is_complement(ab, bb)):
    305                        a.replace(aa)
    306                        b.replace(aa)
    307                    elif ab in rhs and (is_complement(aa, ba) or is_complement(aa, bb)):
    308                        a.replace(ab)
    309                        b.replace(ab)
    310
    311    return expression
    312
    313
    314def simplify_literals(expression, root=True):
    315    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
    316        return _flat_simplify(expression, _simplify_binary, root)
    317    elif isinstance(expression, exp.Neg):
    318        this = expression.this
    319        if this.is_number:
    320            value = this.name
    321            if value[0] == "-":
    322                return exp.Literal.number(value[1:])
    323            return exp.Literal.number(f"-{value}")
    324
    325    return expression
    326
    327
    328def _simplify_binary(expression, a, b):
    329    if isinstance(expression, exp.Is):
    330        if isinstance(b, exp.Not):
    331            c = b.this
    332            not_ = True
    333        else:
    334            c = b
    335            not_ = False
    336
    337        if is_null(c):
    338            if isinstance(a, exp.Literal):
    339                return exp.true() if not_ else exp.false()
    340            if is_null(a):
    341                return exp.false() if not_ else exp.true()
    342    elif isinstance(expression, (exp.NullSafeEQ, exp.NullSafeNEQ)):
    343        return None
    344    elif is_null(a) or is_null(b):
    345        return exp.null()
    346
    347    if a.is_number and b.is_number:
    348        a = int(a.name) if a.is_int else Decimal(a.name)
    349        b = int(b.name) if b.is_int else Decimal(b.name)
    350
    351        if isinstance(expression, exp.Add):
    352            return exp.Literal.number(a + b)
    353        if isinstance(expression, exp.Sub):
    354            return exp.Literal.number(a - b)
    355        if isinstance(expression, exp.Mul):
    356            return exp.Literal.number(a * b)
    357        if isinstance(expression, exp.Div):
    358            # engines have differing int div behavior so intdiv is not safe
    359            if isinstance(a, int) and isinstance(b, int):
    360                return None
    361            return exp.Literal.number(a / b)
    362
    363        boolean = eval_boolean(expression, a, b)
    364
    365        if boolean:
    366            return boolean
    367    elif a.is_string and b.is_string:
    368        boolean = eval_boolean(expression, a.this, b.this)
    369
    370        if boolean:
    371            return boolean
    372    elif isinstance(a, exp.Cast) and isinstance(b, exp.Interval):
    373        a, b = extract_date(a), extract_interval(b)
    374        if a and b:
    375            if isinstance(expression, exp.Add):
    376                return date_literal(a + b)
    377            if isinstance(expression, exp.Sub):
    378                return date_literal(a - b)
    379    elif isinstance(a, exp.Interval) and isinstance(b, exp.Cast):
    380        a, b = extract_interval(a), extract_date(b)
    381        # you cannot subtract a date from an interval
    382        if a and b and isinstance(expression, exp.Add):
    383            return date_literal(a + b)
    384
    385    return None
    386
    387
    388def simplify_parens(expression):
    389    if not isinstance(expression, exp.Paren):
    390        return expression
    391
    392    this = expression.this
    393    parent = expression.parent
    394
    395    if not isinstance(this, exp.Select) and (
    396        not isinstance(parent, (exp.Condition, exp.Binary))
    397        or isinstance(this, exp.Predicate)
    398        or not isinstance(this, exp.Binary)
    399        or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
    400        or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
    401    ):
    402        return expression.this
    403    return expression
    404
    405
    406def remove_where_true(expression):
    407    for where in expression.find_all(exp.Where):
    408        if always_true(where.this):
    409            where.parent.set("where", None)
    410    for join in expression.find_all(exp.Join):
    411        if always_true(join.args.get("on")):
    412            join.set("kind", "CROSS")
    413            join.set("on", None)
    414
    415
    416def always_true(expression):
    417    return (isinstance(expression, exp.Boolean) and expression.this) or isinstance(
    418        expression, exp.Literal
    419    )
    420
    421
    422def is_complement(a, b):
    423    return isinstance(b, exp.Not) and b.this == a
    424
    425
    426def is_false(a: exp.Expression) -> bool:
    427    return type(a) is exp.Boolean and not a.this
    428
    429
    430def is_null(a: exp.Expression) -> bool:
    431    return type(a) is exp.Null
    432
    433
    434def eval_boolean(expression, a, b):
    435    if isinstance(expression, (exp.EQ, exp.Is)):
    436        return boolean_literal(a == b)
    437    if isinstance(expression, exp.NEQ):
    438        return boolean_literal(a != b)
    439    if isinstance(expression, exp.GT):
    440        return boolean_literal(a > b)
    441    if isinstance(expression, exp.GTE):
    442        return boolean_literal(a >= b)
    443    if isinstance(expression, exp.LT):
    444        return boolean_literal(a < b)
    445    if isinstance(expression, exp.LTE):
    446        return boolean_literal(a <= b)
    447    return None
    448
    449
    450def extract_date(cast):
    451    # The "fromisoformat" conversion could fail if the cast is used on an identifier,
    452    # so in that case we can't extract the date.
    453    try:
    454        if cast.args["to"].this == exp.DataType.Type.DATE:
    455            return datetime.date.fromisoformat(cast.name)
    456        if cast.args["to"].this == exp.DataType.Type.DATETIME:
    457            return datetime.datetime.fromisoformat(cast.name)
    458    except ValueError:
    459        return None
    460
    461
    462def extract_interval(interval):
    463    try:
    464        from dateutil.relativedelta import relativedelta  # type: ignore
    465    except ModuleNotFoundError:
    466        return None
    467
    468    n = int(interval.name)
    469    unit = interval.text("unit").lower()
    470
    471    if unit == "year":
    472        return relativedelta(years=n)
    473    if unit == "month":
    474        return relativedelta(months=n)
    475    if unit == "week":
    476        return relativedelta(weeks=n)
    477    if unit == "day":
    478        return relativedelta(days=n)
    479    return None
    480
    481
    482def date_literal(date):
    483    return exp.cast(
    484        exp.Literal.string(date),
    485        "DATETIME" if isinstance(date, datetime.datetime) else "DATE",
    486    )
    487
    488
    489def boolean_literal(condition):
    490    return exp.true() if condition else exp.false()
    491
    492
    493def _flat_simplify(expression, simplifier, root=True):
    494    if root or not expression.same_parent:
    495        operands = []
    496        queue = deque(expression.flatten(unnest=False))
    497        size = len(queue)
    498
    499        while queue:
    500            a = queue.popleft()
    501
    502            for b in queue:
    503                result = simplifier(expression, a, b)
    504
    505                if result:
    506                    queue.remove(b)
    507                    queue.appendleft(result)
    508                    break
    509            else:
    510                operands.append(a)
    511
    512        if len(operands) < size:
    513            return functools.reduce(
    514                lambda a, b: expression.__class__(this=a, expression=b), operands
    515            )
    516    return expression

def simplify(expression): View Source

    13def simplify(expression):
    14    """
    15    Rewrite sqlglot AST to simplify expressions.
    16
    17    Example:
    18        >>> import sqlglot
    19        >>> expression = sqlglot.parse_one("TRUE AND TRUE")
    20        >>> simplify(expression).sql()
    21        'TRUE'
    22
    23    Args:
    24        expression (sqlglot.Expression): expression to simplify
    25    Returns:
    26        sqlglot.Expression: simplified expression
    27    """
    28
    29    generate = cached_generator()
    30
    31    def _simplify(expression, root=True):
    32        node = expression
    33        node = rewrite_between(node)
    34        node = uniq_sort(node, generate, root)
    35        node = absorb_and_eliminate(node, root)
    36        exp.replace_children(node, lambda e: _simplify(e, False))
    37        node = simplify_not(node)
    38        node = flatten(node)
    39        node = simplify_connectors(node, root)
    40        node = remove_compliments(node, root)
    41        node.parent = expression.parent
    42        node = simplify_literals(node, root)
    43        node = simplify_parens(node)
    44        if root:
    45            expression.replace(node)
    46        return node
    47
    48    expression = while_changing(expression, _simplify)
    49    remove_where_true(expression)
    50    return expression

Rewrite sqlglot AST to simplify expressions.

###### Example:

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

###### Arguments:

- expression (sqlglot.Expression): expression to simplify

###### Returns:

> sqlglot.Expression: simplified expression

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

    53def rewrite_between(expression: exp.Expression) -> exp.Expression:
    54    """Rewrite x between y and z to x >= y AND x <= z.
    55
    56    This is done because comparison simplification is only done on lt/lte/gt/gte.
    57    """
    58    if isinstance(expression, exp.Between):
    59        return exp.and_(
    60            exp.GTE(this=expression.this.copy(), expression=expression.args["low"]),
    61            exp.LTE(this=expression.this.copy(), expression=expression.args["high"]),
    62            copy=False,
    63        )
    64    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.

def simplify_not(expression): View Source

     67def simplify_not(expression):
     68    """
     69    Demorgan's Law
     70    NOT (x OR y) -> NOT x AND NOT y
     71    NOT (x AND y) -> NOT x OR NOT y
     72    """
     73    if isinstance(expression, exp.Not):
     74        if is_null(expression.this):
     75            return exp.null()
     76        if isinstance(expression.this, exp.Paren):
     77            condition = expression.this.unnest()
     78            if isinstance(condition, exp.And):
     79                return exp.or_(
     80                    exp.not_(condition.left, copy=False),
     81                    exp.not_(condition.right, copy=False),
     82                    copy=False,
     83                )
     84            if isinstance(condition, exp.Or):
     85                return exp.and_(
     86                    exp.not_(condition.left, copy=False),
     87                    exp.not_(condition.right, copy=False),
     88                    copy=False,
     89                )
     90            if is_null(condition):
     91                return exp.null()
     92        if always_true(expression.this):
     93            return exp.false()
     94        if is_false(expression.this):
     95            return exp.true()
     96        if isinstance(expression.this, exp.Not):
     97            # double negation
     98            # NOT NOT x -> x
     99            return expression.this.this
    100    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

    103def flatten(expression):
    104    """
    105    A AND (B AND C) -> A AND B AND C
    106    A OR (B OR C) -> A OR B OR C
    107    """
    108    if isinstance(expression, exp.Connector):
    109        for node in expression.args.values():
    110            child = node.unnest()
    111            if isinstance(child, expression.__class__):
    112                node.replace(child)
    113    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

    116def simplify_connectors(expression, root=True):
    117    def _simplify_connectors(expression, left, right):
    118        if left == right:
    119            return left
    120        if isinstance(expression, exp.And):
    121            if is_false(left) or is_false(right):
    122                return exp.false()
    123            if is_null(left) or is_null(right):
    124                return exp.null()
    125            if always_true(left) and always_true(right):
    126                return exp.true()
    127            if always_true(left):
    128                return right
    129            if always_true(right):
    130                return left
    131            return _simplify_comparison(expression, left, right)
    132        elif isinstance(expression, exp.Or):
    133            if always_true(left) or always_true(right):
    134                return exp.true()
    135            if is_false(left) and is_false(right):
    136                return exp.false()
    137            if (
    138                (is_null(left) and is_null(right))
    139                or (is_null(left) and is_false(right))
    140                or (is_false(left) and is_null(right))
    141            ):
    142                return exp.null()
    143            if is_false(left):
    144                return right
    145            if is_false(right):
    146                return left
    147            return _simplify_comparison(expression, left, right, or_=True)
    148
    149    if isinstance(expression, exp.Connector):
    150        return _flat_simplify(expression, _simplify_connectors, root)
    151    return expression

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

    233def remove_compliments(expression, root=True):
    234    """
    235    Removing compliments.
    236
    237    A AND NOT A -> FALSE
    238    A OR NOT A -> TRUE
    239    """
    240    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    241        compliment = exp.false() if isinstance(expression, exp.And) else exp.true()
    242
    243        for a, b in itertools.permutations(expression.flatten(), 2):
    244            if is_complement(a, b):
    245                return compliment
    246    return expression

Removing compliments.

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

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

    249def uniq_sort(expression, generate, root=True):
    250    """
    251    Uniq and sort a connector.
    252
    253    C AND A AND B AND B -> A AND B AND C
    254    """
    255    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    256        result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
    257        flattened = tuple(expression.flatten())
    258        deduped = {generate(e): e for e in flattened}
    259        arr = tuple(deduped.items())
    260
    261        # check if the operands are already sorted, if not sort them
    262        # A AND C AND B -> A AND B AND C
    263        for i, (sql, e) in enumerate(arr[1:]):
    264            if sql < arr[i][0]:
    265                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
    266                break
    267        else:
    268            # we didn't have to sort but maybe we need to dedup
    269            if len(deduped) < len(flattened):
    270                expression = result_func(*deduped.values(), copy=False)
    271
    272    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

    275def absorb_and_eliminate(expression, root=True):
    276    """
    277    absorption:
    278        A AND (A OR B) -> A
    279        A OR (A AND B) -> A
    280        A AND (NOT A OR B) -> A AND B
    281        A OR (NOT A AND B) -> A OR B
    282    elimination:
    283        (A AND B) OR (A AND NOT B) -> A
    284        (A OR B) AND (A OR NOT B) -> A
    285    """
    286    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    287        kind = exp.Or if isinstance(expression, exp.And) else exp.And
    288
    289        for a, b in itertools.permutations(expression.flatten(), 2):
    290            if isinstance(a, kind):
    291                aa, ab = a.unnest_operands()
    292
    293                # absorb
    294                if is_complement(b, aa):
    295                    aa.replace(exp.true() if kind == exp.And else exp.false())
    296                elif is_complement(b, ab):
    297                    ab.replace(exp.true() if kind == exp.And else exp.false())
    298                elif (set(b.flatten()) if isinstance(b, kind) else {b}) < set(a.flatten()):
    299                    a.replace(exp.false() if kind == exp.And else exp.true())
    300                elif isinstance(b, kind):
    301                    # eliminate
    302                    rhs = b.unnest_operands()
    303                    ba, bb = rhs
    304
    305                    if aa in rhs and (is_complement(ab, ba) or is_complement(ab, bb)):
    306                        a.replace(aa)
    307                        b.replace(aa)
    308                    elif ab in rhs and (is_complement(aa, ba) or is_complement(aa, bb)):
    309                        a.replace(ab)
    310                        b.replace(ab)
    311
    312    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 simplify_literals(expression, root=True): View Source

    315def simplify_literals(expression, root=True):
    316    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
    317        return _flat_simplify(expression, _simplify_binary, root)
    318    elif isinstance(expression, exp.Neg):
    319        this = expression.this
    320        if this.is_number:
    321            value = this.name
    322            if value[0] == "-":
    323                return exp.Literal.number(value[1:])
    324            return exp.Literal.number(f"-{value}")
    325
    326    return expression

def simplify_parens(expression): View Source

    389def simplify_parens(expression):
    390    if not isinstance(expression, exp.Paren):
    391        return expression
    392
    393    this = expression.this
    394    parent = expression.parent
    395
    396    if not isinstance(this, exp.Select) and (
    397        not isinstance(parent, (exp.Condition, exp.Binary))
    398        or isinstance(this, exp.Predicate)
    399        or not isinstance(this, exp.Binary)
    400        or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
    401        or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
    402    ):
    403        return expression.this
    404    return expression

def remove_where_true(expression): View Source

    407def remove_where_true(expression):
    408    for where in expression.find_all(exp.Where):
    409        if always_true(where.this):
    410            where.parent.set("where", None)
    411    for join in expression.find_all(exp.Join):
    412        if always_true(join.args.get("on")):
    413            join.set("kind", "CROSS")
    414            join.set("on", None)

def always_true(expression): View Source

    417def always_true(expression):
    418    return (isinstance(expression, exp.Boolean) and expression.this) or isinstance(
    419        expression, exp.Literal
    420    )

def is_complement(a, b): View Source

    423def is_complement(a, b):
    424    return isinstance(b, exp.Not) and b.this == a

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

    427def is_false(a: exp.Expression) -> bool:
    428    return type(a) is exp.Boolean and not a.this

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

    431def is_null(a: exp.Expression) -> bool:
    432    return type(a) is exp.Null

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

    435def eval_boolean(expression, a, b):
    436    if isinstance(expression, (exp.EQ, exp.Is)):
    437        return boolean_literal(a == b)
    438    if isinstance(expression, exp.NEQ):
    439        return boolean_literal(a != b)
    440    if isinstance(expression, exp.GT):
    441        return boolean_literal(a > b)
    442    if isinstance(expression, exp.GTE):
    443        return boolean_literal(a >= b)
    444    if isinstance(expression, exp.LT):
    445        return boolean_literal(a < b)
    446    if isinstance(expression, exp.LTE):
    447        return boolean_literal(a <= b)
    448    return None

def extract_date(cast): View Source

    451def extract_date(cast):
    452    # The "fromisoformat" conversion could fail if the cast is used on an identifier,
    453    # so in that case we can't extract the date.
    454    try:
    455        if cast.args["to"].this == exp.DataType.Type.DATE:
    456            return datetime.date.fromisoformat(cast.name)
    457        if cast.args["to"].this == exp.DataType.Type.DATETIME:
    458            return datetime.datetime.fromisoformat(cast.name)
    459    except ValueError:
    460        return None

def extract_interval(interval): View Source

    463def extract_interval(interval):
    464    try:
    465        from dateutil.relativedelta import relativedelta  # type: ignore
    466    except ModuleNotFoundError:
    467        return None
    468
    469    n = int(interval.name)
    470    unit = interval.text("unit").lower()
    471
    472    if unit == "year":
    473        return relativedelta(years=n)
    474    if unit == "month":
    475        return relativedelta(months=n)
    476    if unit == "week":
    477        return relativedelta(weeks=n)
    478    if unit == "day":
    479        return relativedelta(days=n)
    480    return None

def date_literal(date): View Source

    483def date_literal(date):
    484    return exp.cast(
    485        exp.Literal.string(date),
    486        "DATETIME" if isinstance(date, datetime.datetime) else "DATE",
    487    )

def boolean_literal(condition): View Source

    490def boolean_literal(condition):
    491    return exp.true() if condition else exp.false()