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Precedence of NOT isn't quite right #81
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benesch
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May 27, 2019
NOT LIKE has the same precedence as the LIKE operator. The parser was previously assigning it the precedence of the unary NOT operator. Fixes apache#81.
benesch
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May 27, 2019
NOT LIKE has the same precedence as the LIKE operator. The parser was previously assigning it the precedence of the unary NOT operator. Fixes apache#81.
benesch
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May 27, 2019
Udate sqlparser to pull in a fix for andygrove/sqlparser-rs#81 that was causing sqllogictests to fail.
benesch
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May 31, 2019
NOT LIKE has the same precedence as the LIKE operator. The parser was previously assigning it the precedence of the unary NOT operator. NOT BETWEEN and NOT IN are treated similarly, as they are equivalent, from a precedence perspective, to NOT LIKE. The fix for this requires associating precedences with sequences of tokens, rather than single tokens, so that "NOT LIKE" and "NOT <expr>" can have different preferences. Perhaps surprisingly, this change is not very invasive. An alternative I considered involved adjusting the tokenizer to lex NOT, NOT LIKE, NOT BETWEEN, and NOT IN as separate tokens. This broke symmetry in strange ways, though, as NotLike, NotBetween, and NotIn gained dedicated tokens, while LIKE, BETWEEN, and IN remained as stringly identifiers. Fixes apache#81.
benesch
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Jun 1, 2019
NOT LIKE has the same precedence as the LIKE operator. The parser was previously assigning it the precedence of the unary NOT operator. NOT BETWEEN and NOT IN are treated similarly, as they are equivalent, from a precedence perspective, to NOT LIKE. The fix for this requires associating precedences with sequences of tokens, rather than single tokens, so that "NOT LIKE" and "NOT <expr>" can have different preferences. Perhaps surprisingly, this change is not very invasive. An alternative I considered involved adjusting the tokenizer to lex NOT, NOT LIKE, NOT BETWEEN, and NOT IN as separate tokens. This broke symmetry in strange ways, though, as NotLike, NotBetween, and NotIn gained dedicated tokens, while LIKE, BETWEEN, and IN remained as stringly identifiers. Fixes apache#81.
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It took me a while to come up with this example, and it's not totally realistic, but it's probably still worth fixing. Basically, the precedence of
NOT LIKE
is mishandled, because the precedence ofNOT
is fixed to its unary operator precedence, when in it needs to vary based on whether the NOT keyword is followed by LIKE/BETWEEN/IN/.Concretely,
SELECT a LIKE b IS NULL
parses correctly, with the LIKE binding more tightly than the IS NULL:But when NOT LIKE is substituted for LIKE, the IS NULL incorrectly binds more tightly than the NOT LIKE:
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