Fix some minor spec-compliance issues in jsonpath lexer

Enterprise / PostgreSQL - Tom Lane [sss.pgh.pa.us] - 20 September 2019 18:22 EDT

Although the SQL/JSON tech report makes reference to ECMAScript which allows both single- and double-quoted strings, all the rest of the report speaks only of double-quoted string literals in jsonpaths. That's more compatible with JSON itself; moreover single-quoted strings are hard to use inside a jsonpath that is itself a single-quoted SQL literal. So guess that the intent is to allow only double-quoted literals, and remove lexer support for single-quoted literals. It'll be less painful to add this again later if we're wrong, than to remove a shipped feature.

Also, adjust the lexer so that unrecognized backslash sequences are treated as just meaning the escaped character, not as errors. This change has much better support in the standards, as JSON, JavaScript and ECMAScript all make it plain that that's what's supposed to happen.

Back-patch to v12.

Discussion: https://postgr.es/m/CAPpHfdvDci4iqNF9fhRkTqhe-5_8HmzeLt56drH%2B_Rv2rNRqfg@mail.gmail.com

e56cad84d5 Fix some minor spec-compliance issues in jsonpath lexer.
src/backend/utils/adt/jsonpath_scan.l | 79 +++++++++--------------
src/test/regress/expected/jsonpath.out | 18 ++----
src/test/regress/expected/jsonpath_encoding.out | 78 ----------------------
src/test/regress/expected/jsonpath_encoding_1.out | 72 ---------------------
src/test/regress/sql/jsonpath.sql | 3 +-
src/test/regress/sql/jsonpath_encoding.sql | 23 -------
6 files changed, 38 insertions(+), 235 deletions(-)

Upstream: git.postgresql.org


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