postgresql/src/backend/parser
Jeff Davis 87b2968df0 downcase_identifier(): use method table from locale provider.
Previously, libc's tolower() was always used for lowercasing
identifiers, regardless of the database locale (though only characters
beyond 127 in single-byte encodings were affected). Refactor to allow
each provider to supply its own implementation of identifier
downcasing.

For historical compatibility, when using a single-byte encoding, ICU
still relies on tolower().

One minor behavior change is that, before the database default locale
is initialized, it uses ASCII semantics to downcase the
identifiers. Previously, it would use the postmaster's LC_CTYPE
setting from the environment. While that could have some effect during
GUC processing, for example, it would have been fragile to rely on the
environment setting anyway. (Also, it only matters when the encoding
is single-byte.)

Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://postgr.es/m/450ceb6260cad30d7afdf155d991a9caafee7c0d.camel@j-davis.com
2025-12-16 15:32:41 -08:00
..
.gitignore
analyze.c Use palloc_object() and palloc_array() in backend code 2025-12-10 07:36:46 +09:00
check_keywords.pl Update copyright for 2025 2025-01-01 11:21:55 -05:00
gram.y Implement ALTER TABLE ... SPLIT PARTITION ... command 2025-12-14 13:29:38 +02:00
gramparse.h Update copyright for 2025 2025-01-01 11:21:55 -05:00
Makefile Drop warning-free support for Flex 2.5.35 2025-01-15 15:35:08 +01:00
meson.build Drop warning-free support for Flex 2.5.35 2025-01-15 15:35:08 +01:00
parse_agg.c Don't allow CTEs to determine semantic levels of aggregates. 2025-11-18 12:56:55 -05:00
parse_clause.c Reject opclass options in ON CONFLICT clause 2025-12-12 14:26:42 +01:00
parse_coerce.c Don't include access/htup_details.h in executor/tuptable.h 2025-10-05 18:00:38 +02:00
parse_collate.c Update copyright for 2025 2025-01-01 11:21:55 -05:00
parse_cte.c Fix parse_cte.c's failure to examine sub-WITHs in DML statements. 2025-04-05 15:01:48 -04:00
parse_enr.c Update copyright for 2025 2025-01-01 11:21:55 -05:00
parse_expr.c Use palloc_object() and palloc_array() in backend code 2025-12-10 07:36:46 +09:00
parse_func.c Add IGNORE NULLS/RESPECT NULLS option to Window functions. 2025-10-03 09:47:36 +09:00
parse_jsontable.c Update copyright for 2025 2025-01-01 11:21:55 -05:00
parse_merge.c Add OLD/NEW support to RETURNING in DML queries. 2025-01-16 14:57:35 +00:00
parse_node.c Use palloc_object() and palloc_array() in backend code 2025-12-10 07:36:46 +09:00
parse_oper.c Provide more-specific error details/hints for function lookup failures. 2025-09-16 12:17:02 -04:00
parse_param.c Use palloc_object() and palloc_array() in backend code 2025-12-10 07:36:46 +09:00
parse_relation.c Use palloc_object() and palloc_array() in backend code 2025-12-10 07:36:46 +09:00
parse_target.c Avoid including commands/dbcommands.h in so many places 2025-08-28 12:39:04 +02:00
parse_type.c Use palloc_object() and palloc_array() in backend code 2025-12-10 07:36:46 +09:00
parse_utilcmd.c Implement ALTER TABLE ... SPLIT PARTITION ... command 2025-12-14 13:29:38 +02:00
parser.c Use C11 char16_t and char32_t for Unicode code points. 2025-10-29 14:17:13 -07:00
README Update parser README to include parse_jsontable.c 2025-09-08 10:07:14 +09:00
scan.l Use C11 char16_t and char32_t for Unicode code points. 2025-10-29 14:17:13 -07:00
scansup.c downcase_identifier(): use method table from locale provider. 2025-12-16 15:32:41 -08:00

src/backend/parser/README

Parser
======

This directory does more than tokenize and parse SQL queries.  It also
creates Query structures for the various complex queries that are passed
to the optimizer and then executor.

parser.c	things start here
scan.l		break query into tokens
scansup.c	handle escapes in input strings
gram.y		parse the tokens and produce a "raw" parse tree
analyze.c	top level of parse analysis for optimizable queries
parse_agg.c	handle aggregates, like SUM(col1),  AVG(col2), ...
parse_clause.c	handle clauses like WHERE, ORDER BY, GROUP BY, ...
parse_coerce.c	handle coercing expressions to different data types
parse_collate.c	assign collation information in completed expressions
parse_cte.c	handle Common Table Expressions (WITH clauses)
parse_expr.c	handle expressions like col, col + 3, x = 3 or x = 4
parse_enr.c	handle ephemeral named rels (trigger transition tables, ...)
parse_func.c	handle functions, table.column and column identifiers
parse_jsontable.c handle JSON_TABLE
parse_merge.c	handle MERGE
parse_node.c	create nodes for various structures
parse_oper.c	handle operators in expressions
parse_param.c	handle Params (for the cases used in the core backend)
parse_relation.c support routines for tables and column handling
parse_target.c	handle the result list of the query
parse_type.c	support routines for data type handling
parse_utilcmd.c	parse analysis for utility commands (done at execution time)

See also src/common/keywords.c, which contains the table of standard
keywords and the keyword lookup function.  We separated that out because
various frontend code wants to use it too.