database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-08-21 10:42:50 +03:00
Code Activity

Add the ability for the core grammar to have more than one parse target.

Browse Source 
This patch essentially allows gram.y to implement a family of related
syntax trees, rather than necessarily always parsing a list of SQL
statements.  raw_parser() gains a new argument, enum RawParseMode,
to say what to do.  As proof of concept, add a mode that just parses
a TypeName without any other decoration, and use that to greatly
simplify typeStringToTypeName().

In addition, invent a new SPI entry point SPI_prepare_extended() to
allow SPI users (particularly plpgsql) to get at this new functionality.
In hopes of making this the last variant of SPI_prepare(), set up its
additional arguments as a struct rather than direct arguments, and
promise that future additions to the struct can default to zero.
SPI_prepare_cursor() and SPI_prepare_params() can perhaps go away at
some point.

Discussion: https://postgr.es/m/4165684.1607707277@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2021-01-04 11:03:22 -05:00
parent b49154b3b7
commit 844fe9f159
14 changed files with 268 additions and 83 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
src/backend/parser/parser.c
View File

@@ -35,11 +35,11 @@ static char *str_udeescape(const char *str, char escape,
* raw_parser
* Given a query in string form, do lexical and grammatical analysis.
*
* Returns a list of raw (un-analyzed) parse trees. The immediate elements
* of the list are always RawStmt nodes.
* Returns a list of raw (un-analyzed) parse trees. The contents of the
* list have the form required by the specified RawParseMode.
*/
List *
raw_parser(const char *str)
raw_parser(const char *str, RawParseMode mode)
{
core_yyscan_t yyscanner;
base_yy_extra_type yyextra;
@@ -49,8 +49,22 @@ raw_parser(const char *str)
yyscanner = scanner_init(str, &yyextra.core_yy_extra,
&ScanKeywords, ScanKeywordTokens);
/* base_yylex() only needs this much initialization */
yyextra.have_lookahead = false;
/* base_yylex() only needs us to initialize the lookahead token, if any */
if (mode == RAW_PARSE_DEFAULT)
yyextra.have_lookahead = false;
else
{
/* this array is indexed by RawParseMode enum */
static const int mode_token[] = {
0, /* RAW_PARSE_DEFAULT */
MODE_TYPE_NAME /* RAW_PARSE_TYPE_NAME */
};
yyextra.have_lookahead = true;
yyextra.lookahead_token = mode_token[mode];
yyextra.lookahead_yylloc = 0;
yyextra.lookahead_end = NULL;
}
/* initialize the bison parser */
parser_init(&yyextra);
@@ -104,7 +118,8 @@ base_yylex(YYSTYPE *lvalp, YYLTYPE *llocp, core_yyscan_t yyscanner)
cur_token = yyextra->lookahead_token;
lvalp->core_yystype = yyextra->lookahead_yylval;
*llocp = yyextra->lookahead_yylloc;
*(yyextra->lookahead_end) = yyextra->lookahead_hold_char;
if (yyextra->lookahead_end)
*(yyextra->lookahead_end) = yyextra->lookahead_hold_char;
yyextra->have_lookahead = false;
}
else