jsonpath scanner: reentrant scanner

petere · petere · commit 2a7425d7eef9 · 2024-12-24T23:42:41.000+01:00
Use the flex %option reentrant to make the generated scanner reentrant and thread-safe. Note: The parser was already pure. Simplify flex scan buffer management: Instead of constructing the buffer from pieces and then using yy_scan_buffer(), we can just use yy_scan_string(), which does the same thing internally. (Actually, we use yy_scan_bytes() here because we already have the length.) Use flex yyextra to handle context information, instead of global variables. This complements the other changes to make the scanner reentrant. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Reviewed-by: Andreas Karlsson <andreas@proxel.se> Discussion: https://www.postgresql.org/message-id/flat/eb6faeac-2a8a-4b69-9189-c33c520e5b7b@eisentraut.org
diff --git a/src/backend/nls.mk b/src/backend/nls.mk
@@ -7,7 +7,7 @@ GETTEXT_TRIGGERS = $(BACKEND_COMMON_GETTEXT_TRIGGERS) \
                    GUC_check_errhint \
                    write_stderr \
                    yyerror \
-                   jsonpath_yyerror:3 \
+                   jsonpath_yyerror:4 \
                    parser_yyerror \
                    replication_yyerror:2 \
                    scanner_yyerror \
diff --git a/src/backend/utils/adt/jsonpath_gram.y b/src/backend/utils/adt/jsonpath_gram.y
@@ -60,8 +60,10 @@ static bool makeItemLikeRegex(JsonPathParseItem *expr,
 %name-prefix="jsonpath_yy"
 %parse-param {JsonPathParseResult **result}
 %parse-param {struct Node *escontext}
+%parse-param {yyscan_t yyscanner}
 %lex-param {JsonPathParseResult **result}
 %lex-param {struct Node *escontext}
+%lex-param {yyscan_t yyscanner}
 
 %union
 {
diff --git a/src/backend/utils/adt/jsonpath_internal.h b/src/backend/utils/adt/jsonpath_internal.h
@@ -22,17 +22,25 @@ typedef struct JsonPathString
 	int			total;
 } JsonPathString;
 
+#ifndef YY_TYPEDEF_YY_SCANNER_T
+#define YY_TYPEDEF_YY_SCANNER_T
+typedef void *yyscan_t;
+#endif
+
 #include "utils/jsonpath.h"
 #include "jsonpath_gram.h"
 
 #define YY_DECL extern int     jsonpath_yylex(YYSTYPE *yylval_param, \
 							  JsonPathParseResult **result, \
-							  struct Node *escontext)
+							  struct Node *escontext, \
+							  yyscan_t yyscanner)
 YY_DECL;
 extern int	jsonpath_yyparse(JsonPathParseResult **result,
-							 struct Node *escontext);
+							 struct Node *escontext,
+							 yyscan_t yyscanner);
 extern void jsonpath_yyerror(JsonPathParseResult **result,
 							 struct Node *escontext,
+							 yyscan_t yyscanner,
 							 const char *message);
 
 #endif							/* JSONPATH_INTERNAL_H */
diff --git a/src/backend/utils/adt/jsonpath_scan.l b/src/backend/utils/adt/jsonpath_scan.l
