Adding upstream version 16.2.upstream/16.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 253 insertions, 0 deletions

diff --git a/src/interfaces/ecpg/preproc/parser.c b/src/interfaces/ecpg/preproc/parser.c
new file mode 100644
index 0000000..38e7acb
--- /dev/null
+++ b/src/interfaces/ecpg/preproc/parser.c
@@ -0,0 +1,253 @@
+/*-------------------------------------------------------------------------
+ *
+ * parser.c
+ *		Main entry point/driver for PostgreSQL grammar
+ *
+ * This should match src/backend/parser/parser.c, except that we do not
+ * need to bother with re-entrant interfaces.
+ *
+ * Note: ECPG doesn't report error location like the backend does.
+ * This file will need work if we ever want it to.
+ *
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/interfaces/ecpg/preproc/parser.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include "preproc_extern.h"
+#include "preproc.h"
+
+
+static bool have_lookahead;		/* is lookahead info valid? */
+static int	lookahead_token;	/* one-token lookahead */
+static YYSTYPE lookahead_yylval;	/* yylval for lookahead token */
+static YYLTYPE lookahead_yylloc;	/* yylloc for lookahead token */
+static char *lookahead_yytext;	/* start current token */
+
+static bool check_uescapechar(unsigned char escape);
+static bool ecpg_isspace(char ch);
+
+
+/*
+ * Intermediate filter between parser and base lexer (base_yylex in scan.l).
+ *
+ * This filter is needed because in some cases the standard SQL grammar
+ * requires more than one token lookahead.  We reduce these cases to one-token
+ * lookahead by replacing tokens here, in order to keep the grammar LALR(1).
+ *
+ * Using a filter is simpler than trying to recognize multiword tokens
+ * directly in scan.l, because we'd have to allow for comments between the
+ * words.  Furthermore it's not clear how to do that without re-introducing
+ * scanner backtrack, which would cost more performance than this filter
+ * layer does.
+ *
+ * We also use this filter to convert UIDENT and USCONST sequences into
+ * plain IDENT and SCONST tokens.  While that could be handled by additional
+ * productions in the main grammar, it's more efficient to do it like this.
+ */
+int
+filtered_base_yylex(void)
+{
+	int			cur_token;
+	int			next_token;
+	YYSTYPE		cur_yylval;
+	YYLTYPE		cur_yylloc;
+	char	   *cur_yytext;
+
+	/* Get next token --- we might already have it */
+	if (have_lookahead)
+	{
+		cur_token = lookahead_token;
+		base_yylval = lookahead_yylval;
+		base_yylloc = lookahead_yylloc;
+		base_yytext = lookahead_yytext;
+		have_lookahead = false;
+	}
+	else
+		cur_token = base_yylex();
+
+	/*
+	 * If this token isn't one that requires lookahead, just return it.
+	 */
+	switch (cur_token)
+	{
+		case FORMAT:
+		case NOT:
+		case NULLS_P:
+		case WITH:
+		case WITHOUT:
+		case UIDENT:
+		case USCONST:
+			break;
+		default:
+			return cur_token;
+	}
+
+	/* Save and restore lexer output variables around the call */
+	cur_yylval = base_yylval;
+	cur_yylloc = base_yylloc;
+	cur_yytext = base_yytext;
+
+	/* Get next token, saving outputs into lookahead variables */
+	next_token = base_yylex();
+
+	lookahead_token = next_token;
+	lookahead_yylval = base_yylval;
+	lookahead_yylloc = base_yylloc;
+	lookahead_yytext = base_yytext;
+
+	base_yylval = cur_yylval;
+	base_yylloc = cur_yylloc;
+	base_yytext = cur_yytext;
+
+	have_lookahead = true;
+
+	/* Replace cur_token if needed, based on lookahead */
+	switch (cur_token)
+	{
+		case FORMAT:
+			/* Replace FORMAT by FORMAT_LA if it's followed by JSON */
+			switch (next_token)
+			{
+				case JSON:
+					cur_token = FORMAT_LA;
+					break;
+			}
+			break;
+
+		case NOT:
+			/* Replace NOT by NOT_LA if it's followed by BETWEEN, IN, etc */
+			switch (next_token)
+			{
+				case BETWEEN:
+				case IN_P:
+				case LIKE:
+				case ILIKE:
+				case SIMILAR:
+					cur_token = NOT_LA;
+					break;
+			}
+			break;
+
+		case NULLS_P:
+			/* Replace NULLS_P by NULLS_LA if it's followed by FIRST or LAST */
+			switch (next_token)
+			{
+				case FIRST_P:
+				case LAST_P:
+					cur_token = NULLS_LA;
+					break;
+			}
+			break;
+
+		case WITH:
+			/* Replace WITH by WITH_LA if it's followed by TIME or ORDINALITY */
+			switch (next_token)
+			{
+				case TIME:
+				case ORDINALITY:
+					cur_token = WITH_LA;
+					break;
+			}
+			break;
+
+		case WITHOUT:
+			/* Replace WITHOUT by WITHOUT_LA if it's followed by TIME */
+			switch (next_token)
+			{
+				case TIME:
+					cur_token = WITHOUT_LA;
+					break;
+			}
+			break;
+		case UIDENT:
+		case USCONST:
+			/* Look ahead for UESCAPE */
+			if (next_token == UESCAPE)
+			{
+				/* Yup, so get third token, which had better be SCONST */
+				const char *escstr;
+
+				/*
+				 * Again save and restore lexer output variables around the
+				 * call
+				 */
+				cur_yylval = base_yylval;
+				cur_yylloc = base_yylloc;
+				cur_yytext = base_yytext;
+
+				/* Get third token */
+				next_token = base_yylex();
+
+				if (next_token != SCONST)
+					mmerror(PARSE_ERROR, ET_ERROR, "UESCAPE must be followed by a simple string literal");
+
+				/*
+				 * Save and check escape string, which the scanner returns
+				 * with quotes
+				 */
+				escstr = base_yylval.str;
+				if (strlen(escstr) != 3 || !check_uescapechar(escstr[1]))
+					mmerror(PARSE_ERROR, ET_ERROR, "invalid Unicode escape character");
+
+				base_yylval = cur_yylval;
+				base_yylloc = cur_yylloc;
+				base_yytext = cur_yytext;
+
+				/* Combine 3 tokens into 1 */
+				base_yylval.str = psprintf("%s UESCAPE %s", base_yylval.str, escstr);
+
+				/* Clear have_lookahead, thereby consuming all three tokens */
+				have_lookahead = false;
+			}
+
+			if (cur_token == UIDENT)
+				cur_token = IDENT;
+			else if (cur_token == USCONST)
+				cur_token = SCONST;
+			break;
+	}
+
+	return cur_token;
+}
+
+/*
+ * check_uescapechar() and ecpg_isspace() should match their equivalents
+ * in pgc.l.
+ */
+
+/* is 'escape' acceptable as Unicode escape character (UESCAPE syntax) ? */
+static bool
+check_uescapechar(unsigned char escape)
+{
+	if (isxdigit(escape)
+		|| escape == '+'
+		|| escape == '\''
+		|| escape == '"'
+		|| ecpg_isspace(escape))
+		return false;
+	else
+		return true;
+}
+
+/*
+ * ecpg_isspace() --- return true if flex scanner considers char whitespace
+ */
+static bool
+ecpg_isspace(char ch)
+{
+	if (ch == ' ' ||
+		ch == '\t' ||
+		ch == '\n' ||
+		ch == '\r' ||
+		ch == '\f')
+		return true;
+	return false;
+}