Improve parser so that we can show an error cursor position for errors

during parse analysis, not only errors detected in the flex/bison stages.
This is per my earlier proposal.  This commit includes all the basic
infrastructure, but locations are only tracked and reported for errors
involving column references, function calls, and operators.  More could
be done later but this seems like a good set to start with.  I've also
moved the ReportSyntaxErrorPosition logic out of psql and into libpq,
which should make it available to more people --- even within psql this
is an improvement because warnings weren't handled by ReportSyntaxErrorPosition.

1 files changed, 36 insertions, 1 deletions

diff --git a/src/backend/parser/parse_node.c b/src/backend/parser/parse_node.c
index 2ac869c9fcd..23d73a13f25 100644
--- a/src/backend/parser/parse_node.c
+++ b/src/backend/parser/parse_node.c
@@ -8,13 +8,14 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_node.c,v 1.91 2006/03/05 15:58:34 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_node.c,v 1.92 2006/03/14 22:48:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
 
 #include "catalog/pg_type.h"
+#include "mb/pg_wchar.h"
 #include "nodes/makefuncs.h"
 #include "parser/parsetree.h"
 #include "parser/parse_coerce.h"
@@ -44,13 +45,47 @@ make_parsestate(ParseState *parentParseState)
 	pstate->p_next_resno = 1;
 
 	if (parentParseState)
+	{
+		pstate->p_sourcetext = parentParseState->p_sourcetext;
 		pstate->p_variableparams = parentParseState->p_variableparams;
+	}
 
 	return pstate;
 }
 
 
 /*
+ * parser_errposition
+ *		Report a parse-analysis-time cursor position, if possible.
+ *
+ * This is expected to be used within an ereport() call.  The return value
+ * is a dummy (always 0, in fact).
+ *
+ * The locations stored in raw parsetrees are byte offsets into the source
+ * string.  We have to convert them to 1-based character indexes for reporting
+ * to clients.  (We do things this way to avoid unnecessary overhead in the
+ * normal non-error case: computing character indexes would be much more
+ * expensive than storing token offsets.)
+ */
+int
+parser_errposition(ParseState *pstate, int location)
+{
+	int		pos;
+
+	/* No-op if location was not provided */
+	if (location < 0)
+		return 0;
+	/* Can't do anything if source text is not available */
+	if (pstate == NULL || pstate->p_sourcetext == NULL)
+		return 0;
+	/* Convert offset to character number */
+	pos = pg_mbstrlen_with_len(pstate->p_sourcetext, location) + 1;
+	/* And pass it to the ereport mechanism */
+	return errposition(pos);
+}
+
+
+/*
  * make_var
  *		Build a Var node for an attribute identified by RTE and attrno
  */