Implement parser hooks for processing ColumnRef and ParamRef nodes, as per my

recent proposal.  As proof of concept, remove knowledge of Params from the
core parser, arranging for them to be handled entirely by parser hook
functions.  It turns out we need an additional hook for that --- I had
forgotten about the code that handles inferring a parameter's type from
context.

This is a preliminary step towards letting plpgsql handle its variables
through parser hooks.  Additional work remains to be done to expose the
facility through SPI, but I think this is all the changes needed in the core
parser.

1 files changed, 27 insertions, 15 deletions

diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 5eb446f1204..27aa7f2c612 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/parser/parse_node.h,v 1.65 2009/10/27 17:11:18 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/parser/parse_node.h,v 1.66 2009/10/31 01:41:31 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,6 +17,20 @@
 #include "nodes/parsenodes.h"
 #include "utils/relcache.h"
 
+
+/*
+ * Function signatures for parser hooks
+ */
+typedef struct ParseState ParseState;
+
+typedef Node * (*PreParseColumnRefHook) (ParseState *pstate, ColumnRef *cref);
+typedef Node * (*PostParseColumnRefHook) (ParseState *pstate, ColumnRef *cref, Node *var);
+typedef Node * (*ParseParamRefHook) (ParseState *pstate, ParamRef *pref);
+typedef Node * (*CoerceParamHook) (ParseState *pstate, Param *param,
+								   Oid targetTypeId, int32 targetTypeMod,
+								   int location);
+
+
 /*
  * State information used during parse analysis
  *
@@ -68,17 +82,8 @@
  * afterwards (so that any resjunk tlist items needed for the sort/group
  * clauses end up at the end of the query tlist).  A WindowDef's location in
  * this list, counting from 1, is the winref number to use to reference it.
- *
- * p_paramtypes: an array of p_numparams type OIDs for $n parameter symbols
- * (zeroth entry in array corresponds to $1).  If p_variableparams is true, the
- * set of param types is not predetermined; in that case, a zero array entry
- * means that parameter number hasn't been seen, and UNKNOWNOID means the
- * parameter has been used but its type is not yet known.  NOTE: in a stack
- * of ParseStates, only the topmost ParseState contains paramtype info; but
- * we copy the p_variableparams flag down to the child nodes for speed in
- * coerce_type.
  */
-typedef struct ParseState
+struct ParseState
 {
 	struct ParseState *parentParseState;		/* stack link */
 	const char *p_sourcetext;	/* source text, or NULL if not available */
@@ -92,12 +97,9 @@ typedef struct ParseState
 	List	   *p_future_ctes;	/* common table exprs not yet in namespace */
 	CommonTableExpr *p_parent_cte;		/* this query's containing CTE */
 	List	   *p_windowdefs;	/* raw representations of window clauses */
-	Oid		   *p_paramtypes;	/* OIDs of types for $n parameter symbols */
-	int			p_numparams;	/* allocated size of p_paramtypes[] */
 	int			p_next_resno;	/* next targetlist resno to assign */
 	List	   *p_locking_clause;		/* raw FOR UPDATE/FOR SHARE info */
 	Node	   *p_value_substitute;		/* what to replace VALUE with, if any */
-	bool		p_variableparams;
 	bool		p_hasAggs;
 	bool		p_hasWindowFuncs;
 	bool		p_hasSubLinks;
@@ -106,7 +108,17 @@ typedef struct ParseState
 	bool		p_locked_from_parent;
 	Relation	p_target_relation;
 	RangeTblEntry *p_target_rangetblentry;
-} ParseState;
+
+	/*
+	 * Optional hook functions for parser callbacks.  These are null unless
+	 * set up by the caller of make_parsestate.
+	 */
+	PreParseColumnRefHook p_pre_columnref_hook;
+	PostParseColumnRefHook p_post_columnref_hook;
+	ParseParamRefHook p_paramref_hook;
+	CoerceParamHook p_coerce_param_hook;
+	void	   *p_ref_hook_state;	/* common passthrough link for above */
+};
 
 /* Support for parser_errposition_callback function */
 typedef struct ParseCallbackState