From 7c3abe3c92fd3a14a70bc2f888f936cd6fe28c0f Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 7 Jan 2017 16:02:16 -0500
Subject: [PATCH] Get rid of ParseState.p_value_substitute; use a columnref
hook instead.
I noticed that p_value_substitute, which is a single-purpose kluge I added
in 2002 (commit b0422b215), could be replaced by having domainAddConstraint
install a parser hook that looks for the name "value". The parser hook
code only dates back to 2009, so it's not surprising that we had to kluge
this in 2002, but we can do it more cleanly now.
---
src/backend/commands/typecmds.c | 34 ++++++++++++++++++++++++++++++++-
src/backend/parser/parse_expr.c | 21 --------------------
src/include/parser/parse_node.h | 4 ----
3 files changed, 33 insertions(+), 26 deletions(-)
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
index c07babbe972..3ff6cbca56f 100644
--- a/src/backend/commands/typecmds.c
+++ b/src/backend/commands/typecmds.c
@@ -104,6 +104,8 @@ static char *domainAddConstraint(Oid domainOid, Oid domainNamespace,
Oid baseTypeOid,
int typMod, Constraint *constr,
char *domainName, ObjectAddress *constrAddr);
+static Node *replace_domain_constraint_value(ParseState *pstate,
+ ColumnRef *cref);
/*
@@ -3022,7 +3024,8 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid,
domVal->collation = get_typcollation(baseTypeOid);
domVal->location = -1; /* will be set when/if used */
- pstate->p_value_substitute = (Node *) domVal;
+ pstate->p_pre_columnref_hook = replace_domain_constraint_value;
+ pstate->p_ref_hook_state = (void *) domVal;
expr = transformExpr(pstate, constr->raw_expr, EXPR_KIND_DOMAIN_CHECK);
@@ -3099,6 +3102,35 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid,
return ccbin;
}
+/* Parser pre_columnref_hook for domain CHECK constraint parsing */
+static Node *
+replace_domain_constraint_value(ParseState *pstate, ColumnRef *cref)
+{
+ /*
+ * Check for a reference to "value", and if that's what it is, replace
+ * with a CoerceToDomainValue as prepared for us by domainAddConstraint.
+ * (We handle VALUE as a name, not a keyword, to avoid breaking a lot of
+ * applications that have used VALUE as a column name in the past.)
+ */
+ if (list_length(cref->fields) == 1)
+ {
+ Node *field1 = (Node *) linitial(cref->fields);
+ char *colname;
+
+ Assert(IsA(field1, String));
+ colname = strVal(field1);
+ if (strcmp(colname, "value") == 0)
+ {
+ CoerceToDomainValue *domVal = copyObject(pstate->p_ref_hook_state);
+
+ /* Propagate location knowledge, if any */
+ domVal->location = cref->location;
+ return (Node *) domVal;
+ }
+ }
+ return NULL;
+}
+
/*
* Execute ALTER TYPE RENAME
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 38c2535b65f..f62e45f8ac8 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -577,27 +577,6 @@ transformColumnRef(ParseState *pstate, ColumnRef *cref)
/*
* Not known as a column of any range-table entry.
*
- * Consider the possibility that it's VALUE in a domain
- * check expression. (We handle VALUE as a name, not a
- * keyword, to avoid breaking a lot of applications that
- * have used VALUE as a column name in the past.)
- */
- if (pstate->p_value_substitute != NULL &&
- strcmp(colname, "value") == 0)
- {
- node = (Node *) copyObject(pstate->p_value_substitute);
-
- /*
- * Try to propagate location knowledge. This should
- * be extended if p_value_substitute can ever take on
- * other node types.
- */
- if (IsA(node, CoerceToDomainValue))
- ((CoerceToDomainValue *) node)->location = cref->location;
- break;
- }
-
- /*
* Try to find the name as a relation. Note that only
* relations already entered into the rangetable will be
* recognized.
diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 92b2cb35ce7..7cdf142df63 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -149,9 +149,6 @@ typedef Node *(*CoerceParamHook) (ParseState *pstate, Param *param,
* p_locked_from_parent: true if parent query level applies FOR UPDATE/SHARE
* to this subquery as a whole.
*
- * p_value_substitute: replacement for VALUE references, if we're parsing
- * a domain CHECK constraint.
- *
* p_hasAggs, p_hasWindowFuncs, etc: true if we've found any of the indicated
* constructs in the query.
*
@@ -184,7 +181,6 @@ struct ParseState
List *p_locking_clause; /* raw FOR UPDATE/FOR SHARE info */
bool p_locked_from_parent; /* parent has marked this subquery
* with FOR UPDATE/FOR SHARE */
- Node *p_value_substitute; /* what to replace VALUE with, if any */
/* Flags telling about things found in the query: */
bool p_hasAggs;
--
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