Refactoring by Heikki Linnakangas <heikki@enterprisedb.com> with

small editorization by me

- Brake the QueryItem struct into QueryOperator and QueryOperand.
  Type was really the only common field between them. QueryItem still
  exists, and is used in the TSQuery struct as before, but it's now a
  union of the two. Many other changes fell from that, like separation
  of pushval_asis function into pushValue, pushOperator and pushStop.

- Moved some structs that were for internal use only from header files
  to the right .c-files.

- Moved tsvector parser to a new tsvector_parser.c file. Parser code was
  about half of the size of tsvector.c, it's also used from tsquery.c, and
  it has some data structures of its own, so it seems better to separate
  it. Cleaned up the API so that TSVectorParserState is not accessed from
  outside tsvector_parser.c.

- Separated enumerations (#defines, really) used for QueryItem.type
  field and as return codes from gettoken_query. It was just accidental
  code sharing.

- Removed ParseQueryNode struct used internally by makepol and friends.
  push*-functions now construct QueryItems directly.

- Changed int4 variables to just ints for variables like "i" or "array
  size", where the storage-size was not significant.

src/backend/utils/adt/tsquery_rewrite.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery_rewrite.c,v 1.1 2007/08/21 01:11:19 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/tsquery_rewrite.c,v 1.2 2007/09/07 15:09:56 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -34,18 +34,26 @@ addone(int *counters, int last, int total)
 	return 1;
 }
 
+/*
+ * If node is equal to ex, replace it with subs. Replacement is actually done
+ * by returning either node or a copy of subs.
+ */
 static QTNode *
 findeq(QTNode *node, QTNode *ex, QTNode *subs, bool *isfind)
 {
 
-	if ((node->sign & ex->sign) != ex->sign || node->valnode->type != ex->valnode->type || node->valnode->val != ex->valnode->val)
+	if ((node->sign & ex->sign) != ex->sign || 
+		node->valnode->type != ex->valnode->type)
 		return node;
 
 	if (node->flags & QTN_NOCHANGE)
 		return node;
-
-	if (node->valnode->type == OPR)
+	
+	if (node->valnode->type == QI_OPR)
 	{
+		if (node->valnode->operator.oper != ex->valnode->operator.oper)
+			return node;
+
 		if (node->nchild == ex->nchild)
 		{
 			if (QTNEq(node, ex))
@@ -63,6 +71,12 @@ findeq(QTNode *node, QTNode *ex, QTNode *subs, bool *isfind)
 		}
 		else if (node->nchild > ex->nchild)
 		{
+			/*
+			 * AND and NOT are commutative, so we check if a subset of the
+			 * children match. For example, if tnode is A | B | C, and 
+			 * ex is B | C, we have a match after we convert tnode to
+			 * A | (B | C).
+			 */
 			int		   *counters = (int *) palloc(sizeof(int) * node->nchild);
 			int			i;
 			QTNode	   *tnode = (QTNode *) palloc(sizeof(QTNode));
@@ -131,19 +145,26 @@ findeq(QTNode *node, QTNode *ex, QTNode *subs, bool *isfind)
 			pfree(counters);
 		}
 	}
-	else if (QTNEq(node, ex))
+	else 
 	{
-		QTNFree(node);
-		if (subs)
+		Assert(node->valnode->type == QI_VAL);
+
+		if (node->valnode->operand.valcrc != ex->valnode->operand.valcrc)
+			return node;
+		else if (QTNEq(node, ex))
 		{
-			node = QTNCopy(subs);
-			node->flags |= QTN_NOCHANGE;
+			QTNFree(node);
+			if (subs)
+			{
+				node = QTNCopy(subs);
+				node->flags |= QTN_NOCHANGE;
+			}
+			else
+			{
+				node = NULL;
+			}
+			*isfind = true;
 		}
-		else
-		{
-			node = NULL;
-		}
-		*isfind = true;
 	}
 
 	return node;
@@ -154,7 +175,7 @@ dofindsubquery(QTNode *root, QTNode *ex, QTNode *subs, bool *isfind)
 {
 	root = findeq(root, ex, subs, isfind);
 
-	if (root && (root->flags & QTN_NOCHANGE) == 0 && root->valnode->type == OPR)
+	if (root && (root->flags & QTN_NOCHANGE) == 0 && root->valnode->type == QI_OPR)
 	{
 		int			i;
 
@@ -172,7 +193,7 @@ dropvoidsubtree(QTNode * root)
 	if (!root)
 		return NULL;
 
-	if (root->valnode->type == OPR)
+	if (root->valnode->type == QI_OPR)
 	{
 		int			i,
 					j = 0;
@@ -188,7 +209,7 @@ dropvoidsubtree(QTNode * root)
 
 		root->nchild = j;
 
-		if (root->valnode->val == (int4) '!' && root->nchild == 0)
+		if (root->valnode->operator.oper == OP_NOT && root->nchild == 0)
 		{
 			QTNFree(root);
 			root = NULL;
@@ -256,9 +277,9 @@ ts_rewrite_accum(PG_FUNCTION_ARGS)
 		elog(ERROR, "array must be one-dimensional, not %d dimensions",
 			 ARR_NDIM(qa));
 	if (ArrayGetNItems(ARR_NDIM(qa), ARR_DIMS(qa)) != 3)
-		elog(ERROR, "array should have only three elements");
+		elog(ERROR, "array must have three elements");
 	if (ARR_ELEMTYPE(qa) != TSQUERYOID)
-		elog(ERROR, "array should contain tsquery type");
+		elog(ERROR, "array must contain tsquery elements");
 
 	deconstruct_array(qa, TSQUERYOID, -1, false, 'i', &elemsp, NULL, &nelemsp);
 
@@ -499,6 +520,7 @@ tsquery_rewrite_query(PG_FUNCTION_ARGS)
 		subs = QT2QTN(GETQUERY(subst), GETOPERAND(subst));
 
 	tree = findsubquery(tree, qex, subs, NULL);
+
 	QTNFree(qex);
 	QTNFree(subs);