txtidx datatype for full text indexing with GiST.

From Oleg Bartunov and Teodor Sigaev.

contrib/tsearch/rewrite.c

@@ -0,0 +1,234 @@
+/*
+ * Rewrite routines of query tree
+ * Teodor Sigaev <teodor@stack.net>
+ */
+
+#include "postgres.h"
+
+#include <float.h>
+
+#include "access/gist.h"
+#include "access/itup.h"
+#include "access/rtree.h"
+#include "utils/elog.h"
+#include "utils/palloc.h"
+#include "utils/array.h"
+#include "utils/builtins.h"
+#include "storage/bufpage.h"
+
+#include "query.h"
+#include "rewrite.h"
+
+typedef struct NODE {
+	struct NODE *left;	
+	struct NODE *right;
+	ITEM*	valnode;
+} NODE;
+
+/*
+ * make query tree from plain view of query
+ */
+static NODE*
+maketree(ITEM *in) {
+	NODE *node = (NODE*)palloc(sizeof(NODE));
+	node->valnode = in;
+	node->right = node->left = NULL;
+	if ( in->type == OPR ) {
+		node->right = maketree( in + 1 );
+		if ( in->val != (int4)'!' )
+			node->left = maketree( in + in->left );
+	}
+	return node;
+}
+
+typedef struct {
+	ITEM*	ptr;
+	int4 	len;
+	int4	cur;
+} PLAINTREE;
+
+static void
+plainnode(PLAINTREE *state, NODE* node) {
+	if ( state->cur == state->len ) {
+		state->len *= 2;
+		state->ptr=(ITEM*)repalloc( (void*)state->ptr, state->len*sizeof(ITEM) ); 
+	}
+	memcpy( (void*)&(state->ptr[state->cur]), (void*)node->valnode, sizeof(ITEM) );
+	if ( node->valnode->type == VAL ) {
+		state->cur++;
+	} else if ( node->valnode->val == (int4)'!' ) {
+		state->ptr[state->cur].left=1;
+		state->cur++;
+		plainnode(state, node->right);
+	} else {
+		int4 cur = state->cur;
+		state->cur++;
+		plainnode(state, node->right);
+		state->ptr[cur].left = state->cur - cur; 
+		plainnode(state, node->left);
+	}
+	pfree(node);
+}
+
+/*
+ * make plain view of tree from 'normal' view of tree
+ */
+static ITEM*
+plaintree(NODE *root, int4 *len) {
+	PLAINTREE	pl;
+	pl.cur=0;
+	pl.len=16;
+	if ( root && (root->valnode->type == VAL || root->valnode->type == OPR) ) {
+		pl.ptr = (ITEM*)palloc( pl.len*sizeof(ITEM) );
+		plainnode(&pl, root);
+	} else {
+		pl.ptr = NULL;
+	}
+	*len = pl.cur;
+	return pl.ptr;	
+}
+
+static void
+freetree(NODE *node) {
+	if ( !node ) return; 	
+	if ( node->left ) freetree(node->left);
+	if ( node->right ) freetree(node->right);
+	pfree( node );
+}
+
+/*
+ * clean tree for ! operator.
+ * It's usefull for debug, but in 
+ * other case, such view is used with search in index.
+ * Operator ! always return TRUE
+ */
+static NODE*
+clean_NOT_intree( NODE* node ) {
+	if ( node->valnode->type == VAL )
+		return node;
+
+	if ( node->valnode->val == (int4)'!' ) {
+		freetree(node);
+		return NULL;
+	}
+
+	/* operator & or | */
+	if ( node->valnode->val == (int4)'|' ) {
+		if ( (node->left=clean_NOT_intree(node->left)) == NULL || 
+			(node->right=clean_NOT_intree(node->right)) == NULL ) {
+			freetree(node);
+			return NULL;
+		}
+	} else {
+		NODE *res = node; 
+		node->left=clean_NOT_intree(node->left);
+		node->right=clean_NOT_intree(node->right);
+		if ( node->left == NULL && node->right == NULL ) {
+			pfree(node);
+			res = NULL;
+		} else if ( node->left == NULL ) {
+			res = node->right;
+			pfree(node);
+		} else if ( node->right == NULL ) {
+			res = node->left;
+			pfree(node);
+		} 
+		return res;
+	}
+	return node;	
+}
+
+ITEM*
+clean_NOT(ITEM* ptr, int4 *len) {
+	NODE *root = maketree( ptr );
+	return plaintree(clean_NOT_intree(root), len); 
+}
+
+#define V_UNKNOWN	0
+#define V_TRUE		1
+#define V_FALSE		2
+
+/*
+ * Clean query tree from values which is always in 
+ * text (stopword)
+ */ 
+static NODE*
+clean_fakeval_intree( NODE* node, char *result ) {
+	char lresult = V_UNKNOWN, rresult = V_UNKNOWN;
+	if ( node->valnode->type == VAL )
+		return node;
+	else if ( node->valnode->type == VALTRUE ) {
+		pfree( node );
+		*result = V_TRUE;
+		return NULL;
+	} 
+	
+
+	if ( node->valnode->val == (int4)'!' ) {
+		node->right = clean_fakeval_intree( node->right, &rresult );
+		if ( ! node->right ) {
+			*result = ( rresult == V_TRUE ) ? V_FALSE : V_TRUE;
+			freetree(node);
+			return NULL;
+		}
+	} else if ( node->valnode->val == (int4)'|' ) {
+		NODE *res = node; 
+		node->left =clean_fakeval_intree(node->left, &lresult); 
+		node->right=clean_fakeval_intree(node->right,&rresult);
+		if ( lresult == V_TRUE || rresult == V_TRUE ) {
+			freetree(node);
+			*result=V_TRUE;
+			return NULL;
+		} else if ( lresult == V_FALSE && rresult == V_FALSE ) {
+			freetree(node);
+			*result=V_FALSE;
+			return NULL;
+		} else if ( lresult == V_FALSE ) {
+			res = node->right;
+			pfree(node);
+		} else if ( rresult == V_FALSE ) {
+			res = node->left;
+			pfree(node);
+		}
+		return res;	
+	} else {
+		NODE *res = node; 
+		node->left =clean_fakeval_intree(node->left, &lresult); 
+		node->right=clean_fakeval_intree(node->right,&rresult);
+		if ( lresult == V_FALSE || rresult == V_FALSE ) {
+			freetree(node);
+			*result=V_FALSE;
+			return NULL;
+		} else if ( lresult == V_TRUE && rresult == V_TRUE ) {
+			freetree(node);
+			*result=V_TRUE;
+			return NULL;
+		} else if ( lresult == V_TRUE ) {
+			res = node->right;
+			pfree(node);
+		} else if ( rresult == V_TRUE ) {
+			res = node->left;
+			pfree(node);
+		}
+		return res;	
+	}
+	return node;	
+}
+
+ITEM*
+clean_fakeval(ITEM* ptr, int4 *len) {
+	NODE *root = maketree( ptr );
+	char	result = V_UNKNOWN;
+	NODE *resroot;
+	
+	resroot = clean_fakeval_intree(root, &result);
+	if ( result != V_UNKNOWN ) {
+		elog(ERROR,"Your query contained only stopword(s), ignored");
+		*len = 0;
+		return NULL;
+	}
+		
+	return plaintree(resroot, len); 
+}
+
+