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