postgresql/contrib/tsearch/rewrite.c
2003-07-27 17:10:07 +00:00

291 lines
5.1 KiB
C

/*
* 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/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 useful 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(NOTICE, "query contains only stopword(s) or doesn't contain lexeme(s), ignored");
*len = 0;
return NULL;
}
return plaintree(resroot, len);
}