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#include <postgres.h>
#include <executor/spi.h>
#include "qbuilder.h"
#include "parsesql.h"
/* import standard_conforming_strings */
#if PG_VERSION_NUM >= 80500
#include <parser/parser.h>
#else
#ifndef PGDLLIMPORT
#define PGDLLIMPORT DLLIMPORT
#endif
extern PGDLLIMPORT bool standard_conforming_strings;
#endif
/* create QB in right context */
struct QueryBuilder *qb_create(const struct QueryBuilderOps *ops, MemoryContext ctx)
{
struct QueryBuilder *q;
q = MemoryContextAllocZero(ctx, sizeof(*q));
q->op = ops;
q->stdstr = standard_conforming_strings;
q->maxargs = 8;
q->arg_map = MemoryContextAlloc(ctx, q->maxargs * sizeof(int));
/* default size too large? */
q->sql.maxlen = 64;
q->sql.data = MemoryContextAlloc(ctx, q->sql.maxlen);
q->sql.data[0] = 0;
return q;
}
/* add fragment without parsing */
void qb_add_raw(struct QueryBuilder *q, const char *str, int len)
{
if (len < 0)
len = strlen(str);
appendBinaryStringInfo(&q->sql, str, len);
}
/* the ident may or may not be argument reference */
static void qb_handle_ident(struct QueryBuilder *q, const char *ident, int len, void *arg)
{
int real_idx;
int local_idx = -1, i;
char abuf[32];
/* is argument reference? */
real_idx = q->op->name_lookup(arg, ident, len);
if (real_idx < 0) {
qb_add_raw(q, ident, len);
return;
}
/* already referenced? */
for (i = 0; i < q->nargs; i++) {
if (q->arg_map[i] == real_idx) {
local_idx = i;
break;
}
}
/* new referece? */
if (local_idx < 0) {
if (q->nargs >= FUNC_MAX_ARGS)
elog(ERROR, "Too many args");
if (q->nargs >= q->maxargs) {
q->arg_map = repalloc(q->arg_map, q->maxargs * 2 * sizeof(int));
q->maxargs *= 2;
}
local_idx = q->nargs++;
q->arg_map[local_idx] = real_idx;
}
/* add $n to query */
snprintf(abuf, sizeof(abuf), "$%d", local_idx + 1);
return qb_add_raw(q, abuf, strlen(abuf));
}
/* add fragment with parsing - argument references are replaced with $n */
void qb_add_parse(struct QueryBuilder *q, const char *sql, void *arg)
{
int tlen, tok;
/* tokenize sql, pick out argument references */
while (1) {
tok = sql_tokenizer(sql, &tlen, q->stdstr);
if (!tok)
break;
if (tok < 0)
elog(ERROR, "QB: syntax error");
if (tok == T_WORD) {
qb_handle_ident(q, sql, tlen, arg);
} else {
qb_add_raw(q, sql, tlen);
}
sql += tlen;
}
}
/* prepare */
void qb_prepare(struct QueryBuilder *q, void *arg)
{
Oid types[FUNC_MAX_ARGS];
void *plan;
int i;
for (i = 0; i < q->nargs; i++)
types[i] = q->op->type_lookup(arg, q->arg_map[i]);
plan = SPI_prepare(q->sql.data, q->nargs, types);
q->plan = SPI_saveplan(plan);
}
/* lookup values and run plan. returns result from SPI_execute_plan() */
int qb_execute(struct QueryBuilder *q, void *arg)
{
Datum values[FUNC_MAX_ARGS];
char nulls[FUNC_MAX_ARGS];
int i;
if (!q->plan)
elog(ERROR, "QB: query not prepared yet");
for (i = 0; i < q->nargs; i++) {
bool isnull = false;
values[i] = q->op->value_lookup(arg, q->arg_map[i], &isnull);
nulls[i] = isnull ? 'n' : ' ';
}
return SPI_execute_plan(q->plan, values, nulls, true, 0);
}
void qb_free(struct QueryBuilder *q)
{
if (!q)
return;
if (q->plan)
SPI_freeplan(q->plan);
if (q->sql.data)
pfree(q->sql.data);
pfree(q);
}
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