<?php
/**
* This file contains the DBParser class.
*
* @author Gonzalo Chumillas <[email protected]>
* @package database
*/
require_once dirname(__DIR__) . "/database/db-query.php";
require_once dirname(__DIR__) . "/database/db-column.php";
require_once dirname(__DIR__) . "/parser/parser.php";
/**
* class DBParser
*
* This class parses an SQL sentence.
*
* @package database
*/
class DBParser extends Parser {
/**
* A subset of reserved words
* @var array
*/
private $reserved_words = array(
"from", "where", "on", "group", "having", "order", "limit", "union", "inner", "left", "right", "join", "and"
);
/**
* @var DBQuery
*/
private $query;
/**
* @param DBQuery $query
* @param string $sql
*/
public function __construct($query, $sql) {
$this->query = $query;
parent::__construct($sql, Parser::UNGREEDY);
}
/**
* Is a reserved word?
* @param string $word
* @return string
*/
private function isReservedWord($str) {
$str = strtolower(trim($str));
return array_search($str, $this->reserved_words) !== FALSE;
}
/**
* Parses conditions individually.
* @param int $offset0
* @param int $offset1
*/
private function parseConditions($offset0, $offset1) {
$str = trim(substr($this->string, $offset0, $offset1 - $offset0));
$conditions = preg_split("/\s+and\s+/i", $str);
foreach ($conditions as $condition) {
$terms = explode("=", $condition);
if (count($terms) != 2) {
continue;
}
// parse columns
$columns = array();
foreach ($terms as $term) {
$t = new Tokenizer($term);
if ( (list($value) = $t->str()) || (list($value) = $t->number()) ) {
array_push($columns, $value);
} else
if ($t->match("(`?(\w+)`?\s*\.\s*)?`?(\w+)`?", $matches)) {
$table_name = trim($matches[2]);
$column_name = trim($matches[3]);
$column = $this->query->registerColumn($table_name, $column_name);
array_push($columns, $column);
}
}
// links columns
foreach ($columns as $i => $column0) {
$column1 = $columns[($i + 1) % 2];
if ($column0 instanceof DBColumn) {
if ($column1 instanceof DBColumn) {
$column0->registerLink($column1);
$column1->registerLink($column0);
} else {
$column0->setDefaultValue($column1);
}
break;
}
}
}
}
/**
* Is the next an identifier?
* @return array|boolean
*/
protected function identifier() {
if ($this->match("`([^`]+)`", $matches)) {
return array($matches[2]);
} else {
$offset = $this->offset;
if (list($name) = $this->match("\w+")) {
if ($this->isReservedWord($name)) {
$this->offset = $offset;
} else {
return array($name);
}
}
}
return FALSE;
}
/**
* Is the next a join clause?
* @throws ParserError
* @return array|boolean
*/
protected function join() {
// gets join type
if (!list($str) = $this->match("((inner|(left(\s+outer)?))\s+)?join\s+", $matches, Tokenizer::SEARCH_ANYWHERE|Tokenizer::OFFSET_CAPTURE)) {
return FALSE;
}
$join_type = stripos($str, "inner") !== FALSE? DBTable::INNER_JOIN : DBTable::LEFT_JOIN;
$offset = $matches[0][1];
// gets table name
if (!list($table_name) = $this->is("identifier")) {
throw new ParserException($this, "Table name expected");
}
// gets table alias
$table_alias = $table_name;
if ($this->eq("as")) {
if (!list($table_alias) = $this->is("identifier")) {
throw new ParserException($this, "Table alias expected");
}
} else
if (list($str) = $this->is("identifier")) {
$table_alias = $str;
}
// register table
$table = $this->query->registerTable($table_alias, TRUE);
$table->setName($table_name);
$table->setJoinType($join_type);
// optional "on"
$this->eq("on");
return array($offset);
}
/**
* Is the next a where clause?
* @return array|boolean
*/
protected function where() {
if (!$this->match("where\s+", $matches, Tokenizer::SEARCH_ANYWHERE|Tokenizer::OFFSET_CAPTURE)) {
return FALSE;
}
$offset = $matches[0][1];
return array($offset);
}
/**
* Is the next whatever?
* @return array|boolean
*/
protected function whatever() {
if ($this->match("(group|having|order|limit|union)\s+", $matches, Tokenizer::SEARCH_ANYWHERE|Tokenizer::OFFSET_CAPTURE)) {
return array($matches[0][1]);
}
return array(strlen($this->string));
}
/**
* Is the next a select?
* @throws ParserError
* @return array|boolean
*/
protected function select() {
$main_table = NULL;
if ($this->match("select.*from")) {
// gets table name
if (!list($table_name) = $this->is("identifier")) {
throw new ParserException($this, "Table name expected");
}
// gets table alias
$table_alias = $table_name;
if ($this->eq("as")) {
if (!list($table_alias) = $this->is("identifier")) {
throw new ParserException($this, "Table alias expected");
}
} else
if (list($str) = $this->is("identifier")) {
$table_alias = $str;
}
// register main table
$main_table = $this->query->registerTable($table_alias, TRUE);
$main_table->setName($table_name);
$this->query->setMainTable($main_table);
// join clauses
$offset0 = $this->offset;
while (list($offset1) = $this->is("join")) {
$this->parseConditions($offset0, $offset1);
$offset0 = $this->offset;
}
// where clause
if (list($offset1) = $this->is("where")) {
$this->parseConditions($offset0, $offset1);
$offset0 = $this->offset;
}
// whatever else
if (list($offset1) = $this->is("whatever")) {
$this->parseConditions($offset0, $offset1);
}
}
return $main_table != NULL && $main_table->getPrimaryKey() != NULL;
}
/**
* Parses the sql sentence.
* @return array|boolean
*/
public function _parse() {
return $this->is("select");
}
}
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