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<?php
/* vim: set expandtab tabstop=4 shiftwidth=4: */
// +----------------------------------------------------------------------+
// | Copyright (c) 2002-2004 Brent Cook |
// +----------------------------------------------------------------------+
// | This library is free software; you can redistribute it and/or |
// | modify it under the terms of the GNU Lesser General Public |
// | License as published by the Free Software Foundation; either |
// | version 2.1 of the License, or (at your option) any later version. |
// | |
// | This library is distributed in the hope that it will be useful, |
// | but WITHOUT ANY WARRANTY; without even the implied warranty of |
// | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
// | Lesser General Public License for more details. |
// | |
// | You should have received a copy of the GNU Lesser General Public |
// | License along with this library; if not, write to the Free Software |
// | Foundation, Inc., 59 Temple Place, Suite 330,Boston,MA 02111-1307 USA|
// +----------------------------------------------------------------------+
// | Authors: Brent Cook <busterbcook@yahoo.com> |
// | Jason Pell <jasonpell@hotmail.com> |
// +----------------------------------------------------------------------+
//
// $Id: Lexer.php,v 1.20 2004/05/07 12:33:35 busterb Exp $
//
include 'SQL/ctype.php';
// {{{ token definitions
// variables: 'ident', 'sys_var'
// values: 'real_val', 'text_val', 'int_val', null
// }}}
/**
* A lexigraphical analyser inspired by the msql lexer
*
* @author Brent Cook <busterbcook@yahoo.com>
* @version 0.5
* @access public
* @package SQL_Parser
*/
class Lexer
{
// array of valid tokens for the lexer to recognize
// format is 'token literal'=>TOKEN_VALUE
var $symbols = array();
// {{{ instance variables
var $tokPtr = 0;
var $tokStart = 0;
var $tokLen = 0;
var $tokText = '';
var $lineNo = 0;
var $lineBegin = 0;
var $string = '';
var $stringLen = 0;
// Will not be altered by skip()
var $tokAbsStart = 0;
var $skipText = '';
// Provide lookahead capability.
var $lookahead = 0;
// Specify how many tokens to save in tokenStack, so the
// token stream can be pushed back.
var $tokenStack = array();
var $stackPtr = 0;
// }}}
// {{{ incidental functions
function Lexer($string = '', $lookahead=0)
{
$this->string = $string;
$this->stringLen = strlen($string);
$this->lookahead = $lookahead;
}
function get() {
++$this->tokPtr;
++$this->tokLen;
return ($this->tokPtr <= $this->stringLen) ? $this->string{$this->tokPtr - 1} : null;
}
function unget() {
--$this->tokPtr;
--$this->tokLen;
}
function skip() {
++$this->tokStart;
return ($this->tokPtr != $this->stringLen) ? $this->string{$this->tokPtr++} : '';
}
function revert() {
$this->tokPtr = $this->tokStart;
$this->tokLen = 0;
}
function isCompop($c) {
return (($c == '<') || ($c == '>') || ($c == '=') || ($c == '!'));
}
// }}}
// {{{ pushBack()
/*
* Push back a token, so the very next call to lex() will return that token.
* Calls to this function will be ignored if there is no lookahead specified
* to the constructor, or the pushBack() function has already been called the
* maximum number of token's that can be looked ahead.
*/
function pushBack()
{
if($this->lookahead>0 && count($this->tokenStack)>0 && $this->stackPtr>0) {
$this->stackPtr--;
}
}
// }}}
// {{{ lex()
function lex()
{
if($this->lookahead>0) {
// The stackPtr, should always be the same as the count of
// elements in the tokenStack. The stackPtr, can be thought
// of as pointing to the next token to be added. If however
// a pushBack() call is made, the stackPtr, will be less than the
// count, to indicate that we should take that token from the
// stack, instead of calling nextToken for a new token.
if ($this->stackPtr<count($this->tokenStack)) {
$this->tokText = $this->tokenStack[$this->stackPtr]['tokText'];
$this->skipText = $this->tokenStack[$this->stackPtr]['skipText'];
$token = $this->tokenStack[$this->stackPtr]['token'];
// We have read the token, so now iterate again.
$this->stackPtr++;
return $token;
} else {
// If $tokenStack is full (equal to lookahead), pop the oldest
// element off, to make room for the new one.
if ($this->stackPtr == $this->lookahead) {
// For some reason array_shift and
// array_pop screw up the indexing, so we do it manually.
for($i=0; $i<(count($this->tokenStack)-1); $i++) {
$this->tokenStack[$i] = $this->tokenStack[$i+1];
}
// Indicate that we should put the element in
// at the stackPtr position.
$this->stackPtr--;
}
$token = $this->nextToken();
$this->tokenStack[$this->stackPtr] =
array('token'=>$token,
'tokText'=>$this->tokText,
'skipText'=>$this->skipText);
$this->stackPtr++;
return $token;
}
}
else
{
return $this->nextToken();
}
}
// }}}
// {{{ nextToken()
function nextToken()
{
if ($this->string == '') return;
$state = 0;
$this->tokAbsStart = $this->tokStart;
while (true){
//echo "State: $state, Char: $c\n";
switch($state) {
// {{{ State 0 : Start of token
case 0:
$this->tokPtr = $this->tokStart;
$this->tokText = '';
$this->tokLen = 0;
$c = $this->get();
if (is_null($c)) { // End Of Input
$state = 1000;
break;
}
while (($c == ' ') || ($c == "\t")
|| ($c == "\n") || ($c == "\r")) {
if ($c == "\n" || $c == "\r") {
// Handle MAC/Unix/Windows line endings.
if($c == "\r") {
$c = $this->skip();
// If not DOS newline
if($c != "\n")
$this->unget();
}
++$this->lineNo;
$this->lineBegin = $this->tokPtr;
}
$c = $this->skip();
$this->tokLen = 1;
}
// Escape quotes and backslashes
if ($c == '\\') {
$t = $this->get();
if ($t == '\'' || $t == '\\' || $t == '"') {
$this->tokText = $t;
$this->tokStart = $this->tokPtr;
return $this->tokText;
} else {
$this->unget();
// Unknown token. Revert to single char
$state = 999;
break;
}
}
if (($c == '\'') || ($c == '"')) { // text string
$quote = $c;
$state = 12;
break;
}
if ($c == '_') { // system variable
$state = 18;
break;
}
if (ctype_alpha(ord($c))) { // keyword or ident
$state = 1;
break;
}
if (ctype_digit(ord($c))) { // real or int number
$state = 5;
break;
}
if ($c == '.') {
$t = $this->get();
if ($t == '.') { // ellipsis
if ($this->get() == '.') {
$this->tokText = '...';
$this->tokStart = $this->tokPtr;
return $this->tokText;
} else {
$state = 999;
break;
}
} else if (ctype_digit(ord($t))) { // real number
$this->unget();
$state = 7;
break;
} else { // period
$this->unget();
}
}
if ($c == '#') { // Comments
$state = 14;
break;
}
if ($c == '-') {
$t = $this->get();
if ($t == '-') {
$state = 14;
break;
} else { // negative number
$this->unget();
$state = 5;
break;
}
}
if ($this->isCompop($c)) { // comparison operator
$state = 10;
break;
}
// Unknown token. Revert to single char
$state = 999;
break;
// }}}
// {{{ State 1 : Incomplete keyword or ident
case 1:
$c = $this->get();
if (ctype_alnum(ord($c)) || ($c == '_') || ($c == '.')) {
$state = 1;
break;
}
$state = 2;
break;
// }}}
/* {{{ State 2 : Complete keyword or ident */
case 2:
$this->unget();
$this->tokText = substr($this->string, $this->tokStart,
$this->tokLen);
$testToken = strtolower($this->tokText);
if (isset($this->symbols[$testToken])) {
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return $testToken;
} else {
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return 'ident';
}
break;
// }}}
// {{{ State 5: Incomplete real or int number
case 5:
$c = $this->get();
if (ctype_digit(ord($c))) {
$state = 5;
break;
} else if ($c == '.') {
$t = $this->get();
if($t == '.') { // ellipsis
$this->unget();
} else { // real number
$state = 7;
break;
}
} else if(ctype_alpha(ord($c))) { // number must end with non-alpha character
$state = 999;
break;
} else {
// complete number
$state = 6;
break;
}
// }}}
// {{{ State 6: Complete integer number
case 6:
$this->unget();
$this->tokText = intval(substr($this->string, $this->tokStart,
$this->tokLen));
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return 'int_val';
break;
// }}}
// {{{ State 7: Incomplete real number
case 7:
$c = $this->get();
/* Analogy Start */
if ($c == 'e' || $c == 'E') {
$state = 15;
break;
}
/* Analogy End */
if (ctype_digit(ord($c))) {
$state = 7;
break;
}
$state = 8;
break;
// }}}
// {{{ State 8: Complete real number */
case 8:
$this->unget();
$this->tokText = floatval(substr($this->string, $this->tokStart,
$this->tokLen));
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return 'real_val';
// }}}
// {{{ State 10: Incomplete comparison operator
case 10:
$c = $this->get();
if ($this->isCompop($c))
{
$state = 10;
break;
}
$state = 11;
break;
// }}}
// {{{ State 11: Complete comparison operator
case 11:
$this->unget();
$this->tokText = substr($this->string, $this->tokStart,
$this->tokLen);
if($this->tokText) {
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return $this->tokText;
}
$state = 999;
break;
// }}}
// {{{ State 12: Incomplete text string
case 12:
$bail = false;
while (!$bail) {
switch ($this->get()) {
case '':
$this->tokText = null;
$bail = true;
break;
case "\\":
if (!$this->get()) {
$this->tokText = null;
$bail = true;
}
//$bail = true;
break;
case $quote:
$this->tokText = stripslashes(substr($this->string,
($this->tokStart+1), ($this->tokLen-2)));
$bail = true;
break;
}
}
if (!is_null($this->tokText)) {
$state = 13;
break;
}
$state = 999;
break;
// }}}
// {{{ State 13: Complete text string
case 13:
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return 'text_val';
break;
// }}}
// {{{ State 14: Comment
case 14:
$c = $this->skip();
if ($c == "\n" || $c == "\r" || $c == "") {
// Handle MAC/Unix/Windows line endings.
if ($c == "\r") {
$c = $this->skip();
// If not DOS newline
if ($c != "\n") {
$this->unget();
}
}
if ($c != "") {
++$this->lineNo;
$this->lineBegin = $this->tokPtr;
}
// We need to skip all the text.
$this->tokStart = $this->tokPtr;
$state = 0;
} else {
$state = 14;
}
break;
// }}}
// {{{ State 15: Exponent Sign in Scientific Notation
case 15:
$c = $this->get();
if($c == '-' || $c == '+') {
$state = 16;
break;
}
$state = 999;
break;
// }}}
// {{{ state 16: Exponent Value-first digit in Scientific Notation
case 16:
$c = $this->get();
if (ctype_digit(ord($c))) {
$state = 17;
break;
}
$state = 999; // if no digit, then token is unknown
break;
// }}}
// {{{ State 17: Exponent Value in Scientific Notation
case 17:
$c = $this->get();
if (ctype_digit(ord($c))) {
$state = 17;
break;
}
$state = 8; // At least 1 exponent digit was required
break;
// }}}
// {{{ State 18 : Incomplete System Variable
case 18:
$c = $this->get();
if (ctype_alnum(ord($c)) || $c == '_') {
$state = 18;
break;
}
$state = 19;
break;
// }}}
// {{{ State 19: Complete Sys Var
case 19:
$this->unget();
$this->tokText = substr($this->string, $this->tokStart,
$this->tokLen);
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return 'sys_var';
// }}}
// {{{ State 999 : Unknown token. Revert to single char
case 999:
$this->revert();
$this->tokText = $this->get();
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return $this->tokText;
// }}}
// {{{ State 1000 : End Of Input
case 1000:
$this->tokText = '*end of input*';
$this->skipText = substr($this->string, $this->tokAbsStart,
$this->tokStart-$this->tokAbsStart);
$this->tokStart = $this->tokPtr;
return null;
// }}}
}
}
}
// }}}
}
?>
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