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146 lines
4.5 KiB
PHP
146 lines
4.5 KiB
PHP
<?php
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/**
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* US-ASCII transliterations of Unicode text
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* @version $Id: utf8_to_ascii.php,v 1.1 2009/11/25 23:43:14 philipp Exp $
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* @package utf8_to_ascii
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*/
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if ( !defined('UTF8_TO_ASCII_DB') ) {
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define('UTF8_TO_ASCII_DB',dirname(__FILE__).'/db');
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}
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//--------------------------------------------------------------------
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/**
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* US-ASCII transliterations of Unicode text
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* Ported Sean M. Burke's Text::Unidecode Perl module (He did all the hard work!)
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* Warning: you should only pass this well formed UTF-8!
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* Be aware it works by making a copy of the input string which it appends transliterated
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* characters to - it uses a PHP output buffer to do this - it means, memory use will increase,
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* requiring up to the same amount again as the input string
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* @see http://search.cpan.org/~sburke/Text-Unidecode-0.04/lib/Text/Unidecode.pm
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* @param string UTF-8 string to convert
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* @param string (default = ?) Character use if character unknown
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* @return string US-ASCII string
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* @package utf8_to_ascii
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*/
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function utf8_to_ascii($str, $unknown = '?') {
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# The database for transliteration stored here
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static $UTF8_TO_ASCII = array();
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# Variable lookups faster than accessing constants
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$UTF8_TO_ASCII_DB = UTF8_TO_ASCII_DB;
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if ( strlen($str) == 0 ) { return ''; }
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$len = strlen($str);
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$i = 0;
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# Use an output buffer to copy the transliterated string
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# This is done for performance vs. string concatenation - on my system, drops
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# the average request time for the example from ~0.46ms to 0.41ms
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# See http://phplens.com/lens/php-book/optimizing-debugging-php.php
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# Section "High Return Code Optimizations"
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ob_start();
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while ( $i < $len ) {
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$ord = NULL;
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$increment = 1;
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$ord0 = ord($str{$i});
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# Much nested if /else - PHP fn calls expensive, no block scope...
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# 1 byte - ASCII
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if ( $ord0 >= 0 && $ord0 <= 127 ) {
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$ord = $ord0;
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$increment = 1;
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} else {
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# 2 bytes
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$ord1 = ord($str{$i+1});
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if ( $ord0 >= 192 && $ord0 <= 223 ) {
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$ord = ( $ord0 - 192 ) * 64 + ( $ord1 - 128 );
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$increment = 2;
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} else {
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# 3 bytes
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$ord2 = ord($str{$i+2});
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if ( $ord0 >= 224 && $ord0 <= 239 ) {
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$ord = ($ord0-224)*4096 + ($ord1-128)*64 + ($ord2-128);
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$increment = 3;
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} else {
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# 4 bytes
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$ord3 = ord($str{$i+3});
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if ($ord0>=240 && $ord0<=247) {
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$ord = ($ord0-240)*262144 + ($ord1-128)*4096
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+ ($ord2-128)*64 + ($ord3-128);
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$increment = 4;
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} else {
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ob_end_clean();
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trigger_error("utf8_to_ascii: looks like badly formed UTF-8 at byte $i");
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return FALSE;
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}
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}
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}
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}
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$bank = $ord >> 8;
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# If we haven't used anything from this bank before, need to load it...
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if ( !array_key_exists($bank, $UTF8_TO_ASCII) ) {
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$bankfile = UTF8_TO_ASCII_DB. '/'. sprintf("x%02x",$bank).'.php';
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if ( file_exists($bankfile) ) {
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# Load the appropriate database
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if ( !include $bankfile ) {
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ob_end_clean();
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trigger_error("utf8_to_ascii: unable to load $bankfile");
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}
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} else {
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# Some banks are deliberately empty
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$UTF8_TO_ASCII[$bank] = array();
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}
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}
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$newchar = $ord & 255;
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if ( array_key_exists($newchar, $UTF8_TO_ASCII[$bank]) ) {
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echo $UTF8_TO_ASCII[$bank][$newchar];
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} else {
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echo $unknown;
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}
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$i += $increment;
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}
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$str = ob_get_contents();
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ob_end_clean();
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return $str;
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}
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