Lightweight unicode to emojione converter -- generator

generate.php

<?php
/**
    * This php script generates a simplified javascript library that translates unicode emojis to their emojione graphics.
    * It uses a space-efficient tree structure. For emojione 4.0 the library has ~38kb / ~5kb gzip compressed.
    * 
    *
    * USAGE: 
    *  - create a subdirectory containing all emojione images in code point name scheme
    *  - change config in this file (image folder path, file extension, etc.)
    *  - php generate.php > emojione_light.js
    *  - include (<script src="emojione_light.js"></script>)
    *  - convert: ( emojione.convertText("Some Text containing unicode emojis ...") )
    */
    
//config

$file_extension = '.svg';
$emojione_image_folder = 'images/';
$replaced_image_prefix = '<img src="images/';
$replaced_image_postfix = $file_extension . '" class="emoji">';

//config - end


function cleaner(&$node){
    if(!isset($node['s'])){
        unset($node['e']);
    }else{
        foreach($node['s'] AS &$subnode){
            cleaner($subnode);
        }
    }
}

$tmpCWD = getcwd();
chdir($emojione_image_folder);
$files = glob('*'.$file_extension);
chdir($tmpCWD);

$files = array_map(function($item) use ($file_extension){
    return str_replace($file_extension,'',$item);
},$files);

usort($files, function($a,$b){
    return strlen($a) >= strlen($b) ? 1 : -1;
});

$tree = [];
$tree['s'] = [];

foreach($files AS $file){
    $parts = explode('-',$file);
    $parent = &$tree;
    $partCount = count($parts);
    for($i = 0; $i < $partCount; $i++){
        
        $currentCode = $parts[$i];
        
        if(!isset($parent['s'])){
            $parent['s'] = [];
            $parent['s'][$currentCode] = [];
        }
        if($i == $partCount - 1){
            //we are at the last part for this emoji; add ending marker
            $parent['s'][$currentCode]['e'] = 1;
        }
        
        $parent = &$parent['s'][$currentCode];
    }
}

cleaner($tree);

echo <<< PREFIX
(function(ns){
    ns.MAX_EMOJI_LENGTH = 7;
    ns.IMAGE_PREFIX = '{$replaced_image_prefix}';
    ns.IMAGE_POSTFIX = '{$replaced_image_postfix}';
    
    ns.emojiMapping = 
PREFIX;

echo '{s:' . str_replace(':[]',':null',preg_replace('/"([a-f][0-9a-f]+|e|s)"/', '$1', json_encode($tree['s']))).'}';

echo <<< POSTFIX
;

    ns.convertText = function(text){
        var charCode;
        var foundLength;
        var mappingNode;
        var textArray = Array.from(text);
        var emojiFile;
        
        for(var i = 0; i < textArray.length; i++){
            foundLength = 0;
            mappingNode = ns.emojiMapping;
            emojiFile = [];
            
            for(k = i; k < Math.min(i+ns.MAX_EMOJI_LENGTH, textArray.length); k++){
                charCode = textArray[k].codePointAt(0).toString(16);

                if(charCode == "200d"){
                    foundLength++;
                }else if(mappingNode.s.hasOwnProperty(charCode)){
                    
                    emojiFile.push(charCode);
                    foundLength++;
                    
                    if(mappingNode.s[charCode] != null && mappingNode.s[charCode].hasOwnProperty('s')){
                        //we found an end of the path
                        mappingNode = mappingNode.s[charCode];
                    }else{break;}
                    
                }else{
                    break;
                }
            }
            
            if(foundLength > 0){
                if(foundLength > 1){
                    textArray.splice(i+1,foundLength-1);
                }
                textArray[i] = ns.IMAGE_PREFIX + emojiFile.join('-') + ns.IMAGE_POSTFIX;
            }
        }
        
        return textArray.join('');
    }
    
}(this.emojione_light = this.emojione_light || {}));
POSTFIX;