LS String PHP lib added

To compress and decompress strings with LZ compression

LZCompressor/LZContext.php

@@ -0,0 +1,91 @@
+<?php
+namespace LZCompressor;
+
+class LZContext
+{
+    /**
+     * @var array
+     */
+    public $dictionary = [];
+
+    /**
+     * @var array
+     */
+    public $dictionaryToCreate = [];
+
+    /**
+     * @var string
+     */
+    public $c = '';
+
+    /**
+     * @var string
+     */
+    public $wc = '';
+
+    /**
+     * @var string
+     */
+    public $w = '';
+
+    /**
+     * @var int
+     */
+    public $enlargeIn = 2;
+
+    /**
+     * @var int
+     */
+    public $dictSize = 3;
+
+    /**
+     * @var int
+     */
+    public $numBits = 2;
+
+    /**
+     * @var LZData
+     */
+    public $data;
+
+    function __construct()
+    {
+        $this->data = new LZData;
+    }
+
+    // Helper
+
+    /**
+     * @param string $val
+     * @return bool
+     */
+    public function dictionaryContains($val) {
+        return array_key_exists($val, $this->dictionary);
+    }
+
+    /**
+     * @param $val
+     */
+    public function addToDictionary($val) {
+        $this->dictionary[$val] = $this->dictSize++;
+    }
+
+    /**
+     * @param string $val
+     * @return bool
+     */
+    public function dictionaryToCreateContains($val) {
+        return array_key_exists($val, $this->dictionaryToCreate);
+    }
+
+    /**
+     * decrements enlargeIn and extends numbits in case enlargeIn drops to 0
+     */
+    public function enlargeIn() {
+        $this->enlargeIn--;
+        if($this->enlargeIn==0) {
+            $this->enlargeIn = pow(2, $this->numBits);
+            $this->numBits++;
+        }
+    }
+}

LZCompressor/LZData.php

@@ -0,0 +1,29 @@
+<?php
+namespace LZCompressor;
+
+class LZData
+{
+    /**
+     * @var
+     */
+    public $str = '';
+
+    /**
+     * @var
+     */
+    public $val;
+
+    /**
+     * @var int
+     */
+    public $position = 0;
+
+    /**
+     * @var int
+     */
+    public $index = 1;
+
+    public function append($str) {
+        $this->str .= $str;
+    }
+}

LZCompressor/LZReverseDictionary.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: sics
+ * Date: 28.02.2016
+ * Time: 12:53
+ */
+
+namespace LZCompressor;
+
+
+class LZReverseDictionary
+{
+
+    public $entries = [0, 1 ,2];
+
+    public function size() {
+        return count($this->entries);
+    }
+
+    public function hasEntry($index) {
+        return array_key_exists($index, $this->entries);
+    }
+
+    public function getEntry($index) {
+        return $this->entries[$index];
+    }
+
+    public function addEntry($char) {
+        $this->entries[] = $char;
+    }
+
+}

LZCompressor/LZString.php

@@ -0,0 +1,286 @@
+<?php
+namespace LZCompressor;
+
+class LZString
+{
+
+    public static function compressToBase64($input)
+    {
+        $res = self::_compress($input, 6, function($a) {
+            return LZUtil::$keyStrBase64{$a};
+        });
+        switch (strlen($res) % 4) { // To produce valid Base64
+            default: // When could this happen ?
+            case 0 : return $res;
+            case 1 : return $res ."===";
+            case 2 : return $res ."==";
+            case 3 : return $res ."=";
+        }
+    }
+
+    public static function decompressFromBase64($input)
+    {
+        return self::_decompress($input, 32, function($feed, $index) {
+            return LZUtil::getBaseValue(LZUtil::$keyStrBase64, LZUtil::utf8_charAt($feed, $index));
+        });
+    }
+
+    /**
+     * @param string $uncompressed
+     * @return string
+     */
+    public static function compress($uncompressed)
+    {
+        return self::_compress($uncompressed, 16, function($a) {
+            return LZUtil::fromCharCode($a);
+        });
+    }
+
+    /**
+     * @param string $compressed
+     * @return string
+     */
+    public static function decompress($compressed)
+    {
+        return self::_decompress($compressed, 32768, function($feed, $index) {
+            return LZUtil::charCodeAt($feed, $index);
+        });
+    }
+
+    /**
+     * @param string $uncompressed
+     * @param integer $bitsPerChar
+     * @param callable $getCharFromInt
+     * @return string
+     */
+    private static function _compress($uncompressed, $bitsPerChar, $getCharFromInt) {
+
+        if(!is_string($uncompressed) || strlen($uncompressed) === 0) {
+            return '';
+        }
+
+        $context = new LZContext();
+        $length = LZUtil::utf8_strlen($uncompressed);
+        for($ii=0; $ii<$length; $ii++) {
+            $context->c = LZUtil::utf8_charAt($uncompressed, $ii);
+            if(!$context->dictionaryContains($context->c)) {
+                $context->addToDictionary($context->c);
+                $context->dictionaryToCreate[$context->c] = true;
+            }
+            $context->wc = $context->w . $context->c;
+            if($context->dictionaryContains($context->wc)) {
+                $context->w = $context->wc;
+            } else {
+                self::produceW($context, $bitsPerChar, $getCharFromInt);
+            }
+        }
+        if($context->w !== '') {
+            self::produceW($context, $bitsPerChar, $getCharFromInt);
+        }
+
+        $value = 2;
+        for($i=0; $i<$context->numBits; $i++) {
+            self::writeBit($value&1, $context->data, $bitsPerChar, $getCharFromInt);
+            $value = $value >> 1;
+        }
+
+         while (true) {
+            $context->data->val = $context->data->val << 1;
+            if ($context->data->position == ($bitsPerChar-1)) {
+                $context->data->append($getCharFromInt($context->data->val));
+                break;
+            }
+            $context->data->position++;
+        }
+
+        return $context->data->str;
+    }
+
+    /**
+     * @param LZContext $context
+     * @param integer $bitsPerChar
+     * @param callable $getCharFromInt
+     *
+     * @return LZContext
+     */
+    private static function produceW(LZContext $context, $bitsPerChar, $getCharFromInt)
+    {
+        if($context->dictionaryToCreateContains($context->w)) {
+            if(LZUtil::charCodeAt($context->w)<256) {
+                for ($i=0; $i<$context->numBits; $i++) {
+                    self::writeBit(null, $context->data, $bitsPerChar, $getCharFromInt);
+                }
+                $value = LZUtil::charCodeAt($context->w);
+                for ($i=0; $i<8; $i++) {
+                    self::writeBit($value&1, $context->data, $bitsPerChar, $getCharFromInt);
+                    $value = $value >> 1;
+                }
+            } else {
+                $value = 1;
+                for ($i=0; $i<$context->numBits; $i++) {
+                    self::writeBit($value, $context->data, $bitsPerChar, $getCharFromInt);
+                    $value = 0;
+                }
+                $value = LZUtil::charCodeAt($context->w);
+                for ($i=0; $i<16; $i++) {
+                    self::writeBit($value&1, $context->data, $bitsPerChar, $getCharFromInt);
+                    $value = $value >> 1;
+                }
+            }
+            $context->enlargeIn();
+            unset($context->dictionaryToCreate[$context->w]);
+        } else {
+            $value = $context->dictionary[$context->w];
+            for ($i=0; $i<$context->numBits; $i++) {
+                self::writeBit($value&1, $context->data, $bitsPerChar, $getCharFromInt);
+                $value = $value >> 1;
+            }
+        }
+        $context->enlargeIn();
+        $context->addToDictionary($context->wc);
+        $context->w = $context->c.'';
+    }
+
+    /**
+     * @param string $value
+     * @param LZData $data
+     * @param integer $bitsPerChar
+     * @param callable $getCharFromInt
+     */
+    private static function writeBit($value, LZData $data, $bitsPerChar, $getCharFromInt)
+    {
+        if(null !== $value) {
+            $data->val = ($data->val << 1) | $value;
+        } else {
+            $data->val = ($data->val << 1);
+        }
+        if ($data->position == ($bitsPerChar-1)) {
+            $data->position = 0;
+            $data->append($getCharFromInt($data->val));
+            $data->val = 0;
+        } else {
+            $data->position++;
+        }
+    }
+
+    /**
+     * @param LZData $data
+     * @param integer $resetValue
+     * @param callable $getNextValue
+     * @param integer $exponent
+     * @param string $feed
+     * @return integer
+     */
+    private static function readBits(LZData $data, $resetValue, $getNextValue, $feed, $exponent)
+    {
+        $bits = 0;
+        $maxPower = pow(2, $exponent);
+        $power=1;
+        while($power != $maxPower) {
+            $resb = $data->val & $data->position;
+            $data->position >>= 1;
+            if ($data->position == 0) {
+                $data->position = $resetValue;
+                $data->val = $getNextValue($feed, $data->index++);
+            }
+            $bits |= (($resb>0 ? 1 : 0) * $power);
+            $power <<= 1;
+        }
+        return $bits;
+    }
+
+    /**
+     * @param string $compressed
+     * @param integer $resetValue
+     * @param callable $getNextValue
+     * @return string
+     */
+    private static function _decompress($compressed, $resetValue, $getNextValue)
+    {
+        if(!is_string($compressed) || strlen($compressed) === 0) {
+            return '';
+        }
+
+        $length = LZUtil::utf8_strlen($compressed);
+        $entry = null;
+        $enlargeIn = 4;
+        $numBits = 3;
+        $result = '';
+
+        $dictionary = new LZReverseDictionary();
+
+        $data = new LZData();
+        $data->str = $compressed;
+        $data->val = $getNextValue($compressed, 0);
+        $data->position = $resetValue;
+        $data->index = 1;
+
+        $next = self::readBits($data, $resetValue, $getNextValue, $compressed, 2);
+
+        if($next < 0 || $next > 1) {
+            return '';
+        }
+
+        $exponent = ($next == 0) ? 8 : 16;
+        $bits = self::readBits($data, $resetValue, $getNextValue, $compressed, $exponent);
+
+        $c = LZUtil::fromCharCode($bits);
+        $dictionary->addEntry($c);
+        $w = $c;
+
+        $result .= $c;
+
+        while(true) {
+            if($data->index > $length) {
+                return '';
+            }
+            $bits = self::readBits($data, $resetValue, $getNextValue, $compressed, $numBits);
+
+            $c = $bits;
+
+            switch($c) {
+                case 0:
+                    $bits = self::readBits($data, $resetValue, $getNextValue, $compressed, 8);
+                    $c = $dictionary->size();
+                    $dictionary->addEntry(LZUtil::fromCharCode($bits));
+                    $enlargeIn--;
+                    break;
+                case 1:
+                    $bits = self::readBits($data, $resetValue, $getNextValue, $compressed, 16);
+                    $c = $dictionary->size();
+                    $dictionary->addEntry(LZUtil::fromCharCode($bits));
+                    $enlargeIn--;
+                    break;
+                case 2:
+                    return $result;
+                    break;
+            }
+
+            if($enlargeIn == 0) {
+                $enlargeIn = pow(2, $numBits);
+                $numBits++;
+            }
+
+            if($dictionary->hasEntry($c)) {
+                $entry = $dictionary->getEntry($c);
+            }
+            else {
+                if ($c == $dictionary->size()) {
+                    $entry = $w . $w{0};
+                } else {
+                    return null;
+                }
+            }
+
+            $result .= $entry;
+            $dictionary->addEntry($w . $entry{0});
+            $w = $entry;
+
+            $enlargeIn--;
+            if($enlargeIn == 0) {
+                $enlargeIn = pow(2, $numBits);
+                $numBits++;
+            }
+        }
+    }
+}

LZCompressor/LZUtil.php

@@ -0,0 +1,112 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: sics
+ * Date: 27.02.2016
+ * Time: 15:54
+ */
+
+namespace LZCompressor;
+
+
+class LZUtil
+{
+    /**
+    * @var string
+    */
+    public static $keyStrBase64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+    public static $keyStrUriSafe = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-$";
+    private static $baseReverseDic = [];
+
+    /**
+     * @param string $alphabet
+     * @param integer $character
+     * @return string
+     */
+    public static function getBaseValue($alphabet, $character)
+    {
+        if(!array_key_exists($alphabet, self::$baseReverseDic)) {
+            self::$baseReverseDic[$alphabet] = [];
+            for($i=0; $i<strlen($alphabet); $i++) {
+                self::$baseReverseDic[$alphabet][$alphabet{$i}] = $i;
+            }
+        }
+        return self::$baseReverseDic[$alphabet][$character];
+    }
+
+    /**
+     * @return string
+     */
+    public static function fromCharCode()
+    {
+        return array_reduce(func_get_args(), function ($a, $b) {
+            $a .= self::utf8_chr($b);
+            return $a;
+        });
+    }
+
+    /**
+     * Phps chr() equivalent for UTF-8 encoding
+     *
+     * @param int|string $u
+     * @return string
+     */
+    public static function utf8_chr($u)
+    {
+        return mb_convert_encoding('&#' . intval($u) . ';', 'UTF-8', 'HTML-ENTITIES');
+    }
+
+    /**
+     * @param string $str
+     * @param int $num
+     *
+     * @return bool|integer
+     */
+    public static function charCodeAt($str, $num=0)
+    {
+        return self::utf8_ord(self::utf8_charAt($str, $num));
+    }
+
+    /**
+     * @param string $ch
+     *
+     * @return bool|integer
+     */
+    public static function utf8_ord($ch)
+    {
+        // must remain php's strlen
+        $len = strlen($ch);
+        if ($len <= 0) {
+            return -1;
+        }
+        $h = ord($ch{0});
+        if ($h <= 0x7F) return $h;
+        if ($h < 0xC2) return -3;
+        if ($h <= 0xDF && $len > 1) return ($h & 0x1F) << 6 | (ord($ch{1}) & 0x3F);
+        if ($h <= 0xEF && $len > 2) return ($h & 0x0F) << 12 | (ord($ch{1}) & 0x3F) << 6 | (ord($ch{2}) & 0x3F);
+        if ($h <= 0xF4 && $len > 3)
+            return ($h & 0x0F) << 18 | (ord($ch{1}) & 0x3F) << 12 | (ord($ch{2}) & 0x3F) << 6 | (ord($ch{3}) & 0x3F);
+        return -2;
+    }
+
+    /**
+     * @param string $str
+     * @param integer $num
+     *
+     * @return string
+     */
+    public static function utf8_charAt($str, $num)
+    {
+        return mb_substr($str, $num, 1, 'UTF-8');
+    }
+
+    /**
+     * @param string $str
+     * @return integer
+     */
+    public static function utf8_strlen($str) {
+        return mb_strlen($str, 'UTF-8');
+    }
+
+
+}