Improve XLSX Escaper performance

src/Spout/Common/Escaper/XLSX.php

@@ -14,15 +14,23 @@ class XLSX implements EscaperInterface
 {
     use Singleton;
 
-    /** @var string[] Control characters to be escaped */
+    /** @var string Regex pattern to detect control characters that need to be escaped */
+    protected $escapableControlCharactersPattern;
+
+    /** @var string[] Map containing control characters to be escaped (key) and their escaped value (value) */
     protected $controlCharactersEscapingMap;
 
+    /** @var string[] Map containing control characters to be escaped (value) and their escaped value (key) */
+    protected $controlCharactersEscapingReverseMap;
+
     /**
      * Initializes the singleton instance
      */
     protected function init()
     {
+        $this->escapableControlCharactersPattern = $this->getEscapableControlCharactersPattern();
         $this->controlCharactersEscapingMap = $this->getControlCharactersEscapingMap();
+        $this->controlCharactersEscapingReverseMap = array_flip($this->controlCharactersEscapingMap);
     }
 
     /**
@@ -53,6 +61,20 @@ class XLSX implements EscaperInterface
         return $unescapedString;
     }
 
+    /**
+     * @return string Regex pattern containing all escapable control characters
+     */
+    protected function getEscapableControlCharactersPattern()
+    {
+        // control characters values are from 0 to 1F (hex values) in the ASCII table
+        // some characters should not be escaped though: "\t", "\r" and "\n".
+        return '[\x00-\x08' .
+                // skipping "\t" (0x9) and "\n" (0xA)
+                '\x0B-\x0C' .
+                // skipping "\r" (0xD)
+                '\x0E-\x1F]';
+    }
+
     /**
      * Builds the map containing control characters to be escaped
      * mapped to their escaped values.
@@ -66,14 +88,14 @@ class XLSX implements EscaperInterface
     protected function getControlCharactersEscapingMap()
     {
         $controlCharactersEscapingMap = [];
-        $whitelistedControlCharacters = ["\t", "\r", "\n"];
 
         // control characters values are from 0 to 1F (hex values) in the ASCII table
-        for ($charValue = 0x0; $charValue <= 0x1F; $charValue++) {
+        for ($charValue = 0x00; $charValue <= 0x1F; $charValue++) {
-            if (!in_array(chr($charValue), $whitelistedControlCharacters)) {
+            $character = chr($charValue);
+            if (preg_match("/{$this->escapableControlCharactersPattern}/", $character)) {
                 $charHexValue = dechex($charValue);
                 $escapedChar = '_x' . sprintf('%04s' , strtoupper($charHexValue)) . '_';
-                $controlCharactersEscapingMap[$escapedChar] = chr($charValue);
+                $controlCharactersEscapingMap[$escapedChar] = $character;
             }
         }
 
@@ -96,7 +118,15 @@ class XLSX implements EscaperInterface
     protected function escapeControlCharacters($string)
     {
         $escapedString = $this->escapeEscapeCharacter($string);
-        return str_replace(array_values($this->controlCharactersEscapingMap), array_keys($this->controlCharactersEscapingMap), $escapedString);
+
+        // if no control characters
+        if (!preg_match("/{$this->escapableControlCharactersPattern}/", $escapedString)) {
+            return $escapedString;
+        }
+
+        return preg_replace_callback("/({$this->escapableControlCharactersPattern})/", function($matches) {
+            return $this->controlCharactersEscapingReverseMap[$matches[0]];
+        }, $escapedString);
     }
 
     /**
@@ -126,6 +156,7 @@ class XLSX implements EscaperInterface
     protected function unescapeControlCharacters($string)
     {
         $unescapedString = $string;
+
         foreach ($this->controlCharactersEscapingMap as $escapedCharValue => $charValue) {
             // only unescape characters that don't contain the escaped escape character for now
             $unescapedString = preg_replace("/(?<!_x005F)($escapedCharValue)/", $charValue, $unescapedString);

tests/Spout/Common/Escaper/XLSXTest.php

@@ -17,7 +17,11 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         return [
             ['test', 'test'],
             ['adam\'s "car"', 'adam's "car"'],
+            ["\n", "\n"],
+            ["\r", "\r"],
+            ["\t", "\t"],
             [chr(0), '_x0000_'],
+            [chr(4), '_x0004_'],
             ['_x0000_', '_x005F_x0000_'],
             [chr(21), '_x0015_'],
             ['control '.chr(21).' character', 'control _x0015_ character'],
@@ -49,7 +53,11 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         return [
             ['test', 'test'],
             ['adam's "car"', 'adam\'s "car"'],
+            ["\n", "\n"],
+            ["\r", "\r"],
+            ["\t", "\t"],
             ['_x0000_', chr(0)],
+            ['_x0004_', chr(4)],
             ['_x005F_x0000_', '_x0000_'],
             ['_x0015_', chr(21)],
             ['control _x0015_ character', 'control '.chr(21).' character'],