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   1  <?php
   2  
   3  namespace Box\Spout\Autoloader;
   4  
   5  /**
   6   * Class Psr4Autoloader
   7   * @see https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-4-autoloader-examples.md#class-example
   8   *
   9   * @package Box\Spout\Autoloader
  10   */
  11  class Psr4Autoloader
  12  {
  13      /**
  14       * An associative array where the key is a namespace prefix and the value
  15       * is an array of base directories for classes in that namespace.
  16       *
  17       * @var array
  18       */
  19      protected $prefixes = array();
  20  
  21      /**
  22       * Register loader with SPL autoloader stack.
  23       *
  24       * @return void
  25       */
  26      public function register()
  27      {
  28          spl_autoload_register(array($this, 'loadClass'));
  29      }
  30  
  31      /**
  32       * Adds a base directory for a namespace prefix.
  33       *
  34       * @param string $prefix The namespace prefix.
  35       * @param string $baseDir A base directory for class files in the
  36       * namespace.
  37       * @param bool $prepend If true, prepend the base directory to the stack
  38       * instead of appending it; this causes it to be searched first rather
  39       * than last.
  40       * @return void
  41       */
  42      public function addNamespace($prefix, $baseDir, $prepend = false)
  43      {
  44          // normalize namespace prefix
  45          $prefix = trim($prefix, '\\') . '\\';
  46  
  47          // normalize the base directory with a trailing separator
  48          $baseDir = rtrim($baseDir, DIRECTORY_SEPARATOR) . '/';
  49  
  50          // initialize the namespace prefix array
  51          if (isset($this->prefixes[$prefix]) === false) {
  52              $this->prefixes[$prefix] = array();
  53          }
  54  
  55          // retain the base directory for the namespace prefix
  56          if ($prepend) {
  57              array_unshift($this->prefixes[$prefix], $baseDir);
  58          } else {
  59              array_push($this->prefixes[$prefix], $baseDir);
  60          }
  61      }
  62  
  63      /**
  64       * Loads the class file for a given class name.
  65       *
  66       * @param string $class The fully-qualified class name.
  67       * @return mixed The mapped file name on success, or boolean false on
  68       * failure.
  69       */
  70      public function loadClass($class)
  71      {
  72          // the current namespace prefix
  73          $prefix = $class;
  74  
  75          // work backwards through the namespace names of the fully-qualified
  76          // class name to find a mapped file name
  77          while (false !== $pos = strrpos($prefix, '\\')) {
  78  
  79              // retain the trailing namespace separator in the prefix
  80              $prefix = substr($class, 0, $pos + 1);
  81  
  82              // the rest is the relative class name
  83              $relativeClass = substr($class, $pos + 1);
  84  
  85              // try to load a mapped file for the prefix and relative class
  86              $mappedFile = $this->loadMappedFile($prefix, $relativeClass);
  87              if ($mappedFile !== false) {
  88                  return $mappedFile;
  89              }
  90  
  91              // remove the trailing namespace separator for the next iteration
  92              // of strrpos()
  93              $prefix = rtrim($prefix, '\\');
  94          }
  95  
  96          // never found a mapped file
  97          return false;
  98      }
  99  
 100      /**
 101       * Load the mapped file for a namespace prefix and relative class.
 102       *
 103       * @param string $prefix The namespace prefix.
 104       * @param string $relativeClass The relative class name.
 105       * @return mixed Boolean false if no mapped file can be loaded, or the
 106       * name of the mapped file that was loaded.
 107       */
 108      protected function loadMappedFile($prefix, $relativeClass)
 109      {
 110          // are there any base directories for this namespace prefix?
 111          if (isset($this->prefixes[$prefix]) === false) {
 112              return false;
 113          }
 114  
 115          // look through base directories for this namespace prefix
 116          foreach ($this->prefixes[$prefix] as $baseDir) {
 117  
 118              // replace the namespace prefix with the base directory,
 119              // replace namespace separators with directory separators
 120              // in the relative class name, append with .php
 121              $file = $baseDir
 122                    . str_replace('\\', '/', $relativeClass)
 123                    . '.php';
 124  
 125              // if the mapped file exists, require it
 126              if ($this->requireFile($file)) {
 127                  // yes, we're done
 128                  return $file;
 129              }
 130          }
 131  
 132          // never found it
 133          return false;
 134      }
 135  
 136      /**
 137       * If a file exists, require it from the file system.
 138       *
 139       * @param string $file The file to require.
 140       * @return bool True if the file exists, false if not.
 141       */
 142      protected function requireFile($file)
 143      {
 144          if (file_exists($file)) {
 145              require $file;
 146              return true;
 147          }
 148          return false;
 149      }
 150  }