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   1  <?php
   2  namespace GuzzleHttp\Stream;
   3  
   4  use GuzzleHttp\Stream\Exception\CannotAttachException;
   5  
   6  /**
   7   * Provides a buffer stream that can be written to to fill a buffer, and read
   8   * from to remove bytes from the buffer.
   9   *
  10   * This stream returns a "hwm" metadata value that tells upstream consumers
  11   * what the configured high water mark of the stream is, or the maximum
  12   * preferred size of the buffer.
  13   *
  14   * @package GuzzleHttp\Stream
  15   */
  16  class BufferStream implements StreamInterface
  17  {
  18      private $hwm;
  19      private $buffer = '';
  20  
  21      /**
  22       * @param int $hwm High water mark, representing the preferred maximum
  23       *                 buffer size. If the size of the buffer exceeds the high
  24       *                 water mark, then calls to write will continue to succeed
  25       *                 but will return false to inform writers to slow down
  26       *                 until the buffer has been drained by reading from it.
  27       */
  28      public function __construct($hwm = 16384)
  29      {
  30          $this->hwm = $hwm;
  31      }
  32  
  33      public function __toString()
  34      {
  35          return $this->getContents();
  36      }
  37  
  38      public function getContents()
  39      {
  40          $buffer = $this->buffer;
  41          $this->buffer = '';
  42  
  43          return $buffer;
  44      }
  45  
  46      public function close()
  47      {
  48          $this->buffer = '';
  49      }
  50  
  51      public function detach()
  52      {
  53          $this->close();
  54      }
  55  
  56      public function attach($stream)
  57      {
  58          throw new CannotAttachException();
  59      }
  60  
  61      public function getSize()
  62      {
  63          return strlen($this->buffer);
  64      }
  65  
  66      public function isReadable()
  67      {
  68          return true;
  69      }
  70  
  71      public function isWritable()
  72      {
  73          return true;
  74      }
  75  
  76      public function isSeekable()
  77      {
  78          return false;
  79      }
  80  
  81      public function seek($offset, $whence = SEEK_SET)
  82      {
  83          return false;
  84      }
  85  
  86      public function eof()
  87      {
  88          return strlen($this->buffer) === 0;
  89      }
  90  
  91      public function tell()
  92      {
  93          return false;
  94      }
  95  
  96      /**
  97       * Reads data from the buffer.
  98       */
  99      public function read($length)
 100      {
 101          $currentLength = strlen($this->buffer);
 102  
 103          if ($length >= $currentLength) {
 104              // No need to slice the buffer because we don't have enough data.
 105              $result = $this->buffer;
 106              $this->buffer = '';
 107          } else {
 108              // Slice up the result to provide a subset of the buffer.
 109              $result = substr($this->buffer, 0, $length);
 110              $this->buffer = substr($this->buffer, $length);
 111          }
 112  
 113          return $result;
 114      }
 115  
 116      /**
 117       * Writes data to the buffer.
 118       */
 119      public function write($string)
 120      {
 121          $this->buffer .= $string;
 122  
 123          if (strlen($this->buffer) >= $this->hwm) {
 124              return false;
 125          }
 126  
 127          return strlen($string);
 128      }
 129  
 130      public function getMetadata($key = null)
 131      {
 132          if ($key == 'hwm') {
 133              return $this->hwm;
 134          }
 135  
 136          return $key ? null : [];
 137      }
 138  }