krz/vox-populi

  1<?php
  2namespace GuzzleHttp\Psr7;
  3
  4use Psr\Http\Message\StreamInterface;
  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 */
 14class BufferStream implements StreamInterface
 15{
 16    private $hwm;
 17    private $buffer = '';
 18
 19    /**
 20     * @param int $hwm High water mark, representing the preferred maximum
 21     *                 buffer size. If the size of the buffer exceeds the high
 22     *                 water mark, then calls to write will continue to succeed
 23     *                 but will return false to inform writers to slow down
 24     *                 until the buffer has been drained by reading from it.
 25     */
 26    public function __construct($hwm = 16384)
 27    {
 28        $this->hwm = $hwm;
 29    }
 30
 31    public function __toString()
 32    {
 33        return $this->getContents();
 34    }
 35
 36    public function getContents()
 37    {
 38        $buffer = $this->buffer;
 39        $this->buffer = '';
 40
 41        return $buffer;
 42    }
 43
 44    public function close()
 45    {
 46        $this->buffer = '';
 47    }
 48
 49    public function detach()
 50    {
 51        $this->close();
 52    }
 53
 54    public function getSize()
 55    {
 56        return strlen($this->buffer);
 57    }
 58
 59    public function isReadable()
 60    {
 61        return true;
 62    }
 63
 64    public function isWritable()
 65    {
 66        return true;
 67    }
 68
 69    public function isSeekable()
 70    {
 71        return false;
 72    }
 73
 74    public function rewind()
 75    {
 76        $this->seek(0);
 77    }
 78
 79    public function seek($offset, $whence = SEEK_SET)
 80    {
 81        throw new \RuntimeException('Cannot seek a BufferStream');
 82    }
 83
 84    public function eof()
 85    {
 86        return strlen($this->buffer) === 0;
 87    }
 88
 89    public function tell()
 90    {
 91        throw new \RuntimeException('Cannot determine the position of a BufferStream');
 92    }
 93
 94    /**
 95     * Reads data from the buffer.
 96     */
 97    public function read($length)
 98    {
 99        $currentLength = strlen($this->buffer);
100
101        if ($length >= $currentLength) {
102            // No need to slice the buffer because we don't have enough data.
103            $result = $this->buffer;
104            $this->buffer = '';
105        } else {
106            // Slice up the result to provide a subset of the buffer.
107            $result = substr($this->buffer, 0, $length);
108            $this->buffer = substr($this->buffer, $length);
109        }
110
111        return $result;
112    }
113
114    /**
115     * Writes data to the buffer.
116     */
117    public function write($string)
118    {
119        $this->buffer .= $string;
120
121        // TODO: What should happen here?
122        if (strlen($this->buffer) >= $this->hwm) {
123            return false;
124        }
125
126        return strlen($string);
127    }
128
129    public function getMetadata($key = null)
130    {
131        if ($key == 'hwm') {
132            return $this->hwm;
133        }
134
135        return $key ? null : [];
136    }
137}