depicter / modules / GuzzleHttp / Psr7 / CachingStream.php

CachingStream.php in Depicter — Popup & Slider Builder trunk, at modules/GuzzleHttp/Psr7/CachingStream.php

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1	<?php
2
3	declare(strict_types=1);
4
5	namespace Depicter\GuzzleHttp\Psr7;
6
7	use Depicter\Psr\Http\Message\StreamInterface;
8
9	/**
10	* Stream decorator that can cache previously read bytes from a sequentially
11	* read stream.
12	*/
13	final class CachingStream implements StreamInterface
14	{
15	use StreamDecoratorTrait;
16
17	/** @var StreamInterface Stream being wrapped */
18	private $remoteStream;
19
20	/** @var int Number of bytes to skip reading due to a write on the buffer */
21	private $skipReadBytes = 0;
22
23	/**
24	* @var StreamInterface
25	*/
26	private $stream;
27
28	/**
29	* We will treat the buffer object as the body of the stream
30	*
31	* @param StreamInterface $stream Stream to cache. The cursor is assumed to be at the beginning of the stream.
32	* @param StreamInterface $target Optionally specify where data is cached
33	*/
34	public function __construct(
35	StreamInterface $stream,
36	StreamInterface $target = null
37	) {
38	$this->remoteStream = $stream;
39	$this->stream = $target ?: new Stream(Utils::tryFopen('php://temp', 'r+'));
40	}
41
42	public function getSize(): ?int
43	{
44	$remoteSize = $this->remoteStream->getSize();
45
46	if (null === $remoteSize) {
47	return null;
48	}
49
50	return max($this->stream->getSize(), $remoteSize);
51	}
52
53	public function rewind(): void
54	{
55	$this->seek(0);
56	}
57
58	public function seek($offset, $whence = SEEK_SET): void
59	{
60	if ($whence === SEEK_SET) {
61	$byte = $offset;
62	} elseif ($whence === SEEK_CUR) {
63	$byte = $offset + $this->tell();
64	} elseif ($whence === SEEK_END) {
65	$size = $this->remoteStream->getSize();
66	if ($size === null) {
67	$size = $this->cacheEntireStream();
68	}
69	$byte = $size + $offset;
70	} else {
71	throw new \InvalidArgumentException('Invalid whence');
72	}
73
74	$diff = $byte - $this->stream->getSize();
75
76	if ($diff > 0) {
77	// Read the remoteStream until we have read in at least the amount
78	// of bytes requested, or we reach the end of the file.
79	while ($diff > 0 && !$this->remoteStream->eof()) {
80	$this->read($diff);
81	$diff = $byte - $this->stream->getSize();
82	}
83	} else {
84	// We can just do a normal seek since we've already seen this byte.
85	$this->stream->seek($byte);
86	}
87	}
88
89	public function read($length): string
90	{
91	// Perform a regular read on any previously read data from the buffer
92	$data = $this->stream->read($length);
93	$remaining = $length - strlen($data);
94
95	// More data was requested so read from the remote stream
96	if ($remaining) {
97	// If data was written to the buffer in a position that would have
98	// been filled from the remote stream, then we must skip bytes on
99	// the remote stream to emulate overwriting bytes from that
100	// position. This mimics the behavior of other PHP stream wrappers.
101	$remoteData = $this->remoteStream->read(
102	$remaining + $this->skipReadBytes
103	);
104
105	if ($this->skipReadBytes) {
106	$len = strlen($remoteData);
107	$remoteData = substr($remoteData, $this->skipReadBytes);
108	$this->skipReadBytes = max(0, $this->skipReadBytes - $len);
109	}
110
111	$data .= $remoteData;
112	$this->stream->write($remoteData);
113	}
114
115	return $data;
116	}
117
118	public function write($string): int
119	{
120	// When appending to the end of the currently read stream, you'll want
121	// to skip bytes from being read from the remote stream to emulate
122	// other stream wrappers. Basically replacing bytes of data of a fixed
123	// length.
124	$overflow = (strlen($string) + $this->tell()) - $this->remoteStream->tell();
125	if ($overflow > 0) {
126	$this->skipReadBytes += $overflow;
127	}
128
129	return $this->stream->write($string);
130	}
131
132	public function eof(): bool
133	{
134	return $this->stream->eof() && $this->remoteStream->eof();
135	}
136
137	/**
138	* Close both the remote stream and buffer stream
139	*/
140	public function close(): void
141	{
142	$this->remoteStream->close();
143	$this->stream->close();
144	}
145
146	private function cacheEntireStream(): int
147	{
148	$target = new FnStream(['write' => 'strlen']);
149	Utils::copyToStream($this, $target);
150
151	return $this->tell();
152	}
153	}
154