depicter / modules / GuzzleHttp / Psr7 / LimitStream.php

LimitStream.php in Depicter — Popup & Slider Builder trunk, at modules/GuzzleHttp/Psr7/LimitStream.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	* Decorator used to return only a subset of a stream.
11	*/
12	final class LimitStream implements StreamInterface
13	{
14	use StreamDecoratorTrait;
15
16	/** @var int Offset to start reading from */
17	private $offset;
18
19	/** @var int Limit the number of bytes that can be read */
20	private $limit;
21
22	/** @var StreamInterface */
23	private $stream;
24
25	/**
26	* @param StreamInterface $stream Stream to wrap
27	* @param int $limit Total number of bytes to allow to be read
28	* from the stream. Pass -1 for no limit.
29	* @param int $offset Position to seek to before reading (only
30	* works on seekable streams).
31	*/
32	public function __construct(
33	StreamInterface $stream,
34	int $limit = -1,
35	int $offset = 0
36	) {
37	$this->stream = $stream;
38	$this->setLimit($limit);
39	$this->setOffset($offset);
40	}
41
42	public function eof(): bool
43	{
44	// Always return true if the underlying stream is EOF
45	if ($this->stream->eof()) {
46	return true;
47	}
48
49	// No limit and the underlying stream is not at EOF
50	if ($this->limit === -1) {
51	return false;
52	}
53
54	return $this->stream->tell() >= $this->offset + $this->limit;
55	}
56
57	/**
58	* Returns the size of the limited subset of data
59	*/
60	public function getSize(): ?int
61	{
62	if (null === ($length = $this->stream->getSize())) {
63	return null;
64	} elseif ($this->limit === -1) {
65	return $length - $this->offset;
66	} else {
67	return min($this->limit, $length - $this->offset);
68	}
69	}
70
71	/**
72	* Allow for a bounded seek on the read limited stream
73	*/
74	public function seek($offset, $whence = SEEK_SET): void
75	{
76	if ($whence !== SEEK_SET \|\| $offset < 0) {
77	throw new \RuntimeException(sprintf(
78	'Cannot seek to offset %s with whence %s',
79	$offset,
80	$whence
81	));
82	}
83
84	$offset += $this->offset;
85
86	if ($this->limit !== -1) {
87	if ($offset > $this->offset + $this->limit) {
88	$offset = $this->offset + $this->limit;
89	}
90	}
91
92	$this->stream->seek($offset);
93	}
94
95	/**
96	* Give a relative tell()
97	*/
98	public function tell(): int
99	{
100	return $this->stream->tell() - $this->offset;
101	}
102
103	/**
104	* Set the offset to start limiting from
105	*
106	* @param int $offset Offset to seek to and begin byte limiting from
107	*
108	* @throws \RuntimeException if the stream cannot be seeked.
109	*/
110	public function setOffset(int $offset): void
111	{
112	$current = $this->stream->tell();
113
114	if ($current !== $offset) {
115	// If the stream cannot seek to the offset position, then read to it
116	if ($this->stream->isSeekable()) {
117	$this->stream->seek($offset);
118	} elseif ($current > $offset) {
119	throw new \RuntimeException("Could not seek to stream offset $offset");
120	} else {
121	$this->stream->read($offset - $current);
122	}
123	}
124
125	$this->offset = $offset;
126	}
127
128	/**
129	* Set the limit of bytes that the decorator allows to be read from the
130	* stream.
131	*
132	* @param int $limit Number of bytes to allow to be read from the stream.
133	* Use -1 for no limit.
134	*/
135	public function setLimit(int $limit): void
136	{
137	$this->limit = $limit;
138	}
139
140	public function read($length): string
141	{
142	if ($this->limit === -1) {
143	return $this->stream->read($length);
144	}
145
146	// Check if the current position is less than the total allowed
147	// bytes + original offset
148	$remaining = ($this->offset + $this->limit) - $this->stream->tell();
149	if ($remaining > 0) {
150	// Only return the amount of requested data, ensuring that the byte
151	// limit is not exceeded
152	return $this->stream->read(min($remaining, $length));
153	}
154
155	return '';
156	}
157	}
158