JsonStream::seek() - Code Metrics - Inspection of "Improve JsonStream efficiency" - violet-php/streaming-json-encoder - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 44b103...5bf1b6 )

by Riikka

created 2016-12-02 18:50 UTC

JsonStream::seek() A

↳ Parent: JsonStream

Complexity

Conditions	3
Paths	2

Size

Total Lines	12
Code Lines	7

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	9
CRAP Score	3

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
dl	0
loc	12
ccs	9
cts	9
cp	1
rs	9.4285
c	1
b	0
f	0
cc	3
eloc	7
nc	2
nop	2
crap	3

<?php

namespace Violet\StreamingJsonEncoder;

use Psr\Http\Message\StreamInterface;

/**
 * Provides a http stream interface for encoding JSON.
 *
 * @author Riikka Kalliomäki <[email protected]>
 * @copyright Copyright (c) 2016, Riikka Kalliomäki
 * @license http://opensource.org/licenses/mit-license.php MIT License
 */
class JsonStream implements StreamInterface
{
    /** @var BufferJsonEncoder The encoder used to produce the JSON stream */
    private $encoder;

    /** @var int The current position of the cursor in the JSON stream */
    private $cursor;

    /** @var string Buffered output from encoding the value as JSON */
    private $buffer;

    /**
     * JsonStream constructor.
     * @param BufferJsonEncoder|mixed $value A JSON encoder to use or a value to encode
     */
    public function __construct($value)
    {
        if (!$value instanceof BufferJsonEncoder) {
            $value = new BufferJsonEncoder($value);
        }

        $this->encoder = $value;
        $this->rewind();
    }

    /**
     * Returns the JSON encoder used for the JSON stream.
     * @return BufferJsonEncoder The currently used JSON encoder
     * @throws \RuntimeException If the stream has been closed
     */
    private function getEncoder()
    {
        if (!$this->encoder instanceof BufferJsonEncoder) {
            throw new \RuntimeException('Cannot operate on a closed JSON stream');
        }

        return $this->encoder;
    }

    /**
     * Returns the entire JSON stream as a string.
     *
     * Note that this operation performs rewind operation on the JSON encoder. Whether
     * this works or not is dependant on the underlying value being encoded. An empty
     * string is returned if the value cannot be encoded.
     *
     * @return string The entire JSON stream as a string
     */
    public function __toString()
    {
        try {
            $this->rewind();
            return $this->getContents();
        } catch (\Exception $exception) {
            return '';
        }
    }

    /**
     * Frees the JSON encoder from memory and prevents further reading from the JSON stream.
     */
    public function close()
    {
        $this->encoder = null;
    }

    /**
     * Detaches the underlying PHP stream and returns it.
     * @return null Always returns null as no underlying PHP stream exists
     */
    public function detach()
    {
        return null;
    }

    /**
     * Returns the total size of the JSON stream.
     * @return null Always returns null as the total size cannot be determined
     */
    public function getSize()
    {
        return null;
    }

    /**
     * Returns the current position of the cursor in the JSON stream.
     * @return int Current position of the cursor
     */
    public function tell()
    {
        $this->getEncoder();
        return $this->cursor;
    }

    /**
     * Tells if there are no more bytes to read from the JSON stream.
     * @return bool True if there are no more bytes to read, false if there are
     */
    public function eof()
    {
        return $this->buffer === null;
    }

    /**
     * Tells if the JSON stream is seekable or not.
     * @return bool Always returns true as JSON streams as always seekable
     */
    public function isSeekable()
    {
        return true;
    }

    /**
     * Seeks the given cursor position in the JSON stream.
     *
     * If the provided seek position is less than the current cursor position, a rewind
     * operation is performed on the underlying JSON encoder. Whether this works or not
     * depends on whether the encoded value supports rewinding.
     *
     * Note that since it's not possible to determine the end of the JSON stream without
     * encoding the entire value, it's not possible to set the cursor using SEEK_END
     * constant and doing so will result in an exception.
     *
     * @param int $offset The offset for the cursor.
     * @param int $whence Either SEEK_CUR or SEEK_SET to determine new cursor position
     */
    public function seek($offset, $whence = SEEK_SET)
    {
        $position = $this->calculatePosition($offset, $whence);

        if (!isset($this->cursor) || $position < $this->cursor) {
            $this->getEncoder()->rewind();
            $this->buffer = '';
            $this->cursor = 0;
        }

        $this->forward($position);
    }

    /**
     * Calculates new position for the cursor based on offset and whence.
     * @param int $offset The cursor offset
     * @param int $whence One of the SEEK_* constants
     * @return int The new cursor position
     */
    private function calculatePosition($offset, $whence)
    {
        if ($whence === SEEK_CUR) {
            return max(0, $this->cursor + (int) $offset);
        } elseif ($whence === SEEK_SET) {
            return max(0, (int) $offset);
        } elseif ($whence === SEEK_END) {
            throw new \RuntimeException('Cannot set cursor position from the end of a JSON stream');
        }

        throw new \InvalidArgumentException("Invalid cursor relative position '$whence'");
// Instead of
$x = "foo $bar $baz";

// Better use either
$x = "foo " . $bar . " " . $baz;
$x = sprintf("foo %s %s", $bar, $baz);
    }

    /**
     * Forwards the JSON stream reading cursor to the given position or to the end of stream.
     * @param int $position The new position of the cursor.
     */
    private function forward($position)
    {
        $encoder = $this->getEncoder();

        while ($this->cursor < $position) {
            $length = strlen($this->buffer);

            if ($this->cursor + $length > $position) {
                $this->buffer = substr($this->buffer, $position - $this->cursor);
                $this->cursor = $position;
                break;
            }

            $this->cursor += $length;
            $this->buffer = '';

            if (!$encoder->valid()) {
                $this->buffer = null;
                break;
            }

            $this->buffer = $encoder->current();
            $encoder->next();
        }
    }

    /**
     * Seeks the beginning of the JSON stream.
     *
     * If the encoding has already been started, rewinding the encoder may not work,
     * if the underlying value being encoded does not support rewinding.
     */
    public function rewind()
    {
        $this->seek(0);
    }

    /**
     * Tells if the JSON stream is writable or not.
     * @return bool Always returns false as JSON streams are never writable
     */
    public function isWritable()
    {
        return false;
    }

    /**
     * Writes the given bytes to the JSON stream.
     *
     * As the JSON stream does not represent a writable stream, this method will
     * always throw a runtime exception.
     *
     * @param string $string The bytes to write
     * @return int The number of bytes written

     * @throws \RuntimeException Always throws a runtime exception
     */
    public function write($string)
    {
        throw new \RuntimeException('Cannot write to a JSON stream');
    }

    /**
     * Tells if the JSON stream is readable or not.
     * @return bool Always returns true as JSON streams are always readable
     */
    public function isReadable()
    {
        return true;
    }

    /**
     * Returns the given number of bytes from the JSON stream.
     *
     * The underlying value is encoded into JSON until enough bytes have been
     * generated to fulfill the requested number of bytes. The extraneous bytes are
     * then buffered for the next read from the JSON stream. The stream may return
     * fewer number of bytes if the entire value has been encoded and there are no
     * more bytes to return.
     *
     * @param int $length The number of bytes to return
     * @return string The bytes read from the JSON stream
     */
    public function read($length)
    {
        $length = max(0, (int) $length);
        $encoder = $this->getEncoder();

        while (strlen($this->buffer) < $length && $encoder->valid()) {
            $this->buffer .= $encoder->current();
            $encoder->next();
        }

        if (strlen($this->buffer) > $length || $encoder->valid()) {
            $output = substr($this->buffer, 0, $length);
            $this->buffer = substr($this->buffer, $length);
        } else {
            $output = (string) $this->buffer;
            $this->buffer = null;
        }

        $this->cursor += strlen($output);

        return $output;
    }

    /**
     * Returns the remaining bytes from the JSON stream.
     * @return string The remaining bytes from JSON stream
     */
    public function getContents()
    {
        $encoder = $this->getEncoder();
        $output = '';

        while ($encoder->valid()) {
            $output .= $encoder->current();
            $encoder->next();
        }

        $this->cursor += strlen($output);
        $this->buffer = null;

        return $output;
    }

    /**
     * Returns the metadata from the underlying PHP stream.
     *
     * As no underlying PHP stream exists for the JSON stream, this method will
     * always return an empty array or a null.
     *
     * @param string|null The key of the value to return
     * @return array|null Always returns an empty array or a null
     */
    public function getMetadata($key = null)
    {
        return $key === null ? [] : null;
    }
}


1		<?php
2
3		namespace Violet\StreamingJsonEncoder;
4
5		use Psr\Http\Message\StreamInterface;
6
7		/**
8		* Provides a http stream interface for encoding JSON.
9		*
10		* @author Riikka Kalliomäki <[email protected]>
11		* @copyright Copyright (c) 2016, Riikka Kalliomäki
12		* @license http://opensource.org/licenses/mit-license.php MIT License
13		*/
14		class JsonStream implements StreamInterface
15		{
16		/** @var BufferJsonEncoder The encoder used to produce the JSON stream */
17		private $encoder;
18
19		/** @var int The current position of the cursor in the JSON stream */
20		private $cursor;
21
22		/** @var string Buffered output from encoding the value as JSON */
23		private $buffer;
24
25		/**
26		* JsonStream constructor.
27		* @param BufferJsonEncoder\|mixed $value A JSON encoder to use or a value to encode
28		*/
29	20	public function __construct($value)
30		{
31	20	if (!$value instanceof BufferJsonEncoder) {
32	18	$value = new BufferJsonEncoder($value);
33	9	}
34
35	20	$this->encoder = $value;
36	20	$this->rewind();
37	10	}
38
39		/**
40		* Returns the JSON encoder used for the JSON stream.
41		* @return BufferJsonEncoder The currently used JSON encoder
42		* @throws \RuntimeException If the stream has been closed
43		*/
44	20	private function getEncoder()
45		{
46	20	if (!$this->encoder instanceof BufferJsonEncoder) {
47	4	throw new \RuntimeException('Cannot operate on a closed JSON stream');
48		}
49
50	20	return $this->encoder;
51		}
52
53		/**
54		* Returns the entire JSON stream as a string.
55		*
56		* Note that this operation performs rewind operation on the JSON encoder. Whether
57		* this works or not is dependant on the underlying value being encoded. An empty
58		* string is returned if the value cannot be encoded.
59		*
60		* @return string The entire JSON stream as a string
61		*/
62	4	public function __toString()
63		{
64		try {
65	4	$this->rewind();
66	2	return $this->getContents();
67	2	} catch (\Exception $exception) {
68	2	return '';
69		}
70		}
71
72		/**
73		* Frees the JSON encoder from memory and prevents further reading from the JSON stream.
74		*/
75	4	public function close()
76		{
77	4	$this->encoder = null;
78	2	}
79
80		/**
81		* Detaches the underlying PHP stream and returns it.
82		* @return null Always returns null as no underlying PHP stream exists
83		*/
84	2	public function detach()
85		{
86	2	return null;
87		}
88
89		/**
90		* Returns the total size of the JSON stream.
91		* @return null Always returns null as the total size cannot be determined
92		*/
93	2	public function getSize()
94		{
95	2	return null;
96		}
97
98		/**
99		* Returns the current position of the cursor in the JSON stream.
100		* @return int Current position of the cursor
101		*/
102	4	public function tell()
103		{
104	4	$this->getEncoder();
105	4	return $this->cursor;
106		}
107
108		/**
109		* Tells if there are no more bytes to read from the JSON stream.
110		* @return bool True if there are no more bytes to read, false if there are
111		*/
112	6	public function eof()
113		{
114	6	return $this->buffer === null;
115		}
116
117		/**
118		* Tells if the JSON stream is seekable or not.
119		* @return bool Always returns true as JSON streams as always seekable
120		*/
121	2	public function isSeekable()
122		{
123	2	return true;
124		}
125
126		/**
127		* Seeks the given cursor position in the JSON stream.
128		*
129		* If the provided seek position is less than the current cursor position, a rewind
130		* operation is performed on the underlying JSON encoder. Whether this works or not
131		* depends on whether the encoded value supports rewinding.
132		*
133		* Note that since it's not possible to determine the end of the JSON stream without
134		* encoding the entire value, it's not possible to set the cursor using SEEK_END
135		* constant and doing so will result in an exception.
136		*
137		* @param int $offset The offset for the cursor.
138		* @param int $whence Either SEEK_CUR or SEEK_SET to determine new cursor position
139		*/
140	20	public function seek($offset, $whence = SEEK_SET)
141		{
142	20	$position = $this->calculatePosition($offset, $whence);
143
144	20	if (!isset($this->cursor) \|\| $position < $this->cursor) {
145	20	$this->getEncoder()->rewind();
146	20	$this->buffer = '';
147	20	$this->cursor = 0;
148	10	}
149
150	20	$this->forward($position);
151	10	}
152
153		/**
154		* Calculates new position for the cursor based on offset and whence.
155		* @param int $offset The cursor offset
156		* @param int $whence One of the SEEK_* constants
157		* @return int The new cursor position
158		*/
159	20	private function calculatePosition($offset, $whence)
160		{
161	20	if ($whence === SEEK_CUR) {
162	2	return max(0, $this->cursor + (int) $offset);
163	20	} elseif ($whence === SEEK_SET) {
164	20	return max(0, (int) $offset);
165	4	} elseif ($whence === SEEK_END) {
166	2	throw new \RuntimeException('Cannot set cursor position from the end of a JSON stream');
167		}
168
169	2	throw new \InvalidArgumentException("Invalid cursor relative position '$whence'");
		0 ignored issues – show Coding Style Best Practice introduced 2016-12-02 18:52 UTC by Report Bug Copy Issue Report As per coding-style, please use concatenation or `sprintf` for the variable `$whence` instead of interpolation. It is generally a best practice as it is often more readable to use concatenation instead of interpolation for variables inside strings. // Instead of $x = "foo $bar $baz"; // Better use either $x = "foo " . $bar . " " . $baz; $x = sprintf("foo %s %s", $bar, $baz); Loading history...
170		}
171
172		/**
173		* Forwards the JSON stream reading cursor to the given position or to the end of stream.
174		* @param int $position The new position of the cursor.
175		*/
176	20	private function forward($position)
177		{
178	20	$encoder = $this->getEncoder();
179
180	20	while ($this->cursor < $position) {
181	2	$length = strlen($this->buffer);
182
183	2	if ($this->cursor + $length > $position) {
184	2	$this->buffer = substr($this->buffer, $position - $this->cursor);
185	2	$this->cursor = $position;
186	2	break;
187		}
188
189	2	$this->cursor += $length;
190	2	$this->buffer = '';
191
192	2	if (!$encoder->valid()) {
193	2	$this->buffer = null;
194	2	break;
195		}
196
197	2	$this->buffer = $encoder->current();
198	2	$encoder->next();
199	1	}
200	10	}
201
202		/**
203		* Seeks the beginning of the JSON stream.
204		*
205		* If the encoding has already been started, rewinding the encoder may not work,
206		* if the underlying value being encoded does not support rewinding.
207		*/
208	20	public function rewind()
209		{
210	20	$this->seek(0);
211	10	}
212
213		/**
214		* Tells if the JSON stream is writable or not.
215		* @return bool Always returns false as JSON streams are never writable
216		*/
217	2	public function isWritable()
218		{
219	2	return false;
220		}
221
222		/**
223		* Writes the given bytes to the JSON stream.
224		*
225		* As the JSON stream does not represent a writable stream, this method will
226		* always throw a runtime exception.
227		*
228		* @param string $string The bytes to write
229		* @return int The number of bytes written
		0 ignored issues – show Documentation introduced 2016-12-02 18:52 UTC by Report Bug Copy Issue Report Consider making the return type a bit more specific; maybe use `NoType`. This check looks for the generic type `array` as a return type and suggests a more specific type. This type is inferred from the actual code. Loading history...
230		* @throws \RuntimeException Always throws a runtime exception
231		*/
232	2	public function write($string)
233		{
234	2	throw new \RuntimeException('Cannot write to a JSON stream');
235		}
236
237		/**
238		* Tells if the JSON stream is readable or not.
239		* @return bool Always returns true as JSON streams are always readable
240		*/
241	2	public function isReadable()
242		{
243	2	return true;
244		}
245
246		/**
247		* Returns the given number of bytes from the JSON stream.
248		*
249		* The underlying value is encoded into JSON until enough bytes have been
250		* generated to fulfill the requested number of bytes. The extraneous bytes are
251		* then buffered for the next read from the JSON stream. The stream may return
252		* fewer number of bytes if the entire value has been encoded and there are no
253		* more bytes to return.
254		*
255		* @param int $length The number of bytes to return
256		* @return string The bytes read from the JSON stream
257		*/
258	6	public function read($length)
259		{
260	6	$length = max(0, (int) $length);
261	6	$encoder = $this->getEncoder();
262
263	4	while (strlen($this->buffer) < $length && $encoder->valid()) {
264	2	$this->buffer .= $encoder->current();
265	2	$encoder->next();
266	1	}
267
268	4	if (strlen($this->buffer) > $length \|\| $encoder->valid()) {
269	4	$output = substr($this->buffer, 0, $length);
270	4	$this->buffer = substr($this->buffer, $length);
271	2	} else {
272	4	$output = (string) $this->buffer;
273	4	$this->buffer = null;
274		}
275
276	4	$this->cursor += strlen($output);
277
278	4	return $output;
279		}
280
281		/**
282		* Returns the remaining bytes from the JSON stream.
283		* @return string The remaining bytes from JSON stream
284		*/
285	4	public function getContents()
286		{
287	4	$encoder = $this->getEncoder();
288	4	$output = '';
289
290	4	while ($encoder->valid()) {
291	4	$output .= $encoder->current();
292	4	$encoder->next();
293	2	}
294
295	4	$this->cursor += strlen($output);
296	4	$this->buffer = null;
297
298	4	return $output;
299		}
300
301		/**
302		* Returns the metadata from the underlying PHP stream.
303		*
304		* As no underlying PHP stream exists for the JSON stream, this method will
305		* always return an empty array or a null.
306		*
307		* @param string\|null The key of the value to return
308		* @return array\|null Always returns an empty array or a null
309		*/
310	2	public function getMetadata($key = null)
311		{
312	2	return $key === null ? [] : null;
313		}
314		}
315

violet-php / streaming-json-encoder

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JsonStream::seek() A

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