Splitter::switch() - Code Metrics - Inspection of "[WIP] Sequencer to replace regular expressions" - TYPO3/Fluid - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Pull Request — master (#457)

by Claus

created 2019-06-03 13:54 UTC

Splitter::switch() A

↳ Parent: Splitter

Complexity

Conditions	1
Paths	1

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	1
nc	1
nop	1
dl	0
loc	8
rs	10
c	0
b	0
f	0

<?php
declare(strict_types=1);

namespace TYPO3Fluid\Fluid\Core\Parser;

/**
 * Splitter
 *
 * Byte-based calculations to perform splitting on Fluid template sources.
 * Uses (64bit) bit masking to detect characters that may split a template,
 * by grouping "interesting" bytes which have ordinal values within a value
 * range of maximum 64 and comparing the bit mask of this and the byte being
 * analysed.
 *
 * Contains the methods needed to iterate and match bytes based on (mutating)
 * bit-masks, and a couple of shorthand "peek" type methods to determine if
 * the current yield should be a certain type or another.
 *
 * The logic is essentially the equivalent of:
 *
 * - Using arrays of possible byte values
 * - Iterating characters and checking against the must-match bytes
 * - Using "substr" to extract relevant bits of template code
 *
 * The difference is that the method in this class is excessively faster than
 * any array-based counterpart and consumes orders of magnitude less memory.
 * It also means the opcode optimised version of the loop and comparisons use
 * ideal CPU instructions at the bit-level instead, making them both smaller
 * and even more efficient when compiled.
 *
 * Works by:
 *
 * - Iterating a byte value array while maintaining an internal pointer
 * - Yielding byte and position (which contains captured text since last yield)
 * - When yielding, reload the bit masks used in the next iteration
 */
class Splitter
{
    public const MAX_NAMESPACE_LENGTH = 10;

    public const BYTE_NULL = 0; // Zero-byte for terminating documents
    public const BYTE_INLINE = 123; // The "{" character indicating an inline expression started
    public const BYTE_INLINE_END = 125; // The "}" character indicating an inline expression ended
    public const BYTE_PIPE = 124; // The "|" character indicating an inline expression pass operation
    public const BYTE_MINUS = 45; // The "-" character (for legacy pass operations)
    public const BYTE_TAG = 60; // The "<" character indicating a tag has started
    public const BYTE_TAG_END = 62; // The ">" character indicating a tag has ended
    public const BYTE_TAG_CLOSE = 47; // The "/" character indicating a tag is a closing tag
    public const BYTE_QUOTE_DOUBLE = 34; // The " (standard double-quote) character
    public const BYTE_QUOTE_SINGLE = 39; // The ' (standard single-quote) character
    public const BYTE_WHITESPACE_SPACE = 32; // A standard space character
    public const BYTE_WHITESPACE_TAB = 9; // A standard carriage-return character
    public const BYTE_WHITESPACE_RETURN = 13; // A standard tab character
    public const BYTE_WHITESPACE_EOL = 10; // A standard (UNIX) line-break character
    public const BYTE_SEPARATOR_EQUALS = 61; // The "=" character
    public const BYTE_SEPARATOR_COLON = 58; // The ":" character
    public const BYTE_SEPARATOR_COMMA = 44; // The "," character
    public const BYTE_SEPARATOR_PIPE = 124; // The "|" character
    public const BYTE_PARENTHESIS_START = 40; // The "(" character
    public const BYTE_PARENTHESIS_END = 41; // The ")" character
    public const BYTE_ARRAY_START = 91; // The "[" character
    public const BYTE_ARRAY_END = 93; // The "]" character
    public const BYTE_SLASH = 47; // The "/" character
    public const BYTE_BACKSLASH = 92; // The "\" character
    public const BYTE_BACKTICK = 96; // The "`" character
    public const MAP_SHIFT = 64;
    public const MASK_LINEBREAKS = 0 | (1 << self::BYTE_WHITESPACE_EOL) | (1 << self::BYTE_WHITESPACE_RETURN);
    public const MASK_WHITESPACE = 0 | self::MASK_LINEBREAKS | (1 << self::BYTE_WHITESPACE_SPACE) | (1 << self::BYTE_WHITESPACE_TAB);

    /** @var Source */
    public $source;

    /** @var Context */
    public $context;

    public $index = 0;
    private $primaryMask = 0;
    private $secondaryMask = 0;

    public function __construct(Source $source, Contexts $contexts)
    {
        $this->source = $source;
        $this->switch($contexts->root);
    }

    /**
     * Split a string by searching for recognized characters using at least one,
     * optionally two bit masks consisting of OR'ed bit values of each detectable
     * character (byte). The secondary bit mask is costless as it is OR'ed into
     * the primary bit mask.
     *
     * @return \Generator|?string[]

     */
    public function parse(): \Generator
    {
        $bytes = &$this->source->bytes;
        $source = &$this->source->source;

        if (empty($bytes)) {
            yield Splitter::BYTE_NULL => null;
            return;
        }

        $captured = null;

        foreach ($bytes as $this->index => $byte) {
            // Decide which byte we encountered by explicitly checking if the encountered byte was in the minimum
            // range (not-mapped match). Next check is if the matched byte is within 64-128 range in which case
            // it is a mapped match. Anything else (>128) will be non-ASCII that is always captured.
            if ($byte < 64 && ($this->primaryMask & (1 << $byte))) {
                yield $byte => $captured;
                $captured = null;
            } elseif ($byte > 64 && $byte < 128 && ($this->secondaryMask & (1 << ($byte - static::MAP_SHIFT)))) {
                yield $byte => $captured;
                $captured = null;
            } else {
                // Append captured bytes from source, must happen after the conditions above so we avoid appending tokens.
                $captured .= $source{$this->index - 1};
            }
        }
        if ($captured !== null) {
            yield Splitter::BYTE_NULL => $captured;
        }
    }

    public function switch(Context $context): Context
    {
        $previous = $this->context;
        $this->context = $context;
        $this->primaryMask = $context->primaryMask;
        $this->secondaryMask = $context->secondaryMask;
        return $previous ?? $context;
    }

    public function countCharactersMatchingMask(int $primaryMask, int $offset, int $length): int

    {
        $bytes = &$this->source->bytes;
        $counted = 0;
        for ($index = $offset; $index < $this->source->length; $index++) {
            if (($primaryMask & (1 << $bytes[$index])) && $bytes[$index] < 64) {
                $counted++;
            }
        }
        return $counted;
    }

    public function findBytePositionBeforeOffset(int $primaryMask, int $offset): int
    {
        $bytes = &$this->source->bytes;
        for ($index = min($offset, $this->source->length); $index > 0; $index--) {
            if (($primaryMask & (1 << $bytes[$index])) && $bytes[$index] < 64) {
                return $index;
            }
        }
        return 0;
    }

    public function findBytePositionAfterOffset(int $primaryMask, int $offset): int
    {
        $bytes = &$this->source->bytes;
        for ($index = $offset; $index < $this->source->length; $index++) {
            if (($primaryMask & (1 << $bytes[$index])) && $bytes[$index] < 64) {
                return $index;
            }
        }
        return max($this->source->length, $offset);
    }
}


1			<?php
2			declare(strict_types=1);
3
4			namespace TYPO3Fluid\Fluid\Core\Parser;
5
6			/**
7			* Splitter
8			*
9			* Byte-based calculations to perform splitting on Fluid template sources.
10			* Uses (64bit) bit masking to detect characters that may split a template,
11			* by grouping "interesting" bytes which have ordinal values within a value
12			* range of maximum 64 and comparing the bit mask of this and the byte being
13			* analysed.
14			*
15			* Contains the methods needed to iterate and match bytes based on (mutating)
16			* bit-masks, and a couple of shorthand "peek" type methods to determine if
17			* the current yield should be a certain type or another.
18			*
19			* The logic is essentially the equivalent of:
20			*
21			* - Using arrays of possible byte values
22			* - Iterating characters and checking against the must-match bytes
23			* - Using "substr" to extract relevant bits of template code
24			*
25			* The difference is that the method in this class is excessively faster than
26			* any array-based counterpart and consumes orders of magnitude less memory.
27			* It also means the opcode optimised version of the loop and comparisons use
28			* ideal CPU instructions at the bit-level instead, making them both smaller
29			* and even more efficient when compiled.
30			*
31			* Works by:
32			*
33			* - Iterating a byte value array while maintaining an internal pointer
34			* - Yielding byte and position (which contains captured text since last yield)
35			* - When yielding, reload the bit masks used in the next iteration
36			*/
37			class Splitter
38			{
39			public const MAX_NAMESPACE_LENGTH = 10;
40
41			public const BYTE_NULL = 0; // Zero-byte for terminating documents
42			public const BYTE_INLINE = 123; // The "{" character indicating an inline expression started
43			public const BYTE_INLINE_END = 125; // The "}" character indicating an inline expression ended
44			public const BYTE_PIPE = 124; // The "\|" character indicating an inline expression pass operation
45			public const BYTE_MINUS = 45; // The "-" character (for legacy pass operations)
46			public const BYTE_TAG = 60; // The "<" character indicating a tag has started
47			public const BYTE_TAG_END = 62; // The ">" character indicating a tag has ended
48			public const BYTE_TAG_CLOSE = 47; // The "/" character indicating a tag is a closing tag
49			public const BYTE_QUOTE_DOUBLE = 34; // The " (standard double-quote) character
50			public const BYTE_QUOTE_SINGLE = 39; // The ' (standard single-quote) character
51			public const BYTE_WHITESPACE_SPACE = 32; // A standard space character
52			public const BYTE_WHITESPACE_TAB = 9; // A standard carriage-return character
53			public const BYTE_WHITESPACE_RETURN = 13; // A standard tab character
54			public const BYTE_WHITESPACE_EOL = 10; // A standard (UNIX) line-break character
55			public const BYTE_SEPARATOR_EQUALS = 61; // The "=" character
56			public const BYTE_SEPARATOR_COLON = 58; // The ":" character
57			public const BYTE_SEPARATOR_COMMA = 44; // The "," character
58			public const BYTE_SEPARATOR_PIPE = 124; // The "\|" character
59			public const BYTE_PARENTHESIS_START = 40; // The "(" character
60			public const BYTE_PARENTHESIS_END = 41; // The ")" character
61			public const BYTE_ARRAY_START = 91; // The "[" character
62			public const BYTE_ARRAY_END = 93; // The "]" character
63			public const BYTE_SLASH = 47; // The "/" character
64			public const BYTE_BACKSLASH = 92; // The "\" character
65			public const BYTE_BACKTICK = 96; // The "`" character
66			public const MAP_SHIFT = 64;
67			public const MASK_LINEBREAKS = 0 \| (1 << self::BYTE_WHITESPACE_EOL) \| (1 << self::BYTE_WHITESPACE_RETURN);
68			public const MASK_WHITESPACE = 0 \| self::MASK_LINEBREAKS \| (1 << self::BYTE_WHITESPACE_SPACE) \| (1 << self::BYTE_WHITESPACE_TAB);
69
70			/** @var Source */
71			public $source;
72
73			/** @var Context */
74			public $context;
75
76			public $index = 0;
77			private $primaryMask = 0;
78			private $secondaryMask = 0;
79
80			public function __construct(Source $source, Contexts $contexts)
81			{
82			$this->source = $source;
83			$this->switch($contexts->root);
84			}
85
86			/**
87			* Split a string by searching for recognized characters using at least one,
88			* optionally two bit masks consisting of OR'ed bit values of each detectable
89			* character (byte). The secondary bit mask is costless as it is OR'ed into
90			* the primary bit mask.
91			*
92			* @return \Generator\|?string[]
			0 ignored issues – show Documentation introduced 2019-05-31 19:29 UTC by Report Bug Copy Issue Report The doc-type `\Generator\|?string[]` could not be parsed: Unknown type name "?string" at position 11. (view supported doc-types) This check marks PHPDoc comments that could not be parsed by our parser. To see which comment annotations we can parse, please refer to our documentation on supported doc-types. Loading history...
93			*/
94			public function parse(): \Generator
95			{
96			$bytes = &$this->source->bytes;
97			$source = &$this->source->source;
98
99			if (empty($bytes)) {
100			yield Splitter::BYTE_NULL => null;
101			return;
102			}
103
104			$captured = null;
105
106			foreach ($bytes as $this->index => $byte) {
107			// Decide which byte we encountered by explicitly checking if the encountered byte was in the minimum
108			// range (not-mapped match). Next check is if the matched byte is within 64-128 range in which case
109			// it is a mapped match. Anything else (>128) will be non-ASCII that is always captured.
110			if ($byte < 64 && ($this->primaryMask & (1 << $byte))) {
111			yield $byte => $captured;
112			$captured = null;
113			} elseif ($byte > 64 && $byte < 128 && ($this->secondaryMask & (1 << ($byte - static::MAP_SHIFT)))) {
114			yield $byte => $captured;
115			$captured = null;
116			} else {
117			// Append captured bytes from source, must happen after the conditions above so we avoid appending tokens.
118			$captured .= $source{$this->index - 1};
119			}
120			}
121			if ($captured !== null) {
122			yield Splitter::BYTE_NULL => $captured;
123			}
124			}
125
126			public function switch(Context $context): Context
127			{
128			$previous = $this->context;
129			$this->context = $context;
130			$this->primaryMask = $context->primaryMask;
131			$this->secondaryMask = $context->secondaryMask;
132			return $previous ?? $context;
133			}
134
135			public function countCharactersMatchingMask(int $primaryMask, int $offset, int $length): int
			0 ignored issues – show Unused Code introduced 2019-05-31 19:29 UTC by Report Bug Copy Issue Report The parameter `$length` is not used and could be removed. This check looks from parameters that have been defined for a function or method, but which are not used in the method body. Loading history...
136			{
137			$bytes = &$this->source->bytes;
138			$counted = 0;
139			for ($index = $offset; $index < $this->source->length; $index++) {
140			if (($primaryMask & (1 << $bytes[$index])) && $bytes[$index] < 64) {
141			$counted++;
142			}
143			}
144			return $counted;
145			}
146
147			public function findBytePositionBeforeOffset(int $primaryMask, int $offset): int
148			{
149			$bytes = &$this->source->bytes;
150			for ($index = min($offset, $this->source->length); $index > 0; $index--) {
151			if (($primaryMask & (1 << $bytes[$index])) && $bytes[$index] < 64) {
152			return $index;
153			}
154			}
155			return 0;
156			}
157
158			public function findBytePositionAfterOffset(int $primaryMask, int $offset): int
159			{
160			$bytes = &$this->source->bytes;
161			for ($index = $offset; $index < $this->source->length; $index++) {
162			if (($primaryMask & (1 << $bytes[$index])) && $bytes[$index] < 64) {
163			return $index;
164			}
165			}
166			return max($this->source->length, $offset);
167			}
168			}
169

TYPO3 / Fluid

Pull Request — master (#457)

Splitter::switch() A

Complexity

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Duplication

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