Parser - Code Metrics - Inspection of "Merge pull request #19 from peacefulbit/slatelang" - peacefulbit/packet-lite - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Push — master ( 766df6...286284 )

by Roman

created 2016-11-02 12:20 UTC

Parser C

↳ Parent: Project

Complexity

Total Complexity

Size/Duplication

Total Lines	332
Duplicated Lines	6.02 %

Coupling/Cohesion

Components	2
Dependencies	18

Importance

Changes

Metric	Value
dl	20
loc	332
rs	5.1442
c	0
b	0
f	0
wmc	49
lcom	2
cbo	18

19 Methods

Rating	Name	Duplication	Size	Complexity
A	parse()	0	6	1
B	parseToken()	0	19	6
D	parseExpression()	0	28	10
A	parseDeclaration()	0	10	2
A	parseIfExpression()	0	10	2
A	parseOrExpression()	10	10	2
A	parseAndExpression()	10	10	2
A	parseLambdaDeclaration()	0	16	2
A	parseFunctionDeclaration()	0	22	3
A	parseAssignDeclaration()	0	17	3
A	parseCallExpression()	0	9	1
A	parseProgram()	0	4	1
A	parseSequence()	0	4	1
A	parseIdentifier()	0	4	1
A	parseDotIdentifier()	0	4	1
A	parseString()	0	4	1
A	parseNumeric()	0	4	1
B	deflate()	0	22	4
B	findPairClosingBracketIndex()	0	20	5

How to fix Duplicated Code Complexity

Duplicated Code

Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.

Common duplication problems, and corresponding solutions are:

If you have the same expression in different places: Extract expression to a method
If you have the same method in different sub-classes: Extract method, and pull up field to the parent class
If you have the same code in unrelated classes: Consider extracting the code to a new class, and injecting that class

Complex Class

Tip: Before tackling complexity, make sure that you eliminate any duplication first. This often can reduce the size of classes significantly.

Complex classes like Parser often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.

Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.

While breaking up the class, it is a good idea to analyze how other classes use Parser, and based on these observations, apply Extract Interface, too.

<?php

namespace PeacefulBit\Slate\Parser;

use function Nerd\Common\Arrays\all;
use function Nerd\Common\Arrays\toHeadTail;
use function Nerd\Common\Arrays\append;

use function Nerd\Common\Functional\tail;

use PeacefulBit\Slate\Exceptions\ParserException;
use PeacefulBit\Slate\Parser\Nodes;
use PeacefulBit\Slate\Parser\Tokens;

class Parser
{
    /**
     * Convert tokens tree to abstract syntax tree.
     *
     * @param Tokens\Token[] $tokens
     * @return Nodes\Node
     */
    public function parse(array $tokens): Nodes\Node
    {
        $tokensTree = $this->deflate($tokens);

        return $this->parseProgram($tokensTree);
    }

    /**
     * @param $token
     * @return Nodes\Identifier|Nodes\Literal|Nodes\Node
     * @throws ParserException
     */
    private function parseToken($token)
    {
        if (is_array($token)) {
            return $this->parseExpression($token);
        }
        if ($token instanceof Tokens\StringToken) {
            return $this->parseString($token);
        }
        if ($token instanceof Tokens\IdentifierToken) {
            return $this->parseIdentifier($token);
        }
        if ($token instanceof Tokens\DotIdentifierToken) {
            return $this->parseDotIdentifier($token);
class Author {
    private $name;

    public function __construct($name) {
        $this->name = $name;
    }

    public function getName() {
        return $this->name;
    }
}

abstract class Post {
    public function getAuthor() {
        return 'Johannes';
    }
}

class BlogPost extends Post {
    public function getAuthor() {
        return new Author('Johannes');
    }
}

class ForumPost extends Post { /* ... */ }

function my_function(Post $post) {
    echo strtoupper($post->getAuthor());
}
        }
        if ($token instanceof Tokens\NumericToken) {
            return $this->parseNumeric($token);
        }
        throw new ParserException("Unexpected type of token - $token.");
    }

    /**
     * @param array $tokens
     * @return Nodes\Node
     * @throws ParserException
     */
    private function parseExpression(array $tokens): Nodes\Node
    {
        if (empty($tokens)) {
            throw new ParserException("Expression could not be empty.");
        }

        list ($head, $tail) = toHeadTail($tokens);

        if ($head instanceof Tokens\IdentifierToken) {
            switch ($head->getValue()) {
                case 'def':
                    return $this->parseDeclaration($tail);
                case 'lambda':
                    return $this->parseLambdaDeclaration($tail);
                case 'if':
                    return $this->parseIfExpression($tail);
                case 'or':
                    return $this->parseOrExpression($tail);
                case 'and':
                    return $this->parseAndExpression($tail);
                case 'use':
                case 'cond':
                    throw new ParserException('This keyword is reserved');
            }
        }

        return $this->parseCallExpression($tokens);
    }

    /**
     * @param array $tokens
     * @return Nodes\Node
     */
    private function parseDeclaration($tokens): Nodes\Node
    {
        list ($head, $tail) = $tokens;
<?php

function returnThreeValues() {
    return array('a', 'b', 'c');
}

list($a, $b, $c) = returnThreeValues();

print $a . " - " . $c;

        if (!is_array($head)) {
            return $this->parseAssignDeclaration($tokens);
        }

        return $this->parseFunctionDeclaration($tokens);
    }

    /**
     * @param $tokens
     * @return Nodes\Node
     * @throws ParserException
     */
    private function parseIfExpression($tokens): Nodes\Node
    {
        if (sizeof($tokens) != 3) {
            throw new ParserException("'if' requires exactly three arguments");
        }

        list ($test, $cons, $alt) = array_map([$this, 'parseToken'], $tokens);

        return new Nodes\IfExpression($test, $cons, $alt);
    }

    /**
     * @param $tokens
     * @return Nodes\Node
     * @throws ParserException
     */
    private function parseOrExpression($tokens): Nodes\Node

    {
        if (empty($tokens)) {
            throw new ParserException("'or' requires at least one argument");
        }

        $expressions = array_map([$this, 'parseToken'], $tokens);

        return new Nodes\OrExpression($expressions);
    }

    /**
     * @param $tokens
     * @return Nodes\Node
     * @throws ParserException
     */
    private function parseAndExpression($tokens): Nodes\Node

    {
        if (empty($tokens)) {
            throw new ParserException("'and' requires at least one argument");
        }

        $expressions = array_map([$this, 'parseToken'], $tokens);

        return new Nodes\AndExpression($expressions);
    }

    /**
     * @param $tokens
     * @return Nodes\Node
     * @throws ParserException
     */
    private function parseLambdaDeclaration($tokens): Nodes\Node
    {
        list ($head, $body) = toHeadTail($tokens);

        $test = all($head, function ($token) {
            return $token instanceof Tokens\IdentifierToken;
        });

        if (!$test) {
            throw new ParserException("Lambda arguments must be valid identifiers.");
        }

        $params = array_map([$this, 'parseToken'], $head);

        return new Nodes\LambdaExpression($params, $this->parseSequence($body));
    }

    /**
     * @param $tokens
     * @return Nodes\Node
     * @throws ParserException
     */
    private function parseFunctionDeclaration($tokens): Nodes\Node
    {
        list ($head, $body) = toHeadTail($tokens);

        if (sizeof($head) < 1) {
            throw new ParserException("Function must have identifier.");
        }

        $test = all($head, function ($token) {
            return $token instanceof Tokens\IdentifierToken;
        });

        if (!$test) {
            throw new ParserException("Function name and arguments must be valid identifiers.");
        }

        list ($name, $args) = toHeadTail($head);

        $params = array_map([$this, 'parseToken'], $args);

        return new Nodes\FunctionExpression($name->getValue(), $params, $this->parseSequence($body));

    }

    /**
     * @param array $tokens
     * @return Nodes\Assign
     * @throws ParserException
     */
    private function parseAssignDeclaration(array $tokens): Nodes\Assign
    {
        if (sizeof($tokens) % 2 != 0) {
            throw new ParserException("Bad assign declaration");
        }

        $assignments = array_chunk($tokens, 2);

        $result = array_map(function ($assign) {
            if (!$assign[0] instanceof Tokens\IdentifierToken) {
                throw new ParserException("Bad type of identifier in assign declaration");
            }
            return array_map([$this, 'parseToken'], $assign);
        }, $assignments);

        return new Nodes\Assign($result);
    }

    /**
     * @param array $tokens
     * @return Nodes\Node
     */
    private function parseCallExpression(array $tokens): Nodes\Node
    {
        list ($head, $tail) = toHeadTail($tokens);

        return new Nodes\CallExpression(
            $this->parseToken($head),
            array_map([$this, 'parseToken'], $tail)
        );
    }

    /**
     * @param array $tokens
     * @return Nodes\Program
     */
    private function parseProgram(array $tokens): Nodes\Program
    {
        return new Nodes\Program(array_map([$this, 'parseToken'], $tokens));
    }

    /**
     * @param array $tokens
     * @return Nodes\SequenceExpression
     */
    private function parseSequence(array $tokens): Nodes\SequenceExpression
    {
        return new Nodes\SequenceExpression(array_map([$this, 'parseToken'], $tokens));
    }

    /**
     * @param Tokens\IdentifierToken $token
     * @return Nodes\Identifier
     */
    private function parseIdentifier(Tokens\IdentifierToken $token): Nodes\Identifier
    {
        return new Nodes\Identifier($token->getValue());
    }

    /**
     * @param Tokens\DotIdentifierToken $token
     * @return Nodes\DotIdentifier
     */
    private function parseDotIdentifier(Tokens\DotIdentifierToken $token): Nodes\DotIdentifier
    {
        return new Nodes\DotIdentifier($token->getValue());
    }

    /**
     * @param Tokens\StringToken $token
     * @return Nodes\Literal
     */
    private function parseString(Tokens\StringToken $token): Nodes\Literal
    {
        return new Nodes\StringNode($token->getValue());
    }

    /**
     * @param Tokens\NumericToken $token
     * @return Nodes\Literal
     */
    private function parseNumeric(Tokens\NumericToken $token): Nodes\Literal
    {
        return new Nodes\Number($token->getValue());
    }

    /**
     * Convert list of tokens into token tree.
     *
     * @param Tokens\Token[] $tokens
     * @return mixed
     */
    private function deflate(array $tokens)
    {
        $iter = tail(function ($rest, $acc) use (&$iter) {
            if (empty($rest)) {
                return $acc;
            }
            list ($head, $tail) = toHeadTail($rest);
            switch (get_class($head)) {
                case Tokens\OpenBracketToken::class:
                    $pairClosingIndex = $this->findPairClosingBracketIndex($tail);
                    $inner = array_slice($tail, 0, $pairClosingIndex);
                    $innerNode = $this->deflate($inner);
                    $newTail = array_slice($tail, $pairClosingIndex + 1);
                    return $iter($newTail, append($acc, $innerNode));
                case Tokens\CloseBracketToken::class:
                    throw new ParserException("Unpaired opening bracket found");
                default:
                    return $iter($tail, append($acc, $head));
            }
        });
        return $iter($tokens, []);
    }

    /**
     * @param array $tokens
     * @return mixed
     */
    private function findPairClosingBracketIndex(array $tokens)
    {
        $iter = tail(function ($rest, $depth, $position) use (&$iter) {
            if (empty($rest)) {
                throw new ParserException("Unpaired closing bracket found.");
            }
            list ($head, $tail) = toHeadTail($rest);
            if ($head instanceof Tokens\CloseBracketToken) {
                if ($depth == 0) {
                    return $position;
                }
                return $iter($tail, $depth - 1, $position + 1);
            }
            if ($head instanceof Tokens\OpenBracketToken) {
                return $iter($tail, $depth + 1, $position + 1);
            }
            return $iter($tail, $depth, $position + 1);
        });
        return $iter($tokens, 0, 0);
    }
}


1		<?php
2
3		namespace PeacefulBit\Slate\Parser;
4
5		use function Nerd\Common\Arrays\all;
6		use function Nerd\Common\Arrays\toHeadTail;
7		use function Nerd\Common\Arrays\append;
8
9		use function Nerd\Common\Functional\tail;
10
11		use PeacefulBit\Slate\Exceptions\ParserException;
12		use PeacefulBit\Slate\Parser\Nodes;
13		use PeacefulBit\Slate\Parser\Tokens;
14
15		class Parser
16		{
17		/**
18		* Convert tokens tree to abstract syntax tree.
19		*
20		* @param Tokens\Token[] $tokens
21		* @return Nodes\Node
22		*/
23		public function parse(array $tokens): Nodes\Node
24		{
25		$tokensTree = $this->deflate($tokens);
26
27		return $this->parseProgram($tokensTree);
28		}
29
30		/**
31		* @param $token
32		* @return Nodes\Identifier\|Nodes\Literal\|Nodes\Node
33		* @throws ParserException
34		*/
35		private function parseToken($token)
36		{
37		if (is_array($token)) {
38		return $this->parseExpression($token);
39		}
40		if ($token instanceof Tokens\StringToken) {
41		return $this->parseString($token);
42		}
43		if ($token instanceof Tokens\IdentifierToken) {
44		return $this->parseIdentifier($token);
45		}
46		if ($token instanceof Tokens\DotIdentifierToken) {
47		return $this->parseDotIdentifier($token);
		0 ignored issues – show Bug Best Practice introduced 2016-11-02 12:11 UTC by Report Bug Copy Issue Report The return type of `return $this->parseDotIdentifier($token);` (`PeacefulBit\Slate\Parser\Nodes\DotIdentifier`) is incompatible with the return type documented by `PeacefulBit\Slate\Parser\Parser::parseToken` of type `PeacefulBit\Slate\Parser\Nodes\Node`. If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design. Let’s take a look at an example: class Author { private $name; public function __construct($name) { $this->name = $name; } public function getName() { return $this->name; } } abstract class Post { public function getAuthor() { return 'Johannes'; } } class BlogPost extends Post { public function getAuthor() { return new Author('Johannes'); } } class ForumPost extends Post { /* ... */ } function my_function(Post $post) { echo strtoupper($post->getAuthor()); } Our function `my_function` expects a `Post` object, and outputs the author of the post. The base class `Post` returns a simple string and outputting a simple string will work just fine. However, the child class `BlogPost` which is a sub-type of `Post` instead decided to return an `object`, and is therefore violating the SOLID principles. If a `BlogPost` were passed to `my_function`, PHP would not complain, but ultimately fail when executing the `strtoupper` call in its body. Loading history...
48		}
49		if ($token instanceof Tokens\NumericToken) {
50		return $this->parseNumeric($token);
51		}
52		throw new ParserException("Unexpected type of token - $token.");
53		}
54
55		/**
56		* @param array $tokens
57		* @return Nodes\Node
58		* @throws ParserException
59		*/
60		private function parseExpression(array $tokens): Nodes\Node
61		{
62		if (empty($tokens)) {
63		throw new ParserException("Expression could not be empty.");
64		}
65
66		list ($head, $tail) = toHeadTail($tokens);
67
68		if ($head instanceof Tokens\IdentifierToken) {
69		switch ($head->getValue()) {
70		case 'def':
71		return $this->parseDeclaration($tail);
72		case 'lambda':
73		return $this->parseLambdaDeclaration($tail);
74		case 'if':
75		return $this->parseIfExpression($tail);
76		case 'or':
77		return $this->parseOrExpression($tail);
78		case 'and':
79		return $this->parseAndExpression($tail);
80		case 'use':
81		case 'cond':
82		throw new ParserException('This keyword is reserved');
83		}
84		}
85
86		return $this->parseCallExpression($tokens);
87		}
88
89		/**
90		* @param array $tokens
91		* @return Nodes\Node
92		*/
93		private function parseDeclaration($tokens): Nodes\Node
94		{
95		list ($head, $tail) = $tokens;
		0 ignored issues – show Unused Code introduced 2016-11-01 19:52 UTC by Report Bug Copy Issue Report The assignment to `$tail` is unused. Consider omitting it like so `list($first,,$third)`. This checks looks for assignemnts to variables using the `list(...)` function, where not all assigned variables are subsequently used. Consider the following code example. <?php function returnThreeValues() { return array('a', 'b', 'c'); } list($a, $b, $c) = returnThreeValues(); print $a . " - " . $c; Only the variables `$a` and `$c` are used. There was no need to assign `$b`. Instead, the list call could have been. list($a,, $c) = returnThreeValues(); Loading history...
96
97		if (!is_array($head)) {
98		return $this->parseAssignDeclaration($tokens);
99		}
100
101		return $this->parseFunctionDeclaration($tokens);
102		}
103
104		/**
105		* @param $tokens
106		* @return Nodes\Node
107		* @throws ParserException
108		*/
109		private function parseIfExpression($tokens): Nodes\Node
110		{
111		if (sizeof($tokens) != 3) {
112		throw new ParserException("'if' requires exactly three arguments");
113		}
114
115		list ($test, $cons, $alt) = array_map([$this, 'parseToken'], $tokens);
116
117		return new Nodes\IfExpression($test, $cons, $alt);
118		}
119
120		/**
121		* @param $tokens
122		* @return Nodes\Node
123		* @throws ParserException
124		*/
125	View Code Duplication	private function parseOrExpression($tokens): Nodes\Node
		0 ignored issues – show Duplication introduced 2016-11-01 19:52 UTC by Report Bug Copy Issue Report This method seems to be duplicated in your project. Duplicated code is one of the most pungent code smells. If you need to duplicate the same code in three or more different places, we strongly encourage you to look into extracting the code into a single class or operation. You can also find more detailed suggestions in the “Code” section of your repository. Loading history...
126		{
127		if (empty($tokens)) {
128		throw new ParserException("'or' requires at least one argument");
129		}
130
131		$expressions = array_map([$this, 'parseToken'], $tokens);
132
133		return new Nodes\OrExpression($expressions);
134		}
135
136		/**
137		* @param $tokens
138		* @return Nodes\Node
139		* @throws ParserException
140		*/
141	View Code Duplication	private function parseAndExpression($tokens): Nodes\Node
		0 ignored issues – show Duplication introduced 2016-11-01 19:52 UTC by Report Bug Copy Issue Report This method seems to be duplicated in your project. Duplicated code is one of the most pungent code smells. If you need to duplicate the same code in three or more different places, we strongly encourage you to look into extracting the code into a single class or operation. You can also find more detailed suggestions in the “Code” section of your repository. Loading history...
142		{
143		if (empty($tokens)) {
144		throw new ParserException("'and' requires at least one argument");
145		}
146
147		$expressions = array_map([$this, 'parseToken'], $tokens);
148
149		return new Nodes\AndExpression($expressions);
150		}
151
152		/**
153		* @param $tokens
154		* @return Nodes\Node
155		* @throws ParserException
156		*/
157		private function parseLambdaDeclaration($tokens): Nodes\Node
158		{
159		list ($head, $body) = toHeadTail($tokens);
160
161		$test = all($head, function ($token) {
162		return $token instanceof Tokens\IdentifierToken;
163		});
164
165		if (!$test) {
166		throw new ParserException("Lambda arguments must be valid identifiers.");
167		}
168
169		$params = array_map([$this, 'parseToken'], $head);
170
171		return new Nodes\LambdaExpression($params, $this->parseSequence($body));
172		}
173
174		/**
175		* @param $tokens
176		* @return Nodes\Node
177		* @throws ParserException
178		*/
179		private function parseFunctionDeclaration($tokens): Nodes\Node
180		{
181		list ($head, $body) = toHeadTail($tokens);
182
183		if (sizeof($head) < 1) {
184		throw new ParserException("Function must have identifier.");
185		}
186
187		$test = all($head, function ($token) {
188		return $token instanceof Tokens\IdentifierToken;
189		});
190
191		if (!$test) {
192		throw new ParserException("Function name and arguments must be valid identifiers.");
193		}
194
195		list ($name, $args) = toHeadTail($head);
196
197		$params = array_map([$this, 'parseToken'], $args);
198
199		return new Nodes\FunctionExpression($name->getValue(), $params, $this->parseSequence($body));
		0 ignored issues – show Bug introduced 2016-11-01 19:52 UTC by Report Bug Copy Issue Report The method `getValue` cannot be called on `$name` (of type `null`). Methods can only be called on objects. This check looks for methods being called on variables that have been inferred to never be objects. Loading history...
200		}
201
202		/**
203		* @param array $tokens
204		* @return Nodes\Assign
205		* @throws ParserException
206		*/
207		private function parseAssignDeclaration(array $tokens): Nodes\Assign
208		{
209		if (sizeof($tokens) % 2 != 0) {
210		throw new ParserException("Bad assign declaration");
211		}
212
213		$assignments = array_chunk($tokens, 2);
214
215		$result = array_map(function ($assign) {
216		if (!$assign[0] instanceof Tokens\IdentifierToken) {
217		throw new ParserException("Bad type of identifier in assign declaration");
218		}
219		return array_map([$this, 'parseToken'], $assign);
220		}, $assignments);
221
222		return new Nodes\Assign($result);
223		}
224
225		/**
226		* @param array $tokens
227		* @return Nodes\Node
228		*/
229		private function parseCallExpression(array $tokens): Nodes\Node
230		{
231		list ($head, $tail) = toHeadTail($tokens);
232
233		return new Nodes\CallExpression(
234		$this->parseToken($head),
235		array_map([$this, 'parseToken'], $tail)
236		);
237		}
238
239		/**
240		* @param array $tokens
241		* @return Nodes\Program
242		*/
243		private function parseProgram(array $tokens): Nodes\Program
244		{
245		return new Nodes\Program(array_map([$this, 'parseToken'], $tokens));
246		}
247
248		/**
249		* @param array $tokens
250		* @return Nodes\SequenceExpression
251		*/
252		private function parseSequence(array $tokens): Nodes\SequenceExpression
253		{
254		return new Nodes\SequenceExpression(array_map([$this, 'parseToken'], $tokens));
255		}
256
257		/**
258		* @param Tokens\IdentifierToken $token
259		* @return Nodes\Identifier
260		*/
261		private function parseIdentifier(Tokens\IdentifierToken $token): Nodes\Identifier
262		{
263		return new Nodes\Identifier($token->getValue());
264		}
265
266		/**
267		* @param Tokens\DotIdentifierToken $token
268		* @return Nodes\DotIdentifier
269		*/
270		private function parseDotIdentifier(Tokens\DotIdentifierToken $token): Nodes\DotIdentifier
271		{
272		return new Nodes\DotIdentifier($token->getValue());
273		}
274
275		/**
276		* @param Tokens\StringToken $token
277		* @return Nodes\Literal
278		*/
279		private function parseString(Tokens\StringToken $token): Nodes\Literal
280		{
281		return new Nodes\StringNode($token->getValue());
282		}
283
284		/**
285		* @param Tokens\NumericToken $token
286		* @return Nodes\Literal
287		*/
288		private function parseNumeric(Tokens\NumericToken $token): Nodes\Literal
289		{
290		return new Nodes\Number($token->getValue());
291		}
292
293		/**
294		* Convert list of tokens into token tree.
295		*
296		* @param Tokens\Token[] $tokens
297		* @return mixed
298		*/
299		private function deflate(array $tokens)
300		{
301		$iter = tail(function ($rest, $acc) use (&$iter) {
302		if (empty($rest)) {
303		return $acc;
304		}
305		list ($head, $tail) = toHeadTail($rest);
306		switch (get_class($head)) {
307		case Tokens\OpenBracketToken::class:
308		$pairClosingIndex = $this->findPairClosingBracketIndex($tail);
309		$inner = array_slice($tail, 0, $pairClosingIndex);
310		$innerNode = $this->deflate($inner);
311		$newTail = array_slice($tail, $pairClosingIndex + 1);
312		return $iter($newTail, append($acc, $innerNode));
313		case Tokens\CloseBracketToken::class:
314		throw new ParserException("Unpaired opening bracket found");
315		default:
316		return $iter($tail, append($acc, $head));
317		}
318		});
319		return $iter($tokens, []);
320		}
321
322		/**
323		* @param array $tokens
324		* @return mixed
325		*/
326		private function findPairClosingBracketIndex(array $tokens)
327		{
328		$iter = tail(function ($rest, $depth, $position) use (&$iter) {
329		if (empty($rest)) {
330		throw new ParserException("Unpaired closing bracket found.");
331		}
332		list ($head, $tail) = toHeadTail($rest);
333		if ($head instanceof Tokens\CloseBracketToken) {
334		if ($depth == 0) {
335		return $position;
336		}
337		return $iter($tail, $depth - 1, $position + 1);
338		}
339		if ($head instanceof Tokens\OpenBracketToken) {
340		return $iter($tail, $depth + 1, $position + 1);
341		}
342		return $iter($tail, $depth, $position + 1);
343		});
344		return $iter($tokens, 0, 0);
345		}
346		}
347

peacefulbit / packet-lite