functions.php ➔ _curried_function() - Code Metrics - Inspection of "own curry started" - tarsana/functional - Measure and Improve Code Quality continuously with Scrutinizer

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by Amine

created 2016-11-14 15:03 UTC

functions.php ➔ _curried_function() A

↳ Parent: Project

Complexity

Conditions	2
Paths	1

Size

Total Lines	8
Code Lines	6

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	2
eloc	6
nc	1
nop	3
dl	0
loc	8
rs	9.4285
c	0
b	0
f	0

<?php namespace Tarsana\Functional;
/**
 * This file contains functions dealing with functions.
 */

use Tarsana\Functional\Exceptions\InvalidArgument;

/**
 * Gets the number of arguments of a function.
 *
 * @internal
 * @signature (* -> *) -> Number
 * @param  callable $fn
 * @return int
 */
function _number_of_args($fn) {
    $reflector = is_array($fn) ?
        new \ReflectionMethod($fn[0], $fn[1]) :
        new \ReflectionFunction($fn);
    return $reflector->getNumberOfParameters();
}

/**
 * Checks if `$a` is am argument placeholder.
 *
 * @internal
 * @signature * -> Boolean
 * @param  mixed  $a
 * @return boolean
 */
function _is_placeholder($a) {
    return $a instanceof Placeholder;
}

/**
 * Adds new given arguments to the list of bound arguments while filling placeholders.
 *
 * @internal
 * @signature Number -> [a] -> [a] -> [a]
 * @param  int   $fnArgsCount
 * @param  array $boundArgs
 * @param  array $givenArgs
 * @return array
 */
function _merge_args($fnArgsCount, $boundArgs, $givenArgs) {
    $allArgs = array_merge($boundArgs, $givenArgs);
    $args = array_slice($allArgs, 0, $fnArgsCount);
    $boundArgsCount = count($boundArgs);
    $givenArgsCount = count($givenArgs);
    $allArgsCount = $boundArgsCount + $givenArgsCount;
    $placeholdersCount = count(array_filter($args, 'Tarsana\Functional\_is_placeholder'));
    if ($placeholdersCount > 0) {
        if ($allArgsCount > $fnArgsCount) {
            $rest = array_slice($args, $fnArgsCount - $allArgsCount);
            $i = 0; // index in $args
            $k = 0; // index in rest
            $restCount = $allArgsCount - $fnArgsCount;
            while($placeholdersCount > 0 && $k < $restCount) {
                $arg = $rest[$k];
                while(! _is_placeholder($args[$i]))
                    $i++;
                if (! _is_placeholder($arg)) {
                    $args[$i] = $arg;
                    $placeholdersCount --;
                }
                $i ++;
                $k ++;
            }
            if ($k < $restCount) {
                $rest = array_slice($rest, $k);
                $cleanedRest = array_filter($rest, function($a) { return !_is_placeholder($a); });
                $args = array_merge($args, $cleanedRest);
            }
        }
    }
    $count = count($args) - count(array_filter($args, 'Tarsana\Functional\_is_placeholder'));
    return [
        'count' => $count,
        'args' => $args
    ];
}

/**
 * Returns the curried version of a function with some arguments bound to it.
 *
 * @internal
 * @signature (* -> *) -> Number -> [*] -> (* -> *)
 * @param  callable $fn
 * @param  int $argsCount
 * @param  array  $boundArgs
 * @return callable
 */
function _curried_function($fn, $argsCount, $boundArgs = []) {
    return function() use($fn, $argsCount, $boundArgs) {
        $merged = _merge_args($argsCount, $boundArgs, func_get_args());
        if ($merged['count'] >= $argsCount)
            return call_user_func_array($fn, $merged['args']);
        return _curried_function($fn, $argsCount, $merged['args']);
    };
}

/**
 * Returns a curried equivalent of the provided function.
 * ```php
 * $add = curry(function($x, $y){
 *     return $x + $y;
 * });
 * $addFive = $add(5); // a function
 * $addFive(5); // 10
 * $add(5, 5) // 10
 * ```
 *
 * @signature (* -> a) -> (* -> a)
 * @param  callable $fn
 * @return callable
 */
function curry($fn) {
    return _curried_function($fn, _number_of_args($fn));
}

/**
 * Argument placeholder to use with curried functions.
 * ```php
 * $minus = curry(function ($x, $y) { return $x - $y; });
 * $decrement = $minus(__(), 1);
 * $decrement(10) // 9
 *
 * $reduce = curry('array_reduce');
 * $sum = $reduce(__(), 'Tarsana\Functional\plus');
 * $sum([1, 2, 3, 4], 0) // 10
 * ```
 *
 * @signature * -> Placeholder
 * @return \Cypress\Curry\Placeholder
 */
function __() {
    return Placeholder::get();
}

/**
 * Non curried version of apply for internal use.
 *
 * @internal
 * @param  callable $fn
 * @param  array    $args
 * @return mixed
 */
function _apply($fn, $args) {
    return call_user_func_array($fn, $args);
}

/**
 * Apply the provided function to the list of arguments.
 * ```php
 * apply('strlen', ['Hello']) // 5
 * $replace = apply('str_replace');
 * $replace(['l', 'o', 'Hello']) // 'Heooo'
 * ```
 *
 * @signature (*... -> a) -> [*] -> a
 * @param  callable $fn
/**
 * @param array $germany
 * @param array $island
 * @param array $italy
 */
function finale($germany, $island) {
    return "2:1";
}
 * @param  array    $args
/**
 * @param array $germany
 * @param array $island
 * @param array $italy
 */
function finale($germany, $island) {
    return "2:1";
}
 * @return mixed
 */
function apply() {
    return _apply(curry('Tarsana\Functional\_apply'), func_get_args());
}

/**
 * Performs left-to-right function composition.
 * The leftmost function may have any arity;
 * the remaining functions must be unary.
 * The result of pipe is curried.
 * **Calling pipe() without any argument throws Tarsana\Functional\Exceptions\InvalidArgument**
 * ```php
 * function add($x, $y) { return $x + $y; }
 * $double = function($x) { return 2 * $x; };
 * $addThenDouble = pipe('add', $double);
 * $addThenDouble(2, 3) // 10
 * ```
 *
 * @signature (((a, b, ...) -> o), (o -> p), ..., (y -> z)) -> ((a, b, ...) -> z)
 * @param  callable ...$fns
 * @return callable
 */
function pipe() {
    $fns = func_get_args();
    if(count($fns) < 1)
        throw new InvalidArgument("pipe() requires at least one argument");
    return curry(function () use ($fns) {
        $result = _apply(array_shift($fns), func_get_args());
        foreach ($fns as $fn) {
            $result = $fn($result);
        }
        return $result;
    });
}

/**
 * A function that takes one argument and
 * returns exactly the given argument.
 * ```php
 * identity('Hello') // 'Hello'
 * identity([1, 2, 3]) // [1, 2, 3]
 * identity(null) // null
 * ```
 *
 * @signature * -> *
 * @return mixed
 */
function identity() {
    return apply(curry(function($value) {
        return $value;
    }), func_get_args());
}


1			<?php namespace Tarsana\Functional;
2			/**
3			* This file contains functions dealing with functions.
4			*/
5
6			use Tarsana\Functional\Exceptions\InvalidArgument;
7
8			/**
9			* Gets the number of arguments of a function.
10			*
11			* @internal
12			* @signature (* -> *) -> Number
13			* @param callable $fn
14			* @return int
15			*/
16			function _number_of_args($fn) {
17			$reflector = is_array($fn) ?
18			new \ReflectionMethod($fn[0], $fn[1]) :
19			new \ReflectionFunction($fn);
20			return $reflector->getNumberOfParameters();
21			}
22
23			/**
24			* Checks if `$a` is am argument placeholder.
25			*
26			* @internal
27			* @signature * -> Boolean
28			* @param mixed $a
29			* @return boolean
30			*/
31			function _is_placeholder($a) {
32			return $a instanceof Placeholder;
33			}
34
35			/**
36			* Adds new given arguments to the list of bound arguments while filling placeholders.
37			*
38			* @internal
39			* @signature Number -> [a] -> [a] -> [a]
40			* @param int $fnArgsCount
41			* @param array $boundArgs
42			* @param array $givenArgs
43			* @return array
44			*/
45			function _merge_args($fnArgsCount, $boundArgs, $givenArgs) {
46			$allArgs = array_merge($boundArgs, $givenArgs);
47			$args = array_slice($allArgs, 0, $fnArgsCount);
48			$boundArgsCount = count($boundArgs);
49			$givenArgsCount = count($givenArgs);
50			$allArgsCount = $boundArgsCount + $givenArgsCount;
51			$placeholdersCount = count(array_filter($args, 'Tarsana\Functional\_is_placeholder'));
52			if ($placeholdersCount > 0) {
53			if ($allArgsCount > $fnArgsCount) {
54			$rest = array_slice($args, $fnArgsCount - $allArgsCount);
55			$i = 0; // index in $args
56			$k = 0; // index in rest
57			$restCount = $allArgsCount - $fnArgsCount;
58			while($placeholdersCount > 0 && $k < $restCount) {
59			$arg = $rest[$k];
60			while(! _is_placeholder($args[$i]))
61			$i++;
62			if (! _is_placeholder($arg)) {
63			$args[$i] = $arg;
64			$placeholdersCount --;
65			}
66			$i ++;
67			$k ++;
68			}
69			if ($k < $restCount) {
70			$rest = array_slice($rest, $k);
71			$cleanedRest = array_filter($rest, function($a) { return !_is_placeholder($a); });
72			$args = array_merge($args, $cleanedRest);
73			}
74			}
75			}
76			$count = count($args) - count(array_filter($args, 'Tarsana\Functional\_is_placeholder'));
77			return [
78			'count' => $count,
79			'args' => $args
80			];
81			}
82
83			/**
84			* Returns the curried version of a function with some arguments bound to it.
85			*
86			* @internal
87			* @signature (* -> ) -> Number -> [] -> (* -> *)
88			* @param callable $fn
89			* @param int $argsCount
90			* @param array $boundArgs
91			* @return callable
92			*/
93			function _curried_function($fn, $argsCount, $boundArgs = []) {
94			return function() use($fn, $argsCount, $boundArgs) {
95			$merged = _merge_args($argsCount, $boundArgs, func_get_args());
96			if ($merged['count'] >= $argsCount)
97			return call_user_func_array($fn, $merged['args']);
98			return _curried_function($fn, $argsCount, $merged['args']);
99			};
100			}
101
102			/**
103			* Returns a curried equivalent of the provided function.
104			* ```php
105			* $add = curry(function($x, $y){
106			* return $x + $y;
107			* });
108			* $addFive = $add(5); // a function
109			* $addFive(5); // 10
110			* $add(5, 5) // 10
111			* ```
112			*
113			* @signature (* -> a) -> (* -> a)
114			* @param callable $fn
115			* @return callable
116			*/
117			function curry($fn) {
118			return _curried_function($fn, _number_of_args($fn));
119			}
120
121			/**
122			* Argument placeholder to use with curried functions.
123			* ```php
124			* $minus = curry(function ($x, $y) { return $x - $y; });
125			* $decrement = $minus(__(), 1);
126			* $decrement(10) // 9
127			*
128			* $reduce = curry('array_reduce');
129			* $sum = $reduce(__(), 'Tarsana\Functional\plus');
130			* $sum([1, 2, 3, 4], 0) // 10
131			* ```
132			*
133			* @signature * -> Placeholder
134			* @return \Cypress\Curry\Placeholder
135			*/
136			function __() {
137			return Placeholder::get();
138			}
139
140			/**
141			* Non curried version of apply for internal use.
142			*
143			* @internal
144			* @param callable $fn
145			* @param array $args
146			* @return mixed
147			*/
148			function _apply($fn, $args) {
149			return call_user_func_array($fn, $args);
150			}
151
152			/**
153			* Apply the provided function to the list of arguments.
154			* ```php
155			* apply('strlen', ['Hello']) // 5
156			* $replace = apply('str_replace');
157			* $replace(['l', 'o', 'Hello']) // 'Heooo'
158			* ```
159			*
160			* @signature (... -> a) -> [] -> a
161			* @param callable $fn
			0 ignored issues – show Bug introduced 2016-08-15 21:58 UTC by Report Bug Copy Issue Report There is no parameter named `$fn`. Was it maybe removed? This check looks for PHPDoc comments describing methods or function parameters that do not exist on the corresponding method or function. Consider the following example. The parameter `$italy` is not defined by the method `finale(...)`. /** * @param array $germany * @param array $island * @param array $italy */ function finale($germany, $island) { return "2:1"; } The most likely cause is that the parameter was removed, but the annotation was not. Loading history...
162			* @param array $args
			0 ignored issues – show Bug introduced 2016-08-15 21:58 UTC by Report Bug Copy Issue Report There is no parameter named `$args`. Was it maybe removed? This check looks for PHPDoc comments describing methods or function parameters that do not exist on the corresponding method or function. Consider the following example. The parameter `$italy` is not defined by the method `finale(...)`. /** * @param array $germany * @param array $island * @param array $italy */ function finale($germany, $island) { return "2:1"; } The most likely cause is that the parameter was removed, but the annotation was not. Loading history...
163			* @return mixed
164			*/
165			function apply() {
166			return _apply(curry('Tarsana\Functional\_apply'), func_get_args());
167			}
168
169			/**
170			* Performs left-to-right function composition.
171			* The leftmost function may have any arity;
172			* the remaining functions must be unary.
173			* The result of pipe is curried.
174			* Calling pipe() without any argument throws Tarsana\Functional\Exceptions\InvalidArgument
175			* ```php
176			* function add($x, $y) { return $x + $y; }
177			* $double = function($x) { return 2 * $x; };
178			* $addThenDouble = pipe('add', $double);
179			* $addThenDouble(2, 3) // 10
180			* ```
181			*
182			* @signature (((a, b, ...) -> o), (o -> p), ..., (y -> z)) -> ((a, b, ...) -> z)
183			* @param callable ...$fns
184			* @return callable
185			*/
186			function pipe() {
187			$fns = func_get_args();
188			if(count($fns) < 1)
189			throw new InvalidArgument("pipe() requires at least one argument");
190			return curry(function () use ($fns) {
191			$result = _apply(array_shift($fns), func_get_args());
192			foreach ($fns as $fn) {
193			$result = $fn($result);
194			}
195			return $result;
196			});
197			}
198
199			/**
200			* A function that takes one argument and
201			* returns exactly the given argument.
202			* ```php
203			* identity('Hello') // 'Hello'
204			* identity([1, 2, 3]) // [1, 2, 3]
205			* identity(null) // null
206			* ```
207			*
208			* @signature * -> *
209			* @return mixed
210			*/
211			function identity() {
212			return apply(curry(function($value) {
213			return $value;
214			}), func_get_args());
215			}
216

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functions.php ➔ _curried_function() A

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