functions.php ➔ _curried_function() - Code Metrics - Inspection of "adding fns and tests" - tarsana/functional - Measure and Improve Code Quality continuously with Scrutinizer

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by Amine

created 2016-11-15 22:54 UTC

functions.php ➔ _curried_function() A

↳ Parent: Project

Complexity

Conditions	2
Paths	1

Size

Total Lines	10
Code Lines	8

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	2
eloc	8
nc	1
nop	3
dl	0
loc	10
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;

/**
 * Adds the `Tarsana\Functional\` namespace to a function name.
 * This is useful to pass non-curried functions as parameter.
 *
 * @internal
 * @signature String -> Sring
 * @param  string $name
 * @return string
 */
function _f($name) {
    return "Tarsana\\Functional\\{$name}";
}

/**
 * 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->getNumberOfRequiredParameters();
}

/**
 * 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) {
    $addArgument = function($currentBoundArgs, $arg) use($fnArgsCount) {
        $currentBoundArgsCount = count($currentBoundArgs);
        $placeholderPosition = 0;
        while($placeholderPosition < $currentBoundArgsCount && !_is_placeholder($currentBoundArgs[$placeholderPosition]))
            $placeholderPosition ++;
        if ($currentBoundArgsCount < $fnArgsCount || $placeholderPosition == $currentBoundArgsCount) {
            $currentBoundArgs[] = $arg;
        } else { // There is a placeholder and number of bound args >= $fnArgsCount
            $currentBoundArgs[$placeholderPosition] = $arg;
        }
        return $currentBoundArgs;
    };

    return array_reduce($givenArgs, $addArgument, $boundArgs);
}

/**
 * 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) {
        $boundArgs = _merge_args($argsCount, $boundArgs, func_get_args());
        $numberOfPlaceholders = count(array_filter($boundArgs, _f('_is_placeholder')));
        $numberOfGivenArgs = count($boundArgs) - $numberOfPlaceholders;
        if ($numberOfGivenArgs >= $argsCount)
            return call_user_func_array($fn, $boundArgs);
        return _curried_function($fn, $argsCount, $boundArgs);
    };
}

/**
 * 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    $args
 * @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());
}

/**
 * Takes many predicates and returns a new predicate that 
 * returns `true` only if all predicates are satisfied.
 * ```php
 * 
 * ```
 */
function 



1			<?php namespace Tarsana\Functional;
			0 ignored issues – show Coding Style Compatibility introduced 2016-11-15 22:55 UTC by Report Bug Copy Issue Report For compatibility and reusability of your code, PSR1 recommends that a file should introduce either new symbols (like classes, functions, etc.) or have side-effects (like outputting something, or including other files), but not both at the same time. The first symbol is defined on line 17 and the first side effect is on line 218. The PSR-1: Basic Coding Standard recommends that a file should either introduce new symbols, that is classes, functions, constants or similar, or have side effects. Side effects are anything that executes logic, like for example printing output, changing ini settings or writing to a file. The idea behind this recommendation is that merely auto-loading a class should not change the state of an application. It also promotes a cleaner style of programming and makes your code less prone to errors, because the logic is not spread out all over the place. To learn more about the PSR-1, please see the PHP-FIG site on the PSR-1. Loading history...
2			/**
3			* This file contains functions dealing with functions.
4			*/
5
6			use Tarsana\Functional\Exceptions\InvalidArgument;
7
8			/**
9			* Adds the `Tarsana\Functional\` namespace to a function name.
10			* This is useful to pass non-curried functions as parameter.
11			*
12			* @internal
13			* @signature String -> Sring
14			* @param string $name
15			* @return string
16			*/
17			function _f($name) {
18			return "Tarsana\\Functional\\{$name}";
19			}
20
21			/**
22			* Gets the number of arguments of a function.
23			*
24			* @internal
25			* @signature (* -> *) -> Number
26			* @param callable $fn
27			* @return int
28			*/
29			function _number_of_args($fn) {
30			$reflector = is_array($fn) ?
31			new \ReflectionMethod($fn[0], $fn[1]) :
32			new \ReflectionFunction($fn);
33			return $reflector->getNumberOfRequiredParameters();
34			}
35
36			/**
37			* Checks if `$a` is am argument placeholder.
38			*
39			* @internal
40			* @signature * -> Boolean
41			* @param mixed $a
42			* @return boolean
43			*/
44			function _is_placeholder($a) {
45			return $a instanceof Placeholder;
46			}
47
48			/**
49			* Adds new given arguments to the list of bound arguments while filling placeholders.
50			*
51			* @internal
52			* @signature Number -> [a] -> [a] -> [a]
53			* @param int $fnArgsCount
54			* @param array $boundArgs
55			* @param array $givenArgs
56			* @return array
57			*/
58			function _merge_args($fnArgsCount, $boundArgs, $givenArgs) {
59			$addArgument = function($currentBoundArgs, $arg) use($fnArgsCount) {
60			$currentBoundArgsCount = count($currentBoundArgs);
61			$placeholderPosition = 0;
62			while($placeholderPosition < $currentBoundArgsCount && !_is_placeholder($currentBoundArgs[$placeholderPosition]))
63			$placeholderPosition ++;
64			if ($currentBoundArgsCount < $fnArgsCount \|\| $placeholderPosition == $currentBoundArgsCount) {
65			$currentBoundArgs[] = $arg;
66			} else { // There is a placeholder and number of bound args >= $fnArgsCount
67			$currentBoundArgs[$placeholderPosition] = $arg;
68			}
69			return $currentBoundArgs;
70			};
71
72			return array_reduce($givenArgs, $addArgument, $boundArgs);
73			}
74
75			/**
76			* Returns the curried version of a function with some arguments bound to it.
77			*
78			* @internal
79			* @signature (* -> ) -> Number -> [] -> (* -> *)
80			* @param callable $fn
81			* @param int $argsCount
82			* @param array $boundArgs
83			* @return callable
84			*/
85			function _curried_function($fn, $argsCount, $boundArgs = []) {
86			return function() use($fn, $argsCount, $boundArgs) {
87			$boundArgs = _merge_args($argsCount, $boundArgs, func_get_args());
88			$numberOfPlaceholders = count(array_filter($boundArgs, _f('_is_placeholder')));
89			$numberOfGivenArgs = count($boundArgs) - $numberOfPlaceholders;
90			if ($numberOfGivenArgs >= $argsCount)
91			return call_user_func_array($fn, $boundArgs);
92			return _curried_function($fn, $argsCount, $boundArgs);
93			};
94			}
95
96			/**
97			* Returns a curried equivalent of the provided function.
98			* ```php
99			* $add = curry(function($x, $y){
100			* return $x + $y;
101			* });
102			* $addFive = $add(5); // a function
103			* $addFive(5); // 10
104			* $add(5, 5) // 10
105			* ```
106			*
107			* @signature (* -> a) -> (* -> a)
108			* @param callable $fn
109			* @return callable
110			*/
111			function curry($fn) {
112			return _curried_function($fn, _number_of_args($fn));
113			}
114
115			/**
116			* Argument placeholder to use with curried functions.
117			* ```php
118			* $minus = curry(function ($x, $y) { return $x - $y; });
119			* $decrement = $minus(__(), 1);
120			* $decrement(10) // 9
121			*
122			* $reduce = curry('array_reduce');
123			* $sum = $reduce(__(), 'Tarsana\Functional\plus');
124			* $sum([1, 2, 3, 4], 0) // 10
125			* ```
126			*
127			* @signature * -> Placeholder
128			* @return \Cypress\Curry\Placeholder
129			*/
130			function __() {
131			return Placeholder::get();
132			}
133
134			/**
135			* Non curried version of apply for internal use.
136			*
137			* @internal
138			* @param callable $fn
139			* @param array $args
140			* @return mixed
141			*/
142			function _apply($fn, $args) {
143			return call_user_func_array($fn, $args);
144			}
145
146			/**
147			* Apply the provided function to the list of arguments.
148			* ```php
149			* apply('strlen', ['Hello']) // 5
150			* $replace = apply('str_replace');
151			* $replace(['l', 'o', 'Hello']) // 'Heooo'
152			* ```
153			*
154			* @signature (... -> a) -> [] -> a
155			* @param callable $fn
156			* @param array $args
157			* @return mixed
158			*/
159			function apply() {
160			return _apply(curry('Tarsana\Functional\_apply'), func_get_args());
161			}
162
163			/**
164			* Performs left-to-right function composition.
165			* The leftmost function may have any arity;
166			* the remaining functions must be unary.
167			* The result of pipe is curried.
168			* Calling pipe() without any argument throws Tarsana\Functional\Exceptions\InvalidArgument
169			* ```php
170			* function add($x, $y) { return $x + $y; }
171			* $double = function($x) { return 2 * $x; };
172			* $addThenDouble = pipe('add', $double);
173			* $addThenDouble(2, 3) // 10
174			* ```
175			*
176			* @signature (((a, b, ...) -> o), (o -> p), ..., (y -> z)) -> ((a, b, ...) -> z)
177			* @param callable ...$fns
178			* @return callable
179			*/
180			function pipe() {
181			$fns = func_get_args();
182			if(count($fns) < 1)
183			throw new InvalidArgument("pipe() requires at least one argument");
184			return curry(function () use ($fns) {
185			$result = _apply(array_shift($fns), func_get_args());
186			foreach ($fns as $fn) {
187			$result = $fn($result);
188			}
189			return $result;
190			});
191			}
192
193			/**
194			* A function that takes one argument and
195			* returns exactly the given argument.
196			* ```php
197			* identity('Hello') // 'Hello'
198			* identity([1, 2, 3]) // [1, 2, 3]
199			* identity(null) // null
200			* ```
201			*
202			* @signature * -> *
203			* @return mixed
204			*/
205			function identity() {
206			return apply(curry(function($value) {
207			return $value;
208			}), func_get_args());
209			}
210
211			/**
212			* Takes many predicates and returns a new predicate that
213			* returns `true` only if all predicates are satisfied.
214			* ```php
215			*
216			* ```
217			*/
218			function
219
			0 ignored issues – show Bug introduced 2016-11-15 22:55 UTC by Report Bug Copy Issue Report This code did not parse for me. Apparently, there is an error somewhere around this line: Syntax error, unexpected EOF, expecting T_STRING or '(' Loading history...

tarsana / functional

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functions.php ➔ _curried_function() A

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