|
1
|
|
|
<?php namespace Tarsana\Functional; |
|
2
|
|
|
|
|
3
|
|
|
/** |
|
4
|
|
|
* Functions dealing with functions. |
|
5
|
|
|
* @file |
|
6
|
|
|
*/ |
|
7
|
|
|
|
|
8
|
|
|
/** |
|
9
|
|
|
* Returns a curried equivalent of the provided function. |
|
10
|
|
|
* |
|
11
|
|
|
* ```php |
|
12
|
|
|
* $add = F\curry(function($x, $y) { |
|
13
|
|
|
* return $x + $y; |
|
14
|
|
|
* }); |
|
15
|
|
|
* |
|
16
|
|
|
* $add(1, 2); //=> 3 |
|
17
|
|
|
* $addFive = $add(5); // this is a function |
|
18
|
|
|
* $addFive(1); //=> 6 |
|
19
|
|
|
* |
|
20
|
|
|
* $data = [1, 2, 3, 4, 5]; |
|
21
|
|
|
* $slice = F\curry('array_slice'); |
|
22
|
|
|
* $itemsFrom = $slice($data); |
|
23
|
|
|
* $itemsFrom(2); //=> [3, 4, 5] |
|
24
|
|
|
* $itemsFrom(1, 2); //=> [2, 3, 4, 5] |
|
25
|
|
|
* // Notice that optional arguments are ignored ! |
|
26
|
|
|
* |
|
27
|
|
|
* $polynomial = F\curry(function($a, $b, $c, $x) { |
|
28
|
|
|
* return $a * $x * $x + $b * $x + $c; |
|
29
|
|
|
* }); |
|
30
|
|
|
* $f = $polynomial(0, 2, 1); // 2 * $x + 1 |
|
31
|
|
|
* $f(5); //=> 11 |
|
32
|
|
|
* ``` |
|
33
|
|
|
* |
|
34
|
|
|
* @signature (* -> a) -> (* -> a) |
|
35
|
|
|
* @param callable $fn |
|
36
|
|
|
* @return callable |
|
37
|
|
|
*/ |
|
38
|
|
|
function curry($fn) { |
|
39
|
|
|
$n = _number_of_args($fn); |
|
40
|
|
|
switch($n) { |
|
41
|
|
|
case 0: return $fn; |
|
|
|
|
|
|
42
|
|
|
case 1: return _curry_one($fn); |
|
|
|
|
|
|
43
|
|
|
case 2: return _curry_two($fn); |
|
|
|
|
|
|
44
|
|
|
case 3: return _curry_three($fn); |
|
|
|
|
|
|
45
|
|
|
} |
|
46
|
|
|
return _curry_n($fn, $n); |
|
47
|
|
|
} |
|
48
|
|
|
|
|
49
|
|
|
/** |
|
50
|
|
|
* Argument placeholder to use with curried functions. |
|
51
|
|
|
* |
|
52
|
|
|
* ```php |
|
53
|
|
|
* $reduce = F\curry('array_reduce'); |
|
54
|
|
|
* $sum = $reduce(F\__(), F\plus()); |
|
55
|
|
|
* $sum([1, 2, 3, 4], 0); //=> 10 |
|
56
|
|
|
* |
|
57
|
|
|
* $polynomial = F\curry(function($a, $b, $c, $x) { |
|
58
|
|
|
* return $a * $x * $x + $b * $x + $c; |
|
59
|
|
|
* }); |
|
60
|
|
|
* |
|
61
|
|
|
* $multiplier = $polynomial(0, F\__(), 0, F\__()); |
|
62
|
|
|
* $triple = $multiplier(3); |
|
63
|
|
|
* $triple(5); //=> 15 |
|
64
|
|
|
* $multipleOfThree = $multiplier(F\__(), 3); |
|
65
|
|
|
* $multipleOfThree(4); //=> 12 |
|
66
|
|
|
* ``` |
|
67
|
|
|
* |
|
68
|
|
|
* @signature * -> Placeholder |
|
69
|
|
|
* @return Tarsana\Functional\Placeholder |
|
70
|
|
|
*/ |
|
71
|
|
|
function __() { |
|
72
|
|
|
return Placeholder::get(); |
|
73
|
|
|
} |
|
74
|
|
|
|
|
75
|
|
|
/** |
|
76
|
|
|
* Apply the provided function to the list of arguments. |
|
77
|
|
|
* |
|
78
|
|
|
* ```php |
|
79
|
|
|
* F\apply('strlen', ['Hello']); //=> 5 |
|
80
|
|
|
* $replace = F\apply('str_replace'); |
|
81
|
|
|
* $replace(['l', 'o', 'Hello']); //=> 'Heooo' |
|
82
|
|
|
* ``` |
|
83
|
|
|
* |
|
84
|
|
|
* @signature (*... -> a) -> [*] -> a |
|
85
|
|
|
* @param callable $fn |
|
|
|
|
|
|
86
|
|
|
* @param array $args |
|
|
|
|
|
|
87
|
|
|
* @return mixed |
|
88
|
|
|
*/ |
|
89
|
|
|
function apply() { |
|
90
|
|
|
static $apply = false; |
|
91
|
|
|
$apply = $apply ?: curry(_f('_apply')); |
|
92
|
|
|
return _apply($apply, func_get_args()); |
|
93
|
|
|
} |
|
94
|
|
|
|
|
95
|
|
|
/** |
|
96
|
|
|
* Performs left-to-right function composition. |
|
97
|
|
|
* |
|
98
|
|
|
* The leftmost function may have any arity; |
|
99
|
|
|
* the remaining functions must be unary. |
|
100
|
|
|
* The result of pipe is **not curried**. |
|
101
|
|
|
* **Calling pipe() without any argument returns the `identity` function**. |
|
102
|
|
|
* |
|
103
|
|
|
* ```php |
|
104
|
|
|
* $double = function($x) { return 2 * $x; }; |
|
105
|
|
|
* $addThenDouble = F\pipe(F\plus(), $double); |
|
106
|
|
|
* $addThenDouble(2, 3); //=> 10 |
|
107
|
|
|
* ``` |
|
108
|
|
|
* |
|
109
|
|
|
* @signature (((a, b, ...) -> o), (o -> p), ..., (y -> z)) -> ((a, b, ...) -> z) |
|
110
|
|
|
* @param callable $fns... |
|
|
|
|
|
|
111
|
|
|
* @return callable |
|
112
|
|
|
*/ |
|
113
|
|
|
function pipe() { |
|
114
|
|
|
$fns = func_get_args(); |
|
115
|
|
|
if(count($fns) < 1) |
|
116
|
|
|
return identity(); |
|
117
|
|
|
return function () use ($fns) { |
|
118
|
|
|
$result = _apply(array_shift($fns), func_get_args()); |
|
119
|
|
|
foreach ($fns as $fn) { |
|
120
|
|
|
$result = $fn($result); |
|
121
|
|
|
} |
|
122
|
|
|
return $result; |
|
123
|
|
|
}; |
|
124
|
|
|
} |
|
125
|
|
|
|
|
126
|
|
|
/** |
|
127
|
|
|
* A function that takes one argument and |
|
128
|
|
|
* returns exactly the given argument. |
|
129
|
|
|
* |
|
130
|
|
|
* ```php |
|
131
|
|
|
* F\identity('Hello'); //=> 'Hello' |
|
132
|
|
|
* F\identity([1, 2, 3]); //=> [1, 2, 3] |
|
133
|
|
|
* F\identity(null); //=> null |
|
134
|
|
|
* ``` |
|
135
|
|
|
* |
|
136
|
|
|
* @signature * -> * |
|
137
|
|
|
* @return mixed |
|
138
|
|
|
*/ |
|
139
|
|
|
function identity() { |
|
140
|
|
|
static $identity = false; |
|
141
|
|
|
$identity = $identity ?: curry(function($value) { |
|
142
|
|
|
return $value; |
|
143
|
|
|
}); |
|
144
|
|
|
return _apply($identity, func_get_args()); |
|
145
|
|
|
} |
|
146
|
|
|
|
|
147
|
|
|
/** |
|
148
|
|
|
* Returns a function which whenever called will return the specified value. |
|
149
|
|
|
* |
|
150
|
|
|
* ```php |
|
151
|
|
|
* $five = F\give(5); |
|
152
|
|
|
* $five(); //=> 5 |
|
153
|
|
|
* $null = F\give(null); |
|
154
|
|
|
* $null(); //=> null |
|
155
|
|
|
* ``` |
|
156
|
|
|
* |
|
157
|
|
|
* @signature a -> (* -> a) |
|
158
|
|
|
* @param mixed $value |
|
|
|
|
|
|
159
|
|
|
* @return callable |
|
160
|
|
|
*/ |
|
161
|
|
|
function give() { |
|
162
|
|
|
static $give = false; |
|
163
|
|
|
$give = $give ?: curry(function($value) { |
|
164
|
|
|
return function() use($value) { |
|
165
|
|
|
return $value; |
|
166
|
|
|
}; |
|
167
|
|
|
}); |
|
168
|
|
|
return _apply($give, func_get_args()); |
|
169
|
|
|
} |
|
170
|
|
|
|
|
171
|
|
|
/** |
|
172
|
|
|
* Takes many predicates and returns a new predicate that |
|
173
|
|
|
* returns `true` only if all predicates are satisfied. |
|
174
|
|
|
* |
|
175
|
|
|
* If no predicate is given as argument, this function |
|
176
|
|
|
* will return an always passing predicate. |
|
177
|
|
|
* ```php |
|
178
|
|
|
* $betweenOneAndTen = F\all(F\lt(1), F\gt(10)); |
|
179
|
|
|
* $betweenOneAndTen(5); //=> true |
|
180
|
|
|
* $betweenOneAndTen(0); //=> false |
|
181
|
|
|
* $alwaysTrue = F\all(); |
|
182
|
|
|
* $alwaysTrue(1); //=> true |
|
183
|
|
|
* $alwaysTrue(null); //=> true |
|
184
|
|
|
* ``` |
|
185
|
|
|
* |
|
186
|
|
|
* @signature ((a -> Boolean), ..., (a -> Boolean)) -> (a -> Boolean) |
|
187
|
|
|
* @param callable $predicates... |
|
|
|
|
|
|
188
|
|
|
* @return callable |
|
189
|
|
|
*/ |
|
190
|
|
View Code Duplication |
function all() { |
|
|
|
|
|
|
191
|
|
|
$predicates = func_get_args(); |
|
192
|
|
|
return _curry_one(function($value) use(&$predicates) { |
|
193
|
|
|
foreach ($predicates as $predicate) { |
|
194
|
|
|
if (! $predicate($value)) |
|
195
|
|
|
return false; |
|
196
|
|
|
} |
|
197
|
|
|
return true; |
|
198
|
|
|
}); |
|
199
|
|
|
} |
|
200
|
|
|
|
|
201
|
|
|
/** |
|
202
|
|
|
* Takes many predicates and returns a new predicate that |
|
203
|
|
|
* returns `true` if any of the predicates is satisfied. |
|
204
|
|
|
* |
|
205
|
|
|
* If no predicate is given as argument, this function |
|
206
|
|
|
* will return an always non-passing predicate. |
|
207
|
|
|
* ```php |
|
208
|
|
|
* $startsOrEndsWith = function($text) { |
|
209
|
|
|
* return F\any(F\startsWith($text), F\endsWith($text)); |
|
210
|
|
|
* }; |
|
211
|
|
|
* $test = $startsOrEndsWith('b'); |
|
212
|
|
|
* $test('bar'); //=> true |
|
213
|
|
|
* $test('bob'); //=> true |
|
214
|
|
|
* $test('foo'); //=> false |
|
215
|
|
|
* $alwaysFlase = F\any(); |
|
216
|
|
|
* $alwaysFlase(1); //=> false |
|
217
|
|
|
* $alwaysFlase(null); //=> false |
|
218
|
|
|
* ``` |
|
219
|
|
|
* |
|
220
|
|
|
* @signature ((a -> Boolean), ..., (a -> Boolean)) -> (a -> Boolean) |
|
221
|
|
|
* @param callable $predicates... |
|
|
|
|
|
|
222
|
|
|
* @return callable |
|
223
|
|
|
*/ |
|
224
|
|
View Code Duplication |
function any() { |
|
|
|
|
|
|
225
|
|
|
$predicates = func_get_args(); |
|
226
|
|
|
return _curry_one(function($value) use(&$predicates) { |
|
227
|
|
|
foreach ($predicates as $predicate) { |
|
228
|
|
|
if ($predicate($value)) |
|
229
|
|
|
return true; |
|
230
|
|
|
} |
|
231
|
|
|
return false; |
|
232
|
|
|
}); |
|
233
|
|
|
} |
|
234
|
|
|
|
|
235
|
|
|
/** |
|
236
|
|
|
* Takes a function `f` and returns a function `g` so that if `f` returns |
|
237
|
|
|
* `x` for some arguments; `g` will return `! x` for the same arguments. |
|
238
|
|
|
* |
|
239
|
|
|
* Note that `complement($fn) == pipe($fn, not())`, So the resulting function is not curried !. |
|
240
|
|
|
* ```php |
|
241
|
|
|
* $isOdd = function($number) { |
|
242
|
|
|
* return 1 == $number % 2; |
|
243
|
|
|
* }; |
|
244
|
|
|
* |
|
245
|
|
|
* $isEven = F\complement($isOdd); |
|
246
|
|
|
* |
|
247
|
|
|
* $isEven(5); //=> false |
|
248
|
|
|
* $isEven(8); //=> true |
|
249
|
|
|
* ``` |
|
250
|
|
|
* |
|
251
|
|
|
* @signature (* -> ... -> *) -> (* -> ... -> Boolean) |
|
252
|
|
|
* @param callable $fn |
|
|
|
|
|
|
253
|
|
|
* @return callable |
|
254
|
|
|
*/ |
|
255
|
|
|
function complement() { |
|
256
|
|
|
static $complement = false; |
|
257
|
|
|
$complement = $complement ?: curry(function($fn) { |
|
258
|
|
|
return function() use($fn) { |
|
259
|
|
|
return !_apply($fn, func_get_args()); |
|
260
|
|
|
}; |
|
261
|
|
|
}); |
|
262
|
|
|
return _apply($complement, func_get_args()); |
|
263
|
|
|
} |
|
264
|
|
|
|
|
265
|
|
|
/** |
|
266
|
|
|
* Takes a function telling if the first argument is less then the second, and return a compare function. |
|
267
|
|
|
* |
|
268
|
|
|
* A compare function returns `-1`, `0`, or `1` if the first argument is considered |
|
269
|
|
|
* to be respectively less than, equal to, or greater than the second. |
|
270
|
|
|
* ```php |
|
271
|
|
|
* $users = [ |
|
272
|
|
|
* ['name' => 'foo', 'age' => 21], |
|
273
|
|
|
* ['name' => 'bar', 'age' => 11], |
|
274
|
|
|
* ['name' => 'baz', 'age' => 15] |
|
275
|
|
|
* ]; |
|
276
|
|
|
* |
|
277
|
|
|
* usort($users, F\comparator(function($a, $b){ |
|
278
|
|
|
* return $a['age'] < $b['age']; |
|
279
|
|
|
* })); |
|
280
|
|
|
* |
|
281
|
|
|
* F\map(F\get('name'), $users); //=> ['bar', 'baz', 'foo'] |
|
282
|
|
|
* ``` |
|
283
|
|
|
* |
|
284
|
|
|
* @signature (a -> a -> Boolean) -> (a -> a -> Number) |
|
285
|
|
|
* @param callable $fn |
|
|
|
|
|
|
286
|
|
|
* @return callable |
|
287
|
|
|
*/ |
|
288
|
|
|
function comparator() { |
|
289
|
|
|
static $comparator = false; |
|
290
|
|
|
$comparator = $comparator ?: curry(function($fn) { |
|
291
|
|
|
return function($a, $b) use($fn) { |
|
292
|
|
|
if ($fn($a, $b)) return -1; |
|
293
|
|
|
if ($fn($b, $a)) return 1; |
|
294
|
|
|
return 0; |
|
295
|
|
|
}; |
|
296
|
|
|
}); |
|
297
|
|
|
return _apply($comparator, func_get_args()); |
|
298
|
|
|
} |
|
299
|
|
|
|
According to the PSR-2, the body of a case statement must start on the line immediately following the case statement.
}
To learn more about the PSR-2 coding standard, please refer to the PHP-Fig.