Added \nspl\f\throttled higher order function

ihor · Jun 26, 2018 · 3c4eb5c · 3c4eb5c
1 parent 10631fb
commit 3c4eb5c
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diff --git a/README.md b/README.md
@@ -102,6 +102,7 @@ $pairs = a\zip([1, 2, 3], ['a', 'b', 'c']);
     * [curried](#curriedfunction-withoptionalargs--false)
     * [uncurried](#uncurriedfunction)
     * [memoized](#memoizedfunction)
+    * [throttled](#throttledfunction-wait))
     * [Callbacks](#callbacks)
 * [nspl\op](#nsplop)
     * [Callbacks](#callbacks-1)
@@ -288,6 +289,28 @@ Hello world!
 Hello world!
 ```
 
+##### throttled($function, $wait)
+
+Returns throttled version of the passed function, that, when invoked repeatedly, will only actually call the original function at most once per every wait milliseconds.
+```php
+$f = function() {
+    echo "Invoked\n";
+};
+
+$throttled = throttled($f, 10);
+
+$startedAt = microtime(true);
+do {
+    $throttled();
+} while((microtime(true) - $startedAt) * 1000 < 30); // 30ms
+```
+which outputs
+```
+Invoked
+Invoked
+Invoked
+```
+
 ##### Callbacks
 
 ```nspl\f``` provides all these functions as callbacks in its constants which have the same names as the functions.

diff --git a/index.md b/index.md
@@ -102,6 +102,7 @@ $pairs = a\zip([1, 2, 3], ['a', 'b', 'c']);
     * [curried](#curriedfunction-withoptionalargs--false)
     * [uncurried](#uncurriedfunction)
     * [memoized](#memoizedfunction)
+    * [throttled](#throttledfunction-wait))
     * [Callbacks](#callbacks)
 * [nspl\op](#nsplop)
     * [Callbacks](#callbacks-1)
@@ -288,6 +289,28 @@ Hello world!
 Hello world!
 ```
 
+##### throttled($function, $wait)
+
+Returns throttled version of the passed function, that, when invoked repeatedly, will only actually call the original function at most once per every wait milliseconds.
+```php
+$f = function() {
+    echo "Invoked\n";
+};
+
+$throttled = throttled($f, 10);
+
+$startedAt = microtime(true);
+do {
+    $throttled();
+} while((microtime(true) - $startedAt) * 1000 < 30); // 30ms
+```
+which outputs
+```
+Invoked
+Invoked
+Invoked
+```
+
 ##### Callbacks
 
 ```nspl\f``` provides all these functions as callbacks in its constants which have the same names as the functions.

diff --git a/nspl/f.php b/nspl/f.php
@@ -238,6 +238,27 @@ function memoized(callable $function)
 }
 const memoized = '\nspl\f\memoized';
 
+/**
+ * Returns throttled version of the passed function, that, when invoked repeatedly, will only
+ * actually call the original function at most once per every wait milliseconds.
+ *
+ * @param callable $function
+ * @param int $wait
+ * @return callable
+ */
+function throttled(callable $function, $wait)
+{
+    return function () use ($function, $wait) {
+        static $invokedAt = 0;
+        $now = microtime(true);
+        if ($now - $invokedAt >= $wait / 1000) {
+            $invokedAt = $now;
+            $function();
+        }
+    };
+}
+const throttled = '\nspl\f\throttled';
+
 //region deprecated
 /**
  * @deprecated

diff --git a/tests/NsplTest/FTest.php b/tests/NsplTest/FTest.php
@@ -14,6 +14,7 @@
 use function \nspl\f\I;
 use function \nspl\f\curried;
 use function \nspl\f\uncurried;
+use function \nspl\f\throttled;
 
 use const \nspl\f\apply;
 use const \nspl\f\flipped;
@@ -26,6 +27,7 @@
 use const \nspl\f\pipe;
 use const \nspl\f\curried;
 use const \nspl\f\uncurried;
+use const \nspl\f\throttled;
 
 //region deprecated
 use function \nspl\f\map;
@@ -261,6 +263,8 @@ public function testCurried()
         $f2 = $f1('b');
         $f3 = $f2('c');
         $this->assertEquals('abcd', $f3('d'));
+
+        $this->assertEquals('\nspl\f\curried', curried);
     }
 
     public function testUncurried()
@@ -269,6 +273,28 @@ public function testUncurried()
         $strReplace = uncurried($curriedStrReplace);
 
         $this->assertEquals('Hello world!', $strReplace('_', ' ', 'Hello_world!'));
+
+        $this->assertEquals('\nspl\f\uncurried', uncurried);
+    }
+
+    public function testThrottled()
+    {
+        $counter = 0;
+
+        $count = function() use (&$counter) {
+            ++$counter;
+        };
+
+        $throttled = throttled($count, 10);
+
+        $startedAt = microtime(true);
+        do {
+            $throttled();
+        } while((microtime(true) - $startedAt) * 1000 < 100); // 100ms
+
+        $this->assertEquals(10, $counter);
+
+        $this->assertEquals('\nspl\f\throttled', throttled);
     }
 
     //region deprecated