Added glue option.

Author: bpolaszek

README.md

@@ -110,52 +110,52 @@ cb
 cc
 ```
 
-**Using an array as first argument**
+**Using an array as first argument, and a separator**
 
 ```php
-foreach (string_combinations(['woof', 'meow', 'roar'], 2, 3) as $combination) {
+foreach (string_combinations(['woof', 'meow', 'roar'], 2, 3, '-') as $combination) {
     echo $combination . PHP_EOL;
 }
 ```
 
 Output:
 ```
-woofwoof
-woofmeow
-woofroar
-meowwoof
-meowmeow
-meowroar
-roarwoof
-roarmeow
-roarroar
-woofwoofwoof
-woofwoofmeow
-woofwoofroar
-woofmeowwoof
-woofmeowmeow
-woofmeowroar
-woofroarwoof
-woofroarmeow
-woofroarroar
-meowwoofwoof
-meowwoofmeow
-meowwoofroar
-meowmeowwoof
-meowmeowmeow
-meowmeowroar
-meowroarwoof
-meowroarmeow
-meowroarroar
-roarwoofwoof
-roarwoofmeow
-roarwoofroar
-roarmeowwoof
-roarmeowmeow
-roarmeowroar
-roarroarwoof
-roarroarmeow
-roarroarroar
+woof-woof
+woof-meow
+woof-roar
+meow-woof
+meow-meow
+meow-roar
+roar-woof
+roar-meow
+roar-roar
+woof-woof-woof
+woof-woof-meow
+woof-woof-roar
+woof-meow-woof
+woof-meow-meow
+woof-meow-roar
+woof-roar-woof
+woof-roar-meow
+woof-roar-roar
+meow-woof-woof
+meow-woof-meow
+meow-woof-roar
+meow-meow-woof
+meow-meow-meow
+meow-meow-roar
+meow-roar-woof
+meow-roar-meow
+meow-roar-roar
+roar-woof-woof
+roar-woof-meow
+roar-woof-roar
+roar-meow-woof
+roar-meow-meow
+roar-meow-roar
+roar-roar-woof
+roar-roar-meow
+roar-roar-roar
 ```
 
 Performance considerations

src/StringCombinations.php

@@ -26,13 +26,20 @@ class StringCombinations implements \IteratorAggregate, \Countable
      */
     private $count;
 
+    /**
+     * @var string
+     */
+    private $glue;
+
     /**
      * StringCombination constructor.
      * @param mixed  $charset
      * @param int    $min
      * @param int    $max
+     * @param string $glue
+     * @throws \InvalidArgumentException
      */
-    public function __construct($charset, $min = 1, $max = null)
+    public function __construct($charset, $min = 1, $max = null, $glue = '')
     {
         if (is_string($charset) || is_integer($charset)) {
             $this->charset = preg_split('/(?<!^)(?!$)/u', $charset);
@@ -45,6 +52,7 @@ public function __construct($charset, $min = 1, $max = null)
         }
         $this->min = (int) $min;
         $this->max = is_null($max) ? count($this->charset) : (int) $max;
+        $this->glue = $glue;
     }
 
     /**
@@ -67,7 +75,7 @@ public function getIterator()
     {
         foreach ($this->generateSets() as $set) {
             foreach (cartesian_product($set) as $combination) {
-                yield implode('', $combination);
+                yield implode($this->glue, $combination);
             }
         }
     }

src/function.php

@@ -10,7 +10,7 @@
  * @param int|null $max
  * @return StringCombinations
  */
-function string_combinations($charset, $min = 1, $max = null)
+function string_combinations($charset, $min = 1, $max = null, $glue = '')
 {
-    return new StringCombinations($charset, $min, $max);
+    return new StringCombinations($charset, $min, $max, $glue);
 }

tests/TestStringCombinations.php

@@ -133,18 +133,18 @@ public function testWithMinAndMaxValue()
 
     public function testWithArrayCharset()
     {
-        $sc = string_combinations(['a1', 'b2', 'c3'], 2, 2);
+        $sc = string_combinations(['a1', 'b2', 'c3'], 2, 2, '-');
         $expectedCount = 9; // (3^2)
         $expectedResult = [
-            'a1a1',
-            'a1b2',
-            'a1c3',
-            'b2a1',
-            'b2b2',
-            'b2c3',
-            'c3a1',
-            'c3b2',
-            'c3c3',
+            'a1-a1',
+            'a1-b2',
+            'a1-c3',
+            'b2-a1',
+            'b2-b2',
+            'b2-c3',
+            'c3-a1',
+            'c3-b2',
+            'c3-c3',
         ];
         $this->assertCount($expectedCount, $sc);
         $result = $sc->asArray();