Add `intersect()` and `intersectKeys()`.

src/collections_me.c

@@ -160,6 +160,8 @@ const zend_function_entry collection_methods[] = {
     PHP_ME(Collection, indexOfLast, predicate_arginfo, ZEND_ACC_PUBLIC)
     PHP_ME(Collection, init, elements_arginfo, ZEND_ACC_PUBLIC | ZEND_ACC_STATIC)
     PHP_ME(Collection, intersect, other_arginfo, ZEND_ACC_PUBLIC)
+    PHP_ME(Collection, intersectKeys, other_arginfo, ZEND_ACC_PUBLIC)
+    PHP_ME(Collection, intersectValues, other_arginfo, ZEND_ACC_PUBLIC)
     PHP_ME(Collection, isEmpty, NULL, ZEND_ACC_PUBLIC)
     PHP_ME(Collection, isNotEmpty, NULL, ZEND_ACC_PUBLIC)
     PHP_ME(Collection, keys, NULL, ZEND_ACC_PUBLIC)

src/collections_methods.c

@@ -1781,7 +1781,74 @@ PHP_METHOD(Collection, init)
 
 PHP_METHOD(Collection, intersect)
 {
-    
+    zval* elements;
+    ZEND_PARSE_PARAMETERS_START(1, 1)
+        Z_PARAM_ZVAL(elements)
+    ZEND_PARSE_PARAMETERS_END();
+    ELEMENTS_VALIDATE(elements, ERR_BAD_ARGUMENT_TYPE, return);
+    zend_array* current = COLLECTION_FETCH_CURRENT();
+    ARRAY_NEW(intersected, 8);
+    equal_check_func_t eql = NULL;
+    ZEND_HASH_FOREACH_BUCKET(elements_arr, Bucket* bucket)
+        if (UNEXPECTED(eql == NULL))
+        {
+            eql = equal_check_func_init(&bucket->val);
+        }
+        if (bucket->key)
+        {
+            zval* result = zend_hash_find(current, bucket->key);
+            if (result && eql(&bucket->val, result))
+            {
+                zend_hash_add(intersected, bucket->key, result);
+                Z_TRY_ADDREF_P(result);
+            }
+        }
+        else
+        {
+            zval* result = zend_hash_index_find(current, bucket->h);
+            if (result && eql(&bucket->val, result))
+            {
+                zend_hash_index_add(intersected, bucket->h, result);
+                Z_TRY_ADDREF_P(result);
+            }
+        }
+    ZEND_HASH_FOREACH_END();
+    RETVAL_NEW_COLLECTION(intersected);
+}
+
+PHP_METHOD(Collection, intersectKeys)
+{
+    zval* elements;
+    ZEND_PARSE_PARAMETERS_START(1, 1)
+        Z_PARAM_ZVAL(elements)
+    ZEND_PARSE_PARAMETERS_END();
+    ELEMENTS_VALIDATE(elements, ERR_BAD_ARGUMENT_TYPE, return);
+    zend_array* current = COLLECTION_FETCH_CURRENT();
+    ARRAY_NEW(intersected, 8);
+    ZEND_HASH_FOREACH_BUCKET(current, Bucket* bucket)
+        if (bucket->key)
+        {
+            if (zend_hash_exists(elements_arr, bucket->key))
+            {
+                zend_hash_add(intersected, bucket->key, &bucket->val);
+                Z_TRY_ADDREF(bucket->val);
+            }
+        }
+        else
+        {
+            if (zend_hash_index_exists(elements_arr, bucket->h))
+            {
+                zend_hash_index_add(intersected, bucket->h, &bucket->val);
+                Z_TRY_ADDREF(bucket->val);
+            }
+        }
+    ZEND_HASH_FOREACH_END();
+    RETVAL_NEW_COLLECTION(intersected);
+}
+
+PHP_METHOD(Collection, intersectValues)
+{
+
 }
 
 PHP_METHOD(Collection, isEmpty)

src/php_collections_me.h

@@ -48,6 +48,8 @@ PHP_METHOD(Collection, indexOfFirst);
 PHP_METHOD(Collection, indexOfLast);
 PHP_METHOD(Collection, init);
 PHP_METHOD(Collection, intersect);
+PHP_METHOD(Collection, intersectKeys);
+PHP_METHOD(Collection, intersectValues);
 PHP_METHOD(Collection, isEmpty);
 PHP_METHOD(Collection, isNotEmpty);
 PHP_METHOD(Collection, keys);

stubs/Collection.php

@@ -373,13 +373,34 @@ class Collection implements ArrayAccess, Countable
     static function init($elements) {}
 
     /**
-     * Returns a collection containing all elements that are contained by both this collection and the
-     * specified collection.
+     * Returns a collection containing all key-value pairs that are contained by both this collection
+     * and the specified collection.
      *
      * @param array|Collection $other
+     * @return Collection
      */
     function intersect($other) {}
 
+    /**
+     * Returns a collection containing all elements with keys contained by both this collection
+     * and the specified collection. Values are that of the original collection.
+     *
+     * @param array|Collection $other
+     * @return Collection
+     */
+    function intersectKeys($other) {}
+
+    /**
+     * Returns a collection containing all elements with values contained by both this collection
+     * and the specified collection. Keys are that of the original collection.
+     * 
+     * Duplicate values will be removed.
+     *
+     * @param array|Collection $other
+     * @return Collection
+     */
+    function intersectValues($other) {}
+
     /**
      * Returns true if the collection is empty.
      *
@@ -389,6 +410,8 @@ class Collection implements ArrayAccess, Countable
 
     /**
      * Returns true if the collection is not empty.
+     * 
+     * @return bool
      */
     function isNotEmpty() {}
 

tests/051-intersect-keys.phpt

@@ -0,0 +1,27 @@
+--TEST--
+Test Collection::intersect() and Collection::intersectKeys().
+--FILE--
+<?php
+$array = [
+    'a' => 'b',
+    'c' => 'd',
+    'e' => 'f'
+];
+$array1 = [
+    'a' => 'c',
+    'b' => strval(12),
+    'c' => 'd',
+    'g' => 'h'
+];
+$collection = Collection::init($array);
+$intersected = array_intersect_assoc($array, $array1);
+if ($collection->intersect($array1)->toArray() != $intersected) {
+    echo 'Collection::intersect() failed.', PHP_EOL;
+}
+$collection1 = Collection::init($array1);
+$intersected = array_intersect_key($array, $array1);
+if ($collection->intersectKeys($collection1)->toArray() != $intersected) {
+    echo 'Collection::intersectKeys() failed.', PHP_EOL;
+}
+?>
+--EXPECT--