diff --git a/collections.c b/collections.c
index 97f2266..2033dfd 100644
--- a/collections.c
+++ b/collections.c
@@ -25,13 +25,16 @@ PHP_MINIT_FUNCTION(collections)
 {
     collection_property_name = zend_string_init("_a", strlen("_a"), 1);
     pair_first_name = zend_string_init("first", strlen("first"), 1);
-    pair_second_name = zend_string_init("first", strlen("second"), 1);
+    pair_second_name = zend_string_init("second", strlen("second"), 1);
     zend_class_entry collection_ce;
     INIT_CLASS_ENTRY_EX(collection_ce, "Collection", strlen("Collection"), collection_methods);
     collections_collection_ce = zend_register_internal_class(&collection_ce);
+    zend_declare_property_null(collections_collection_ce, "_a", strlen("_a"), ZEND_ACC_PRIVATE);
     zend_class_entry pair_ce;
     INIT_CLASS_ENTRY_EX(pair_ce, "Pair", strlen("Pair"), pair_methods);
     collections_pair_ce = zend_register_internal_class(&pair_ce);
+    zend_declare_property_null(collections_pair_ce, "first", strlen("first"), ZEND_ACC_PUBLIC);
+    zend_declare_property_null(collections_pair_ce, "second", strlen("second"), ZEND_ACC_PUBLIC);
     return SUCCESS;
 }
 
diff --git a/collections_methods.c b/collections_methods.c
index 63f2a2e..65c4cfa 100644
--- a/collections_methods.c
+++ b/collections_methods.c
@@ -29,19 +29,72 @@
 #define PHP_COLLECTIONS_ERROR(type, msg) php_error_docref(NULL, type, msg)
 #define ERR_BAD_ARGUMENT_TYPE() PHP_COLLECTIONS_ERROR(E_WARNING, "Bad argument type")
 
-PHP_METHOD(Collection, __construct)
-{
-    
-}
+#define ELEMENTS_VALIDATE(elements) \
+    if (IS_COLLECTION(elements)) { \
+        zval rv; \
+        (elements) = COLLECTION_FETCH(elements); \
+    } else if (UNEXPECTED(Z_TYPE_P(elements) != IS_ARRAY)) { \
+        ERR_BAD_ARGUMENT_TYPE(); \
+        RETVAL_NULL(); \
+    }
+
+#define ARRAY_CLONE(dest, src) \
+    zend_array (dest); \
+    zend_hash_init(&(dest), zend_hash_num_elements(Z_ARRVAL_P(src)), NULL, ZVAL_PTR_DTOR, 0); \
+    zend_hash_copy(&(dest), Z_ARRVAL_P(src), NULL)
+
+#define RETVAL_NEW_COLLECTION(collection) \
+    do { \
+        NEW_COLLECTION_OBJ(obj); \
+        zval retval; \
+        ZVAL_OBJ(&retval, obj); \
+        zval property; \
+        ZVAL_ARR(&property, collection); \
+        COLLECTION_UPDATE(&retval, &property); \
+        RETVAL_OBJ(obj); \
+    } while (0)
+
+PHP_METHOD(Collection, __construct) {}
 
 PHP_METHOD(Collection, addAll)
 {
-    
+    zval* elements;
+    ZEND_PARSE_PARAMETERS_START(1, 1)
+        Z_PARAM_ZVAL(elements)
+    ZEND_PARSE_PARAMETERS_END();
+    ELEMENTS_VALIDATE(elements);
+    zval rv;
+    zval* current = COLLECTION_FETCH_EX();
+    ZEND_HASH_FOREACH_VAL_IND(Z_ARRVAL_P(elements), zval* val)
+        zend_hash_next_index_insert(Z_ARRVAL_P(current), val);
+    ZEND_HASH_FOREACH_END();
+    COLLECTION_UPDATE_EX(current);
 }
 
 PHP_METHOD(Collection, all)
 {
-    
+    zend_fcall_info fci;
+    zend_fcall_info_cache fcc;
+    ZEND_PARSE_PARAMETERS_START(1, 1)
+        Z_PARAM_FUNC(fci, fcc)
+    ZEND_PARSE_PARAMETERS_END();
+    zval params[3], rv, retval;
+    fci.param_count = 3;
+    fci.retval = &retval;
+    fci.params = params;
+    zval* current = COLLECTION_FETCH_EX();
+    ZEND_HASH_FOREACH_BUCKET(Z_ARRVAL_P(current), Bucket* bucket)
+        ZVAL_COPY(&params[0], &bucket->val);
+        if (bucket->key)
+            ZVAL_STR(&params[1], bucket->key);
+        else
+            ZVAL_NULL(&params[1]);
+        ZVAL_LONG(&params[2], bucket->h);
+        zend_call_function(&fci, &fcc);
+        if (Z_TYPE(retval) == IS_FALSE)
+            RETURN_FALSE;
+    ZEND_HASH_FOREACH_END();
+    RETURN_TRUE;
 }
 
 PHP_METHOD(Collection, any)
@@ -245,13 +298,7 @@ PHP_METHOD(Collection, init)
     zval retval;
     ZVAL_OBJ(&retval, obj);
     if (elements) {
-        if (IS_COLLECTION(elements)) {
-            zval rv;
-            elements = COLLECTION_FETCH(elements);
-        } else if (UNEXPECTED(Z_TYPE_P(elements) != IS_ARRAY)) {
-            ERR_BAD_ARGUMENT_TYPE();
-            RETVAL_NULL();
-        }
+        ELEMENTS_VALIDATE(elements);
         COLLECTION_UPDATE(&retval, elements);
     } else {
         zval collection;
@@ -260,7 +307,7 @@ PHP_METHOD(Collection, init)
         COLLECTION_UPDATE(&retval, &collection);
         zval_ptr_dtor(&collection);
     }
-    ZVAL_COPY_VALUE(return_value, &retval);
+    RETVAL_OBJ(obj);
 }
 
 PHP_METHOD(Collection, intersect)
diff --git a/stubs/Collection.php b/stubs/Collection.php
index 10d1bcf..d0de4b4 100644
--- a/stubs/Collection.php
+++ b/stubs/Collection.php
@@ -15,14 +15,14 @@ class Collection implements ArrayAccess, Countable
      * Adds all elements of the given elements collection to this Collection.
      *
      * @param array|Collection $elements
-     * @return bool
+     * @return void
      */
     function addAll($elements) {}
 
     /**
      * Returns true if all elements match the given predicate.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return bool
      */
     function all($predicate) {}
@@ -30,7 +30,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns true if at least one element matches the given predicate.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return bool
      */
     function any($predicate) {}
@@ -141,7 +141,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a collection containing only elements from the given array having distinct keys
      * returned by the given selector function.
      *
-     * @param callable $selector ($value, $key) -> $key
+     * @param callable $selector ($value, $key, $index) -> $key
      * @return Collection
      */
     function distinctBy($selector) {}
@@ -166,7 +166,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a collection containing all elements except last elements that satisfy
      * the given predicate.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return Collection
      */
     function dropLastWhile($predicate) {}
@@ -175,7 +175,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a collection containing all elements except first elements that satisfy
      * the given predicate.
      *
-     * @param $predicate $predicate ($value, $key) -> bool
+     * @param $predicate $predicate ($value, $key, $index) -> bool
      * @return Collection
      */
     function dropWhile($predicate) {}
@@ -193,7 +193,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns a collection containing only elements matching the given predicate.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return Collection
      */
     function filter($predicate) {}
@@ -201,7 +201,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns a collection containing only elements not matching the given predicate.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return Collection
      */
     function filterNot($predicate) {}
@@ -210,7 +210,7 @@ class Collection implements ArrayAccess, Countable
      * Appends all elements not matching the given predicate to the given destination.
      *
      * @param Collection $destination
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return Collection
      */
     function filterNotTo($destination, $predicate) {}
@@ -219,7 +219,7 @@ class Collection implements ArrayAccess, Countable
      * Appends all elements matching the given predicate to the given destination.
      *
      * @param Collection $destination
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return Collection
      */
     function filterTo($destination, $predicate) {}
@@ -228,7 +228,7 @@ class Collection implements ArrayAccess, Countable
      * Returns the first element matching the given predicate, or null if no such
      * element was found.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return mixed
      */
     function find($predicate) {}
@@ -237,7 +237,7 @@ class Collection implements ArrayAccess, Countable
      * Returns the last element matching the given predicate, or null if no such
      * element was found.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return mixed
      */
     function findLast($predicate) {}
@@ -245,7 +245,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns the first element matching the given predicate.
      *
-     * @param callable $predicate[optional] ($value, $key) -> bool
+     * @param callable $predicate[optional] ($value, $key, $index) -> bool
      * @return mixed
      */
     function first($predicate) {}
@@ -254,7 +254,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a collection of all elements yielded from results of transform function
      * being invoked on each element of original collection.
      *
-     * @param callable $transform ($value, $key) -> array|Collection
+     * @param callable $transform ($value, $key, $index) -> array|Collection
      * @return Collection
      */
     function flatMap($transform) {}
@@ -264,7 +264,7 @@ class Collection implements ArrayAccess, Countable
      * original collection, to the given destination.
      *
      * @param Collection $destination
-     * @param callable $transform ($value, $key) -> array|Collection
+     * @param callable $transform ($value, $key, $index) -> array|Collection
      * @return Collection
      */
     function flatMapTo($destination, $transform) {}
@@ -299,7 +299,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Performs the given action on each element.
      *
-     * @param callable $action ($value, $key) -> void
+     * @param callable $action ($value, $key, $index) -> void
      * @return void
      */
     function forEach($action) {}
@@ -319,7 +319,7 @@ class Collection implements ArrayAccess, Countable
      * original array by the key returned by the given key_selector function applied to the element
      * and returns a collection where each group key is associated with a list of corresponding values.
      *
-     * @param callable $key_selector ($value, $key) -> $new_key
+     * @param callable $key_selector ($value, $key, $index) -> $new_key
      * @param callable $value_transform[optional] ($value) -> $new_value
      * @return Collection
      */
@@ -331,7 +331,7 @@ class Collection implements ArrayAccess, Countable
      * puts to the destination collection each group key associated with a list of corresponding values.
      *
      * @param Collection $destination
-     * @param callable $key_selector ($value, $key) -> $new_key
+     * @param callable $key_selector ($value, $key, $index) -> $new_key
      * @param callable $value_transform[optional] ($value) -> $new_value
      * @return Collection
      */
@@ -401,7 +401,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns the last element matching the given predicate.
      *
-     * @param callable $predicate[optional] ($value, $key) -> bool
+     * @param callable $predicate[optional] ($value, $key, $index) -> bool
      * @return mixed
      */
     function last($predicate) {}
@@ -418,7 +418,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a collection containing the results of applying the given transform function
      * to each element in the original collection.
      *
-     * @param callable $transform ($value, $key) -> Pair
+     * @param callable $transform ($value, $key, $index) -> Pair
      * @return Collection
      */
     function map($transform) {}
@@ -427,7 +427,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a new collection with entries having the keys obtained by applying the transform function
      * to each keys and values of this collection.
      *
-     * @param callable $transform ($value, $key) -> $new_key
+     * @param callable $transform ($value, $key, $index) -> $new_key
      * @return Collection
      */
     function mapKeys($transform) {}
@@ -437,7 +437,7 @@ class Collection implements ArrayAccess, Countable
      * transform function to each keys and values of this collections.
      *
      * @param Collection $destination
-     * @param callable $transform ($value, $key) -> $new_key
+     * @param callable $transform ($value, $key, $index) -> $new_key
      * @return Collection
      */
     function mapKeysTo($destination, $transform) {}
@@ -447,7 +447,7 @@ class Collection implements ArrayAccess, Countable
      * results to the given destination.
      *
      * @param Collection $destination
-     * @param callable $transform ($value, $key) -> Pair
+     * @param callable $transform ($value, $key, $index) -> Pair
      * @return Collection
      */
     function mapTo($destination, $transform) {}
@@ -456,7 +456,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a new collection with entries having the keys of this collection and the values obtained
      * by applying the transform function to each entry in this collection.
      *
-     * @param callable $transform ($value, $key) -> $new_value
+     * @param callable $transform ($value, $key, $index) -> $new_value
      * @return Collection
      */
     function mapValues($transform) {}
@@ -466,7 +466,7 @@ class Collection implements ArrayAccess, Countable
      * the values obtained by applying the transform function to each entry in this collection.
      *
      * @param Collection $destination
-     * @param callable $transform ($value, $key) -> $new_value
+     * @param callable $transform ($value, $key, $index) -> $new_value
      * @return Collection
      */
     function mapValuesTo($destination, $transform) {}
@@ -482,7 +482,7 @@ class Collection implements ArrayAccess, Countable
      * Returns the first element yielding the largest value of the given function or null if
      * there are no elements.
      *
-     * @param callable $selector ($value, $key) -> $new_value
+     * @param callable $selector ($value, $key, $index) -> $new_value
      * @return mixed
      */
     function maxBy($selector) {}
@@ -507,7 +507,7 @@ class Collection implements ArrayAccess, Countable
      * Returns the first element yielding the smallest value of the given function or null if
      * there are no elements.
      *
-     * @param callable $selector ($value, $key) -> $new_value
+     * @param callable $selector ($value, $key, $index) -> $new_value
      * @return mixed
      */
     function minBy($selector) {}
@@ -576,7 +576,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns true if no elements match the given predicate.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return bool
      */
     function none($predicate) {}
@@ -604,7 +604,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Performs the given action on each element and returns the collection itself afterwards.
      *
-     * @param callable $action ($value, $key) -> void
+     * @param callable $action ($value, $key, $index) -> void
      * @return Collection
      */
     function onEach($action) {}
@@ -621,7 +621,7 @@ class Collection implements ArrayAccess, Countable
      * elements for which predicate yielded true, while second collection contains elements for
      * which predicate yielded false.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return Pair
      */
     function partition($predicate) {}
@@ -697,7 +697,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Removes all elements from this collection that match the given predicate.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return bool
      */
     function removeAll($predicate) {}
@@ -705,7 +705,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Retains only elements of this collection that match the given predicate.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return bool
      */
     function retainAll($predicate) {}
@@ -735,7 +735,7 @@ class Collection implements ArrayAccess, Countable
      * Returns the single element matching the given predicate, or null if there is no or more than
      * one matching element.
      *
-     * @param callable $predicate ($value, $key) -> bool
+     * @param callable $predicate ($value, $key, $index) -> bool
      * @return mixed
      */
     function single($predicate) {}
@@ -766,7 +766,7 @@ class Collection implements ArrayAccess, Countable
      * Sorts elements in the collection in-place according to natural sort order of the value returned
      * by specified selector function.
      *
-     * @param callable $selector ($value, $key) -> $new_value
+     * @param callable $selector ($value, $key, $index) -> $new_value
      * @return void
      */
     function sortBy($selector) {}
@@ -775,7 +775,7 @@ class Collection implements ArrayAccess, Countable
      * Sorts elements in the collection in-place descending according to natural sort order of the
      * value returned by specified selector function.
      *
-     * @param callable $selector ($value, $key) -> $new_value
+     * @param callable $selector ($value, $key, $index) -> $new_value
      * @return void
      */
     function sortByDescending($selector) {}
@@ -806,7 +806,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a collection of all elements sorted according to natural sort order of the
      * value returned by specified selector function.
      *
-     * @param callable $selector ($value, $key) -> $new_value
+     * @param callable $selector ($value, $key, $index) -> $new_value
      * @return Collection
      */
     function sortedBy($selector) {}
@@ -815,7 +815,7 @@ class Collection implements ArrayAccess, Countable
      * Returns a collection of all elements sorted descending according to natural sort order
      * of the value returned by specified selector function.
      *
-     * @param callable $selector ($value, $key) -> $new_value
+     * @param callable $selector ($value, $key, $index) -> $new_value
      * @return Collection
      */
     function sortedByDescending($selector) {}
@@ -823,7 +823,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns a collection of all elements sorted descending according to their natural sort order.
      *
-     * @param callable $selector ($value, $key) -> $new_value
+     * @param callable $selector ($value, $key, $index) -> $new_value
      * @return Collection
      */
     function sortedDescending($selector) {}
@@ -855,7 +855,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns a collection containing last elements satisfying the given predicate.
      *
-     * @param $predicate ($value, $key) -> bool
+     * @param $predicate ($value, $key, $index) -> bool
      * @return Collection
      */
     function takeLastWhile($predicate) {}
@@ -863,7 +863,7 @@ class Collection implements ArrayAccess, Countable
     /**
      * Returns a collection containing first elements satisfying the given predicate.
      *
-     * @param $predicate ($value, $key) -> bool
+     * @param $predicate ($value, $key, $index) -> bool
      * @return Collection
      */
     function takeWhile($predicate) {}
diff --git a/tests/002-add-all.phpt b/tests/002-add-all.phpt
new file mode 100644
index 0000000..7936fca
--- /dev/null
+++ b/tests/002-add-all.phpt
@@ -0,0 +1,12 @@
+--TEST--
+Test Collection::addAll().
+--FILE--
+<?php
+$array = [3, 7, 5, 6, 1, 2];
+$collection = Collection::init([6, 1, 2]);
+$collection2 = Collection::init([3, 7, 5]);
+$collection2->addAll($collection);
+if ($array != $collection2->toArray())
+    echo 'Collection::addAll() failed.', PHP_EOL;
+?>
+--EXPECT--
diff --git a/tests/003-all.phpt b/tests/003-all.phpt
new file mode 100644
index 0000000..dd6d827
--- /dev/null
+++ b/tests/003-all.phpt
@@ -0,0 +1,19 @@
+--TEST--
+Test Collection::all().
+--FILE--
+<?php
+$collection = Collection::init([
+    "abc" => 12,
+    "de" => 5,
+    "f" => 100
+]);
+$result = $collection->all(function ($value) {
+    return $value < 100;
+});
+$result2 = $collection->all(function ($value, $key) {
+    return strlen($key) < 4;
+});
+if ($result || !$result2)
+    echo 'Collection::all() failed.', PHP_EOL;
+?>
+--EXPECT--