LibJS: Add spec comments to MapPrototype

1 files changed, 112 insertions, 23 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/MapPrototype.cpp b/Userland/Libraries/LibJS/Runtime/MapPrototype.cpp
index b165315e88..4dff35c5b7 100644
--- a/Userland/Libraries/LibJS/Runtime/MapPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/MapPrototype.cpp
@@ -44,16 +44,35 @@ ThrowCompletionOr<void> MapPrototype::initialize(Realm& realm)
 // 24.1.3.1 Map.prototype.clear ( ), https://tc39.es/ecma262/#sec-map.prototype.clear
 JS_DEFINE_NATIVE_FUNCTION(MapPrototype::clear)
 {
+    // 1. Let M be the this value.
+    // 2. Perform ? RequireInternalSlot(M, [[MapData]]).
     auto map = TRY(typed_this_object(vm));
+
+    // 3. For each Record { [[Key]], [[Value]] } p of M.[[MapData]], do
+    //     a. Set p.[[Key]] to empty.
+    //     b. Set p.[[Value]] to empty.
     map->map_clear();
+
+    // 4. Return undefined.
     return js_undefined();
 }
 
 // 24.1.3.3 Map.prototype.delete ( key ), https://tc39.es/ecma262/#sec-map.prototype.delete
 JS_DEFINE_NATIVE_FUNCTION(MapPrototype::delete_)
 {
+    auto key = vm.argument(0);
+
+    // 1. Let M be the this value.
+    // 2. Perform ? RequireInternalSlot(M, [[MapData]]).
     auto map = TRY(typed_this_object(vm));
-    return Value(map->map_remove(vm.argument(0)));
+
+    // 3. For each Record { [[Key]], [[Value]] } p of M.[[MapData]], do
+    //    a. If p.[[Key]] is not empty and SameValueZero(p.[[Key]], key) is true, then
+    //        i. Set p.[[Key]] to empty.
+    //        ii. Set p.[[Value]] to empty.
+    //        iii. Return true.
+    // 4. Return false.
+    return Value(map->map_remove(key));
 }
 
 // 24.1.3.4 Map.prototype.entries ( ), https://tc39.es/ecma262/#sec-map.prototype.entries
@@ -61,38 +80,80 @@ JS_DEFINE_NATIVE_FUNCTION(MapPrototype::entries)
 {
     auto& realm = *vm.current_realm();
 
+    // 1. Let M be the this value.
     auto map = TRY(typed_this_object(vm));
 
-    return MapIterator::create(realm, map, Object::PropertyKind::KeyAndValue);
+    // 2. Return ? CreateMapIterator(M, key+value).
+    return MapIterator::create(realm, *map, Object::PropertyKind::KeyAndValue);
 }
 
 // 24.1.3.5 Map.prototype.forEach ( callbackfn [ , thisArg ] ), https://tc39.es/ecma262/#sec-map.prototype.foreach
 JS_DEFINE_NATIVE_FUNCTION(MapPrototype::for_each)
 {
+    auto callbackfn = vm.argument(0);
+    auto this_arg = vm.argument(1);
+
+    // 1. Let M be the this value.
+    // 2. Perform ? RequireInternalSlot(M, [[MapData]]).
     auto map = TRY(typed_this_object(vm));
-    if (!vm.argument(0).is_function())
-        return vm.throw_completion<TypeError>(ErrorType::NotAFunction, TRY_OR_THROW_OOM(vm, vm.argument(0).to_string_without_side_effects()));
-    auto this_value = vm.this_value();
-    for (auto& entry : *map)
-        TRY(call(vm, vm.argument(0).as_function(), vm.argument(1), entry.value, entry.key, this_value));
+
+    // 3. If IsCallable(callbackfn) is false, throw a TypeError exception.
+    if (!callbackfn.is_function())
+        return vm.throw_completion<TypeError>(ErrorType::NotAFunction, TRY_OR_THROW_OOM(vm, callbackfn.to_string_without_side_effects()));
+
+    // 4. Let entries be M.[[MapData]].
+    // 5. Let numEntries be the number of elements in entries.
+    // 6. Let index be 0.
+    // 7. Repeat, while index < numEntries,
+    for (auto& entry : *map) {
+        // i. Let e be entries[index].
+        // b. Set index to index + 1.
+        // c. If e.[[Key]] is not empty, then
+        // NOTE: This is handled by Map's IteratorImpl.
+
+        // i. Perform ? Call(callbackfn, thisArg, « e.[[Value]], e.[[Key]], M »).
+        TRY(call(vm, callbackfn.as_function(), this_arg, entry.value, entry.key, map));
+
+        // ii. NOTE: The number of elements in entries may have increased during execution of callbackfn.
+        // iii. Set numEntries to the number of elements in entries.
+    }
+
+    // 8. Return undefined.
     return js_undefined();
 }
 
 // 24.1.3.6 Map.prototype.get ( key ), https://tc39.es/ecma262/#sec-map.prototype.get
 JS_DEFINE_NATIVE_FUNCTION(MapPrototype::get)
 {
+    auto key = vm.argument(0);
+
+    // 1. Let M be the this value.
+    // 2. Perform ? RequireInternalSlot(M, [[MapData]]).
     auto map = TRY(typed_this_object(vm));
-    auto result = map->map_get(vm.argument(0));
-    if (!result.has_value())
-        return js_undefined();
-    return result.value();
+
+    // 3. For each Record { [[Key]], [[Value]] } p of M.[[MapData]], do
+    //    a. If p.[[Key]] is not empty and SameValueZero(p.[[Key]], key) is true, return p.[[Value]].
+    auto result = map->map_get(key);
+    if (result.has_value())
+        return result.value();
+
+    // 4. Return undefined.
+    return js_undefined();
 }
 
 // 24.1.3.7 Map.prototype.has ( key ), https://tc39.es/ecma262/#sec-map.prototype.has
 JS_DEFINE_NATIVE_FUNCTION(MapPrototype::has)
 {
+    auto key = vm.argument(0);
+
+    // 1. Let M be the this value.
+    // 2. Perform ? RequireInternalSlot(M, [[MapData]]).
     auto map = TRY(typed_this_object(vm));
-    return map->map_has(vm.argument(0));
+
+    // 3. For each Record { [[Key]], [[Value]] } p of M.[[MapData]], do
+    //    a. If p.[[Key]] is not empty and SameValueZero(p.[[Key]], key) is true, return true.
+    // 4. Return false.
+    return map->map_has(key);
 }
 
 // 24.1.3.8 Map.prototype.keys ( ), https://tc39.es/ecma262/#sec-map.prototype.keys
@@ -100,37 +161,65 @@ JS_DEFINE_NATIVE_FUNCTION(MapPrototype::keys)
 {
     auto& realm = *vm.current_realm();
 
+    // 1. Let M be the this value.
     auto map = TRY(typed_this_object(vm));
 
-    return MapIterator::create(realm, map, Object::PropertyKind::Key);
+    // 2. Return ? CreateMapIterator(M, key).
+    return MapIterator::create(realm, *map, Object::PropertyKind::Key);
 }
 
 // 24.1.3.9 Map.prototype.set ( key, value ), https://tc39.es/ecma262/#sec-map.prototype.set
 JS_DEFINE_NATIVE_FUNCTION(MapPrototype::set)
 {
-    auto map = TRY(typed_this_object(vm));
     auto key = vm.argument(0);
+    auto value = vm.argument(1);
+
+    // 1. Let M be the this value.
+    // 2. Perform ? RequireInternalSlot(M, [[MapData]]).
+    auto map = TRY(typed_this_object(vm));
+
+    // 4. If key is -0𝔽, set key to +0𝔽.
     if (key.is_negative_zero())
         key = Value(0);
-    map->map_set(key, vm.argument(1));
+
+    // 3. For each Record { [[Key]], [[Value]] } p of M.[[MapData]], do
+    //    a. If p.[[Key]] is not empty and SameValueZero(p.[[Key]], key) is true, then
+    //        i. Set p.[[Value]] to value.
+    //        ii. Return M.
+    // 5. Let p be the Record { [[Key]]: key, [[Value]]: value }.
+    // 6. Append p to M.[[MapData]].
+    map->map_set(key, value);
+
+    // 7. Return M.
     return map;
 }
 
-// 24.1.3.11 Map.prototype.values ( ), https://tc39.es/ecma262/#sec-map.prototype.values
-JS_DEFINE_NATIVE_FUNCTION(MapPrototype::values)
+// 24.1.3.10 get Map.prototype.size, https://tc39.es/ecma262/#sec-get-map.prototype.size
+JS_DEFINE_NATIVE_FUNCTION(MapPrototype::size_getter)
 {
-    auto& realm = *vm.current_realm();
-
+    // 1. Let M be the this value.
+    // 2. Perform ? RequireInternalSlot(M, [[MapData]]).
     auto map = TRY(typed_this_object(vm));
 
-    return MapIterator::create(realm, map, Object::PropertyKind::Value);
+    // 3. Let count be 0.
+    // 4. For each Record { [[Key]], [[Value]] } p of M.[[MapData]], do
+    //    a. If p.[[Key]] is not empty, set count to count + 1.
+    auto count = map->map_size();
+
+    // 5. Return 𝔽(count).
+    return Value(count);
 }
 
-// 24.1.3.10 get Map.prototype.size, https://tc39.es/ecma262/#sec-get-map.prototype.size
-JS_DEFINE_NATIVE_FUNCTION(MapPrototype::size_getter)
+// 24.1.3.11 Map.prototype.values ( ), https://tc39.es/ecma262/#sec-map.prototype.values
+JS_DEFINE_NATIVE_FUNCTION(MapPrototype::values)
 {
+    auto& realm = *vm.current_realm();
+
+    // 1. Let M be the this value.
     auto map = TRY(typed_this_object(vm));
-    return Value(map->map_size());
+
+    // 2. Return ? CreateMapIterator(M, value).
+    return MapIterator::create(realm, *map, Object::PropertyKind::Value);
 }
 
 }