Implement ES6+ String methods, Iterator, Map, Set Object (#43)

Signed-off-by: seonghyun kim <sh8281.kim@samsung.com>

src/runtime/StringObject.cpp

@@ -106,4 +106,82 @@ ObjectGetResult StringObject::getIndexedProperty(ExecutionState& state, const Va
     }
     return get(state, ObjectPropertyName(state, property));
 }
+
+IteratorObject* StringObject::iterator(ExecutionState& state)
+{
+    return new StringIteratorObject(state, m_primitiveValue);
+}
+
+StringIteratorObject::StringIteratorObject(ExecutionState& state, String* s)
+    : IteratorObject(state)
+    , m_string(s)
+    , m_iteratorNextIndex(0)
+{
+    setPrototype(state, state.context()->globalObject()->stringIteratorPrototype());
+}
+
+void* StringIteratorObject::operator new(size_t size)
+{
+    static bool typeInited = false;
+    static GC_descr descr;
+    if (!typeInited) {
+        GC_word obj_bitmap[GC_BITMAP_SIZE(StringIteratorObject)] = { 0 };
+        GC_set_bit(obj_bitmap, GC_WORD_OFFSET(StringIteratorObject, m_structure));
+        GC_set_bit(obj_bitmap, GC_WORD_OFFSET(StringIteratorObject, m_prototype));
+        GC_set_bit(obj_bitmap, GC_WORD_OFFSET(StringIteratorObject, m_values));
+        GC_set_bit(obj_bitmap, GC_WORD_OFFSET(StringIteratorObject, m_string));
+        descr = GC_make_descriptor(obj_bitmap, GC_WORD_LEN(StringIteratorObject));
+        typeInited = true;
+    }
+    return GC_MALLOC_EXPLICITLY_TYPED(size, descr);
+}
+
+std::pair<Value, bool> StringIteratorObject::advance(ExecutionState& state)
+{
+    // Let s be the value of the [[IteratedString]] internal slot of O.
+    String* s = m_string;
+    // If a is undefined, return CreateIterResultObject(undefined, true).
+    if (s == nullptr) {
+        return std::make_pair(Value(), true);
+    }
+    // Let position be the value of the [[StringIteratorNextIndex]] internal slot of O.
+    size_t position = m_iteratorNextIndex;
+    // Let len be the number of elements in s.
+    auto len = s->length();
+
+    // If position ≥ len, then
+    if (position >= len) {
+        // Set the value of the [[IteratedString]] internal slot of O to undefined.
+        m_string = nullptr;
+        // Return CreateIterResultObject(undefined, true).
+        return std::make_pair(Value(), true);
+    }
+
+    // Let first be the code unit value at index position in s.
+    auto first = s->charAt(position);
+    // If first < 0xD800 or first > 0xDBFF or position+1 = len, let resultString be the string consisting of the single code unit first.
+    String* resultString;
+    if (first < 0xD800 || first > 0xDBFF || (position + 1 == len)) {
+        resultString = String::fromInt32(first);
+    } else {
+        // Let second be the code unit value at index position+1 in the String S.
+        auto second = s->charAt(position + 1);
+        // If second < 0xDC00 or second > 0xDFFF, let resultString be the string consisting of the single code unit first.
+        if (second < 0xDC00 || second > 0xDFFF) {
+            resultString = String::fromInt32(first);
+        } else {
+            // Else, let resultString be the string consisting of the code unit first followed by the code unit second.
+            char16_t s[2] = { first, second };
+            resultString = new UTF16String(s, 2);
+        }
+    }
+    // Let resultSize be the number of code units in resultString.
+    auto resultSize = resultString->length();
+
+    // Set the value of the [[StringIteratorNextIndex]] internal slot of O to position + resultSize.
+    m_iteratorNextIndex = position + resultSize;
+
+    // Return CreateIterResultObject(resultString, false).
+    return std::make_pair(Value(resultString), false);
+}
 }