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LibJS: Add String.prototype.slice

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This commit is contained in:
Kesse Jones 2020-04-29 08:42:00 -03:00 • committed by Andreas Kling
parent bf727eb44c
commit 58f6f50de4
3 changed files with 65 additions and 0 deletions
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42
Libraries/LibJS/Runtime/StringPrototype.cpp
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@ -60,6 +60,7 @@ StringPrototype::StringPrototype()
put_native_function("concat", concat, 1, attr);
put_native_function("substring", substring, 2, attr);
put_native_function("includes", includes, 1, attr);
put_native_function("slice", slice, 2, attr);
}
StringPrototype::~StringPrototype()
@ -399,4 +400,45 @@ Value StringPrototype::includes(Interpreter& interpreter)
return Value(substring_search.contains(search_string));
}
Value StringPrototype::slice(Interpreter& interpreter)
{
auto* string_object = string_object_from(interpreter);
if (!string_object)
return {};
auto& string = string_object->primitive_string().string();
if (interpreter.argument_count() == 0)
return js_string(interpreter, string);
i32 string_length = static_cast<i32>(string.length());
i32 index_start = interpreter.argument(0).to_i32();
i32 index_end = string_length;
auto negative_min_index = -(string_length - 1);
if (index_start < negative_min_index)
index_start = 0;
else if (index_start < 0)
index_start = string_length + index_start;
if (interpreter.argument_count() >= 2) {
index_end = interpreter.argument(1).to_i32();
if (index_end < negative_min_index)
return js_string(interpreter, String::empty());
if (index_end > string_length)
index_end = string_length;
else if (index_end < 0)
index_end = string_length + index_end;
}
if (index_start >= index_end)
return js_string(interpreter, String::empty());
auto part_length = index_end - index_start;
auto string_part = string.substring(index_start, part_length);
return js_string(interpreter, string_part);
}
}

1
Libraries/LibJS/Runtime/StringPrototype.h
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@ -56,6 +56,7 @@ private:
static Value trim_end(Interpreter&);
static Value concat(Interpreter&);
static Value includes(Interpreter&);
static Value slice(Interpreter&);
};
}