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LibJS: Implement StringPad abstract operation with UTF-16 code units

Affects String.prototype.padStart and String.prototype.padEnd.
This commit is contained in:
Timothy Flynn 2021-07-19 14:36:30 -04:00 committed by Andreas Kling
parent ef2ff5f88b
commit eaa1360eee
3 changed files with 51 additions and 7 deletions

View file

@ -399,14 +399,19 @@ enum class PadPlacement {
};
// 22.1.3.15.1 StringPad ( O, maxLength, fillString, placement ), https://tc39.es/ecma262/#sec-stringpad
static Value pad_string(GlobalObject& global_object, const String& string, PadPlacement placement)
static Value pad_string(GlobalObject& global_object, String const& string, PadPlacement placement)
{
auto& vm = global_object.vm();
auto utf16_string = AK::utf8_to_utf16(string);
Utf16View utf16_string_view { utf16_string };
auto string_length = utf16_string_view.length_in_code_units();
auto max_length = vm.argument(0).to_length(global_object);
if (vm.exception())
return {};
if (max_length <= string.length())
return js_string(vm, string);
if (max_length <= string_length)
return js_string(vm, utf16_string_view);
String fill_string = " ";
if (!vm.argument(1).is_undefined()) {
@ -414,15 +419,22 @@ static Value pad_string(GlobalObject& global_object, const String& string, PadPl
if (vm.exception())
return {};
if (fill_string.is_empty())
return js_string(vm, string);
return js_string(vm, utf16_string_view);
}
auto fill_length = max_length - string.length();
auto utf16_fill_string = AK::utf8_to_utf16(fill_string);
Utf16View utf16_fill_view { utf16_fill_string };
auto fill_code_units = utf16_fill_view.length_in_code_units();
auto fill_length = max_length - string_length;
StringBuilder filler_builder;
while (filler_builder.length() < fill_length)
for (size_t i = 0; i < fill_length / fill_code_units; ++i)
filler_builder.append(fill_string);
auto filler = filler_builder.build().substring(0, fill_length);
utf16_fill_view = utf16_fill_view.substring_view(0, fill_length % fill_code_units);
filler_builder.append(utf16_fill_view.to_utf8(Utf16View::AllowInvalidCodeUnits::Yes));
auto filler = filler_builder.build();
auto formatted = placement == PadPlacement::Start
? String::formatted("{}{}", filler, string)

View file

@ -16,3 +16,19 @@ test("basic functionality", () => {
expect(s.padEnd(10, "bar")).toBe("foobarbarb");
expect(s.padEnd(10, "123456789")).toBe("foo1234567");
});
test("UTF-16", () => {
var s = "😀";
expect(s).toHaveLength(2);
expect(s.padEnd(-1)).toBe("😀");
expect(s.padEnd(0)).toBe("😀");
expect(s.padEnd(1)).toBe("😀");
expect(s.padEnd(2)).toBe("😀");
expect(s.padEnd(3)).toBe("😀 ");
expect(s.padEnd(10)).toBe("😀 ");
expect(s.padEnd(2, "😀")).toBe("😀");
expect(s.padEnd(3, "😀")).toBe("😀\ud83d");
expect(s.padEnd(4, "😀")).toBe("😀😀");
expect(s.padEnd(5, "😀")).toBe("😀😀\ud83d");
});

View file

@ -16,3 +16,19 @@ test("basic functionality", () => {
expect(s.padStart(10, "bar")).toBe("barbarbfoo");
expect(s.padStart(10, "123456789")).toBe("1234567foo");
});
test("UTF-16", () => {
var s = "😀";
expect(s).toHaveLength(2);
expect(s.padStart(-1)).toBe("😀");
expect(s.padStart(0)).toBe("😀");
expect(s.padStart(1)).toBe("😀");
expect(s.padStart(2)).toBe("😀");
expect(s.padStart(3)).toBe(" 😀");
expect(s.padStart(10)).toBe(" 😀");
expect(s.padStart(2, "😀")).toBe("😀");
expect(s.padStart(3, "😀")).toBe("\ud83d😀");
expect(s.padStart(4, "😀")).toBe("😀😀");
expect(s.padStart(5, "😀")).toBe("😀\ud83d😀");
});