text: /*
   * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
   *
   * SPDX-License-Identifier: BSD-2-Clause
   */
  
  #include <AK/StringBuilder.h>
  #include <AK/Utf16View.h>
  #include <AK/Utf32View.h>
  #include <LibJS/Runtime/AbstractOperations.h>
  #include <LibJS/Runtime/Array.h>
  #include <LibJS/Runtime/Error.h>
  #include <LibJS/Runtime/GlobalObject.h>
  #include <LibJS/Runtime/StringConstructor.h>
  #include <LibJS/Runtime/StringObject.h>
  #include <LibJS/Runtime/Utf16String.h>
  
  namespace JS {
  
  StringConstructor::StringConstructor(GlobalObject& global_object)
      : NativeFunction(vm().names.String.as_string(), *global_object.function_prototype())
  {
  }
  
  void StringConstructor::initialize(GlobalObject& global_object)
  {
      auto& vm = this->vm();
      NativeFunction::initialize(global_object);
  
      // 22.1.2.3 String.prototype, https://tc39.es/ecma262/#sec-string.prototype
      define_direct_property(vm.names.prototype, global_object.string_prototype(), 0);
  
      u8 attr = Attribute::Writable | Attribute::Configurable;
      define_native_function(vm.names.raw, raw, 1, attr);
      define_native_function(vm.names.fromCharCode, from_char_code, 1, attr);
      define_native_function(vm.names.fromCodePoint, from_code_point, 1, attr);
  
      define_direct_property(vm.names.length, Value(1), Attribute::Configurable);
  }
  
  StringConstructor::~StringConstructor()
  {
  }
  
  // 22.1.1.1 String ( value ), https://tc39.es/ecma262/#sec-string-constructor-string-value
  Value StringConstructor::call()
  {
      if (!vm().argument_count())
          return js_string(heap(), "");
      if (vm().argument(0).is_symbol())
          return js_string(heap(), vm().argument(0).as_symbol().to_string());
      return TRY_OR_DISCARD(vm().argument(0).to_primitive_string(global_object()));
  }
  
  // 22.1.1.1 String ( value ), https://tc39.es/ecma262/#sec-string-constructor-string-value
  Value StringConstructor::construct(FunctionObject& new_target)
  {
      auto& vm = global_object().vm();
  
      PrimitiveString* primitive_string;
      if (!vm.argument_count())
          primitive_string = js_string(vm, "");
      else
          primitive_string = TRY_OR_DISCARD(vm.argument(0).to_primitive_string(global_object()));
      auto* prototype = TRY_OR_DISCARD(get_prototype_from_constructor(global_object(), new_target, &GlobalObject::string_prototype));
      return StringObject::create(global_object(), *primitive_string, *prototype);
  }
  
  // 22.1.2.4 String.raw ( template, ...substitutions ), https://tc39.es/ecma262/#sec-string.raw
  JS_DEFINE_NATIVE_FUNCTION(StringConstructor::raw)
  {
      auto* cooked = TRY_OR_DISCARD(vm.argument(0).to_object(global_object));
      auto raw_value = TRY_OR_DISCARD(cooked->get(vm.names.raw));
      auto* raw = TRY_OR_DISCARD(raw_value.to_object(global_object));
      auto literal_segments = TRY_OR_DISCARD(length_of_array_like(global_object, *raw));
  
      if (literal_segments == 0)
          return js_string(vm, "");
  
      const auto number_of_substituions = vm.argument_count() - 1;
  
      StringBuilder builder;
      for (size_t i = 0; i < literal_segments; ++i) {
          auto next_key = String::number(i);
          auto next_segment_value = TRY_OR_DISCARD(raw->get(next_key));
          auto next_segment = TRY_OR_DISCARD(next_segment_value.to_string(global_object));
  
          builder.append(next_segment);
  
          if (i + 1 == literal_segments)
              break;
  
          if (i < number_of_substituions) {
              auto next = vm.argument(i + 1);
              auto next_sub = TRY_OR_DISCARD(next.to_string(global_object));
              builder.append(next_sub);
          }
      }
      return js_string(vm, builder.build());
  }
  
  // 22.1.2.1 String.fromCharCode ( ...codeUnits ), https://tc39.es/ecma262/#sec-string.fromcharcode
  JS_DEFINE_NATIVE_FUNCTION(StringConstructor::from_char_code)
  {
      Vector<u16, 1> string;
      string.ensure_capacity(vm.argument_count());
  
      for (size_t i = 0; i < vm.argument_count(); ++i) {
          auto code_unit = vm.argument(i).to_u16(global_object);
          if (vm.exception())
              return {};
          string.append(code_unit);
      }
  
      return js_string(vm, Utf16String(move(string)));
  }
  
  // 22.1.2.2 String.fromCodePoint ( ...codePoints ), https://tc39.es/ecma262/#sec-string.fromcodepoint
  JS_DEFINE_NATIVE_FUNCTION(StringConstructor::from_code_point)
  {
      Vector<u16, 1> string;
      string.ensure_capacity(vm.argument_count()); // This will be an under-estimate if any code point is > 0xffff.
  
      for (size_t i = 0; i < vm.argument_count(); ++i) {
          auto next_code_point = vm.argument(i).to_number(global_object);
          if (vm.exception())
              return {};
          if (!next_code_point.is_integral_number()) {
              vm.throw_exception<RangeError>(global_object, ErrorType::InvalidCodePoint, next_code_point.to_string_without_side_effects());
              return {};
          }
          auto code_point = next_code_point.to_i32(global_object);
          if (code_point < 0 || code_point > 0x10FFFF) {
              vm.throw_exception<RangeError>(global_object, ErrorType::InvalidCodePoint, next_code_point.to_string_without_side_effects());
              return {};
          }
  
          AK::code_point_to_utf16(string, static_cast<u32>(code_point));
      }
  
      return js_string(vm, Utf16String(move(string)));
  }
  
  }
  