dart-sass/lib/src/value/list.dart

// Copyright 2016 Google Inc. Use of this source code is governed by an
// MIT-style license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT.

import '../utils.dart';
import '../visitor/interface/value.dart';
import '../value.dart';

class SassList extends Value {
  // TODO(nweiz): Use persistent data structures rather than copying here. An
  // RRB vector should fit our use-cases well.
  //
  // We may also want to fall back to a plain unmodifiable List for small lists
  // (<32 items?).
  final List<Value> contents;

  final ListSeparator separator;

  final bool hasBrackets;

  bool get isBlank => contents.every((element) => element.isBlank);

  List<Value> get asList => contents;

  const SassList.empty({ListSeparator separator, bool brackets: false})
      : contents = const [],
        separator = separator ?? ListSeparator.undecided,
        hasBrackets = brackets;

  SassList(Iterable<Value> contents, this.separator, {bool brackets: false})
      : contents = new List.unmodifiable(contents),
        hasBrackets = brackets {
    if (separator == ListSeparator.undecided && contents.length > 1) {
      throw new ArgumentError(
          "A list with more than one element must have an explicit separator.");
    }
  }

  /*=T*/ accept/*<T>*/(ValueVisitor/*<T>*/ visitor) => visitor.visitList(this);

  SassMap assertMap([String name]) =>
      contents.isEmpty ? const SassMap.empty() : super.assertMap(name);

  bool operator ==(other) =>
      (other is SassList &&
          other.separator == separator &&
          other.hasBrackets == hasBrackets &&
          listEquals(other.contents, contents)) ||
      (contents.isEmpty && other is SassMap && other.contents.isEmpty);

  int get hashCode => listHash(contents);
}

class ListSeparator {
  static const space = const ListSeparator._("space");
  static const comma = const ListSeparator._("comma");
  static const undecided = const ListSeparator._("undecided");

  final String name;

  const ListSeparator._(this.name);

  String toString() => name;
}