dart-sass/lib/src/value/list.dart
Natalie Weizenbaum f1e58e083e
Make SassList.contents private (#227)
This forces users to use Value.asList, which encourages them to be
aware that every value counts as a list.
2018-02-02 17:36:29 -08:00

83 lines
2.6 KiB
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';
import 'external/value.dart' as ext;
class SassList extends Value implements ext.SassList {
// 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 => asList.every((element) => element.isBlank);
List<Value> get asList => _contents;
int get lengthAsList => asList.length;
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 && asList.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]) =>
asList.isEmpty ? const SassMap.empty() : super.assertMap(name);
bool operator ==(other) =>
(other is SassList &&
other.separator == separator &&
other.hasBrackets == hasBrackets &&
listEquals(other.asList, asList)) ||
(asList.isEmpty && other is SassMap && other.asList.isEmpty);
int get hashCode => listHash(asList);
}
/// An enum of list separator types.
class ListSeparator {
/// A space-separated list.
static const space = const ListSeparator._("space", " ");
/// A comma-separated list.
static const comma = const ListSeparator._("comma", ",");
/// A separator that hasn't yet been determined.
///
/// Singleton lists and empty lists don't have separators defiend. This means
/// that list functions will prefer other lists' separators if possible.
static const undecided = const ListSeparator._("undecided", null);
final String _name;
/// The separator character.
///
/// If the separator of a list has not been decided, this value will be
/// `null`.
final String separator;
const ListSeparator._(this._name, this.separator);
String toString() => _name;
}