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dart_style/lib/src/nesting_level.dart

-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-library dart_style.src.nesting_level;
-
-import 'fast_hash.dart';
-
-/// A single level of expression nesting.
-///
-/// When a line is split in the middle of an expression, this tracks the
-/// context of where in the expression that split occurs. It ensures that the
-/// [LineSplitter] obeys the expression nesting when deciding what column to
-/// start lines at when split inside an expression.
-///
-/// Each instance of this represents a single level of expression nesting. If we
-/// split at to chunks with different levels of nesting, the splitter ensures
-/// they each get assigned to different columns.
-///
-/// In addition, each level has an indent. This is the number of spaces it is
-/// indented relative to the outer expression. It's almost always
-/// [Indent.expression], but cascades are special magic snowflakes and use
-/// [Indent.cascade].
-class NestingLevel extends FastHash {
-  /// The nesting level surrounding this one, or `null` if this is represents
-  /// top level code in a block.
-  NestingLevel get parent => _parent;
-  NestingLevel _parent;
-
-  /// The number of characters that this nesting level is indented relative to
-  /// the containing level.
-  ///
-  /// Normally, this is [Indent.expression], but cascades use [Indent.cascade].
-  final int indent;
-
-  /// The total number of characters of indentation from this level and all of
-  /// its parents, after determining which nesting levels are actually used.
-  ///
-  /// This is only valid during line splitting.
-  int get totalUsedIndent => _totalUsedIndent;
-  int _totalUsedIndent;
-
-  bool get isNested => _parent != null;
-
-  NestingLevel() : indent = 0;
-
-  NestingLevel._(this._parent, this.indent);
-
-  /// Creates a new deeper level of nesting indented [spaces] more characters
-  /// that the outer level.
-  NestingLevel nest(int spaces) => new NestingLevel._(this, spaces);
-
-  /// Clears the previously calculated total indent of this nesting level.
-  void clearTotalUsedIndent() {
-    _totalUsedIndent = null;
-    if (_parent != null) _parent.clearTotalUsedIndent();
-  }
-
-  /// Calculates the total amount of indentation from this nesting level and
-  /// all of its parents assuming only [usedNesting] levels are in use.
-  void refreshTotalUsedIndent(Set<NestingLevel> usedNesting) {
-    if (_totalUsedIndent != null) return;
-
-    _totalUsedIndent = 0;
-
-    if (_parent != null) {
-      _parent.refreshTotalUsedIndent(usedNesting);
-      _totalUsedIndent += _parent.totalUsedIndent;
-    }
-
-    if (usedNesting.contains(this)) _totalUsedIndent += indent;
-  }
-
-  String toString() {
-    if (_parent == null) return indent.toString();
-    return "$parent:$indent";
-  }
-}