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// 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) => 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) {
_totalUsedIndent += _parent.totalUsedIndent;
if (usedNesting.contains(this)) _totalUsedIndent += indent;
String toString() {
if (_parent == null) return indent.toString();
return '$parent:$indent';