| 1 | | // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
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| 2 | | // for details. All rights reserved. Use of this source code is governed by a
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| 3 | | // BSD-style license that can be found in the LICENSE file.
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| 4 | |
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| 5 | | library dart_style.src.nesting_level;
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| 6 | |
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| 7 | | import 'fast_hash.dart';
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| 8 | |
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| 9 | | /// A single level of expression nesting.
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| 10 | | ///
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| 11 | | /// When a line is split in the middle of an expression, this tracks the
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| 12 | | /// context of where in the expression that split occurs. It ensures that the
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| 13 | | /// [LineSplitter] obeys the expression nesting when deciding what column to
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| 14 | | /// start lines at when split inside an expression.
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| 15 | | ///
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| 16 | | /// Each instance of this represents a single level of expression nesting. If we
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| 17 | | /// split at to chunks with different levels of nesting, the splitter ensures
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| 18 | | /// they each get assigned to different columns.
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| 19 | | ///
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| 20 | | /// In addition, each level has an indent. This is the number of spaces it is
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| 21 | | /// indented relative to the outer expression. It's almost always
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| 22 | | /// [Indent.expression], but cascades are special magic snowflakes and use
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| 23 | | /// [Indent.cascade].
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| 24 | | class NestingLevel extends FastHash {
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| 25 | | /// The nesting level surrounding this one, or `null` if this is represents
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| 26 | | /// top level code in a block.
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| 27 | 6 | NestingLevel get parent => _parent;
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| 28 | | NestingLevel _parent;
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| 29 | |
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| 30 | | /// The number of characters that this nesting level is indented relative to
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| 31 | | /// the containing level.
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| 32 | | ///
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| 33 | | /// Normally, this is [Indent.expression], but cascades use [Indent.cascade].
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| 34 | | final int indent;
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| 35 | |
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| 36 | | /// The total number of characters of indentation from this level and all of
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| 37 | | /// its parents, after determining which nesting levels are actually used.
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| 38 | | ///
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| 39 | | /// This is only valid during line splitting.
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| 40 | 4 | int get totalUsedIndent => _totalUsedIndent;
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| 41 | | int _totalUsedIndent;
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| 42 | |
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| 43 | 4 | bool get isNested => _parent != null;
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| 44 | |
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| 45 | 3 | NestingLevel() : indent = 0;
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| 46 | |
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| 47 | 3 | NestingLevel._(this._parent, this.indent);
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| 48 | |
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| 49 | | /// Creates a new deeper level of nesting indented [spaces] more characters
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| 50 | | /// that the outer level.
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| 51 | 6 | NestingLevel nest(int spaces) => new NestingLevel._(this, spaces);
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| 52 | |
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| 53 | | /// Clears the previously calculated total indent of this nesting level.
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| 54 | 2 | void clearTotalUsedIndent() {
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| 55 | 2 | _totalUsedIndent = null;
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| 56 | 6 | if (_parent != null) _parent.clearTotalUsedIndent();
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| 57 | | }
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| 58 | |
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| 59 | | /// Calculates the total amount of indentation from this nesting level and
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| 60 | | /// all of its parents assuming only [usedNesting] levels are in use.
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| 61 | 2 | void refreshTotalUsedIndent(Set<NestingLevel> usedNesting) {
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| 62 | 2 | if (_totalUsedIndent != null) return;
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| 63 | |
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| 64 | 2 | _totalUsedIndent = 0;
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| 65 | |
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| 66 | 2 | if (_parent != null) {
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| 67 | 4 | _parent.refreshTotalUsedIndent(usedNesting);
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| 68 | 8 | _totalUsedIndent += _parent.totalUsedIndent;
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| 69 | | }
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| 70 | |
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| 71 | 8 | if (usedNesting.contains(this)) _totalUsedIndent += indent;
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| 72 | | }
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| 73 | |
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| 74 | 0 | String toString() {
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| 75 | 0 | if (_parent == null) return indent.toString();
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| 76 | 0 | return "$parent:$indent";
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| 77 | | }
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| 78 | | }
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