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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