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| 1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file | |
| 2 // for details. All rights reserved. Use of this source code is governed by a | |
| 3 // BSD-style license that can be found in the LICENSE file. | |
| 4 | |
| 5 library string_scanner.span_scanner; | |
| 6 | |
| 7 import 'package:source_span/source_span.dart'; | |
| 8 | |
| 9 import 'exception.dart'; | |
| 10 import 'line_scanner.dart'; | |
| 11 import 'string_scanner.dart'; | |
| 12 import 'utils.dart'; | |
| 13 | |
| 14 /// A subclass of [LineScanner] that exposes matched ranges as source map | |
| 15 /// [Span]s. | |
| 16 class SpanScanner extends StringScanner implements LineScanner { | |
| 17 /// The source of the scanner. | |
| 18 /// | |
| 19 /// This caches line break information and is used to generate [Span]s. | |
| 20 final SourceFile _sourceFile; | |
| 21 | |
| 22 int get line => _sourceFile.getLine(position); | |
| 23 int get column => _sourceFile.getColumn(position); | |
| 24 | |
| 25 LineScannerState get state => new _SpanScannerState(this, position); | |
| 26 | |
| 27 set state(LineScannerState state) { | |
| 28 if (state is! _SpanScannerState || | |
| 29 !identical((state as _SpanScannerState)._scanner, this)) { | |
| 30 throw new ArgumentError("The given LineScannerState was not returned by " | |
| 31 "this LineScanner."); | |
| 32 } | |
| 33 | |
| 34 this.position = state.position; | |
| 35 } | |
| 36 | |
| 37 /// The [FileSpan] for [lastMatch]. | |
| 38 /// | |
| 39 /// This is the span for the entire match. There's no way to get spans for | |
| 40 /// subgroups since [Match] exposes no information about their positions. | |
| 41 FileSpan get lastSpan => _lastSpan; | |
| 42 FileSpan _lastSpan; | |
| 43 | |
| 44 /// The current location of the scanner. | |
| 45 FileLocation get location => _sourceFile.location(position); | |
| 46 | |
| 47 /// Returns an empty span at the current location. | |
| 48 FileSpan get emptySpan => location.pointSpan(); | |
| 49 | |
| 50 /// Creates a new [SpanScanner] that starts scanning from [position]. | |
| 51 /// | |
| 52 /// [sourceUrl] is used as [SourceLocation.sourceUrl] for the returned | |
| 53 /// [FileSpan]s as well as for error reporting. It can be a [String], a | |
| 54 /// [Uri], or `null`. | |
| 55 SpanScanner(String string, {sourceUrl, int position}) | |
| 56 : _sourceFile = new SourceFile(string, url: sourceUrl), | |
| 57 super(string, sourceUrl: sourceUrl, position: position); | |
| 58 | |
| 59 /// Creates a [FileSpan] representing the source range between [startState] | |
| 60 /// and the current position. | |
| 61 FileSpan spanFrom(LineScannerState startState, [LineScannerState endState]) { | |
| 62 var endPosition = endState == null ? position : endState.position; | |
| 63 return _sourceFile.span(startState.position, endPosition); | |
| 64 } | |
| 65 | |
| 66 bool matches(Pattern pattern) { | |
| 67 if (!super.matches(pattern)) { | |
| 68 _lastSpan = null; | |
| 69 return false; | |
| 70 } | |
| 71 | |
| 72 _lastSpan = _sourceFile.span(position, lastMatch.end); | |
| 73 return true; | |
| 74 } | |
| 75 | |
| 76 void error(String message, {Match match, int position, int length}) { | |
| 77 validateErrorArgs(string, match, position, length); | |
| 78 | |
| 79 if (match == null && position == null && length == null) match = lastMatch; | |
| 80 if (position == null) { | |
| 81 position = match == null ? this.position : match.start; | |
| 82 } | |
| 83 if (length == null) length = match == null ? 1 : match.end - match.start; | |
| 84 | |
| 85 var span = _sourceFile.span(position, position + length); | |
| 86 throw new StringScannerException(message, span, string); | |
| 87 } | |
| 88 } | |
| 89 | |
| 90 /// A class representing the state of a [SpanScanner]. | |
| 91 class _SpanScannerState implements LineScannerState { | |
| 92 /// The [SpanScanner] that created this. | |
| 93 final SpanScanner _scanner; | |
| 94 | |
| 95 final int position; | |
| 96 int get line => _scanner._sourceFile.getLine(position); | |
| 97 int get column => _scanner._sourceFile.getColumn(position); | |
| 98 | |
| 99 _SpanScannerState(this._scanner, this.position); | |
| 100 } | |
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