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| 1 // Copyright (c) 2016, 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 import 'package:source_span/source_span.dart'; |
| 6 |
| 7 import 'exception.dart'; |
| 8 import 'line_scanner.dart'; |
| 9 import 'span_scanner.dart'; |
| 10 import 'string_scanner.dart'; |
| 11 import 'utils.dart'; |
| 12 |
| 13 /// A [SpanScanner] that scans within an existing [FileSpan]. |
| 14 /// |
| 15 /// This re-implements chunks of [SpanScanner] rather than using a dummy span or |
| 16 /// inheritance because scanning is often a performance-critical operation, so |
| 17 /// it's important to avoid adding extra overhead when relative scanning isn't |
| 18 /// needed. |
| 19 class RelativeSpanScanner extends StringScanner implements SpanScanner { |
| 20 /// The source of the scanner. |
| 21 /// |
| 22 /// This caches line break information and is used to generate [Span]s. |
| 23 final SourceFile _sourceFile; |
| 24 |
| 25 /// The start location of the span within which this scanner is scanning. |
| 26 /// |
| 27 /// This is used to convert between span-relative and file-relative fields. |
| 28 final FileLocation _startLocation; |
| 29 |
| 30 int get line => _sourceFile.getLine(_startLocation.offset + position) - |
| 31 _startLocation.line; |
| 32 |
| 33 int get column { |
| 34 var line = _sourceFile.getLine(_startLocation.offset + position); |
| 35 var column = _sourceFile.getColumn(_startLocation.offset + position, |
| 36 line: line); |
| 37 return line == _startLocation.line |
| 38 ? column - _startLocation.column |
| 39 : column; |
| 40 } |
| 41 |
| 42 LineScannerState get state => new _SpanScannerState(this, position); |
| 43 |
| 44 set state(LineScannerState state) { |
| 45 if (state is! _SpanScannerState || |
| 46 !identical((state as _SpanScannerState)._scanner, this)) { |
| 47 throw new ArgumentError("The given LineScannerState was not returned by " |
| 48 "this LineScanner."); |
| 49 } |
| 50 |
| 51 this.position = state.position; |
| 52 } |
| 53 |
| 54 FileSpan get lastSpan => _lastSpan; |
| 55 FileSpan _lastSpan; |
| 56 |
| 57 FileLocation get location => |
| 58 _sourceFile.location(_startLocation.offset + position); |
| 59 |
| 60 FileSpan get emptySpan => location.pointSpan(); |
| 61 |
| 62 RelativeSpanScanner(FileSpan span) |
| 63 : _sourceFile = span.file, |
| 64 _startLocation = span.start, |
| 65 super(span.text, sourceUrl: span.sourceUrl); |
| 66 |
| 67 FileSpan spanFrom(LineScannerState startState, [LineScannerState endState]) { |
| 68 var endPosition = endState == null ? position : endState.position; |
| 69 return _sourceFile.span( |
| 70 _startLocation.offset + startState.position, |
| 71 _startLocation.offset + endPosition); |
| 72 } |
| 73 |
| 74 bool matches(Pattern pattern) { |
| 75 if (!super.matches(pattern)) { |
| 76 _lastSpan = null; |
| 77 return false; |
| 78 } |
| 79 |
| 80 _lastSpan = _sourceFile.span( |
| 81 _startLocation.offset + position, |
| 82 _startLocation.offset + lastMatch.end); |
| 83 return true; |
| 84 } |
| 85 |
| 86 void error(String message, {Match match, int position, int length}) { |
| 87 validateErrorArgs(string, match, position, length); |
| 88 |
| 89 if (match == null && position == null && length == null) match = lastMatch; |
| 90 if (position == null) { |
| 91 position = match == null ? this.position : match.start; |
| 92 } |
| 93 if (length == null) length = match == null ? 1 : match.end - match.start; |
| 94 |
| 95 var span = _sourceFile.span( |
| 96 _startLocation.offset + position, |
| 97 _startLocation.offset + position + length); |
| 98 throw new StringScannerException(message, span, string); |
| 99 } |
| 100 } |
| 101 |
| 102 /// A class representing the state of a [SpanScanner]. |
| 103 class _SpanScannerState implements LineScannerState { |
| 104 /// The [SpanScanner] that created this. |
| 105 final RelativeSpanScanner _scanner; |
| 106 |
| 107 final int position; |
| 108 int get line => _scanner._sourceFile.getLine(position); |
| 109 int get column => _scanner._sourceFile.getColumn(position); |
| 110 |
| 111 _SpanScannerState(this._scanner, this.position); |
| 112 } |
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