| // Copyright (c) 2016, 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. |
| |
| import 'package:source_span/source_span.dart'; |
| |
| import 'exception.dart'; |
| import 'line_scanner.dart'; |
| import 'span_scanner.dart'; |
| import 'string_scanner.dart'; |
| import 'utils.dart'; |
| |
| /// A [SpanScanner] that scans within an existing [FileSpan]. |
| /// |
| /// This re-implements chunks of [SpanScanner] rather than using a dummy span or |
| /// inheritance because scanning is often a performance-critical operation, so |
| /// it's important to avoid adding extra overhead when relative scanning isn't |
| /// needed. |
| class RelativeSpanScanner extends StringScanner implements SpanScanner { |
| /// The source of the scanner. |
| /// |
| /// This caches line break information and is used to generate [Span]s. |
| final SourceFile _sourceFile; |
| |
| /// The start location of the span within which this scanner is scanning. |
| /// |
| /// This is used to convert between span-relative and file-relative fields. |
| final FileLocation _startLocation; |
| |
| int get line => |
| _sourceFile.getLine(_startLocation.offset + position) - |
| _startLocation.line; |
| |
| int get column { |
| var line = _sourceFile.getLine(_startLocation.offset + position); |
| var column = |
| _sourceFile.getColumn(_startLocation.offset + position, line: line); |
| return line == _startLocation.line |
| ? column - _startLocation.column |
| : column; |
| } |
| |
| LineScannerState get state => new _SpanScannerState(this, position); |
| |
| set state(LineScannerState state) { |
| if (state is! _SpanScannerState || |
| !identical((state as _SpanScannerState)._scanner, this)) { |
| throw new ArgumentError("The given LineScannerState was not returned by " |
| "this LineScanner."); |
| } |
| |
| this.position = state.position; |
| } |
| |
| FileSpan get lastSpan => _lastSpan; |
| FileSpan _lastSpan; |
| |
| FileLocation get location => |
| _sourceFile.location(_startLocation.offset + position); |
| |
| FileSpan get emptySpan => location.pointSpan(); |
| |
| RelativeSpanScanner(FileSpan span) |
| : _sourceFile = span.file, |
| _startLocation = span.start, |
| super(span.text, sourceUrl: span.sourceUrl); |
| |
| FileSpan spanFrom(LineScannerState startState, [LineScannerState endState]) { |
| var endPosition = endState == null ? position : endState.position; |
| return _sourceFile.span(_startLocation.offset + startState.position, |
| _startLocation.offset + endPosition); |
| } |
| |
| bool matches(Pattern pattern) { |
| if (!super.matches(pattern)) { |
| _lastSpan = null; |
| return false; |
| } |
| |
| _lastSpan = _sourceFile.span(_startLocation.offset + position, |
| _startLocation.offset + lastMatch.end); |
| return true; |
| } |
| |
| void error(String message, {Match match, int position, int length}) { |
| validateErrorArgs(string, match, position, length); |
| |
| if (match == null && position == null && length == null) match = lastMatch; |
| if (position == null) { |
| position = match == null ? this.position : match.start; |
| } |
| if (length == null) length = match == null ? 1 : match.end - match.start; |
| |
| var span = _sourceFile.span(_startLocation.offset + position, |
| _startLocation.offset + position + length); |
| throw new StringScannerException(message, span, string); |
| } |
| } |
| |
| /// A class representing the state of a [SpanScanner]. |
| class _SpanScannerState implements LineScannerState { |
| /// The [SpanScanner] that created this. |
| final RelativeSpanScanner _scanner; |
| |
| final int position; |
| int get line => _scanner._sourceFile.getLine(position); |
| int get column => _scanner._sourceFile.getColumn(position); |
| |
| _SpanScannerState(this._scanner, this.position); |
| } |