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Merge in the flutter gallery (#176)
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rami-a
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412
gallery/codeviewer_cli/lib/prehighlighter.dart
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412
gallery/codeviewer_cli/lib/prehighlighter.dart
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// Copyright 2019 The Flutter team. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:string_scanner/string_scanner.dart';
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abstract class SyntaxPrehighlighter {
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List<CodeSpan> format(String src);
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}
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class DartSyntaxPrehighlighter extends SyntaxPrehighlighter {
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DartSyntaxPrehighlighter() {
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_spans = <_HighlightSpan>[];
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}
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static const List<String> _keywords = <String>[
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'abstract',
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'as',
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'assert',
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'async',
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'await',
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'break',
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'case',
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'catch',
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'class',
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'const',
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'continue',
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'default',
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'deferred',
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'do',
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'dynamic',
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'else',
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'enum',
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'export',
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'external',
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'extends',
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'factory',
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'false',
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'final',
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'finally',
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'for',
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'get',
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'if',
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'implements',
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'import',
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'in',
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'is',
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'library',
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'new',
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'null',
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'operator',
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'part',
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'rethrow',
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'return',
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'set',
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'static',
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'super',
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'switch',
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'sync',
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'this',
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'throw',
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'true',
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'try',
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'typedef',
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'var',
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'void',
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'while',
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'with',
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'yield',
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];
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static const List<String> _builtInTypes = <String>[
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'int',
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'double',
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'num',
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'bool',
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];
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String _src;
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StringScanner _scanner;
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List<_HighlightSpan> _spans;
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@override
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List<CodeSpan> format(String src) {
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_src = src;
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_scanner = StringScanner(_src);
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if (_generateSpans()) {
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// Successfully parsed the code
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final List<CodeSpan> formattedText = <CodeSpan>[];
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int currentPosition = 0;
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for (_HighlightSpan span in _spans) {
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if (currentPosition != span.start) {
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formattedText
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.add(CodeSpan(text: _src.substring(currentPosition, span.start)));
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}
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formattedText
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.add(CodeSpan(type: span.type, text: span.textForSpan(_src)));
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currentPosition = span.end;
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}
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if (currentPosition != _src.length) {
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formattedText
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.add(CodeSpan(text: _src.substring(currentPosition, _src.length)));
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}
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return formattedText;
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} else {
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// Parsing failed, return with only basic formatting
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return [CodeSpan(type: _HighlightType.base, text: src)];
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}
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}
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bool _generateSpans() {
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int lastLoopPosition = _scanner.position;
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while (!_scanner.isDone) {
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// Skip White space
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_scanner.scan(RegExp(r'\s+'));
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// Block comments
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if (_scanner.scan(RegExp(r'/\*(.|\n)*\*/'))) {
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_spans.add(_HighlightSpan(
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_HighlightType.comment,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// Line comments
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if (_scanner.scan('//')) {
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final int startComment = _scanner.lastMatch.start;
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bool eof = false;
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int endComment;
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if (_scanner.scan(RegExp(r'.*\n'))) {
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endComment = _scanner.lastMatch.end - 1;
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} else {
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eof = true;
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endComment = _src.length;
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}
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_spans.add(_HighlightSpan(
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_HighlightType.comment,
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startComment,
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endComment,
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));
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if (eof) {
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break;
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}
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continue;
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}
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// Raw r"String"
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if (_scanner.scan(RegExp(r'r".*"'))) {
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_spans.add(_HighlightSpan(
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_HighlightType.string,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// Raw r'String'
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if (_scanner.scan(RegExp(r"r'.*'"))) {
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_spans.add(_HighlightSpan(
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_HighlightType.string,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// Multiline """String"""
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if (_scanner.scan(RegExp(r'"""(?:[^"\\]|\\(.|\n))*"""'))) {
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_spans.add(_HighlightSpan(
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_HighlightType.string,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// Multiline '''String'''
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if (_scanner.scan(RegExp(r"'''(?:[^'\\]|\\(.|\n))*'''"))) {
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_spans.add(_HighlightSpan(
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_HighlightType.string,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// "String"
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if (_scanner.scan(RegExp(r'"(?:[^"\\]|\\.)*"'))) {
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_spans.add(_HighlightSpan(
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_HighlightType.string,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// 'String'
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if (_scanner.scan(RegExp(r"'(?:[^'\\]|\\.)*'"))) {
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_spans.add(_HighlightSpan(
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_HighlightType.string,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// Double
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if (_scanner.scan(RegExp(r'\d+\.\d+'))) {
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_spans.add(_HighlightSpan(
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_HighlightType.number,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// Integer
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if (_scanner.scan(RegExp(r'\d+'))) {
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_spans.add(_HighlightSpan(_HighlightType.number,
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_scanner.lastMatch.start, _scanner.lastMatch.end));
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continue;
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}
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// Punctuation
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if (_scanner.scan(RegExp(r'[\[\]{}().!=<>&\|\?\+\-\*/%\^~;:,]'))) {
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_spans.add(_HighlightSpan(
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_HighlightType.punctuation,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// Meta data
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if (_scanner.scan(RegExp(r'@\w+'))) {
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_spans.add(_HighlightSpan(
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_HighlightType.keyword,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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continue;
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}
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// Words
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if (_scanner.scan(RegExp(r'\w+'))) {
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_HighlightType type;
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String word = _scanner.lastMatch[0];
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if (word.startsWith('_')) {
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word = word.substring(1);
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}
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if (_keywords.contains(word)) {
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type = _HighlightType.keyword;
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} else if (_builtInTypes.contains(word)) {
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type = _HighlightType.keyword;
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} else if (_firstLetterIsUpperCase(word)) {
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type = _HighlightType.klass;
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} else if (word.length >= 2 &&
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word.startsWith('k') &&
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_firstLetterIsUpperCase(word.substring(1))) {
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type = _HighlightType.constant;
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}
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if (type != null) {
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_spans.add(_HighlightSpan(
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type,
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_scanner.lastMatch.start,
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_scanner.lastMatch.end,
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));
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}
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}
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// Check if this loop did anything
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if (lastLoopPosition == _scanner.position) {
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// Failed to parse this file, abort gracefully
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return false;
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}
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lastLoopPosition = _scanner.position;
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}
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_simplify();
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return true;
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}
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void _simplify() {
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for (int i = _spans.length - 2; i >= 0; i -= 1) {
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if (_spans[i].type == _spans[i + 1].type &&
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_spans[i].end == _spans[i + 1].start) {
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_spans[i] = _HighlightSpan(
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_spans[i].type,
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_spans[i].start,
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_spans[i + 1].end,
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);
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_spans.removeAt(i + 1);
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}
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}
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}
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bool _firstLetterIsUpperCase(String str) {
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if (str.isNotEmpty) {
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final String first = str.substring(0, 1);
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return first == first.toUpperCase();
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}
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return false;
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}
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}
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enum _HighlightType {
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number,
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comment,
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keyword,
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string,
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punctuation,
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klass,
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constant,
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base,
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}
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class _HighlightSpan {
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_HighlightSpan(this.type, this.start, this.end);
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final _HighlightType type;
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final int start;
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final int end;
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String textForSpan(String src) {
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return src.substring(start, end);
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}
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}
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class CodeSpan {
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CodeSpan({this.type = _HighlightType.base, this.text});
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final _HighlightType type;
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final String text;
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@override
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String toString() {
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return 'TextSpan('
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'style: codeStyle.${_styleNameOf(type)}, '
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"text: '${_escape(text)}'"
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')';
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}
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}
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String _styleNameOf(_HighlightType type) {
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switch (type) {
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case _HighlightType.number:
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return 'numberStyle';
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case _HighlightType.comment:
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return 'commentStyle';
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case _HighlightType.keyword:
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return 'keywordStyle';
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case _HighlightType.string:
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return 'stringStyle';
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case _HighlightType.punctuation:
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return 'punctuationStyle';
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case _HighlightType.klass:
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return 'classStyle';
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case _HighlightType.constant:
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return 'constantStyle';
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case _HighlightType.base:
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return 'baseStyle';
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}
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return '';
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}
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String _escape(String text) {
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StringBuffer escapedText = StringBuffer();
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for (final char in text.runes) {
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if (char < 0x20 ||
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char >= 0x7F ||
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char == 0x22 ||
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char == 0x24 ||
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char == 0x27 ||
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char == 0x5C) {
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if (char <= 0xffff) {
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escapedText.write("\\u${_encodeAndPad(char)}");
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} else {
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escapedText.write("\\u{${_encode(char)}}");
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}
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} else {
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escapedText.write(String.fromCharCode(char));
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}
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}
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return escapedText.toString();
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}
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String _encode(int charCode) {
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return charCode.toRadixString(16);
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}
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String _encodeAndPad(int charCode) {
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String encoded = _encode(charCode);
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return '0' * (4 - encoded.length) + encoded;
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}
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