Fix bug in source-maps parsing: parser failed when most information could be

pkg/source_maps/lib/parser.dart

 // Copyright (c) 2013, 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.
 
 /// Contains the top-level function to parse source maps version 3.
 library source_maps.parser;
 
 import 'dart:json' as json;
 
 import 'span.dart';
 import 'src/utils.dart';
 import 'src/vlq.dart';
 
 /// Parses a source map directly from a json string.
 // TODO(sigmund): evaluate whether other maps should have the json parsed, or
 // the string represenation.
 Mapping parse(String jsonMap, {Map<String, Map> otherMaps}) =>
   parseJson(json.parse(jsonMap), otherMaps: otherMaps);
 
 /// Parses a source map directly from a json map object.
 Mapping parseJson(Map map, {Map<String, Map> otherMaps}) {
   if (map['version'] != 3) {
     throw new ArgumentError(
         'unexpected source map version: ${map["version"]}. '
         'Only version 3 is supported.');
   }
 
-  // TODO(sigmund): relax this? dart2js doesn't generate the file entry.
   if (!map.containsKey('file')) {
-    throw new ArgumentError('missing "file" in source map');
+    print('warning: missing "file" entry in source map');
   }
 
   if (map.containsKey('sections')) {
     if (map.containsKey('mappings') || map.containsKey('sources') ||
         map.containsKey('names')) {
       throw new FormatException('map containing "sections" '
           'cannot contain "mappings", "sources", or "names".');
     }
     return new MultiSectionMapping.fromJson(map['sections'], otherMaps);
   }
@@ skipping 138 matching lines @@
       // following order:
       //   0: the starting column in the current line of the generated file
       //   1: the id of the original source file
       //   2: the starting line in the original source
       //   3: the starting column in the original source
       //   4: the id of the original symbol name
       // The values are relative to the previous encountered values.
       if (tokenizer.nextKind.isNewSegment) throw _segmentError(0, line);
       column += tokenizer._consumeValue();
       if (!tokenizer.nextKind.isValue) {
-        entries.add(new TargetEntry(column));
+        entries.add(new TargetEntry(column, srcUrlId, srcLine, srcColumn));
       } else {
         srcUrlId += tokenizer._consumeValue();
         if (srcUrlId >= urls.length) {
           throw new StateError(
               'Invalid source url id. $targetUrl, $line, $srcUrlId');
         }
         if (!tokenizer.nextKind.isValue) throw _segmentError(2, line);
         srcLine += tokenizer._consumeValue();
         if (!tokenizer.nextKind.isValue) throw _segmentError(3, line);
         srcColumn += tokenizer._consumeValue();
@@ skipping 35 matching lines @@
   /// the very last entry on that line.
   TargetEntry _findColumn(int line, int column, TargetLineEntry lineEntry) {
     if (lineEntry == null || lineEntry.entries.length == 0) return null;
     if (lineEntry.line != line) return lineEntry.entries.last;
     var entries = lineEntry.entries;
     int index = binarySearch(entries, (e) => e.column > column);
     return (index <= 0) ? null : entries[index - 1];
   }
 
   Span spanFor(int line, int column, {Map<String, SourceFile> files}) {
-    var lineEntry = _findLine(line);
     var entry = _findColumn(line, column, _findLine(line));
     if (entry == null) return null;
     var url = urls[entry.sourceUrlId];
     if (files != null && files[url] != null) {
       var file = files[url];
       var start = file.getOffset(entry.sourceLine, entry.sourceColumn);
       if (entry.sourceNameId != null) {
         var text = names[entry.sourceNameId];
         return new FileSpan(files[url], start, start + text.length, true);
       } else {
@@ skipping 60 matching lines @@
   String toString() => '$runtimeType: $line $entries';
 }
 
 /// A target segment entry read from a source map
 class TargetEntry {
   final int column;
   final int sourceUrlId;
   final int sourceLine;
   final int sourceColumn;
   final int sourceNameId;
-  TargetEntry(this.column, [this.sourceUrlId, this.sourceLine,
-      this.sourceColumn, this.sourceNameId]);
+
+  TargetEntry(this.column, this.sourceUrlId, this.sourceLine,
+      this.sourceColumn, [this.sourceNameId]);
 
   String toString() => '$runtimeType: '
       '($column, $sourceUrlId, $sourceLine, $sourceColumn, $sourceNameId)';
 }
 
 /** A character iterator over a string that can peek one character ahead. */
 class _MappingTokenizer implements Iterator<String> {
   final String _internal;
   final int _length;
   int index = -1;
@@ skipping 44 matching lines @@
   static const _TokenKind EOF = const _TokenKind(isEof: true);
   static const _TokenKind VALUE = const _TokenKind();
   final bool isNewLine;
   final bool isNewSegment;
   final bool isEof;
   bool get isValue => !isNewLine && !isNewSegment && !isEof;
 
   const _TokenKind(
       {this.isNewLine: false, this.isNewSegment: false, this.isEof: false});
 }