Attach source range information to parsed YAML nodes.

pkg/yaml/lib/src/parser.dart

 // Copyright (c) 2012, 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.
 
 library yaml.parser;
 
 import 'dart:collection';
 
+import 'package:source_maps/source_maps.dart';
 import 'package:string_scanner/string_scanner.dart';
 
+import 'equality.dart';
 import 'model.dart';
+import 'utils.dart';
 import 'yaml_exception.dart';
-import 'yaml_map.dart';
 
 /// Translates a string of characters into a YAML serialization tree.
 ///
 /// This parser is designed to closely follow the spec. All productions in the
 /// spec are numbered, and the corresponding methods in the parser have the same
 /// numbers. This is certainly not the most efficient way of parsing YAML, but
 /// it is the easiest to write and read in the context of the spec.
 ///
 /// Methods corresponding to productions are also named as in the spec,
 /// translating the name of the method (although not the annotation characters)
@@ skipping 286 matching lines @@
     return res;
   }
 
   void flushCapture() {
     _capturedString.write(_scanner.string.substring(
         _captureStart, _scanner.position));
     _captureStart = _scanner.position;
   }
 
   /// Adds a tag and an anchor to [node], if they're defined.
-  Node addProps(Node node, _Pair<Tag, String> props) {
+  Node addProps(Node node, Pair<Tag, String> props) {
     if (props == null || node == null) return node;
     if (truth(props.first)) node.tag = props.first;
     if (truth(props.last)) node.anchor = props.last;
     return node;
   }
 
   /// Creates a MappingNode from [pairs].
-  MappingNode map(List<_Pair<Node, Node>> pairs) {
+  MappingNode map(List<Pair<Node, Node>> pairs, Span span) {
     var content = new Map<Node, Node>();
     pairs.forEach((pair) => content[pair.first] = pair.last);
-    return new MappingNode("?", content);
+    return new MappingNode("?", content, span);
   }
 
   /// Runs [fn] in a context named [name]. Used for error reporting.
   context(String name, fn()) {
     try {
       _contextStack.add(name);
       return fn();
     } finally {
       var popped = _contextStack.removeLast();
       assert(popped == name);
@@ skipping 410 matching lines @@
   // 81
   bool s_separateLines(int indent) {
     return transaction(() => s_l_comments() && s_flowLinePrefix(indent)) ||
       s_separateInLine();
   }
 
   // 82
   bool l_directive() => false; // TODO(nweiz): implement
 
   // 96
-  _Pair<Tag, String> c_ns_properties(int indent, int ctx) {
+  Pair<Tag, String> c_ns_properties(int indent, int ctx) {
     var tag, anchor;
     tag = c_ns_tagProperty();
     if (truth(tag)) {
       anchor = transaction(() {
         if (!truth(s_separate(indent, ctx))) return null;
         return c_ns_anchorProperty();
       });
-      return new _Pair<Tag, String>(tag, anchor);
+      return new Pair<Tag, String>(tag, anchor);
     }
 
     anchor = c_ns_anchorProperty();
     if (truth(anchor)) {
       tag = transaction(() {
         if (!truth(s_separate(indent, ctx))) return null;
         return c_ns_tagProperty();
       });
-      return new _Pair<Tag, String>(tag, anchor);
+      return new Pair<Tag, String>(tag, anchor);
     }
 
     return null;
   }
 
   // 97
   Tag c_ns_tagProperty() => null; // TODO(nweiz): implement
 
   // 101
   String c_ns_anchorProperty() => null; // TODO(nweiz): implement
 
   // 102
   bool isAnchorChar(int char) => isNonSpace(char) && !isFlowIndicator(char);
 
   // 103
   String ns_anchorName() =>
     captureString(() => oneOrMore(() => consume(isAnchorChar)));
 
   // 104
   Node c_ns_aliasNode() {
+    var start = _scanner.state;
     if (!truth(c_indicator(C_ALIAS))) return null;
     var name = expect(ns_anchorName(), 'anchor name');
-    return new AliasNode(name);
+    return new AliasNode(name, _scanner.spanFrom(start));
   }
 
   // 105
-  ScalarNode e_scalar() => new ScalarNode("?", content: "");
+  ScalarNode e_scalar() => new ScalarNode("?", _scanner.emptySpan, content: "");
 
   // 106
   ScalarNode e_node() => e_scalar();
 
   // 107
   bool nb_doubleChar() => or([
     c_ns_escChar,
     () => consume((c) => isJson(c) && c != BACKSLASH && c != DOUBLE_QUOTE)
   ]);
 
   // 108
   bool ns_doubleChar() => !isSpace(peek()) && truth(nb_doubleChar());
 
   // 109
   Node c_doubleQuoted(int indent, int ctx) => context('string', () {
     return transaction(() {
+      var start = _scanner.state;
       if (!truth(c_indicator(C_DOUBLE_QUOTE))) return null;
       var contents = nb_doubleText(indent, ctx);
       if (!truth(c_indicator(C_DOUBLE_QUOTE))) return null;
-      return new ScalarNode("!", content: contents);
+      return new ScalarNode("!", _scanner.spanFrom(start), content: contents);
     });
   });
 
   // 110
   String nb_doubleText(int indent, int ctx) => captureString(() {
     switch (ctx) {
     case FLOW_OUT:
     case FLOW_IN:
       nb_doubleMultiLine(indent);
       break;
@@ skipping 64 matching lines @@
     c_quotedQuote,
     () => consume((c) => isJson(c) && c != SINGLE_QUOTE)
   ]);
 
   // 119
   bool ns_singleChar() => !isSpace(peek()) && truth(nb_singleChar());
 
   // 120
   Node c_singleQuoted(int indent, int ctx) => context('string', () {
     return transaction(() {
+      var start = _scanner.state;
       if (!truth(c_indicator(C_SINGLE_QUOTE))) return null;
       var contents = nb_singleText(indent, ctx);
       if (!truth(c_indicator(C_SINGLE_QUOTE))) return null;
-      return new ScalarNode("!", content: contents);
+      return new ScalarNode("!", _scanner.spanFrom(start), content: contents);
     });
   });
 
   // 121
   String nb_singleText(int indent, int ctx) => captureString(() {
     switch (ctx) {
     case FLOW_OUT:
     case FLOW_IN:
       nb_singleMultiLine(indent);
       break;
@@ skipping 143 matching lines @@
         return FLOW_IN;
       case BLOCK_KEY:
       case FLOW_KEY:
         return FLOW_KEY;
     }
     throw "unreachable";
   }
 
   // 137
   SequenceNode c_flowSequence(int indent, int ctx) => transaction(() {
+    var start = _scanner.state;
     if (!truth(c_indicator(C_SEQUENCE_START))) return null;
     zeroOrOne(() => s_separate(indent, ctx));
     var content = zeroOrOne(() => ns_s_flowSeqEntries(indent, inFlow(ctx)));
     if (!truth(c_indicator(C_SEQUENCE_END))) return null;
-    return new SequenceNode("?", new List<Node>.from(content));
+    return new SequenceNode("?", new List<Node>.from(content),
+        _scanner.spanFrom(start));
   });
 
   // 138
   Iterable<Node> ns_s_flowSeqEntries(int indent, int ctx) {
     var first = ns_flowSeqEntry(indent, ctx);
     if (!truth(first)) return new Queue<Node>();
     zeroOrOne(() => s_separate(indent, ctx));
 
     var rest;
     if (truth(c_indicator(C_COLLECT_ENTRY))) {
       zeroOrOne(() => s_separate(indent, ctx));
       rest = zeroOrOne(() => ns_s_flowSeqEntries(indent, ctx));
     }
 
     if (rest == null) rest = new Queue<Node>();
     rest.addFirst(first);
 
     return rest;
   }
 
   // 139
   Node ns_flowSeqEntry(int indent, int ctx) => or([
     () => ns_flowPair(indent, ctx),
     () => ns_flowNode(indent, ctx)
   ]);
 
   // 140
   Node c_flowMapping(int indent, int ctx) {
+    var start = _scanner.state;
     if (!truth(c_indicator(C_MAPPING_START))) return null;
     zeroOrOne(() => s_separate(indent, ctx));
     var content = zeroOrOne(() => ns_s_flowMapEntries(indent, inFlow(ctx)));
     if (!truth(c_indicator(C_MAPPING_END))) return null;
-    return new MappingNode("?", content);
+    return new MappingNode("?", content, _scanner.spanFrom(start));
   }
 
   // 141
-  YamlMap ns_s_flowMapEntries(int indent, int ctx) {
+  Map ns_s_flowMapEntries(int indent, int ctx) {
     var first = ns_flowMapEntry(indent, ctx);
-    if (!truth(first)) return new YamlMap();
+    if (!truth(first)) return deepEqualsMap();
     zeroOrOne(() => s_separate(indent, ctx));
 
     var rest;
     if (truth(c_indicator(C_COLLECT_ENTRY))) {
       zeroOrOne(() => s_separate(indent, ctx));
       rest = ns_s_flowMapEntries(indent, ctx);
     }
 
-    if (rest == null) rest = new YamlMap();
+    if (rest == null) rest = deepEqualsMap();
 
     // TODO(nweiz): Duplicate keys should be an error. This includes keys with
     // different representations but the same value (e.g. 10 vs 0xa). To make
     // this user-friendly we'll probably also want to associate nodes with a
     // source range.
     if (!rest.containsKey(first.first)) rest[first.first] = first.last;
 
     return rest;
   }
 
   // 142
-  _Pair<Node, Node> ns_flowMapEntry(int indent, int ctx) => or([
+  Pair<Node, Node> ns_flowMapEntry(int indent, int ctx) => or([
     () => transaction(() {
       if (!truth(c_indicator(C_MAPPING_KEY))) return false;
       if (!truth(s_separate(indent, ctx))) return false;
       return ns_flowMapExplicitEntry(indent, ctx);
     }),
     () => ns_flowMapImplicitEntry(indent, ctx)
   ]);
 
   // 143
-  _Pair<Node, Node> ns_flowMapExplicitEntry(int indent, int ctx) => or([
+  Pair<Node, Node> ns_flowMapExplicitEntry(int indent, int ctx) => or([
     () => ns_flowMapImplicitEntry(indent, ctx),
-    () => new _Pair<Node, Node>(e_node(), e_node())
+    () => new Pair<Node, Node>(e_node(), e_node())
   ]);
 
   // 144
-  _Pair<Node, Node> ns_flowMapImplicitEntry(int indent, int ctx) => or([
+  Pair<Node, Node> ns_flowMapImplicitEntry(int indent, int ctx) => or([
     () => ns_flowMapYamlKeyEntry(indent, ctx),
     () => c_ns_flowMapEmptyKeyEntry(indent, ctx),
     () => c_ns_flowMapJsonKeyEntry(indent, ctx)
   ]);
 
   // 145
-  _Pair<Node, Node> ns_flowMapYamlKeyEntry(int indent, int ctx) {
+  Pair<Node, Node> ns_flowMapYamlKeyEntry(int indent, int ctx) {
     var key = ns_flowYamlNode(indent, ctx);
     if (!truth(key)) return null;
     var value = or([
       () => transaction(() {
         zeroOrOne(() => s_separate(indent, ctx));
         return c_ns_flowMapSeparateValue(indent, ctx);
       }),
       e_node
     ]);
-    return new _Pair<Node, Node>(key, value);
+    return new Pair<Node, Node>(key, value);
   }
 
   // 146
-  _Pair<Node, Node> c_ns_flowMapEmptyKeyEntry(int indent, int ctx) {
+  Pair<Node, Node> c_ns_flowMapEmptyKeyEntry(int indent, int ctx) {
     var value = c_ns_flowMapSeparateValue(indent, ctx);
     if (!truth(value)) return null;
-    return new _Pair<Node, Node>(e_node(), value);
+    return new Pair<Node, Node>(e_node(), value);
   }
 
   // 147
   Node c_ns_flowMapSeparateValue(int indent, int ctx) => transaction(() {
     if (!truth(c_indicator(C_MAPPING_VALUE))) return null;
     if (isPlainSafe(ctx, peek())) return null;
 
     return or([
       () => transaction(() {
         if (!s_separate(indent, ctx)) return null;
         return ns_flowNode(indent, ctx);
       }),
       e_node
     ]);
   });
 
   // 148
-  _Pair<Node, Node> c_ns_flowMapJsonKeyEntry(int indent, int ctx) {
+  Pair<Node, Node> c_ns_flowMapJsonKeyEntry(int indent, int ctx) {
     var key = c_flowJsonNode(indent, ctx);
     if (!truth(key)) return null;
     var value = or([
       () => transaction(() {
         zeroOrOne(() => s_separate(indent, ctx));
         return c_ns_flowMapAdjacentValue(indent, ctx);
       }),
       e_node
     ]);
-    return new _Pair<Node, Node>(key, value);
+    return new Pair<Node, Node>(key, value);
   }
 
   // 149
   Node c_ns_flowMapAdjacentValue(int indent, int ctx) {
     if (!truth(c_indicator(C_MAPPING_VALUE))) return null;
     return or([
       () => transaction(() {
         zeroOrOne(() => s_separate(indent, ctx));
         return ns_flowNode(indent, ctx);
       }),
       e_node
     ]);
   }
 
   // 150
   Node ns_flowPair(int indent, int ctx) {
+    var start = _scanner.state;
     var pair = or([
       () => transaction(() {
         if (!truth(c_indicator(C_MAPPING_KEY))) return null;
         if (!truth(s_separate(indent, ctx))) return null;
         return ns_flowMapExplicitEntry(indent, ctx);
       }),
       () => ns_flowPairEntry(indent, ctx)
     ]);
     if (!truth(pair)) return null;
 
-    return map([pair]);
+    return map([pair], _scanner.spanFrom(start));
   }
 
   // 151
-  _Pair<Node, Node> ns_flowPairEntry(int indent, int ctx) => or([
+  Pair<Node, Node> ns_flowPairEntry(int indent, int ctx) => or([
     () => ns_flowPairYamlKeyEntry(indent, ctx),
     () => c_ns_flowMapEmptyKeyEntry(indent, ctx),
     () => c_ns_flowPairJsonKeyEntry(indent, ctx)
   ]);
 
   // 152
-  _Pair<Node, Node> ns_flowPairYamlKeyEntry(int indent, int ctx) =>
+  Pair<Node, Node> ns_flowPairYamlKeyEntry(int indent, int ctx) =>
     transaction(() {
       var key = ns_s_implicitYamlKey(FLOW_KEY);
       if (!truth(key)) return null;
       var value = c_ns_flowMapSeparateValue(indent, ctx);
       if (!truth(value)) return null;
-      return new _Pair<Node, Node>(key, value);
+      return new Pair<Node, Node>(key, value);
     });
 
   // 153
-  _Pair<Node, Node> c_ns_flowPairJsonKeyEntry(int indent, int ctx) =>
+  Pair<Node, Node> c_ns_flowPairJsonKeyEntry(int indent, int ctx) =>
     transaction(() {
       var key = c_s_implicitJsonKey(FLOW_KEY);
       if (!truth(key)) return null;
       var value = c_ns_flowMapAdjacentValue(indent, ctx);
       if (!truth(value)) return null;
-      return new _Pair<Node, Node>(key, value);
+      return new Pair<Node, Node>(key, value);
     });
 
   // 154
   Node ns_s_implicitYamlKey(int ctx) => transaction(() {
     // TODO(nweiz): this is supposed to be limited to 1024 characters.
 
     // The indentation parameter is "null" since it's unused in this path
     var node = ns_flowYamlNode(null, ctx);
     if (!truth(node)) return null;
     zeroOrOne(s_separateInLine);
     return node;
   });
 
   // 155
   Node c_s_implicitJsonKey(int ctx) => transaction(() {
     // TODO(nweiz): this is supposed to be limited to 1024 characters.
 
     // The indentation parameter is "null" since it's unused in this path
     var node = c_flowJsonNode(null, ctx);
     if (!truth(node)) return null;
     zeroOrOne(s_separateInLine);
     return node;
   });
 
   // 156
   Node ns_flowYamlContent(int indent, int ctx) {
+    var start = _scanner.state;
     var str = ns_plain(indent, ctx);
     if (!truth(str)) return null;
-    return new ScalarNode("?", content: str);
+    return new ScalarNode("?", _scanner.spanFrom(start), content: str);
   }
 
   // 157
   Node c_flowJsonContent(int indent, int ctx) => or([
     () => c_flowSequence(indent, ctx),
     () => c_flowMapping(indent, ctx),
     () => c_singleQuoted(indent, ctx),
     () => c_doubleQuoted(indent, ctx)
   ]);
 
@@ skipping 126 matching lines @@
   bool l_trailComments(int indent) => transaction(() {
     if (!truth(s_indentLessThanOrEqualTo(indent))) return false;
     if (!truth(c_nb_commentText())) return false;
     if (!truth(b_comment())) return false;
     zeroOrMore(l_comment);
     return true;
   });
 
   // 170
   Node c_l_literal(int indent) => transaction(() {
+    var start = _scanner.state;
     if (!truth(c_indicator(C_LITERAL))) return null;
     var header = c_b_blockHeader();
     if (!truth(header)) return null;
 
     var additionalIndent = blockScalarAdditionalIndentation(header, indent);
     var content = l_literalContent(indent + additionalIndent, header.chomping);
     if (!truth(content)) return null;
 
-    return new ScalarNode("!", content: content);
+    return new ScalarNode("!", _scanner.spanFrom(start), content: content);
   });
 
   // 171
   bool l_nb_literalText(int indent) => transaction(() {
     zeroOrMore(() => captureAs("\n", () => l_empty(indent, BLOCK_IN)));
     if (!truth(captureAs("", () => s_indent(indent)))) return false;
     return truth(oneOrMore(() => consume(isNonBreak)));
   });
 
   // 172
   bool b_nb_literalNext(int indent) => transaction(() {
     if (!truth(b_asLineFeed())) return false;
     return l_nb_literalText(indent);
   });
 
   // 173
   String l_literalContent(int indent, int chomping) => captureString(() {
     transaction(() {
       if (!truth(l_nb_literalText(indent))) return false;
       zeroOrMore(() => b_nb_literalNext(indent));
       return b_chompedLast(chomping);
     });
     l_chompedEmpty(indent, chomping);
     return true;
   });
 
   // 174
   Node c_l_folded(int indent) => transaction(() {
+    var start = _scanner.state;
     if (!truth(c_indicator(C_FOLDED))) return null;
     var header = c_b_blockHeader();
     if (!truth(header)) return null;
 
     var additionalIndent = blockScalarAdditionalIndentation(header, indent);
     var content = l_foldedContent(indent + additionalIndent, header.chomping);
     if (!truth(content)) return null;
 
-    return new ScalarNode("!", content: content);
+    return new ScalarNode("!", _scanner.spanFrom(start), content: content);
   });
 
   // 175
   bool s_nb_foldedText(int indent) => transaction(() {
     if (!truth(captureAs('', () => s_indent(indent)))) return false;
     if (!truth(consume(isNonSpace))) return false;
     zeroOrMore(() => consume(isNonBreak));
     return true;
   });
 
@@ skipping 59 matching lines @@
     });
     l_chompedEmpty(indent, chomping);
     return true;
   });
 
   // 183
   SequenceNode l_blockSequence(int indent) => context('sequence', () {
     var additionalIndent = countIndentation() - indent;
     if (additionalIndent <= 0) return null;
 
+    var start = _scanner.state;
     var content = oneOrMore(() => transaction(() {
       if (!truth(s_indent(indent + additionalIndent))) return null;
       return c_l_blockSeqEntry(indent + additionalIndent);
     }));
     if (!truth(content)) return null;
 
-    return new SequenceNode("?", content);
+    return new SequenceNode("?", content, _scanner.spanFrom(start));
   });
 
   // 184
   Node c_l_blockSeqEntry(int indent) => transaction(() {
     if (!truth(c_indicator(C_SEQUENCE_ENTRY))) return null;
     if (isNonSpace(peek())) return null;
 
     return s_l_blockIndented(indent, BLOCK_IN);
   });
 
   // 185
   Node s_l_blockIndented(int indent, int ctx) {
     var additionalIndent = countIndentation();
     return or([
       () => transaction(() {
         if (!truth(s_indent(additionalIndent))) return null;
         return or([
           () => ns_l_compactSequence(indent + 1 + additionalIndent),
           () => ns_l_compactMapping(indent + 1 + additionalIndent)]);
       }),
       () => s_l_blockNode(indent, ctx),
       () => s_l_comments() ? e_node() : null]);
   }
 
   // 186
   Node ns_l_compactSequence(int indent) => context('sequence', () {
+    var start = _scanner.state;
     var first = c_l_blockSeqEntry(indent);
     if (!truth(first)) return null;
 
     var content = zeroOrMore(() => transaction(() {
         if (!truth(s_indent(indent))) return null;
         return c_l_blockSeqEntry(indent);
       }));
     content.insert(0, first);
 
-    return new SequenceNode("?", content);
+    return new SequenceNode("?", content, _scanner.spanFrom(start));
   });
 
   // 187
   Node l_blockMapping(int indent) => context('mapping', () {
     var additionalIndent = countIndentation() - indent;
     if (additionalIndent <= 0) return null;
 
+    var start = _scanner.state;
     var pairs = oneOrMore(() => transaction(() {
       if (!truth(s_indent(indent + additionalIndent))) return null;
       return ns_l_blockMapEntry(indent + additionalIndent);
     }));
     if (!truth(pairs)) return null;
 
-    return map(pairs);
+    return map(pairs, _scanner.spanFrom(start));
   });
 
   // 188
-  _Pair<Node, Node> ns_l_blockMapEntry(int indent) => or([
+  Pair<Node, Node> ns_l_blockMapEntry(int indent) => or([
     () => c_l_blockMapExplicitEntry(indent),
     () => ns_l_blockMapImplicitEntry(indent)
   ]);
 
   // 189
-  _Pair<Node, Node> c_l_blockMapExplicitEntry(int indent) {
+  Pair<Node, Node> c_l_blockMapExplicitEntry(int indent) {
     var key = c_l_blockMapExplicitKey(indent);
     if (!truth(key)) return null;
 
     var value = or([
       () => l_blockMapExplicitValue(indent),
       e_node
     ]);
 
-    return new _Pair<Node, Node>(key, value);
+    return new Pair<Node, Node>(key, value);
   }
 
   // 190
   Node c_l_blockMapExplicitKey(int indent) => transaction(() {
     if (!truth(c_indicator(C_MAPPING_KEY))) return null;
     return s_l_blockIndented(indent, BLOCK_OUT);
   });
 
   // 191
   Node l_blockMapExplicitValue(int indent) => transaction(() {
     if (!truth(s_indent(indent))) return null;
     if (!truth(c_indicator(C_MAPPING_VALUE))) return null;
     return s_l_blockIndented(indent, BLOCK_OUT);
   });
 
   // 192
-  _Pair<Node, Node> ns_l_blockMapImplicitEntry(int indent) => transaction(() {
+  Pair<Node, Node> ns_l_blockMapImplicitEntry(int indent) => transaction(() {
     var key = or([ns_s_blockMapImplicitKey, e_node]);
     var value = c_l_blockMapImplicitValue(indent);
-    return truth(value) ? new _Pair<Node, Node>(key, value) : null;
+    return truth(value) ? new Pair<Node, Node>(key, value) : null;
   });
 
   // 193
   Node ns_s_blockMapImplicitKey() => context('mapping key', () => or([
     () => c_s_implicitJsonKey(BLOCK_KEY),
     () => ns_s_implicitYamlKey(BLOCK_KEY)
   ]));
 
   // 194
   Node c_l_blockMapImplicitValue(int indent) => context('mapping value', () =>
     transaction(() {
       if (!truth(c_indicator(C_MAPPING_VALUE))) return null;
       return or([
         () => s_l_blockNode(indent, BLOCK_OUT),
         () => s_l_comments() ? e_node() : null
       ]);
     }));
 
   // 195
   Node ns_l_compactMapping(int indent) => context('mapping', () {
+    var start = _scanner.state;
     var first = ns_l_blockMapEntry(indent);
     if (!truth(first)) return null;
 
     var pairs = zeroOrMore(() => transaction(() {
         if (!truth(s_indent(indent))) return null;
         return ns_l_blockMapEntry(indent);
       }));
     pairs.insert(0, first);
 
-    return map(pairs);
+    return map(pairs, _scanner.spanFrom(start));
   });
 
   // 196
   Node s_l_blockNode(int indent, int ctx) => or([
     () => s_l_blockInBlock(indent, ctx),
     () => s_l_flowInBlock(indent)
   ]);
 
   // 197
   Node s_l_flowInBlock(int indent) => transaction(() {
@@ skipping 99 matching lines @@
     if (doc != null) return doc;
     parseFailed();
     return null; // Unreachable.
   }
 
   // 210
   Node l_anyDocument() =>
     or([l_directiveDocument, l_explicitDocument, l_bareDocument]);
 
   // 211
-  List<Node> l_yamlStream() {
+  Pair<List<Node>, Span> l_yamlStream() {
+    var start = _scanner.state;
     var docs = [];
     zeroOrMore(l_documentPrefix);
     var first = zeroOrOne(l_anyDocument);
     if (!truth(first)) first = e_node();
     docs.add(first);
 
     zeroOrMore(() {
       var doc;
       if (truth(oneOrMore(l_documentSuffix))) {
         zeroOrMore(l_documentPrefix);
         doc = zeroOrOne(l_anyDocument);
       } else {
         zeroOrMore(l_documentPrefix);
         doc = zeroOrOne(l_explicitDocument);
       }
       if (truth(doc)) docs.add(doc);
       return doc;
     });
 
     if (!_scanner.isDone) parseFailed();
-    return docs;
+    return new Pair(docs, _scanner.spanFrom(start));
   }
 }
 
-/// A pair of values.
-class _Pair<E, F> {
-  E first;
-  F last;
-
-  _Pair(this.first, this.last);
-
-  String toString() => '($first, $last)';
-}
-
 /// The information in the header for a block scalar.
 class _BlockHeader {
   final int additionalIndent;
   final int chomping;
 
   _BlockHeader(this.additionalIndent, this.chomping);
 
   bool get autoDetectIndent => additionalIndent == null;
 }
 
@@ skipping 10 matching lines @@
 
   /// Returns whether or not [pos] lies within this range.
   bool contains(int pos) => pos >= start && pos <= end;
 }
 
 /// A map that associates [E] values with [_Range]s. It's efficient to create
 /// new associations, but finding the value associated with a position is more
 /// expensive.
 class _RangeMap<E> {
   /// The ranges and their associated elements.
-  final List<_Pair<_Range, E>> _contents = <_Pair<_Range, E>>[];
+  final List<Pair<_Range, E>> _contents = <Pair<_Range, E>>[];
 
   _RangeMap();
 
   /// Returns the value associated with the range in which [pos] lies, or null
   /// if there is no such range. If there's more than one such range, the most
   /// recently set one is used.
   E operator[](int pos) {
     // Iterate backwards through contents so the more recent range takes
     // precedence.
     for (var pair in _contents.reversed) {
       if (pair.first.contains(pos)) return pair.last;
     }
     return null;
   }
 
   /// Associates [value] with [range].
   operator[]=(_Range range, E value) =>
-    _contents.add(new _Pair<_Range, E>(range, value));
+    _contents.add(new Pair<_Range, E>(range, value));
 }