Move Yaml into utils/pub.

utils/yaml/parser.dart

Index: utils/yaml/parser.dart
diff --git a/utils/yaml/parser.dart b/utils/yaml/parser.dart
deleted file mode 100644
index 78a0787f7d7c2f4b75e9d40ee9682fa021f5ac6c..0000000000000000000000000000000000000000
--- a/utils/yaml/parser.dart
+++ /dev/null
@@ -1,985 +0,0 @@
-// 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.
-
-/**
- * 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)
- * into camel-case for dart style.. For example, the spec has a production named
- * `nb-ns-plain-in-line`, and the method implementing it is named
- * `nb_ns_plainInLine`. The exception to that rule is methods that just
- * recognize character classes; these are named `is*`.
- */
-class _Parser {
-  static final TAB = 0x9;
-  static final LF = 0xA;
-  static final CR = 0xD;
-  static final SP = 0x20;
-  static final TILDE = 0x7E;
-  static final NEL = 0x85;
-  static final HYPHEN = 0x2D;
-  static final QUESTION_MARK = 0x3F;
-  static final COLON = 0x3A;
-  static final COMMA = 0x2C;
-  static final LEFT_BRACKET = 0x5B;
-  static final RIGHT_BRACKET = 0x5D;
-  static final LEFT_BRACE = 0x7B;
-  static final RIGHT_BRACE = 0x7D;
-  static final HASH = 0x23;
-  static final AMPERSAND = 0x26;
-  static final ASTERISK = 0x2A;
-  static final EXCLAMATION = 0x21;
-  static final VERTICAL_BAR = 0x7C;
-  static final GREATER_THAN = 0x3E;
-  static final SINGLE_QUOTE = 0x27;
-  static final DOUBLE_QUOTE = 0x22;
-  static final PERCENT = 0x25;
-  static final AT = 0x40;
-  static final GRAVE_ACCENT = 0x60;
-
-  static final NULL = 0x0;
-  static final BELL = 0x7;
-  static final BACKSPACE = 0x8;
-  static final VERTICAL_TAB = 0xB;
-  static final FORM_FEED = 0xC;
-  static final ESCAPE = 0x1B;
-  static final BACKSLASH = 0x5C;
-  static final NBSP = 0xA0;
-  static final LINE_SEPARATOR = 0x2028;
-  static final PARAGRAPH_SEPARATOR = 0x2029;
-
-  static final C_SEQUENCE_ENTRY = 4;
-  static final C_MAPPING_KEY = 5;
-  static final C_MAPPING_VALUE = 6;
-  static final C_COLLECT_ENTRY = 7;
-  static final C_SEQUENCE_START = 8;
-  static final C_SEQUENCE_END = 9;
-  static final C_MAPPING_START = 10;
-  static final C_MAPPING_END = 11;
-  static final C_COMMENT = 12;
-  static final C_ANCHOR = 13;
-  static final C_ALIAS = 14;
-  static final C_TAG = 15;
-  static final C_LITERAL = 16;
-  static final C_FOLDED = 17;
-  static final C_SINGLE_QUOTE = 18;
-  static final C_DOUBLE_QUOTE = 19;
-  static final C_DIRECTIVE = 20;
-  static final C_RESERVED = 21;
-
-  static final BLOCK_OUT = 0;
-  static final BLOCK_IN = 1;
-  static final FLOW_OUT = 2;
-  static final FLOW_IN = 3;
-  static final BLOCK_KEY = 4;
-  static final FLOW_KEY = 5;
-
-  /** The source string being parsed. */
-  final String s;
-
-  /** The current position in the source string. */
-  int pos = 0;
-
-  /** The length of the string being parsed. */
-  final int len;
-
-  /** The current (0-based) line in the source string. */
-  int line = 0;
-
-  /** The current (0-based) column in the source string. */
-  int column = 0;
-
-  /**
-   * Whether we're parsing a bare document (that is, one that doesn't begin with
-   * `---`). Bare documents don't allow `%` immediately following newlines.
-   */
-  bool inBareDocument = false;
-
-  /**
-   * The line number of the farthest position that has been parsed successfully
-   * before backtracking. Used for error reporting.
-   */
-  int farthestLine = 0;
-
-  /**
-   * The column number of the farthest position that has been parsed
-   * successfully before backtracking. Used for error reporting.
-   */
-  int farthestColumn = 0;
-
-  /**
-   * The name of the context of the farthest position that has been parsed
-   * successfully before backtracking. Used for error reporting.
-   */
-  String farthestContext = "document";
-
-  /** A stack of the names of parse contexts. Used for error reporting. */
-  List<String> contextStack;
-
-  _Parser(String s)
-    : this.s = s,
-      len = s.length,
-      contextStack = <String>["document"];
-
-  /**
-   * Return the character at the current position, then move that position
-   * forward one character. Also updates the current line and column numbers.
-   */
-  int next() {
-    if (pos == len) return -1;
-    var char = s.charCodeAt(pos++);
-    if (isBreak(char)) {
-      line++;
-      column = 0;
-    } else {
-      column++;
-    }
-
-    if (farthestLine < line) {
-      farthestLine = line;
-      farthestColumn = column;
-      farthestContext = contextStack.last();
-    } else if (farthestLine == line && farthestColumn < column) {
-      farthestColumn = column;
-      farthestContext = contextStack.last();
-    }
-
-    return char;
-  }
-
-  /**
-   * Returns the character at the current position, or the character [i]
-   * characters after the current position.
-   *
-   * Returns -1 if this would return a character after the end or before the
-   * beginning of the input string.
-   */
-  int peek([int i = 0]) {
-    var peekPos = pos + i;
-    return (peekPos >= len || peekPos < 0) ? -1 : s.charCodeAt(peekPos);
-  }
-
-  /**
-   * The truthiness operator. Returns `false` if [obj] is `null` or `false`,
-   * `true` otherwise.
-   */
-  bool truth(obj) => obj != null && obj != false;
-
-  /**
-   * Consumes the current character if it matches [matcher]. Returns the result
-   * of [matcher].
-   */
-  bool consume(bool matcher(int)) {
-    if (matcher(peek())) {
-      next();
-      return true;
-    }
-    return false;
-  }
-
-  /**
-   * Calls [consumer] until it returns a falsey value. Returns a list of all
-   * truthy return values of [consumer], or null if it didn't consume anything.
-   *
-   * Conceptually, repeats a production one or more times.
-   */
-  List oneOrMore(consumer()) {
-    var first = consumer();
-    if (!truth(first)) return null;
-    var out = [first];
-    while (true) {
-      var el = consumer();
-      if (!truth(el)) return out;
-      out.add(el);
-    }
-  }
-
-  /**
-   * Calls [consumer] until it returns a falsey value. Returns a list of all
-   * truthy return values of [consumer], or the empty list if it didn't consume
-   * anything.
-   *
-   * Conceptually, repeats a production any number of times.
-   */
-  List zeroOrMore(consumer()) {
-    var out = [];
-    var oldPos = pos;
-    while (true) {
-      var el = consumer();
-      if (!truth(el) || oldPos == pos) return out;
-      oldPos = pos;
-      out.add(el);
-    }
-  }
-
-  /**
-   * Just calls [consumer] and returns its result. Used to make it explicit that
-   * a production is intended to be optional.
-   */
-  zeroOrOne(consumer()) => consumer();
-
-  /**
-   * Calls each function in [consumers] until one returns a truthy value, then
-   * returns that.
-   */
-  or(List<Function> consumers) {
-    for (var c in consumers) {
-      var res = c();
-      if (truth(res)) return res;
-    }
-    return null;
-  }
-
-  /**
-   * Calls [consumer] and returns its result, but rolls back the parser state if
-   * [consumer] returns a falsey value.
-   */
-  transaction(consumer()) {
-    int oldPos = pos, oldLine = line, oldColumn = column;
-    var res = consumer();
-    if (truth(res)) return res;
-
-    pos = oldPos;
-    line = oldLine;
-    column = oldColumn;
-    return res;
-  }
-
-  /**
-   * Consumes [n] characters matching [matcher], or none if there isn't a
-   * complete match. The first argument to [matcher] is the character code, the
-   * second is the index (from 0 to [n] - 1).
-   *
-   * Returns whether or not the characters were consumed.
-   */
-  bool nAtOnce(int n, bool matcher(int c, int i)) => transaction(() {
-    for (int i = 0; i < n; i++) {
-      if (!consume((c) => matcher(c, i))) return false;
-    }
-    return true;
-  });
-
-  /**
-   * Consumes the exact characters in [str], or nothing.
-   *
-   * Returns whether or not the string was consumed.
-   */
-  bool rawString(String str) =>
-    nAtOnce(str.length, (c, i) => str.charCodeAt(i) == c);
-
-  /**
-   * Consumes and returns a string of characters matching [matcher], or null if
-   * there are no such characters.
-   */
-  String stringOf(bool matcher(int)) =>
-    captureString(() => oneOrMore(() => consume(matcher)));
-
-  /**
-   * Calls [consumer] and returns the string that was consumed while doing so,
-   * or null if [consumer] returned a falsey value. Automatically wraps
-   * [consumer] in `transaction`.
-   */
-  String captureString(consumer()) {
-    int start = pos;
-    var res = transaction(consumer);
-    if (!truth(res)) return null;
-    return s.substring(start, pos);
-  }
-
-  /**
-   * Adds a tag and an anchor to [node], if they're defined.
-   */
-  _Node addProps(_Node node, _Pair<_Tag, String> props) {
-    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) {
-    var content = new Map<_Node, _Node>();
-    pairs.forEach((pair) => content[pair.first] = pair.last);
-    return new _MappingNode("?", content);
-  }
-
-  /** 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);
-    }
-  }
-
-  /** Throws an error with additional context information. */
-  error(String message) {
-    // Line and column should be one-based.
-    throw new SyntaxError(line + 1, column + 1,
-        "$message (in $farthestContext)");
-  }
-
-  /**
-   * If [result] is falsey, throws an error saying that [expected] was
-   * expected.
-   */
-  expect(result, String expected) {
-    if (truth(result)) return result;
-    error("expected $expected");
-  }
-
-  /**
-   * Throws an error saying that the parse failed. Uses [farthestLine],
-   * [farthestColumn], and [farthestContext] to provide additional information.
-   */
-  parseFailed() {
-    throw new SyntaxError(farthestLine + 1, farthestColumn + 1,
-        "invalid YAML in $farthestContext");
-  }
-
-  /** Returns the number of spaces after the current position. */ 
-  int countIndentation() {
-    var i = 0;
-    while (peek(i) == SP) i++;
-    return i;
-  }
-
-  /** Returns whether the current position is at the beginning of a line. */
-  bool get atStartOfLine() => column == 0;
-
-  /** Returns whether the current position is at the end of the input. */
-  bool get atEndOfFile() => pos == len;
-
-  /**
-   * Given an indicator character, returns the type of that indicator (or null
-   * if the indicator isn't found.
-   */
-  int indicatorType(int char) {
-    switch (char) {
-    case HYPHEN: return C_SEQUENCE_ENTRY;
-    case QUESTION_MARK: return C_MAPPING_KEY;
-    case COLON: return C_MAPPING_VALUE;
-    case COMMA: return C_COLLECT_ENTRY;
-    case LEFT_BRACKET: return C_SEQUENCE_START;
-    case RIGHT_BRACKET: return C_SEQUENCE_END;
-    case LEFT_BRACE: return C_MAPPING_START;
-    case RIGHT_BRACE: return C_MAPPING_END;
-    case HASH: return C_COMMENT;
-    case AMPERSAND: return C_ANCHOR;
-    case ASTERISK: return C_ALIAS;
-    case EXCLAMATION: return C_TAG;
-    case VERTICAL_BAR: return C_LITERAL;
-    case GREATER_THAN: return C_FOLDED;
-    case SINGLE_QUOTE: return C_SINGLE_QUOTE;
-    case DOUBLE_QUOTE: return C_DOUBLE_QUOTE;
-    case PERCENT: return C_DIRECTIVE;
-    case AT:
-    case GRAVE_ACCENT:
-      return C_RESERVED;
-    default: return null;
-    }
-  }
-
-  // 1
-  bool isPrintable(int char) {
-    return char == TAB ||
-      char == LF ||
-      char == CR ||
-      (char >= SP && char <= TILDE) ||
-      char == NEL ||
-      (char >= 0xA0 && char <= 0xD7FF) ||
-      (char >= 0xE000 && char <= 0xFFFD) ||
-      (char >= 0x10000 && char <= 0x10FFFF);
-  }
-
-  // 22
-  bool c_indicator(int type) => consume((c) => indicatorType(c) == type);
-
-  // 23
-  bool isFlowIndicator(int char) {
-    var indicator = indicatorType(char);
-    return indicator == C_COLLECT_ENTRY ||
-      indicator == C_SEQUENCE_START ||
-      indicator == C_SEQUENCE_END ||
-      indicator == C_MAPPING_START ||
-      indicator == C_MAPPING_END;
-  }
-
-  // 26
-  bool isBreak(int char) => char == LF || char == CR;
-
-  // 27
-  bool isNonBreak(int char) => isPrintable(char) && !isBreak(char);
-
-  // 30
-  bool b_non_content() => consume(isBreak);
-
-  // 33
-  bool isSpace(int char) => char == SP || char == TAB;
-
-  // 34
-  bool isNonSpace(int char) => isNonBreak(char) && !isSpace(char);
-
-  // 63
-  bool s_indent(int indent) => nAtOnce(indent, (c, i) => c == SP);
-
-  // 66
-  bool s_separateInLine() => transaction(() =>
-    truth(oneOrMore(() => consume(isSpace))) || atStartOfLine);
-
-  // 69
-  bool s_flowLinePrefix(int indent) {
-    if (!s_indent(indent)) return false;
-    zeroOrOne(s_separateInLine);
-    return true;
-  }
-
-  // 74
-  bool s_flowFolded(int indent) => false; // TODO(nweiz): implement
-
-  // 75
-  bool c_nb_commentText() {
-    if (!c_indicator(C_COMMENT)) return false;
-    zeroOrMore(() => consume(isNonBreak));
-    return true;
-  }
-
-  // 76
-  bool b_comment() => atEndOfFile || b_non_content();
-
-  // 77
-  bool s_b_comment() {
-    if (s_separateInLine()) {
-      zeroOrOne(c_nb_commentText);
-    }
-    return b_comment();
-  }
-
-  // 78
-  bool l_comment() => transaction(() {
-    if (!s_separateInLine()) return false;
-    zeroOrOne(c_nb_commentText);
-    return b_comment();
-  });
-
-  // 79
-  bool s_l_comments() {
-    if (!s_b_comment() && !atStartOfLine) return false;
-    zeroOrMore(l_comment);
-    return true;
-  }
-
-  // 80
-  bool s_separate(int indent, int ctx) {
-    switch (ctx) {
-    case BLOCK_OUT:
-    case BLOCK_IN:
-    case FLOW_OUT:
-    case FLOW_IN:
-      return s_separateLines(indent);
-    case BLOCK_KEY:
-    case FLOW_KEY:
-      return s_separateInLine();
-    default: throw 'invalid context "$ctx"';
-    }
-  }
-
-  // 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) {
-    var tag, anchor;
-    tag = c_ns_tagProperty();
-    if (truth(tag)) {
-      anchor = transaction(() {
-        if (!s_separate(indent, ctx)) return null;
-        return c_ns_anchorProperty();
-      });
-      return new _Pair<_Tag, String>(tag, anchor);
-    }
-
-    anchor = c_ns_anchorProperty();
-    if (truth(anchor)) {
-      tag = transaction(() {
-        if (!s_separate(indent, ctx)) return null;
-        return c_ns_tagProperty();
-      });
-      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() {
-    if (!c_indicator(C_ALIAS)) return null;
-    var name = expect(ns_anchorName(), 'anchor name');
-    return new _AliasNode(name);
-  }
-
-  // 105
-  _ScalarNode e_scalar() => new _ScalarNode("?", content: "");
-
-  // 106
-  _ScalarNode e_node() => e_scalar();
-
-  // 126
-  bool ns_plainFirst(int ctx) {
-    var char = peek();
-    var indicator = indicatorType(char);
-    if (indicator == C_RESERVED) {
-      error("reserved indicators can't start a plain scalar");
-    }
-    var match = (isNonSpace(char) && indicator == null) ||
-      ((indicator == C_MAPPING_KEY ||
-        indicator == C_MAPPING_VALUE ||
-        indicator == C_SEQUENCE_ENTRY) &&
-       isPlainSafe(ctx, peek(1)));
-
-    if (match) next();
-    return match;
-  }
-
-  // 127
-  bool isPlainSafe(int ctx, int char) {
-    switch (ctx) {
-    case FLOW_OUT:
-    case BLOCK_KEY:
-      // 128
-      return isNonSpace(char);
-    case FLOW_IN:
-    case FLOW_KEY:
-      // 129
-      return isNonSpace(char) && !isFlowIndicator(char);
-    default: throw 'invalid context "$ctx"';
-    }
-  }
-
-  // 130
-  bool ns_plainChar(int ctx) {
-    var char = peek();
-    var indicator = indicatorType(char);
-    var safeChar = isPlainSafe(ctx, char) && indicator != C_MAPPING_VALUE &&
-      indicator != C_COMMENT;
-    var nonCommentHash = isNonSpace(peek(-1)) && indicator == C_COMMENT;
-    var nonMappingColon = indicator == C_MAPPING_VALUE &&
-      isPlainSafe(ctx, peek(1));
-    var match = safeChar || nonCommentHash || nonMappingColon;
-
-    if (match) next();
-    return match;
-  }
-
-  // 131
-  String ns_plain(int indent, int ctx) => context('plain scalar', () {
-    switch (ctx) {
-    case FLOW_OUT:
-    case FLOW_IN:
-      return ns_plainMultiLine(indent, ctx);
-    case BLOCK_KEY:
-    case FLOW_KEY:
-      return ns_plainOneLine(ctx);
-    default: throw 'invalid context "$ctx"';
-    }
-  });
-
-  // 132
-  void nb_ns_plainInLine(int ctx) {
-    zeroOrMore(() => transaction(() {
-      zeroOrMore(() => consume(isSpace));
-      return ns_plainChar(ctx);
-    }));
-  }
-
-  // 133
-  String ns_plainOneLine(int ctx) => captureString(() {
-    if (c_forbidden()) return false;
-    if (!ns_plainFirst(ctx)) return false;
-    nb_ns_plainInLine(ctx);
-    return true;
-  });
-
-  // 134
-  bool s_ns_plainNextLine(int indent, int ctx) => transaction(() {
-    if (c_forbidden()) return false;
-    if (!s_flowFolded(indent)) return false;
-    if (!ns_plainChar(ctx)) return false;
-    nb_ns_plainInLine(ctx);
-    return true;
-  });
-
-  // 135
-  String ns_plainMultiLine(int indent, int ctx) => captureString(() {
-    if (!truth(ns_plainOneLine(ctx))) return false;
-    zeroOrMore(() => s_ns_plainNextLine(indent, ctx));
-    return true;
-  });
-
-  // 154
-  _Node c_s_implicitYamlKey(int ctx) => transaction(() {
-    // 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) => null; // TODO(nweiz): implement
-
-  // 156
-  _Node ns_flowYamlContent(int indent, int ctx) {
-    var str = ns_plain(indent, ctx);
-    if (!truth(str)) return null;
-    return new _ScalarNode("?", content: str);
-  }
-
-  // 157
-  // TODO(nweiz): implement
-  _Node ns_flowJsonContent(int indent, int ctx) => null;
-
-  // 158
-  _Node ns_flowContent(int indent, int ctx) => or([
-    () => ns_flowYamlContent(indent, ctx),
-    () => ns_flowJsonContent(indent, ctx)
-  ]);
-
-  // 159
-  _Node ns_flowYamlNode(int indent, int ctx) => or([
-    c_ns_aliasNode,
-    () => ns_flowYamlContent(indent, ctx),
-    () {
-      var props = c_ns_properties(indent, ctx);
-      if (!truth(props)) return null;
-      var node = or([
-        () => transaction(() {
-          if (!s_separate(indent, ctx)) return null;
-          return ns_flowYamlContent(indent, ctx);
-        }),
-        e_scalar
-      ]);
-      return addProps(node, props);
-    }
-  ]);
-
-  // 161
-  _Node ns_flowNode(int indent, int ctx) => or([
-    c_ns_aliasNode,
-    () => ns_flowContent(indent, ctx),
-    () => transaction(() {
-      var props = c_ns_properties(indent, ctx);
-      if (!truth(props)) return null;
-      var node = or([
-        () => transaction(() => s_separate(indent, ctx) ?
-            ns_flowContent(indent, ctx) : null),
-        e_scalar]);
-      return addProps(node, props);
-    })
-  ]);
-
-  // 170
-  _Node c_l_literal(int indent) => null; // TODO(nweiz); implement
-
-  // 174
-  _Node c_l_folded(int indent) => null; // TODO(nweiz); implement
-
-  // 183
-  _SequenceNode l_blockSequence(int indent) => context('sequence', () {
-    var additionalIndent = countIndentation() - indent;
-    if (additionalIndent <= 0) return null;
-
-    var content = oneOrMore(() => transaction(() {
-      if (!s_indent(indent + additionalIndent)) return null;
-      return c_l_blockSeqEntry(indent + additionalIndent);
-    }));
-    if (!truth(content)) return null;
-
-    return new _SequenceNode("?", content);
-  });
-
-  // 184
-  _Node c_l_blockSeqEntry(int indent) => transaction(() {
-    if (!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 (!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 first = c_l_blockSeqEntry(indent);
-    if (!truth(first)) return null;
-
-    var content = zeroOrMore(() => transaction(() {
-        if (!s_indent(indent)) return null;
-        return c_l_blockSeqEntry(indent);
-      }));
-    content.insertRange(0, 1, first);
-
-    return new _SequenceNode("?", content);
-  });
-
-  // 187
-  _Node l_blockMapping(int indent) => context('mapping', () {
-    var additionalIndent = countIndentation() - indent;
-    if (additionalIndent <= 0) return null;
-
-    var pairs = oneOrMore(() => transaction(() {
-      if (!s_indent(indent + additionalIndent)) return null;
-      return ns_l_blockMapEntry(indent + additionalIndent);
-    }));
-    if (!truth(pairs)) return null;
-
-    return map(pairs);
-  });
-
-  // 188
-  _Pair<_Node, _Node> ns_l_blockMapEntry(int indent) => or([
-    () => c_l_blockMapExplicitEntry(indent),
-    () => ns_l_blockMapImplicitEntry(indent)
-  ]);
-
-  // 189
-  // TODO(nweiz): implement
-  _Pair<_Node, _Node> c_l_blockMapExplicitEntry(int indent) => null;
-
-  // 192
-  _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;
-  });
-
-  // 193
-  _Node ns_s_blockMapImplicitKey() => context('mapping key', () => or([
-    () => c_s_implicitJsonKey(BLOCK_KEY),
-    () => c_s_implicitYamlKey(BLOCK_KEY)
-  ]));
-
-  // 194
-  _Node c_l_blockMapImplicitValue(int indent) => context('mapping value', () =>
-    transaction(() {
-      if (!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 first = ns_l_blockMapEntry(indent);
-    if (!truth(first)) return null;
-
-    var pairs = zeroOrMore(() => transaction(() {
-        if (!s_indent(indent)) return null;
-        return ns_l_blockMapEntry(indent);
-      }));
-    pairs.insertRange(0, 1, first);
-
-    return map(pairs);
-  });
-
-  // 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(() {
-    if (!s_separate(indent + 1, FLOW_OUT)) return null;
-    var node = ns_flowNode(indent + 1, FLOW_OUT);
-    if (!truth(node)) return null;
-    if (!s_l_comments()) return null;
-    return node;
-  });
-
-  // 198
-  _Node s_l_blockInBlock(int indent, int ctx) => or([
-    () => s_l_blockScalar(indent, ctx),
-    () => s_l_blockCollection(indent, ctx)
-  ]);
-
-  // 199
-  _Node s_l_blockScalar(int indent, int ctx) => transaction(() {
-    if (!s_separate(indent + 1, ctx)) return null;
-    var props = transaction(() {
-      var props = c_ns_properties(indent + 1, ctx);
-      if (!truth(props)) return null;
-      if (!s_separate(indent + 1, ctx)) return null;
-      return props;
-    });
-    if (!truth(props)) props = new _Pair<_Tag, String>(null, null);
-
-    var node = or([() => c_l_literal(indent), () => c_l_folded(indent)]);
-    if (!truth(node)) return null;
-    return addProps(node, props);
-  });
-
-  // 200
-  _Node s_l_blockCollection(int indent, int ctx) => transaction(() {
-    var props = transaction(() {
-      if (!s_separate(indent + 1, ctx)) return null;
-      return c_ns_properties(indent + 1, ctx);
-    });
-    if (!truth(props)) props = new _Pair<_Tag, String>(null, null);
-
-    if (!s_l_comments()) return null;
-    return or([
-      () => l_blockSequence(seqSpaces(indent, ctx)),
-      () => l_blockMapping(indent)]);
-  });
-
-  // 201
-  int seqSpaces(int indent, int ctx) => ctx == BLOCK_OUT ? indent - 1 : indent;
-
-  // 202
-  void l_documentPrefix() {
-    zeroOrMore(l_comment);
-  }
-
-  // 203
-  bool c_directivesEnd() => rawString("---");
-
-  // 204
-  bool c_documentEnd() => rawString("...");
-
-  // 205
-  bool l_documentSuffix() => transaction(() {
-    if (!c_documentEnd()) return false;
-    return s_l_comments();
-  });
-
-  // 206
-  bool c_forbidden() {
-    if (!inBareDocument || !atStartOfLine) return false;
-    var forbidden = false;
-    transaction(() {
-      if (!truth(or([c_directivesEnd, c_documentEnd]))) return;
-      var char = peek();
-      forbidden = isBreak(char) || isSpace(char) || atEndOfFile;
-      return;
-    });
-    return forbidden;
-  }
-
-  // 207
-  _Node l_bareDocument() {
-    try {
-      inBareDocument = true;
-      return s_l_blockNode(-1, BLOCK_IN);
-    } finally {
-      inBareDocument = false;
-    }
-  }
-
-  // 208
-  _Node l_explicitDocument() {
-    if (!c_directivesEnd()) return null;
-    var doc = l_bareDocument();
-    if (truth(doc)) return doc;
-
-    doc = e_node();
-    s_l_comments();
-    return doc;
-  }
-
-  // 209
-  _Node l_directiveDocument() {
-    if (!truth(oneOrMore(l_directive))) return null;
-    var doc = l_explicitDocument();
-    if (doc != null) return doc;
-    parseFailed();
-  }
-
-  // 210
-  _Node l_anyDocument() =>
-    or([l_directiveDocument, l_explicitDocument, l_bareDocument]);
-
-  // 211
-  List<_Node> l_yamlStream() {
-    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 (!atEndOfFile) parseFailed();
-    return docs;
-  }
-}
-
-class SyntaxError extends YamlException {
-  final int line;
-  final int column;
-
-  SyntaxError(this.line, this.column, String msg) : super(msg);
-
-  String toString() => "Syntax error on line $line, column $column: $msg";
-}
-
-/** A pair of values. */
-class _Pair<E, F> {
-  E first;
-  F last;
-
-  _Pair(this.first, this.last);
-
-  String toString() => '($first, $last)';
-}