Restructure YAML package suitable for pub lish

utils/pub/yaml/parser.dart

Index: utils/pub/yaml/parser.dart
diff --git a/utils/pub/yaml/parser.dart b/utils/pub/yaml/parser.dart
deleted file mode 100644
index f2f255e7652df22f79254adf898a5daea80e53a7..0000000000000000000000000000000000000000
--- a/utils/pub/yaml/parser.dart
+++ /dev/null
@@ -1,1939 +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.
-
-part of yaml;
-
-/// 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 const TAB = 0x9;
-  static const LF = 0xA;
-  static const CR = 0xD;
-  static const SP = 0x20;
-  static const TILDE = 0x7E;
-  static const NEL = 0x85;
-  static const PLUS = 0x2B;
-  static const HYPHEN = 0x2D;
-  static const QUESTION_MARK = 0x3F;
-  static const COLON = 0x3A;
-  static const COMMA = 0x2C;
-  static const LEFT_BRACKET = 0x5B;
-  static const RIGHT_BRACKET = 0x5D;
-  static const LEFT_BRACE = 0x7B;
-  static const RIGHT_BRACE = 0x7D;
-  static const HASH = 0x23;
-  static const AMPERSAND = 0x26;
-  static const ASTERISK = 0x2A;
-  static const EXCLAMATION = 0x21;
-  static const VERTICAL_BAR = 0x7C;
-  static const GREATER_THAN = 0x3E;
-  static const SINGLE_QUOTE = 0x27;
-  static const DOUBLE_QUOTE = 0x22;
-  static const PERCENT = 0x25;
-  static const AT = 0x40;
-  static const GRAVE_ACCENT = 0x60;
-
-  static const NULL = 0x0;
-  static const BELL = 0x7;
-  static const BACKSPACE = 0x8;
-  static const VERTICAL_TAB = 0xB;
-  static const FORM_FEED = 0xC;
-  static const ESCAPE = 0x1B;
-  static const SLASH = 0x2F;
-  static const BACKSLASH = 0x5C;
-  static const UNDERSCORE = 0x5F;
-  static const NBSP = 0xA0;
-  static const LINE_SEPARATOR = 0x2028;
-  static const PARAGRAPH_SEPARATOR = 0x2029;
-
-  static const NUMBER_0 = 0x30;
-  static const NUMBER_9 = 0x39;
-
-  static const LETTER_A = 0x61;
-  static const LETTER_B = 0x62;
-  static const LETTER_E = 0x65;
-  static const LETTER_F = 0x66;
-  static const LETTER_N = 0x6E;
-  static const LETTER_R = 0x72;
-  static const LETTER_T = 0x74;
-  static const LETTER_U = 0x75;
-  static const LETTER_V = 0x76;
-  static const LETTER_X = 0x78;
-
-  static const LETTER_CAP_A = 0x41;
-  static const LETTER_CAP_F = 0x46;
-  static const LETTER_CAP_L = 0x4C;
-  static const LETTER_CAP_N = 0x4E;
-  static const LETTER_CAP_P = 0x50;
-  static const LETTER_CAP_U = 0x55;
-  static const LETTER_CAP_X = 0x58;
-
-  static const C_SEQUENCE_ENTRY = 4;
-  static const C_MAPPING_KEY = 5;
-  static const C_MAPPING_VALUE = 6;
-  static const C_COLLECT_ENTRY = 7;
-  static const C_SEQUENCE_START = 8;
-  static const C_SEQUENCE_END = 9;
-  static const C_MAPPING_START = 10;
-  static const C_MAPPING_END = 11;
-  static const C_COMMENT = 12;
-  static const C_ANCHOR = 13;
-  static const C_ALIAS = 14;
-  static const C_TAG = 15;
-  static const C_LITERAL = 16;
-  static const C_FOLDED = 17;
-  static const C_SINGLE_QUOTE = 18;
-  static const C_DOUBLE_QUOTE = 19;
-  static const C_DIRECTIVE = 20;
-  static const C_RESERVED = 21;
-
-  static const BLOCK_OUT = 0;
-  static const BLOCK_IN = 1;
-  static const FLOW_OUT = 2;
-  static const FLOW_IN = 3;
-  static const BLOCK_KEY = 4;
-  static const FLOW_KEY = 5;
-
-  static const CHOMPING_STRIP = 0;
-  static const CHOMPING_KEEP = 1;
-  static const CHOMPING_CLIP = 2;
-
-  /// 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 farthest position in the source string that has been parsed
-  /// successfully before backtracking. Used for error reporting.
-  int farthestPos = 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;
-
-  /// Annotations attached to ranges of the source string that add extra
-  /// information to any errors that occur in the annotated range.
-  _RangeMap<String> errorAnnotations;
-
-  /// The buffer containing the string currently being captured.
-  StringBuffer capturedString;
-
-  /// The beginning of the current section of the captured string.
-  int captureStart;
-
-  /// Whether the current string capture is being overridden.
-  bool capturingAs = false;
-
-  _Parser(String s)
-    : this.s = s,
-      len = s.length,
-      contextStack = <String>["document"],
-      errorAnnotations = new _RangeMap();
-
-  /// 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;
-    }
-    farthestPos = pos;
-
-    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;
-  }
-
-  /// Consumes the current character if it equals [char].
-  bool consumeChar(int char) => consume((c) => c == char);
-
-  /// 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);
-    }
-    return null; // Unreachable.
-  }
-
-  /// 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);
-    }
-    return null; // Unreachable.
-  }
-
-  /// 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()) {
-    var oldPos = pos;
-    var oldLine = line;
-    var oldColumn = column;
-    var oldCaptureStart = captureStart;
-    String capturedSoFar = capturedString == null ? null :
-      capturedString.toString();
-    var res = consumer();
-    if (truth(res)) return res;
-
-    pos = oldPos;
-    line = oldLine;
-    column = oldColumn;
-    captureStart = oldCaptureStart;
-    capturedString = capturedSoFar == null ? null :
-      new StringBuffer(capturedSoFar);
-    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()) {
-    // captureString calls may not be nested
-    assert(capturedString == null);
-
-    captureStart = pos;
-    capturedString = new StringBuffer();
-    var res = transaction(consumer);
-    if (!truth(res)) {
-      captureStart = null;
-      capturedString = null;
-      return null;
-    }
-
-    flushCapture();
-    var result = capturedString.toString();
-    captureStart = null;
-    capturedString = null;
-    return result;
-  }
-
-  captureAs(String replacement, consumer()) =>
-      captureAndTransform(consumer, (_) => replacement);
-
-  captureAndTransform(consumer(), String transformation(String captured)) {
-    if (capturedString == null) return consumer();
-    if (capturingAs) return consumer();
-
-    flushCapture();
-    capturingAs = true;
-    var res = consumer();
-    capturingAs = false;
-    if (!truth(res)) return res;
-
-    capturedString.add(transformation(s.substring(captureStart, pos)));
-    captureStart = pos;
-    return res;
-  }
-
-  void flushCapture() {
-    capturedString.add(s.substring(captureStart, pos));
-    captureStart = pos;
-  }
-
-  /// Adds a tag and an anchor to [node], if they're defined.
-  _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) {
-    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);
-    }
-  }
-
-  /// Adds [message] as extra information to any errors that occur between the
-  /// current position and the position of the cursor after running [fn]. The
-  /// cursor is reset after [fn] is run.
-  annotateError(String message, fn()) {
-    var start = pos;
-    var end;
-    transaction(() {
-      fn();
-      end = pos;
-      return false;
-    });
-    errorAnnotations[new _Range(start, end)] = message;
-  }
-
-  /// 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() {
-    var message = "invalid YAML in $farthestContext";
-    var extraError = errorAnnotations[farthestPos];
-    if (extraError != null) message = "$message ($extraError)";
-    throw new SyntaxError(farthestLine + 1, farthestColumn + 1, message);
-  }
-
-  /// Returns the number of spaces after the current position.
-  int countIndentation() {
-    var i = 0;
-    while (peek(i) == SP) i++;
-    return i;
-  }
-
-  /// Returns the indentation for a block scalar.
-  int blockScalarAdditionalIndentation(_BlockHeader header, int indent) {
-    if (!header.autoDetectIndent) return header.additionalIndent;
-
-    var maxSpaces = 0;
-    var maxSpacesLine = 0;
-    var spaces = 0;
-    transaction(() {
-      do {
-        spaces = captureString(() => zeroOrMore(() => consumeChar(SP))).length;
-        if (spaces > maxSpaces) {
-          maxSpaces = spaces;
-          maxSpacesLine = line;
-        }
-      } while (b_break());
-      return false;
-    });
-
-    // If the next non-empty line isn't indented further than the start of the
-    // block scalar, that means the scalar is going to be empty. Returning any
-    // value > 0 will cause the parser not to consume any text.
-    if (spaces <= indent) return 1;
-
-    // It's an error for a leading empty line to be indented more than the first
-    // non-empty line.
-    if (maxSpaces > spaces) {
-      throw new SyntaxError(maxSpacesLine + 1, maxSpaces,
-          "Leading empty lines may not be indented more than the first "
-          "non-empty line.");
-    }
-
-    return spaces - indent;
-  }
-
-  /// 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);
-  }
-
-  // 2
-  bool isJson(int char) => char == TAB || (char >= SP && 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);
-
-  // 28
-  bool b_break() {
-    if (consumeChar(CR)) {
-      zeroOrOne(() => consumeChar(LF));
-      return true;
-    }
-    return consumeChar(LF);
-  }
-
-  // 29
-  bool b_asLineFeed() => captureAs("\n", () => b_break());
-
-  // 30
-  bool b_nonContent() => captureAs("", () => b_break());
-
-  // 33
-  bool isSpace(int char) => char == SP || char == TAB;
-
-  // 34
-  bool isNonSpace(int char) => isNonBreak(char) && !isSpace(char);
-
-  // 35
-  bool isDecDigit(int char) => char >= NUMBER_0 && char <= NUMBER_9;
-
-  // 36
-  bool isHexDigit(int char) {
-    return isDecDigit(char) ||
-      (char >= LETTER_A && char <= LETTER_F) ||
-      (char >= LETTER_CAP_A && char <= LETTER_CAP_F);
-  }
-
-  // 41
-  bool c_escape() => captureAs("", () => consumeChar(BACKSLASH));
-
-  // 42
-  bool ns_escNull() => captureAs("\x00", () => consumeChar(NUMBER_0));
-
-  // 43
-  bool ns_escBell() => captureAs("\x07", () => consumeChar(LETTER_A));
-
-  // 44
-  bool ns_escBackspace() => captureAs("\b", () => consumeChar(LETTER_B));
-
-  // 45
-  bool ns_escHorizontalTab() => captureAs("\t", () {
-    return consume((c) => c == LETTER_T || c == TAB);
-  });
-
-  // 46
-  bool ns_escLineFeed() => captureAs("\n", () => consumeChar(LETTER_N));
-
-  // 47
-  bool ns_escVerticalTab() => captureAs("\v", () => consumeChar(LETTER_V));
-
-  // 48
-  bool ns_escFormFeed() => captureAs("\f", () => consumeChar(LETTER_F));
-
-  // 49
-  bool ns_escCarriageReturn() => captureAs("\r", () => consumeChar(LETTER_R));
-
-  // 50
-  bool ns_escEscape() => captureAs("\x1B", () => consumeChar(LETTER_E));
-
-  // 51
-  bool ns_escSpace() => consumeChar(SP);
-
-  // 52
-  bool ns_escDoubleQuote() => consumeChar(DOUBLE_QUOTE);
-
-  // 53
-  bool ns_escSlash() => consumeChar(SLASH);
-
-  // 54
-  bool ns_escBackslash() => consumeChar(BACKSLASH);
-
-  // 55
-  bool ns_escNextLine() => captureAs("\x85", () => consumeChar(LETTER_CAP_N));
-
-  // 56
-  bool ns_escNonBreakingSpace() =>
-    captureAs("\xA0", () => consumeChar(UNDERSCORE));
-
-  // 57
-  bool ns_escLineSeparator() =>
-    captureAs("\u2028", () => consumeChar(LETTER_CAP_L));
-
-  // 58
-  bool ns_escParagraphSeparator() =>
-    captureAs("\u2029", () => consumeChar(LETTER_CAP_P));
-
-  // 59
-  bool ns_esc8Bit() => ns_escNBit(LETTER_X, 2);
-
-  // 60
-  bool ns_esc16Bit() => ns_escNBit(LETTER_U, 4);
-
-  // 61
-  bool ns_esc32Bit() => ns_escNBit(LETTER_CAP_U, 8);
-
-  // Helper method for 59 - 61
-  bool ns_escNBit(int char, int digits) {
-    if (!captureAs('', () => consumeChar(char))) return false;
-    var captured = captureAndTransform(
-        () => nAtOnce(digits, (c, _) => isHexDigit(c)),
-        (hex) => new String.fromCharCodes([int.parse("0x$hex")]));
-    return expect(captured, "$digits hexidecimal digits");
-  }
-
-  // 62
-  bool c_ns_escChar() => context('escape sequence', () => transaction(() {
-      if (!truth(c_escape())) return false;
-      return truth(or([
-        ns_escNull, ns_escBell, ns_escBackspace, ns_escHorizontalTab,
-        ns_escLineFeed, ns_escVerticalTab, ns_escFormFeed, ns_escCarriageReturn,
-        ns_escEscape, ns_escSpace, ns_escDoubleQuote, ns_escSlash,
-        ns_escBackslash, ns_escNextLine, ns_escNonBreakingSpace,
-        ns_escLineSeparator, ns_escParagraphSeparator, ns_esc8Bit, ns_esc16Bit,
-        ns_esc32Bit
-      ]));
-    }));
-
-  // 63
-  bool s_indent(int indent) {
-    var result = nAtOnce(indent, (c, i) => c == SP);
-    if (peek() == TAB) {
-      annotateError("tab characters are not allowed as indentation in YAML",
-          () => zeroOrMore(() => consume(isSpace)));
-    }
-    return result;
-  }
-
-  // 64
-  bool s_indentLessThan(int indent) {
-    for (int i = 0; i < indent - 1; i++) {
-      if (!consumeChar(SP)) {
-        if (peek() == TAB) {
-          annotateError("tab characters are not allowed as indentation in YAML",
-              () {
-            for (; i < indent - 1; i++) {
-              if (!consume(isSpace)) break;
-            }
-          });
-        }
-        break;
-      }
-    }
-    return true;
-  }
-
-  // 65
-  bool s_indentLessThanOrEqualTo(int indent) => s_indentLessThan(indent + 1);
-
-  // 66
-  bool s_separateInLine() => transaction(() {
-    return captureAs('', () =>
-        truth(oneOrMore(() => consume(isSpace))) || atStartOfLine);
-  });
-
-  // 67
-  bool s_linePrefix(int indent, int ctx) => captureAs("", () {
-    switch (ctx) {
-    case BLOCK_OUT:
-    case BLOCK_IN:
-      return s_blockLinePrefix(indent);
-    case FLOW_OUT:
-    case FLOW_IN:
-      return s_flowLinePrefix(indent);
-    }
-  });
-
-  // 68
-  bool s_blockLinePrefix(int indent) => s_indent(indent);
-
-  // 69
-  bool s_flowLinePrefix(int indent) => captureAs('', () {
-    if (!truth(s_indent(indent))) return false;
-    zeroOrOne(s_separateInLine);
-    return true;
-  });
-
-  // 70
-  bool l_empty(int indent, int ctx) => transaction(() {
-    var start = or([
-      () => s_linePrefix(indent, ctx),
-      () => s_indentLessThan(indent)
-    ]);
-    if (!truth(start)) return false;
-    return b_asLineFeed();
-  });
-
-  // 71
-  bool b_asSpace() => captureAs(" ", () => consume(isBreak));
-
-  // 72
-  bool b_l_trimmed(int indent, int ctx) => transaction(() {
-    if (!truth(b_nonContent())) return false;
-    return truth(oneOrMore(() => captureAs("\n", () => l_empty(indent, ctx))));
-  });
-
-  // 73
-  bool b_l_folded(int indent, int ctx) =>
-    or([() => b_l_trimmed(indent, ctx), b_asSpace]);
-
-  // 74
-  bool s_flowFolded(int indent) => transaction(() {
-    zeroOrOne(s_separateInLine);
-    if (!truth(b_l_folded(indent, FLOW_IN))) return false;
-    return s_flowLinePrefix(indent);
-  });
-
-  // 75
-  bool c_nb_commentText() {
-    if (!truth(c_indicator(C_COMMENT))) return false;
-    zeroOrMore(() => consume(isNonBreak));
-    return true;
-  }
-
-  // 76
-  bool b_comment() => atEndOfFile || b_nonContent();
-
-  // 77
-  bool s_b_comment() {
-    if (truth(s_separateInLine())) {
-      zeroOrOne(c_nb_commentText);
-    }
-    return b_comment();
-  }
-
-  // 78
-  bool l_comment() => transaction(() {
-    if (!truth(s_separateInLine())) return false;
-    zeroOrOne(c_nb_commentText);
-    return b_comment();
-  });
-
-  // 79
-  bool s_l_comments() {
-    if (!truth(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 (!truth(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 (!truth(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 (!truth(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();
-
-  // 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(() {
-      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);
-    });
-  });
-
-  // 110
-  String nb_doubleText(int indent, int ctx) => captureString(() {
-    switch (ctx) {
-    case FLOW_OUT:
-    case FLOW_IN:
-      nb_doubleMultiLine(indent);
-      break;
-    case BLOCK_KEY:
-    case FLOW_KEY:
-      nb_doubleOneLine();
-      break;
-    }
-    return true;
-  });
-
-  // 111
-  void nb_doubleOneLine() {
-    zeroOrMore(nb_doubleChar);
-  }
-
-  // 112
-  bool s_doubleEscaped(int indent) => transaction(() {
-    zeroOrMore(() => consume(isSpace));
-    if (!captureAs("", () => consumeChar(BACKSLASH))) return false;
-    if (!truth(b_nonContent())) return false;
-    zeroOrMore(() => captureAs("\n", () => l_empty(indent, FLOW_IN)));
-    return s_flowLinePrefix(indent);
-  });
-
-  // 113
-  bool s_doubleBreak(int indent) => or([
-    () => s_doubleEscaped(indent),
-    () => s_flowFolded(indent)
-  ]);
-
-  // 114
-  void nb_ns_doubleInLine() {
-    zeroOrMore(() => transaction(() {
-        zeroOrMore(() => consume(isSpace));
-        return ns_doubleChar();
-      }));
-  }
-
-  // 115
-  bool s_doubleNextLine(int indent) {
-    if (!truth(s_doubleBreak(indent))) return false;
-    zeroOrOne(() {
-      if (!truth(ns_doubleChar())) return;
-      nb_ns_doubleInLine();
-      or([
-        () => s_doubleNextLine(indent),
-        () => zeroOrMore(() => consume(isSpace))
-      ]);
-    });
-    return true;
-  }
-
-  // 116
-  void nb_doubleMultiLine(int indent) {
-    nb_ns_doubleInLine();
-    or([
-      () => s_doubleNextLine(indent),
-      () => zeroOrMore(() => consume(isSpace))
-    ]);
-  }
-
-  // 117
-  bool c_quotedQuote() => captureAs("'", () => rawString("''"));
-
-  // 118
-  bool nb_singleChar() => or([
-    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(() {
-      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);
-    });
-  });
-
-  // 121
-  String nb_singleText(int indent, int ctx) => captureString(() {
-    switch (ctx) {
-    case FLOW_OUT:
-    case FLOW_IN:
-      nb_singleMultiLine(indent);
-      break;
-    case BLOCK_KEY:
-    case FLOW_KEY:
-      nb_singleOneLine(indent);
-      break;
-    }
-    return true;
-  });
-
-  // 122
-  void nb_singleOneLine(int indent) {
-    zeroOrMore(nb_singleChar);
-  }
-
-  // 123
-  void nb_ns_singleInLine() {
-    zeroOrMore(() => transaction(() {
-      zeroOrMore(() => consume(isSpace));
-      return ns_singleChar();
-    }));
-  }
-
-  // 124
-  bool s_singleNextLine(int indent) {
-    if (!truth(s_flowFolded(indent))) return false;
-    zeroOrOne(() {
-      if (!truth(ns_singleChar())) return;
-      nb_ns_singleInLine();
-      or([
-        () => s_singleNextLine(indent),
-        () => zeroOrMore(() => consume(isSpace))
-      ]);
-    });
-    return true;
-  }
-
-  // 125
-  void nb_singleMultiLine(int indent) {
-    nb_ns_singleInLine();
-    or([
-      () => s_singleNextLine(indent),
-      () => zeroOrMore(() => consume(isSpace))
-    ]);
-  }
-
-  // 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 "$ctx"';
-    }
-  }
-
-  // 130
-  bool ns_plainChar(int ctx) {
-    var char = peek();
-    var indicator = indicatorType(char);
-    var safeChar = isPlainSafe(ctx, char) && indicator != C_MAPPING_VALUE &&
-      indicator != C_COMMENT;
-    var nonCommentHash = isNonSpace(peek(-1)) && indicator == C_COMMENT;
-    var nonMappingColon = indicator == C_MAPPING_VALUE &&
-      isPlainSafe(ctx, peek(1));
-    var match = safeChar || nonCommentHash || nonMappingColon;
-
-    if (match) next();
-    return match;
-  }
-
-  // 131
-  String ns_plain(int indent, int ctx) => context('plain scalar', () {
-    return captureString(() {
-      switch (ctx) {
-      case FLOW_OUT:
-      case FLOW_IN:
-        return ns_plainMultiLine(indent, ctx);
-      case BLOCK_KEY:
-      case FLOW_KEY:
-        return ns_plainOneLine(ctx);
-      default: throw 'invalid context "$ctx"';
-      }
-    });
-  });
-
-  // 132
-  void nb_ns_plainInLine(int ctx) {
-    zeroOrMore(() => transaction(() {
-      zeroOrMore(() => consume(isSpace));
-      return ns_plainChar(ctx);
-    }));
-  }
-
-  // 133
-  bool ns_plainOneLine(int ctx) {
-    if (truth(c_forbidden())) return false;
-    if (!truth(ns_plainFirst(ctx))) return false;
-    nb_ns_plainInLine(ctx);
-    return true;
-  }
-
-  // 134
-  bool s_ns_plainNextLine(int indent, int ctx) => transaction(() {
-    if (!truth(s_flowFolded(indent))) return false;
-    if (truth(c_forbidden())) return false;
-    if (!truth(ns_plainChar(ctx))) return false;
-    nb_ns_plainInLine(ctx);
-    return true;
-  });
-
-  // 135
-  bool ns_plainMultiLine(int indent, int ctx) {
-    if (!truth(ns_plainOneLine(ctx))) return false;
-    zeroOrMore(() => s_ns_plainNextLine(indent, ctx));
-    return true;
-  }
-
-  // 136
-  int inFlow(int ctx) {
-    switch (ctx) {
-    case FLOW_OUT:
-    case FLOW_IN:
-      return FLOW_IN;
-    case BLOCK_KEY:
-    case FLOW_KEY:
-      return FLOW_KEY;
-    }
-  }
-
-  // 137
-  _SequenceNode c_flowSequence(int indent, int ctx) => transaction(() {
-    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));
-  });
-
-  // 138
-  Collection<_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) {
-    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);
-  }
-
-  // 141
-  YamlMap ns_s_flowMapEntries(int indent, int ctx) {
-    var first = ns_flowMapEntry(indent, ctx);
-    if (!truth(first)) return new YamlMap();
-    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();
-
-    // 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([
-    () => 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([
-    () => ns_flowMapImplicitEntry(indent, ctx),
-    () => new _Pair<_Node, _Node>(e_node(), e_node())
-  ]);
-
-  // 144
-  _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) {
-    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);
-  }
-
-  // 146
-  _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);
-  }
-
-  // 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) {
-    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);
-  }
-
-  // 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 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]);
-  }
-
-  // 151
-  _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) =>
-    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);
-    });
-
-  // 153
-  _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);
-    });
-
-  // 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 str = ns_plain(indent, ctx);
-    if (!truth(str)) return null;
-    return new _ScalarNode("?", 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)
-  ]);
-
-  // 158
-  _Node ns_flowContent(int indent, int ctx) => or([
-    () => ns_flowYamlContent(indent, ctx),
-    () => c_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 (!truth(s_separate(indent, ctx))) return null;
-          return ns_flowYamlContent(indent, ctx);
-        }),
-        e_scalar
-      ]);
-      return addProps(node, props);
-    }
-  ]);
-
-  // 160
-  _Node c_flowJsonNode(int indent, int ctx) => transaction(() {
-    var props;
-    zeroOrOne(() => transaction(() {
-        props = c_ns_properties(indent, ctx);
-        if (!truth(props)) return null;
-        return s_separate(indent, ctx);
-      }));
-
-    return addProps(c_flowJsonContent(indent, ctx), 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);
-    })
-  ]);
-
-  // 162
-  _BlockHeader c_b_blockHeader() => transaction(() {
-    var indentation = c_indentationIndicator();
-    var chomping = c_chompingIndicator();
-    if (!truth(indentation)) indentation = c_indentationIndicator();
-    if (!truth(s_b_comment())) return null;
-
-    return new _BlockHeader(indentation, chomping);
-  });
-
-  // 163
-  int c_indentationIndicator() {
-    if (!isDecDigit(peek())) return null;
-    return next() - NUMBER_0;
-  }
-
-  // 164
-  int c_chompingIndicator() {
-    switch (peek()) {
-    case HYPHEN:
-      next();
-      return CHOMPING_STRIP;
-    case PLUS:
-      next();
-      return CHOMPING_KEEP;
-    default:
-      return CHOMPING_CLIP;
-    }
-  }
-
-  // 165
-  bool b_chompedLast(int chomping) {
-    if (atEndOfFile) return true;
-    switch (chomping) {
-    case CHOMPING_STRIP:
-      return b_nonContent();
-    case CHOMPING_CLIP:
-    case CHOMPING_KEEP:
-      return b_asLineFeed();
-    }
-  }
-
-  // 166
-  void l_chompedEmpty(int indent, int chomping) {
-    switch (chomping) {
-    case CHOMPING_STRIP:
-    case CHOMPING_CLIP:
-      l_stripEmpty(indent);
-      break;
-    case CHOMPING_KEEP:
-      l_keepEmpty(indent);
-      break;
-    }
-  }
-
-  // 167
-  void l_stripEmpty(int indent) {
-    captureAs('', () {
-      zeroOrMore(() => transaction(() {
-          if (!truth(s_indentLessThanOrEqualTo(indent))) return false;
-          return b_nonContent();
-        }));
-      zeroOrOne(() => l_trailComments(indent));
-      return true;
-    });
-  }
-
-  // 168
-  void l_keepEmpty(int indent) {
-    zeroOrMore(() => captureAs('\n', () => l_empty(indent, BLOCK_IN)));
-    zeroOrOne(() => captureAs('', () => l_trailComments(indent)));
-  }
-
-  // 169
-  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(() {
-    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);
-  });
-
-  // 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(() {
-    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);
-  });
-
-  // 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;
-  });
-
-  // 176
-  bool l_nb_foldedLines(int indent) {
-    if (!truth(s_nb_foldedText(indent))) return false;
-    zeroOrMore(() => transaction(() {
-        if (!truth(b_l_folded(indent, BLOCK_IN))) return false;
-        return s_nb_foldedText(indent);
-      }));
-    return true;
-  }
-
-  // 177
-  bool s_nb_spacedText(int indent) => transaction(() {
-    if (!truth(captureAs('', () => s_indent(indent)))) return false;
-    if (!truth(consume(isSpace))) return false;
-    zeroOrMore(() => consume(isNonBreak));
-    return true;
-  });
-
-  // 178
-  bool b_l_spaced(int indent) {
-    if (!truth(b_asLineFeed())) return false;
-    zeroOrMore(() => captureAs("\n", () => l_empty(indent, BLOCK_IN)));
-    return true;
-  }
-
-  // 179
-  bool l_nb_spacedLines(int indent) {
-    if (!truth(s_nb_spacedText(indent))) return false;
-    zeroOrMore(() => transaction(() {
-        if (!truth(b_l_spaced(indent))) return false;
-        return s_nb_spacedText(indent);
-      }));
-    return true;
-  }
-
-  // 180
-  bool l_nb_sameLines(int indent) => transaction(() {
-    zeroOrMore(() => captureAs('\n', () => l_empty(indent, BLOCK_IN)));
-    return or([
-      () => l_nb_foldedLines(indent),
-      () => l_nb_spacedLines(indent)
-    ]);
-  });
-
-  // 181
-  bool l_nb_diffLines(int indent) {
-    if (!truth(l_nb_sameLines(indent))) return false;
-    zeroOrMore(() => transaction(() {
-        if (!truth(b_asLineFeed())) return false;
-        return l_nb_sameLines(indent);
-      }));
-    return true;
-  }
-
-  // 182
-  String l_foldedContent(int indent, int chomping) => captureString(() {
-    transaction(() {
-      if (!truth(l_nb_diffLines(indent))) return false;
-      return b_chompedLast(chomping);
-    });
-    l_chompedEmpty(indent, chomping);
-    return true;
-  });
-
-  // 183
-  _SequenceNode l_blockSequence(int indent) => context('sequence', () {
-    var additionalIndent = countIndentation() - indent;
-    if (additionalIndent <= 0) return null;
-
-    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);
-  });
-
-  // 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 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.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 (!truth(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
-  _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);
-  }
-
-  // 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(() {
-    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),
-    () => 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 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.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 (!truth(s_separate(indent + 1, FLOW_OUT))) return null;
-    var node = ns_flowNode(indent + 1, FLOW_OUT);
-    if (!truth(node)) return null;
-    if (!truth(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 (!truth(s_separate(indent + 1, ctx))) return null;
-    var props = transaction(() {
-      var innerProps = c_ns_properties(indent + 1, ctx);
-      if (!truth(innerProps)) return null;
-      if (!truth(s_separate(indent + 1, ctx))) return null;
-      return innerProps;
-    });
-
-    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 (!truth(s_separate(indent + 1, ctx))) return null;
-      return c_ns_properties(indent + 1, ctx);
-    });
-
-    if (!truth(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 (!truth(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 (!truth(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();
-    return null; // Unreachable.
-  }
-
-  // 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)';
-}
-
-/// 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;
-}
-
-/// A range of characters in the YAML document, from [start] to [end]
-/// (inclusive).
-class _Range {
-  /// The first character in the range.
-  final int start;
-
-  /// The last character in the range.
-  final int end;
-
-  _Range(this.start, this.end);
-
-  /// 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;
-
-  _RangeMap() : this.contents = <_Pair<_Range, E>>[];
-
-  /// 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. TODO(nweiz): clean this up when issue 2804 is fixed.
-    for (var i = contents.length - 1; i >= 0; i--) {
-      var pair = contents[i];
-      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));
-}