public static object ConstructYamlBool(IConstructor ctor, Node node) {
     bool result;
     if (TryConstructYamlBool(ctor, node, out result)) {
         return result;
     }
     return null;
 }

 private void AddAnchor(string anchor, Node node) {
     if (_anchors.ContainsKey(anchor)) {
         _anchors[anchor] = node;
     } else {
         _anchors.Add(anchor, node);
     }
 }

        private void AnchorNode(Node node) {
            while (node is LinkNode) {
                node = ((LinkNode)node).Linked;
            }
            if (!IgnoreAnchor(node)) {
                string anchor;
                if (_anchors.TryGetValue(node, out anchor)) {
                    if (null == anchor) {
                        _anchors[node] = GenerateAnchor(node);
                    }
                } else {
                    _anchors.Add(node, null);

                    SequenceNode seq;
                    MappingNode map;
                    if ((seq = node as SequenceNode) != null) {
                        foreach (Node n in seq.Nodes) {
                            AnchorNode(n);
                        }
                    } else if ((map = node as MappingNode) != null) {
                        foreach (KeyValuePair<Node, Node> e in map.Nodes) {
                            AnchorNode(e.Key);
                            AnchorNode(e.Value);
                        }
                    }
                }
            }
        }

        public void Serialize(Node node) {
            if (_closed) {
                throw new SerializerException("serializer is closed");
            }
            _emitter.Emit(new DocumentStartEvent(_useExplicitStart, _useVersion, null));
            AnchorNode(node);
            SerializeNode(node, null, null);
            _emitter.Emit(_useExplicitEnd ? DocumentEndEvent.ExplicitInstance : DocumentEndEvent.ImplicitInstance);

            _serializedNodes.Clear();
            _anchors.Clear();
            _lastAnchorId = 0;
        }

        private static Range ConstructRubyRange(RubyConstructor/*!*/ ctor, Node node) {
            object begin = null;
            object end = null;
            bool excludeEnd = false;
            ScalarNode scalar = node as ScalarNode;                        
            if (scalar != null) {
                string value = scalar.Value;                
                int dotsIdx;
                if ((dotsIdx = value.IndexOf("...")) != -1) {
                    begin = ParseObject(ctor, value.Substring(0, dotsIdx));                
                    end = ParseObject(ctor, value.Substring(dotsIdx + 3));
                    excludeEnd = true;
                } else if ((dotsIdx = value.IndexOf("..")) != -1) {
                    begin = ParseObject(ctor, value.Substring(0, dotsIdx));
                    end = ParseObject(ctor, value.Substring(dotsIdx + 2));
                } else {
                    throw new ConstructorException("Invalid Range: " + value);
                }
            } else {
                MappingNode mapping = node as MappingNode;
                if (mapping == null) {
                    throw new ConstructorException("Invalid Range: " + node);    
                }
                foreach (KeyValuePair<Node, Node> n in mapping.Nodes) {
                    string key = ctor.ConstructScalar(n.Key).ToString();
                    switch (key) {
                        case "begin":
                            begin = ctor.ConstructObject(n.Value);
                            break;
                        case "end":
                            end = ctor.ConstructObject(n.Value);
                            break;
                        case "excl":
                            TryConstructYamlBool(ctor, n.Value, out excludeEnd);
                            break;
                        default:
                            throw new ConstructorException(string.Format("'{0}' is not allowed as an instance variable name for class Range", key));
                    }
                }                
            }

            var comparisonStorage = new BinaryOpStorage(ctor.GlobalScope.Context);
            return new Range(comparisonStorage, ctor.GlobalScope.Context, begin, end, excludeEnd);            
        }

 public static byte[] ConstructYamlBinary(IConstructor ctor, Node node) {
     string val = ctor.ConstructScalar(node).ToString().Replace("\r", "").Replace("\n", "");
     return Convert.FromBase64String(val);
 }

 private static object ConstructRubyScalar(RubyConstructor/*!*/ ctor, Node node) {
     object value = ctor.ConstructScalar(node);
     if (value == null) {
         return value;
     }
     string str = value as string;
     if (str != null) {
         return MutableString.Create(str, RubyEncoding.UTF8);
     }
     return value;
 }

 private string GenerateAnchor(Node node) {
     return string.Format(_anchorTemplate, ++_lastAnchorId);
 }

 protected virtual bool IgnoreAnchor(Node node) {
     // This is possibly Ruby specific.
     // but it didn't seem worth subclassing Serializer for this one method
     return !(node is CollectionNode);
     //return false;
 }

        private static object ConstructRubyStruct(RubyConstructor/*!*/ ctor, string className, Node node) {
            MappingNode mapping = node as MappingNode;
            if (mapping == null) {
                throw new ConstructorException("can only construct struct from mapping node");
            }

            RubyContext context = ctor.GlobalScope.Context;
            RubyModule module;
            RubyClass cls;
            if (context.TryGetModule(ctor.GlobalScope, className, out module)) {
                cls = module as RubyClass;
                if (cls == null) {
                    throw new ConstructorException("Struct type name must be Ruby class");
                }
            } else {
                RubyModule structModule = context.GetModule(typeof(RubyStruct));
                cls = RubyUtils.GetConstant(ctor.GlobalScope, structModule, className, false) as RubyClass;
                if (cls == null) {
                    throw new ConstructorException(String.Format("Cannot find struct class \"{0}\"", className));
                }
            }

            RubyStruct newStruct = RubyStruct.Create(cls);
            foreach (var pair in ctor.ConstructMapping(mapping)) {
                RubyStructOps.SetValue(newStruct, SymbolTable.StringToId(pair.Key.ToString()), pair.Value);        
            }
            return newStruct;
        }

        private static object ConstructRubyTimestampYMD(RubyConstructor/*!*/ ctor, Node node) {
            ScalarNode scalar = node as ScalarNode;
            if (scalar == null) {
                throw new ConstructorException("Can only contruct timestamp from scalar node.");
            }

            Match match = BaseConstructor.YmdRegex.Match(scalar.Value);
            if (match.Success) {
                int year_ymd = Int32.Parse(match.Groups[1].Value, CultureInfo.InvariantCulture);
                int month_ymd = Int32.Parse(match.Groups[2].Value, CultureInfo.InvariantCulture);
                int day_ymd = Int32.Parse(match.Groups[3].Value, CultureInfo.InvariantCulture);

                RubyModule module;
                if (ctor.GlobalScope.Context.TryGetModule(ctor.GlobalScope, "Date", out module)) {
                    return ctor._newSite.Target(ctor._newSite, module, year_ymd, month_ymd, day_ymd);
                } else {
                    throw new ConstructorException("Date class not found.");
                }
            }
            throw new ConstructorException("Invalid tag:yaml.org,2002:timestamp#ymd value.");
        }

 public static bool TryConstructYamlBool(IConstructor ctor, Node node, out bool result) {            
     if (BOOL_VALUES.TryGetValue(ctor.ConstructScalar(node).ToString(), out result)) {
         return true;
     }
     return false;
 }

 public static object ConstructYamlOmap(IConstructor ctor, Node node) {
     return ctor.ConstructPairs(node);
 }

 public static object ConstructYamlNull(IConstructor ctor, Node node) {
     return null;
 }

        public static object ConstructYamlInt(IConstructor ctor, Node node) {
            string value = ctor.ConstructScalar(node).ToString().Replace("_","").Replace(",","");
            int sign = +1;
            char first = value[0];
            if(first == '-') {
                sign = -1;
                value = value.Substring(1);
            } else if(first == '+') {
                value = value.Substring(1);
            }
            int @base = 10;
            if (value == "0") {
                return 0;
            } else if (value.StartsWith("0b")) {
                value = value.Substring(2);
                @base = 2;
            } else if (value.StartsWith("0x")) {
                value = value.Substring(2);
                @base = 16;
            } else if (value.StartsWith("0")) {
                value = value.Substring(1);
                @base = 8;
            } else if (value.IndexOf(':') != -1) {
                string[] digits = value.Split(':');
                int bes = 1;
                int val = 0;
                for (int i = 0, j = digits.Length; i < j; i++) {
                    val += (int.Parse(digits[(j - i) - 1]) * bes);
                    bes *= 60;
                }
                return sign*val;
            }

            try {
                // LiteralParser.ParseInteger delegate handles parsing & conversion to BigInteger (if needed)
                return LiteralParser.ParseInteger(sign, value, @base);
            } catch (Exception e) {
                throw new ConstructorException(string.Format("Could not parse integer value: '{0}' (sign {1}, base {2})", value, sign, @base), e);
            }
        }

        public static object ConstructCliObject(IConstructor ctor, string pref, Node node) {
            // TODO: should this use serialization or some more standard CLR mechanism?
            //       (it is very ad-hoc)
            // TODO: use DLR APIs instead of reflection
            try {
                Type type = Type.GetType(pref);
                object result = type.GetConstructor(Type.EmptyTypes).Invoke(null);

                foreach (KeyValuePair<object, object> e in ctor.ConstructMapping(node)) {
                    string name = e.Key.ToString();
                    name = "" + char.ToUpper(name[0]) + name.Substring(1);
                    PropertyInfo prop = type.GetProperty(name);

                    prop.SetValue(result, Convert.ChangeType(e.Value, prop.PropertyType), null);
                }
                return result;

            } catch (Exception e) {
                throw new ConstructorException("Can't construct a CLI object from class: " + pref, e);
            }
        }

 public static object ConstructSpecializedMap(IConstructor ctor, string pref, Node node) {
     Hash result = null;
     try {
         result = (Hash)Type.GetType(pref).GetConstructor(Type.EmptyTypes).Invoke(null);
     } catch (Exception e) {
         throw new ConstructorException("Can't construct a mapping from class: " + pref, e);
     }
     foreach (KeyValuePair<object, object> e in ctor.ConstructMapping(node)) {
         result.Add(e.Key, e.Value);
     }
     return result;
 }

 public static object ConstructSpecializedSequence(IConstructor ctor, string pref, Node node) {
     RubyArray result = null;
     try {
         result = (RubyArray)Type.GetType(pref).GetConstructor(Type.EmptyTypes).Invoke(null);
     } catch (Exception e) {
         throw new ConstructorException("Can't construct a sequence from class: " + pref, e);
     }
     foreach (object x in ctor.ConstructSequence(node)) {
         result.Add(x);
     }
     return result;
 }

 private static RubyRegex ConstructRubyRegexp(RubyConstructor/*!*/ ctor, Node node) {
     ScalarNode scalar = node as ScalarNode;
     if (node == null) {
         throw RubyExceptions.CreateTypeError("Can only create regex from scalar node");
     }                        
     Match match = _regexPattern.Match(scalar.Value);
     if (!match.Success) {
         throw new ConstructorException("Invalid Regular expression: \"" + scalar.Value + "\"");
     }
     RubyRegexOptions options = new RubyRegexOptions();
     foreach (char c in match.Groups["opts"].Value) {
         switch (c) {
             case 'i': options |= RubyRegexOptions.IgnoreCase; break;
             case 'x': options |= RubyRegexOptions.Extended; break;
             case 'm': options |= RubyRegexOptions.Multiline; break;
             case 'o': break;
             case 'n': options |= RubyRegexOptions.FIXED; break;
             case 'e': options |= RubyRegexOptions.EUC; break;
             case 's': options |= RubyRegexOptions.SJIS; break;
             case 'u': options |= RubyRegexOptions.UTF8; break;
             default:
                 throw new ConstructorException("Unknown regular expression option: '" + c + "'");
         }
     }            
     // TODO: encoding (ignore kcode on 1.9, string enc?):
     return new RubyRegex(MutableString.CreateMutable(match.Groups["expr"].Value, RubyEncoding.UTF8), options);            
 }

        /// <summary>
        /// Returns MutableString or RubySymbol.
        /// </summary>
        private static object ConstructRubyString(RubyConstructor/*!*/ ctor, Node/*!*/ node) {
            ScalarNode scalar = (ScalarNode)node;
            string value = ctor.ConstructScalar(node);

            if (value == null) {
                return null;
            }

            if (value.Length > 1 && value[0] == ':' && scalar.Style == ScalarQuotingStyle.None) {
                return ctor.GlobalScope.Context.CreateAsciiSymbol(value.Substring(1));
            }

            return MutableString.CreateMutable(value, ctor.RubyEncoding);
        }