QilXmlWriter.cs source code in C# .NET

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Code:

/ Net / Net / 3.5.50727.3053 / DEVDIV / depot / DevDiv / releases / whidbey / netfxsp / ndp / fx / src / XmlUtils / System / Xml / Xsl / QIL / QilXmlWriter.cs / 2 / QilXmlWriter.cs

                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
using System; 
using System.Collections; 
using System.Collections.Generic;
using System.Diagnostics; 
using System.Globalization;
using System.Text;
using System.Xml;
 
namespace System.Xml.Xsl.Qil {
 
    ///  
    /// If an annotation implements this interface, then QilXmlWriter will call ToString() on the annotation
    /// and serialize the result (if non-empty). 
    /// 
    interface IQilAnnotation {
        string Name { get; }
    }; 

 
    ///  
    /// An example of QilVisitor.  Prints the QilExpression tree as XML.
    ///  
    /// 
    /// The QilXmlWriter Visits every node in the tree, printing out an XML representation of
    /// each node.  Several formatting options are available, including whether or not to include annotations
    /// and type information.  When full information is printed out, the graph can be reloaded from 
    /// its serialized form using QilXmlReader.
    /// The XML format essentially uses one XML element for each node in the QIL graph. 
    /// Node properties such as type information are serialized as XML attributes. 
    /// Annotations are serialized as processing-instructions in front of a node.
    /// Feel free to subclass this visitor to customize its behavior. 
    /// 
    internal class QilXmlWriter : QilScopedVisitor {
        protected XmlWriter     writer;
        protected Options       options; 
        private   NameGenerator ngen;
 
        [Flags] 
        public enum Options {
            None = 0,               // No options selected 
            Annotations = 1,        // Print annotations
            TypeInfo = 2,           // Print type information using "G" option
            RoundTripTypeInfo = 4,  // Print type information using "S" option
            LineInfo = 8,           // Print source line information 
            NodeIdentity = 16,      // Print node identity (only works if QIL_TRACE_NODE_CREATION is defined)
            NodeLocation = 32,      // Print node creation location (only works if QIL_TRACE_NODE_CREATION is defined) 
        }; 

        ///  
        /// Construct a QilXmlWriter.
        /// 
        public QilXmlWriter(XmlWriter writer) : this(writer, Options.Annotations | Options.TypeInfo | Options.LineInfo | Options.NodeIdentity | Options.NodeLocation) {
        } 

        ///  
        /// Construct a QilXmlWriter. 
        /// 
        public QilXmlWriter(XmlWriter writer, Options options) { 
            this.writer = writer;
            this.ngen = new NameGenerator();
            this.options = options;
        } 

        ///  
        /// Serialize a QilExpression graph as XML. 
        /// 
        /// the QilExpression graph 
        public void ToXml(QilNode node) {
            VisitAssumeReference(node);
        }
 
        //-----------------------------------------------
        // QilXmlWrite methods 
        //----------------------------------------------- 

        ///  
        /// Write all annotations as comments:
        ///     1. string -- 
        ///     2. IQilAnnotation -- 
        ///     3. IList -- recursively call WriteAnnotations for each object in list 
        ///     4. otherwise, do not write the annotation
        ///  
        protected virtual void WriteAnnotations(object ann) { 
            string s = null, name = null;
 
            if (ann == null) {
                return;
            }
            else if (ann is string) { 
                s = ann as string;
            } 
            else if (ann is IQilAnnotation) { 
                // Get annotation's name and string value
                IQilAnnotation qilann = ann as IQilAnnotation; 
                name = qilann.Name;
                s = ann.ToString();
            }
            else if (ann is IList) { 
                IList list = (IList) ann;
 
                foreach (object annItem in list) 
                    WriteAnnotations(annItem);
                return; 
            }

            if (s != null && s.Length != 0)
                this.writer.WriteComment(name != null && name.Length != 0 ? name + ": " + s : s); 
        }
 
        ///  
        /// Called in order to write out source line information.
        ///  
        protected virtual void WriteLineInfo(QilNode node) {
            this.writer.WriteAttributeString("lineInfo", string.Format(CultureInfo.InvariantCulture, "[{0},{1} -- {2},{3}]",
                node.SourceLine.StartLine, node.SourceLine.StartPos,
                node.SourceLine.EndLine  , node.SourceLine.EndPos 
                ));
        } 
 
        /// 
        /// Called in order to write out the xml type of a node. 
        /// 
        protected virtual void WriteXmlType(QilNode node) {
            this.writer.WriteAttributeString("xmlType", node.XmlType.ToString((this.options & Options.RoundTripTypeInfo) != 0 ? "S" : "G"));
        } 

 
        //----------------------------------------------- 
        // QilVisitor overrides
        //----------------------------------------------- 

        /// 
        /// Override certain node types in order to add additional attributes, suppress children, etc.
        ///  
        protected override QilNode VisitChildren(QilNode node) {
            if (node is QilLiteral) { 
                // If literal is not handled elsewhere, print its string value 
                this.writer.WriteValue(Convert.ToString(((QilLiteral) node).Value, CultureInfo.InvariantCulture));
                return node; 
            }
            else if (node is QilReference) {
                QilReference reference = (QilReference) node;
 
                // Write the generated identifier for this iterator
                this.writer.WriteAttributeString("id", this.ngen.NameOf(node)); 
 
                // Write the debug name of this reference (if it's defined) as a "name" attribute
                if (reference.DebugName != null) 
                    this.writer.WriteAttributeString("name", reference.DebugName.ToString());

                if (node.NodeType == QilNodeType.Parameter) {
                    // Don't visit parameter's name, or its default value if it is null 
                    QilParameter param = (QilParameter) node;
 
                    if (param.DefaultValue != null) 
                        Visit(param.DefaultValue);
 
                    return node;
                }
             }
 
            return base.VisitChildren(node);
        } 
 
        /// 
        /// Write references to functions or iterators like this: . 
        /// 
        protected override QilNode VisitReference(QilNode node) {
            QilReference reference = (QilReference) node;
            string name = ngen.NameOf(node); 
            if (name == null)
                name = "OUT-OF-SCOPE REFERENCE"; 
 
            this.writer.WriteStartElement("RefTo");
            this.writer.WriteAttributeString("id", name); 
            if (reference.DebugName != null)
                this.writer.WriteAttributeString("name", reference.DebugName.ToString());
            this.writer.WriteEndElement();
 
            return node;
        } 
 
        /// 
        /// Scan through the external parameters, global variables, and function list for forward references. 
        /// 
        protected override QilNode VisitQilExpression(QilExpression qil) {
            IList fdecls = new ForwardRefFinder().Find(qil);
            if (fdecls != null && fdecls.Count > 0) { 
                this.writer.WriteStartElement("ForwardDecls");
                foreach (QilNode n in fdecls) { 
                    // i.e.  
                    this.writer.WriteStartElement(Enum.GetName(typeof(QilNodeType), n.NodeType));
                    this.writer.WriteAttributeString("id", this.ngen.NameOf(n)); 
                    WriteXmlType(n);

                    if (n.NodeType == QilNodeType.Function) {
                        // Visit Arguments and SideEffects operands 
                        Visit(n[0]);
                        Visit(n[2]); 
                    } 

                    this.writer.WriteEndElement(); 
                }
                this.writer.WriteEndElement();
            }
 
            return VisitChildren(qil);
        } 
 
        /// 
        /// Serialize literal types using either "S" or "G" formatting, depending on the option which has been set. 
        /// 
        protected override QilNode VisitLiteralType(QilLiteral value) {
            this.writer.WriteString(((XmlQueryType) value).ToString((this.options & Options.TypeInfo) != 0 ? "G" : "S"));
            return value; 
        }
 
        ///  
        /// Serialize literal QName as three separate attributes.
        ///  
        protected override QilNode VisitLiteralQName(QilName value) {
            this.writer.WriteAttributeString("name", value.ToString());
            return value;
        } 

 
        //----------------------------------------------- 
        // QilScopedVisitor overrides
        //----------------------------------------------- 

        /// 
        /// Annotate this iterator or function with a generated name.
        ///  
        protected override void BeginScope(QilNode node) {
            this.ngen.NameOf(node); 
        } 

        ///  
        /// Clear the name annotation on this iterator or function.
        /// 
        protected override void EndScope(QilNode node) {
            this.ngen.ClearName(node); 
        }
 
        ///  
        /// By default, call WriteStartElement for every node type.
        ///  
        protected override void BeforeVisit(QilNode node) {
            base.BeforeVisit(node);

            // Write the annotations in front of the element, to avoid issues with attributes 
            // and make it easier to round-trip
            if ((this.options & Options.Annotations) != 0) 
                WriteAnnotations(node.Annotation); 

            // Call WriteStartElement 
            this.writer.WriteStartElement("", Enum.GetName(typeof(QilNodeType), node.NodeType), "");

            // Write common attributes
#if QIL_TRACE_NODE_CREATION 
            if ((this.options & Options.NodeIdentity) != 0)
                this.writer.WriteAttributeString("nodeId", node.NodeId.ToString(CultureInfo.InvariantCulture)); 
 
            if ((this.options & Options.NodeLocation) != 0)
                this.writer.WriteAttributeString("nodeLoc", node.NodeLocation); 
#endif
            if ((this.options & (Options.TypeInfo | Options.RoundTripTypeInfo)) != 0)
                WriteXmlType(node);
 
            if ((this.options & Options.LineInfo) != 0 && node.SourceLine != null)
                WriteLineInfo(node); 
        } 

        ///  
        /// By default, call WriteEndElement for every node type.
        /// 
        protected override void AfterVisit(QilNode node) {
            this.writer.WriteEndElement(); 

            base.AfterVisit(node); 
        } 

 
        //-----------------------------------------------
        // Helper methods
        //-----------------------------------------------
 
        /// 
        /// Find list of all iterators and functions which are referenced before they have been declared. 
        ///  
        internal class ForwardRefFinder : QilVisitor {
            private List fwdrefs = new List(); 
            private List backrefs = new List();

            public IList Find(QilExpression qil) {
                Visit(qil); 
                return this.fwdrefs;
            } 
 
            /// 
            /// Add iterators and functions to backrefs list as they are visited. 
            /// 
            protected override QilNode Visit(QilNode node) {
                if (node is QilIterator || node is QilFunction)
                    this.backrefs.Add(node); 

                return base.Visit(node); 
            } 

            ///  
            /// If reference is not in scope, then it must be a forward reference.
            /// 
            protected override QilNode VisitReference(QilNode node) {
                if (!this.backrefs.Contains(node) && !this.fwdrefs.Contains(node)) 
                    this.fwdrefs.Add(node);
 
                return node; 
            }
        } 

        //=================================== Helper class: NameGenerator =========================================

        private sealed class NameGenerator { 
            StringBuilder name;
            int len; 
            int zero; 
            char start;
            char end; 

            /// 
            /// Construct a new name generator with prefix "$" and alphabetical mode.
            ///  
            public NameGenerator()
            { 
                string prefix = "$"; 
                len = zero = prefix.Length;
                start = 'a'; 
                end = 'z';
                name = new StringBuilder(prefix, len + 2);
                name.Append(start);
            } 

            ///  
            /// Skolem function for names. 
            /// 
            /// a unique name beginning with the prefix 
            public string NextName()
            {
                string result = name.ToString();
 
                char c = name[len];
                if (c == end) 
                { 
                    name[len] = start;
                    int i = len; 
                    for ( ; i-- > zero && name[i]==end; )
                        name[i] = start;

                    if (i < zero) 
                    {
                        len++; 
                        name.Append(start); 
                    }
                    else 
                        name[i]++;
                }
                else
                    name[len] = ++c; 

                return result; 
            } 

            ///  
            /// Lookup or generate a name for a node.  Uses annotations to store the name on the node.
            /// 
            /// the node
            /// the node name (unique across nodes) 
            public string NameOf(QilNode n)
            { 
                string name = null; 

                object old = n.Annotation; 
                NameAnnotation a = old as NameAnnotation;
                if (a == null)
                {
                    name = NextName(); 
                    n.Annotation = new NameAnnotation(name, old);
                } 
                else 
                {
                    name = a.Name; 
                }
                return name;
            }
 
            /// 
            /// Clear name annotation from a node. 
            ///  
            /// the node
            public void ClearName(QilNode n) 
            {
                if (n.Annotation is NameAnnotation)
                    n.Annotation = ((NameAnnotation)n.Annotation).PriorAnnotation;
            } 

            ///  
            /// Class used to hold our annotations on the graph 
            /// 
            private class NameAnnotation : ListBase 
            {
                public string Name;
                public object PriorAnnotation;
 
                public NameAnnotation(string s, object a)
                { 
                    Name = s; 
                    PriorAnnotation = a;
                } 

                public override int Count {
                    get { return 1; }
                } 

                public override object this[int index] { 
                    get { 
                        if (index == 0)
                            return PriorAnnotation; 

                        throw new IndexOutOfRangeException();
                    }
                    set { throw new NotSupportedException(); } 
                }
            } 
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
using System; 
using System.Collections; 
using System.Collections.Generic;
using System.Diagnostics; 
using System.Globalization;
using System.Text;
using System.Xml;
 
namespace System.Xml.Xsl.Qil {
 
    ///  
    /// If an annotation implements this interface, then QilXmlWriter will call ToString() on the annotation
    /// and serialize the result (if non-empty). 
    /// 
    interface IQilAnnotation {
        string Name { get; }
    }; 

 
    ///  
    /// An example of QilVisitor.  Prints the QilExpression tree as XML.
    ///  
    /// 
    /// The QilXmlWriter Visits every node in the tree, printing out an XML representation of
    /// each node.  Several formatting options are available, including whether or not to include annotations
    /// and type information.  When full information is printed out, the graph can be reloaded from 
    /// its serialized form using QilXmlReader.
    /// The XML format essentially uses one XML element for each node in the QIL graph. 
    /// Node properties such as type information are serialized as XML attributes. 
    /// Annotations are serialized as processing-instructions in front of a node.
    /// Feel free to subclass this visitor to customize its behavior. 
    /// 
    internal class QilXmlWriter : QilScopedVisitor {
        protected XmlWriter     writer;
        protected Options       options; 
        private   NameGenerator ngen;
 
        [Flags] 
        public enum Options {
            None = 0,               // No options selected 
            Annotations = 1,        // Print annotations
            TypeInfo = 2,           // Print type information using "G" option
            RoundTripTypeInfo = 4,  // Print type information using "S" option
            LineInfo = 8,           // Print source line information 
            NodeIdentity = 16,      // Print node identity (only works if QIL_TRACE_NODE_CREATION is defined)
            NodeLocation = 32,      // Print node creation location (only works if QIL_TRACE_NODE_CREATION is defined) 
        }; 

        ///  
        /// Construct a QilXmlWriter.
        /// 
        public QilXmlWriter(XmlWriter writer) : this(writer, Options.Annotations | Options.TypeInfo | Options.LineInfo | Options.NodeIdentity | Options.NodeLocation) {
        } 

        ///  
        /// Construct a QilXmlWriter. 
        /// 
        public QilXmlWriter(XmlWriter writer, Options options) { 
            this.writer = writer;
            this.ngen = new NameGenerator();
            this.options = options;
        } 

        ///  
        /// Serialize a QilExpression graph as XML. 
        /// 
        /// the QilExpression graph 
        public void ToXml(QilNode node) {
            VisitAssumeReference(node);
        }
 
        //-----------------------------------------------
        // QilXmlWrite methods 
        //----------------------------------------------- 

        ///  
        /// Write all annotations as comments:
        ///     1. string -- 
        ///     2. IQilAnnotation -- 
        ///     3. IList -- recursively call WriteAnnotations for each object in list 
        ///     4. otherwise, do not write the annotation
        ///  
        protected virtual void WriteAnnotations(object ann) { 
            string s = null, name = null;
 
            if (ann == null) {
                return;
            }
            else if (ann is string) { 
                s = ann as string;
            } 
            else if (ann is IQilAnnotation) { 
                // Get annotation's name and string value
                IQilAnnotation qilann = ann as IQilAnnotation; 
                name = qilann.Name;
                s = ann.ToString();
            }
            else if (ann is IList) { 
                IList list = (IList) ann;
 
                foreach (object annItem in list) 
                    WriteAnnotations(annItem);
                return; 
            }

            if (s != null && s.Length != 0)
                this.writer.WriteComment(name != null && name.Length != 0 ? name + ": " + s : s); 
        }
 
        ///  
        /// Called in order to write out source line information.
        ///  
        protected virtual void WriteLineInfo(QilNode node) {
            this.writer.WriteAttributeString("lineInfo", string.Format(CultureInfo.InvariantCulture, "[{0},{1} -- {2},{3}]",
                node.SourceLine.StartLine, node.SourceLine.StartPos,
                node.SourceLine.EndLine  , node.SourceLine.EndPos 
                ));
        } 
 
        /// 
        /// Called in order to write out the xml type of a node. 
        /// 
        protected virtual void WriteXmlType(QilNode node) {
            this.writer.WriteAttributeString("xmlType", node.XmlType.ToString((this.options & Options.RoundTripTypeInfo) != 0 ? "S" : "G"));
        } 

 
        //----------------------------------------------- 
        // QilVisitor overrides
        //----------------------------------------------- 

        /// 
        /// Override certain node types in order to add additional attributes, suppress children, etc.
        ///  
        protected override QilNode VisitChildren(QilNode node) {
            if (node is QilLiteral) { 
                // If literal is not handled elsewhere, print its string value 
                this.writer.WriteValue(Convert.ToString(((QilLiteral) node).Value, CultureInfo.InvariantCulture));
                return node; 
            }
            else if (node is QilReference) {
                QilReference reference = (QilReference) node;
 
                // Write the generated identifier for this iterator
                this.writer.WriteAttributeString("id", this.ngen.NameOf(node)); 
 
                // Write the debug name of this reference (if it's defined) as a "name" attribute
                if (reference.DebugName != null) 
                    this.writer.WriteAttributeString("name", reference.DebugName.ToString());

                if (node.NodeType == QilNodeType.Parameter) {
                    // Don't visit parameter's name, or its default value if it is null 
                    QilParameter param = (QilParameter) node;
 
                    if (param.DefaultValue != null) 
                        Visit(param.DefaultValue);
 
                    return node;
                }
             }
 
            return base.VisitChildren(node);
        } 
 
        /// 
        /// Write references to functions or iterators like this: . 
        /// 
        protected override QilNode VisitReference(QilNode node) {
            QilReference reference = (QilReference) node;
            string name = ngen.NameOf(node); 
            if (name == null)
                name = "OUT-OF-SCOPE REFERENCE"; 
 
            this.writer.WriteStartElement("RefTo");
            this.writer.WriteAttributeString("id", name); 
            if (reference.DebugName != null)
                this.writer.WriteAttributeString("name", reference.DebugName.ToString());
            this.writer.WriteEndElement();
 
            return node;
        } 
 
        /// 
        /// Scan through the external parameters, global variables, and function list for forward references. 
        /// 
        protected override QilNode VisitQilExpression(QilExpression qil) {
            IList fdecls = new ForwardRefFinder().Find(qil);
            if (fdecls != null && fdecls.Count > 0) { 
                this.writer.WriteStartElement("ForwardDecls");
                foreach (QilNode n in fdecls) { 
                    // i.e.  
                    this.writer.WriteStartElement(Enum.GetName(typeof(QilNodeType), n.NodeType));
                    this.writer.WriteAttributeString("id", this.ngen.NameOf(n)); 
                    WriteXmlType(n);

                    if (n.NodeType == QilNodeType.Function) {
                        // Visit Arguments and SideEffects operands 
                        Visit(n[0]);
                        Visit(n[2]); 
                    } 

                    this.writer.WriteEndElement(); 
                }
                this.writer.WriteEndElement();
            }
 
            return VisitChildren(qil);
        } 
 
        /// 
        /// Serialize literal types using either "S" or "G" formatting, depending on the option which has been set. 
        /// 
        protected override QilNode VisitLiteralType(QilLiteral value) {
            this.writer.WriteString(((XmlQueryType) value).ToString((this.options & Options.TypeInfo) != 0 ? "G" : "S"));
            return value; 
        }
 
        ///  
        /// Serialize literal QName as three separate attributes.
        ///  
        protected override QilNode VisitLiteralQName(QilName value) {
            this.writer.WriteAttributeString("name", value.ToString());
            return value;
        } 

 
        //----------------------------------------------- 
        // QilScopedVisitor overrides
        //----------------------------------------------- 

        /// 
        /// Annotate this iterator or function with a generated name.
        ///  
        protected override void BeginScope(QilNode node) {
            this.ngen.NameOf(node); 
        } 

        ///  
        /// Clear the name annotation on this iterator or function.
        /// 
        protected override void EndScope(QilNode node) {
            this.ngen.ClearName(node); 
        }
 
        ///  
        /// By default, call WriteStartElement for every node type.
        ///  
        protected override void BeforeVisit(QilNode node) {
            base.BeforeVisit(node);

            // Write the annotations in front of the element, to avoid issues with attributes 
            // and make it easier to round-trip
            if ((this.options & Options.Annotations) != 0) 
                WriteAnnotations(node.Annotation); 

            // Call WriteStartElement 
            this.writer.WriteStartElement("", Enum.GetName(typeof(QilNodeType), node.NodeType), "");

            // Write common attributes
#if QIL_TRACE_NODE_CREATION 
            if ((this.options & Options.NodeIdentity) != 0)
                this.writer.WriteAttributeString("nodeId", node.NodeId.ToString(CultureInfo.InvariantCulture)); 
 
            if ((this.options & Options.NodeLocation) != 0)
                this.writer.WriteAttributeString("nodeLoc", node.NodeLocation); 
#endif
            if ((this.options & (Options.TypeInfo | Options.RoundTripTypeInfo)) != 0)
                WriteXmlType(node);
 
            if ((this.options & Options.LineInfo) != 0 && node.SourceLine != null)
                WriteLineInfo(node); 
        } 

        ///  
        /// By default, call WriteEndElement for every node type.
        /// 
        protected override void AfterVisit(QilNode node) {
            this.writer.WriteEndElement(); 

            base.AfterVisit(node); 
        } 

 
        //-----------------------------------------------
        // Helper methods
        //-----------------------------------------------
 
        /// 
        /// Find list of all iterators and functions which are referenced before they have been declared. 
        ///  
        internal class ForwardRefFinder : QilVisitor {
            private List fwdrefs = new List(); 
            private List backrefs = new List();

            public IList Find(QilExpression qil) {
                Visit(qil); 
                return this.fwdrefs;
            } 
 
            /// 
            /// Add iterators and functions to backrefs list as they are visited. 
            /// 
            protected override QilNode Visit(QilNode node) {
                if (node is QilIterator || node is QilFunction)
                    this.backrefs.Add(node); 

                return base.Visit(node); 
            } 

            ///  
            /// If reference is not in scope, then it must be a forward reference.
            /// 
            protected override QilNode VisitReference(QilNode node) {
                if (!this.backrefs.Contains(node) && !this.fwdrefs.Contains(node)) 
                    this.fwdrefs.Add(node);
 
                return node; 
            }
        } 

        //=================================== Helper class: NameGenerator =========================================

        private sealed class NameGenerator { 
            StringBuilder name;
            int len; 
            int zero; 
            char start;
            char end; 

            /// 
            /// Construct a new name generator with prefix "$" and alphabetical mode.
            ///  
            public NameGenerator()
            { 
                string prefix = "$"; 
                len = zero = prefix.Length;
                start = 'a'; 
                end = 'z';
                name = new StringBuilder(prefix, len + 2);
                name.Append(start);
            } 

            ///  
            /// Skolem function for names. 
            /// 
            /// a unique name beginning with the prefix 
            public string NextName()
            {
                string result = name.ToString();
 
                char c = name[len];
                if (c == end) 
                { 
                    name[len] = start;
                    int i = len; 
                    for ( ; i-- > zero && name[i]==end; )
                        name[i] = start;

                    if (i < zero) 
                    {
                        len++; 
                        name.Append(start); 
                    }
                    else 
                        name[i]++;
                }
                else
                    name[len] = ++c; 

                return result; 
            } 

            ///  
            /// Lookup or generate a name for a node.  Uses annotations to store the name on the node.
            /// 
            /// the node
            /// the node name (unique across nodes) 
            public string NameOf(QilNode n)
            { 
                string name = null; 

                object old = n.Annotation; 
                NameAnnotation a = old as NameAnnotation;
                if (a == null)
                {
                    name = NextName(); 
                    n.Annotation = new NameAnnotation(name, old);
                } 
                else 
                {
                    name = a.Name; 
                }
                return name;
            }
 
            /// 
            /// Clear name annotation from a node. 
            ///  
            /// the node
            public void ClearName(QilNode n) 
            {
                if (n.Annotation is NameAnnotation)
                    n.Annotation = ((NameAnnotation)n.Annotation).PriorAnnotation;
            } 

            ///  
            /// Class used to hold our annotations on the graph 
            /// 
            private class NameAnnotation : ListBase 
            {
                public string Name;
                public object PriorAnnotation;
 
                public NameAnnotation(string s, object a)
                { 
                    Name = s; 
                    PriorAnnotation = a;
                } 

                public override int Count {
                    get { return 1; }
                } 

                public override object this[int index] { 
                    get { 
                        if (index == 0)
                            return PriorAnnotation; 

                        throw new IndexOutOfRangeException();
                    }
                    set { throw new NotSupportedException(); } 
                }
            } 
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

                        

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