System.Xml.Xsl.IlGen.XmlILVisitor.Visit C# (CSharp) Метод

        protected override QilNode Visit(QilNode nd) {
            if (nd == null)
                return null;

            // DebugInfo: Sequence point just before generating code for this expression
            if (this.qil.IsDebug && nd.SourceLine != null && !(nd is QilIterator))
                this.helper.DebugSequencePoint(nd.SourceLine);

            // Expressions are constructed using one of several possible methods
            switch (XmlILConstructInfo.Read(nd).ConstructMethod) {
                case XmlILConstructMethod.WriterThenIterator:
                    // Push results of expression to cached writer; then iterate over cached results
                    NestedConstruction(nd);
                    break;

                case XmlILConstructMethod.IteratorThenWriter:
                    // Iterate over items in the sequence; send items to writer
                    CopySequence(nd);
                    break;

                case XmlILConstructMethod.Iterator:
                    Debug.Assert(nd.XmlType.IsSingleton || CachesResult(nd) || this.iterCurr.HasLabelNext,
                                 "When generating code for a non-singleton expression, LabelNext must be defined.");
                    goto default;

                default:
                    // Allow base internal class to dispatch to correct Visit method
                    base.Visit(nd);
                    break;
            }

            return nd;
        }

        /// <summary>
        /// Given the logical query plan (QilExpression) generate a physical query plan (MSIL) that can be executed.
        /// </summary>
        // SxS Note: The way the trace file names are created (hardcoded) is NOT SxS safe. However the files are
        // created only for internal tracing purposes. In addition XmlILTrace class is not compiled into retail 
        // builds. As a result it is fine to suppress the FxCop SxS warning.
        public XmlILCommand Generate(QilExpression query, TypeBuilder typeBldr)
        {
            _qil = query;

            bool useLRE = (
                !_qil.IsDebug &&
                (typeBldr == null)
#if DEBUG
                && !XmlILTrace.IsEnabled // Dump assembly to disk; can't do this when using LRE
#endif
            );
            bool emitSymbols = _qil.IsDebug;

            // In debug code, ensure that input QIL is correct
            QilValidationVisitor.Validate(_qil);

#if DEBUG
            // Trace Qil before optimization
            XmlILTrace.WriteQil(this.qil, "qilbefore.xml");

            // Trace optimizations
            XmlILTrace.TraceOptimizations(this.qil, "qilopt.xml");
#endif

            // Optimize and annotate the Qil graph
            _optVisitor = new XmlILOptimizerVisitor(_qil, !_qil.IsDebug);
            _qil = _optVisitor.Optimize();

            // In debug code, ensure that output QIL is correct
            QilValidationVisitor.Validate(_qil);

#if DEBUG
            // Trace Qil after optimization
            XmlILTrace.WriteQil(this.qil, "qilafter.xml");
#endif

            // Create module in which methods will be generated
            if (typeBldr != null)
            {
                _module = new XmlILModule(typeBldr);
            }
            else
            {
                _module = new XmlILModule(useLRE, emitSymbols);
            }

            // Create a code generation helper for the module; enable optimizations if IsDebug is false
            _helper = new GenerateHelper(_module, _qil.IsDebug);

            // Create helper methods
            CreateHelperFunctions();

            // Create metadata for the Execute function, which is the entry point to the query
            // public static void Execute(XmlQueryRuntime);
            MethodInfo methExec = _module.DefineMethod("Execute", typeof(void), new Type[] { }, new string[] { }, XmlILMethodAttributes.NonUser);

            // Create metadata for the root expression
            // public void Root()
            Debug.Assert(_qil.Root != null);
            XmlILMethodAttributes methAttrs = (_qil.Root.SourceLine == null) ? XmlILMethodAttributes.NonUser : XmlILMethodAttributes.None;
            MethodInfo methRoot = _module.DefineMethod("Root", typeof(void), new Type[] { }, new string[] { }, methAttrs);

            // Declare all early bound function objects
            foreach (EarlyBoundInfo info in _qil.EarlyBoundTypes)
            {
                _helper.StaticData.DeclareEarlyBound(info.NamespaceUri, info.EarlyBoundType);
            }

            // Create metadata for each QilExpression function that has at least one caller
            CreateFunctionMetadata(_qil.FunctionList);

            // Create metadata for each QilExpression global variable and parameter
            CreateGlobalValueMetadata(_qil.GlobalVariableList);
            CreateGlobalValueMetadata(_qil.GlobalParameterList);

            // Generate Execute method
            GenerateExecuteFunction(methExec, methRoot);

            // Visit the QilExpression graph
            _xmlIlVisitor = new XmlILVisitor();
            _xmlIlVisitor.Visit(_qil, _helper, methRoot);

            // Collect all static information required by the runtime
            XmlQueryStaticData staticData = new XmlQueryStaticData(
                _qil.DefaultWriterSettings,
                _qil.WhitespaceRules,
                _helper.StaticData
            );

            // Create static constructor that initializes XmlQueryStaticData instance at runtime
            if (typeBldr != null)
            {
                CreateTypeInitializer(staticData);

                // Finish up creation of the type
                _module.BakeMethods();

                return null;
            }
            else
            {
                // Finish up creation of the type
                _module.BakeMethods();

                // Create delegate over "Execute" method
                ExecuteDelegate delExec = (ExecuteDelegate)_module.CreateDelegate("Execute", typeof(ExecuteDelegate));
                return new XmlILCommand(delExec, staticData);
            }
        }