path: root/mcs/class/referencesource/System.Xml/System/Xml/Schema/XsdValidator.cs

//------------------------------------------------------------------------------
// <copyright file="XsdValidator.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// <owner current="true" primary="true">[....]</owner> 
//------------------------------------------------------------------------------

namespace System.Xml.Schema {

    using System.Collections;
    using System.Collections.Specialized;
    using System.Text;
    using System.IO;
    using System.Diagnostics;
    using System.Xml.Schema;
    using System.Xml.XPath;
    using System.Runtime.Versioning;

#pragma warning disable 618
    internal sealed class XsdValidator : BaseValidator {
        
        private  int startIDConstraint = -1;    
        private const int        STACK_INCREMENT = 10;
        private HWStack          validationStack;  // validaton contexts
        
        private Hashtable        attPresence;
        private XmlNamespaceManager  nsManager;
        private bool bManageNamespaces = false;
        private Hashtable       IDs;
        private IdRefNode       idRefListHead;
        private Parser  inlineSchemaParser = null;
        private XmlSchemaContentProcessing processContents;

        private static  readonly XmlSchemaDatatype dtCDATA = XmlSchemaDatatype.FromXmlTokenizedType(XmlTokenizedType.CDATA);
        private static  readonly XmlSchemaDatatype dtQName = XmlSchemaDatatype.FromXmlTokenizedTypeXsd(XmlTokenizedType.QName);
        private static  readonly XmlSchemaDatatype dtStringArray = dtCDATA.DeriveByList(null);
        
        //To avoid SchemaNames creation
        private string NsXmlNs;
        private string NsXs;
        private string NsXsi;
        private string XsiType;
        private string XsiNil;
        private string XsiSchemaLocation;
        private string XsiNoNamespaceSchemaLocation;
        private string XsdSchema;


        internal XsdValidator(BaseValidator validator) : base(validator) {
            Init();
        }

        internal XsdValidator(XmlValidatingReaderImpl reader, XmlSchemaCollection schemaCollection, IValidationEventHandling eventHandling) : base(reader, schemaCollection, eventHandling) {
            Init();
        }

        private void Init() {
            nsManager = reader.NamespaceManager;
            if (nsManager == null) {
                nsManager = new XmlNamespaceManager(NameTable);
                bManageNamespaces = true;
            }
            validationStack = new HWStack(STACK_INCREMENT);
            textValue = new StringBuilder();
            attPresence = new Hashtable();
            schemaInfo = new SchemaInfo ();
            checkDatatype = false;
            processContents = XmlSchemaContentProcessing.Strict;
            Push (XmlQualifiedName.Empty);

            //Add common strings to be compared to NameTable
            NsXmlNs = NameTable.Add(XmlReservedNs.NsXmlNs);       
            NsXs = NameTable.Add(XmlReservedNs.NsXs);
            NsXsi = NameTable.Add(XmlReservedNs.NsXsi);
            XsiType = NameTable.Add("type");
            XsiNil = NameTable.Add("nil");
            XsiSchemaLocation = NameTable.Add("schemaLocation");
            XsiNoNamespaceSchemaLocation = NameTable.Add("noNamespaceSchemaLocation");
            XsdSchema = NameTable.Add("schema");
        }

        public override void Validate() {
            if (IsInlineSchemaStarted) {
                ProcessInlineSchema();
            }
            else {
                switch (reader.NodeType) {
                    case XmlNodeType.Element:
                        ValidateElement();
                        if (reader.IsEmptyElement) {
                            goto case XmlNodeType.EndElement;
                        }
                        break;
                    case XmlNodeType.Whitespace:
                        ValidateWhitespace();
                        break;
                    case XmlNodeType.Text:          // text inside a node
                    case XmlNodeType.CDATA:         // <![CDATA[...]]>
                    case XmlNodeType.SignificantWhitespace:
                        ValidateText();
                        break;
                    case XmlNodeType.EndElement:
                        ValidateEndElement();
                        break;
                }
            }
        }

        
        public override void CompleteValidation() {
            CheckForwardRefs();
        }

        //for frag validation
        public ValidationState Context{
            set { context = value; }
     }

        //share for frag validation
        public static XmlSchemaDatatype DtQName {
            get { return dtQName; }
        }

        private bool IsInlineSchemaStarted {
            get { return inlineSchemaParser != null; }
        }

        private void ProcessInlineSchema() {
            if (!inlineSchemaParser.ParseReaderNode()) { // Done
                inlineSchemaParser.FinishParsing();
                XmlSchema schema = inlineSchemaParser.XmlSchema;
                string inlineNS = null;
                if (schema  != null && schema.ErrorCount == 0) {
                    try {
                        SchemaInfo inlineSchemaInfo = new SchemaInfo();
                        inlineSchemaInfo.SchemaType = SchemaType.XSD;
                        inlineNS = schema.TargetNamespace == null? string.Empty : schema.TargetNamespace;
                        if (!SchemaInfo.TargetNamespaces.ContainsKey(inlineNS)) {
                            if (SchemaCollection.Add(inlineNS, inlineSchemaInfo, schema, true) != null) { //If no errors on compile
                                //Add to validator's SchemaInfo
                                SchemaInfo.Add(inlineSchemaInfo, EventHandler);
                            }
                        }
                    }
                    catch(XmlSchemaException e) {
                        SendValidationEvent(Res.Sch_CannotLoadSchema, new string[] {BaseUri.AbsoluteUri, e.Message}, XmlSeverityType.Error);
                    }
                }
                inlineSchemaParser = null;
            }
        }

        private void ValidateElement() {
            elementName.Init(reader.LocalName, reader.NamespaceURI);
            object particle = ValidateChildElement ();
            if (IsXSDRoot(elementName.Name, elementName.Namespace) && reader.Depth > 0) {
                inlineSchemaParser = new Parser(SchemaType.XSD, NameTable, SchemaNames, EventHandler);
                inlineSchemaParser.StartParsing(reader, null);
                ProcessInlineSchema();
            }
            else {
                ProcessElement(particle);
            }
        }

        private object ValidateChildElement() {
            object particle = null;
            int errorCode = 0;
            if (context.NeedValidateChildren) {
                if (context.IsNill) {
                    SendValidationEvent(Res.Sch_ContentInNill, elementName.ToString());
                    return null;
                }
                particle = context.ElementDecl.ContentValidator.ValidateElement(elementName, context, out errorCode);
                if (particle == null) {
                    processContents = context.ProcessContents = XmlSchemaContentProcessing.Skip;
                    if (errorCode == -2) { //ContentModel all group error
                        SendValidationEvent(Res.Sch_AllElement, elementName.ToString());
                    }
                    XmlSchemaValidator.ElementValidationError(elementName, context, EventHandler, reader, reader.BaseURI, PositionInfo.LineNumber, PositionInfo.LinePosition, null);
                }
            }
            return particle;
        }

        private void ProcessElement(object particle) {
            XmlQualifiedName xsiType;
            string xsiNil;
            SchemaElementDecl elementDecl = FastGetElementDecl (particle);
            Push(elementName); 
            if (bManageNamespaces) { 
                nsManager.PushScope();
            }
            ProcessXsiAttributes(out xsiType, out xsiNil);
            if (processContents != XmlSchemaContentProcessing.Skip) {
                if (elementDecl == null || !xsiType.IsEmpty || xsiNil != null) {
                    elementDecl = ThoroughGetElementDecl(elementDecl, xsiType, xsiNil);
                }
                if (elementDecl == null) {
                    if (HasSchema && processContents == XmlSchemaContentProcessing.Strict) {
                        SendValidationEvent(Res.Sch_UndeclaredElement, XmlSchemaValidator.QNameString(context.LocalName, context.Namespace));
                    }
                    else {
                        SendValidationEvent(Res.Sch_NoElementSchemaFound, XmlSchemaValidator.QNameString(context.LocalName, context.Namespace), XmlSeverityType.Warning);
                    }
                }
            }

            context.ElementDecl = elementDecl;
            ValidateStartElementIdentityConstraints();
            ValidateStartElement();
            if (context.ElementDecl != null) {  
                ValidateEndStartElement();
                context.NeedValidateChildren = processContents != XmlSchemaContentProcessing.Skip;
                context.ElementDecl.ContentValidator.InitValidation(context);
            }
        }

        // SxS: This method processes attributes read from source document and does not expose any resources. 
        // It's OK to suppress the SxS warning.
        [ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
        [ResourceExposure(ResourceScope.None)]
        private void ProcessXsiAttributes(out XmlQualifiedName xsiType, out string xsiNil) {
            string[] xsiSchemaLocation = null;
            string xsiNoNamespaceSchemaLocation = null;
            xsiType = XmlQualifiedName.Empty;
            xsiNil = null;

            if (reader.Depth == 0) {
                //Load schema for empty namespace
                LoadSchema(string.Empty, null);
            
                //Should load schemas for namespaces already added to nsManager
                foreach(string ns in nsManager.GetNamespacesInScope(XmlNamespaceScope.ExcludeXml).Values) {
                    LoadSchema(ns, null);
                }
            }

            if (reader.MoveToFirstAttribute()) {
                do {
                    string objectNs = reader.NamespaceURI;
                    string objectName = reader.LocalName;
                    if (Ref.Equal(objectNs, NsXmlNs)) {
                        LoadSchema(reader.Value, null);
                        if (bManageNamespaces) {
                            nsManager.AddNamespace(reader.Prefix.Length == 0 ? string.Empty : reader.LocalName, reader.Value);
                        }
                    }
                    else if (Ref.Equal(objectNs, NsXsi)) {
                        if (Ref.Equal(objectName, XsiSchemaLocation)) {
                            xsiSchemaLocation = (string[])dtStringArray.ParseValue(reader.Value, NameTable, nsManager);
                        }
                        else if (Ref.Equal(objectName, XsiNoNamespaceSchemaLocation)) {
                            xsiNoNamespaceSchemaLocation = reader.Value;
                        }
                        else if (Ref.Equal(objectName, XsiType)) {
                            xsiType = (XmlQualifiedName)dtQName.ParseValue(reader.Value, NameTable, nsManager);
                        }
                        else if (Ref.Equal(objectName, XsiNil)) {
                            xsiNil = reader.Value;
                        }
                    }
                } while(reader.MoveToNextAttribute());
                reader.MoveToElement();
            }
            if (xsiNoNamespaceSchemaLocation != null) {
                LoadSchema(string.Empty, xsiNoNamespaceSchemaLocation);
            }
            if (xsiSchemaLocation != null) {
                for (int i = 0; i < xsiSchemaLocation.Length - 1; i += 2) {
                    LoadSchema((string)xsiSchemaLocation[i], (string)xsiSchemaLocation[i + 1]);
                }
            }
        }

        private void ValidateEndElement() {
            if (bManageNamespaces) {
                nsManager.PopScope();
            }
            if (context.ElementDecl != null) {
                if (!context.IsNill) {
                    if (context.NeedValidateChildren) {
                        if(!context.ElementDecl.ContentValidator.CompleteValidation(context)) {
                            XmlSchemaValidator.CompleteValidationError(context, EventHandler, reader, reader.BaseURI, PositionInfo.LineNumber, PositionInfo.LinePosition, null);
                        }
                    }

                    if (checkDatatype && !context.IsNill) {
                        string stringValue = !hasSibling ? textString : textValue.ToString();  // only for identity-constraint exception reporting
                        if(!(stringValue.Length == 0 && context.ElementDecl.DefaultValueTyped != null)) {
                            CheckValue(stringValue, null);
                            checkDatatype = false;
                        }
                    }
                }

                // for each level in the stack, endchildren and fill value from element
                if (HasIdentityConstraints) {
                    EndElementIdentityConstraints();
                }
            }
            Pop();

        }

        private SchemaElementDecl FastGetElementDecl(object particle) {
            SchemaElementDecl elementDecl = null;
            if (particle != null) {
                XmlSchemaElement element = particle as XmlSchemaElement;
                if (element != null) {
                    elementDecl = element.ElementDecl;
                }
                else {
                    XmlSchemaAny any = (XmlSchemaAny)particle;
                    processContents = any.ProcessContentsCorrect;
                }
            }
            return elementDecl;
        }

        private SchemaElementDecl ThoroughGetElementDecl(SchemaElementDecl elementDecl, XmlQualifiedName xsiType, string xsiNil) {
            if (elementDecl == null) {
                elementDecl = schemaInfo.GetElementDecl(elementName);
            }
            if (elementDecl != null) {
                if (xsiType.IsEmpty) {
                    if (elementDecl.IsAbstract) {
                        SendValidationEvent(Res.Sch_AbstractElement, XmlSchemaValidator.QNameString(context.LocalName, context.Namespace));
                        elementDecl = null;
                    }
                }
                else if(xsiNil != null && xsiNil.Equals("true")) {
                    SendValidationEvent(Res.Sch_XsiNilAndType);
                }
                else {
                    SchemaElementDecl elementDeclXsi;
                    if (!schemaInfo.ElementDeclsByType.TryGetValue(xsiType, out elementDeclXsi) && xsiType.Namespace == NsXs) {
                        XmlSchemaSimpleType simpleType = DatatypeImplementation.GetSimpleTypeFromXsdType(new XmlQualifiedName(xsiType.Name,NsXs));
                        if (simpleType != null) {
                            elementDeclXsi = simpleType.ElementDecl;
                        }
                    }
                    if (elementDeclXsi == null) {
                        SendValidationEvent(Res.Sch_XsiTypeNotFound, xsiType.ToString());
                        elementDecl = null;
                    }
                    else if (!XmlSchemaType.IsDerivedFrom(elementDeclXsi.SchemaType,elementDecl.SchemaType,elementDecl.Block)) {
                        SendValidationEvent(Res.Sch_XsiTypeBlockedEx, new string[] { xsiType.ToString(), XmlSchemaValidator.QNameString(context.LocalName, context.Namespace) });
                        elementDecl = null;
                    }
                    else {
                        elementDecl = elementDeclXsi;
                    }
                }
                if (elementDecl != null && elementDecl.IsNillable) {
                    if (xsiNil != null) {
                        context.IsNill = XmlConvert.ToBoolean(xsiNil);
                        if (context.IsNill && elementDecl.DefaultValueTyped != null) {
                            SendValidationEvent(Res.Sch_XsiNilAndFixed);
                        }
                    }
                }
                else if (xsiNil != null) {
                    SendValidationEvent(Res.Sch_InvalidXsiNill);
                }
            }
            return elementDecl;
        }

        private void ValidateStartElement() {
            if (context.ElementDecl != null) {
                if (context.ElementDecl.IsAbstract) {
                    SendValidationEvent(Res.Sch_AbstractElement, XmlSchemaValidator.QNameString(context.LocalName, context.Namespace));
                }
                
                reader.SchemaTypeObject =  context.ElementDecl.SchemaType;

                if (reader.IsEmptyElement && !context.IsNill && context.ElementDecl.DefaultValueTyped != null) {
                    reader.TypedValueObject = UnWrapUnion(context.ElementDecl.DefaultValueTyped);
                    context.IsNill = true; // reusing IsNill
                }
                else {
                    reader.TypedValueObject = null; //Typed value cleanup 
                }
                if (this.context.ElementDecl.HasRequiredAttribute || HasIdentityConstraints) {
                    attPresence.Clear();
                }
            }

            if (reader.MoveToFirstAttribute()) {
                do {
                    if ((object)reader.NamespaceURI == (object)NsXmlNs) {
                        continue;
                    }
                    if ((object)reader.NamespaceURI == (object)NsXsi) {
                        continue;
                    }

                    try {
                        reader.SchemaTypeObject = null;
                        XmlQualifiedName attQName = new XmlQualifiedName(reader.LocalName, reader.NamespaceURI);
                        bool skipContents = (processContents == XmlSchemaContentProcessing.Skip);
                        SchemaAttDef attnDef = schemaInfo.GetAttributeXsd(context.ElementDecl, attQName, ref skipContents);

                        if (attnDef != null) {
                            if (context.ElementDecl != null && (context.ElementDecl.HasRequiredAttribute || this.startIDConstraint != -1)) {
                                attPresence.Add(attnDef.Name, attnDef);
                            }
                            Debug.Assert(attnDef.SchemaType != null);
                            reader.SchemaTypeObject = attnDef.SchemaType;
                            if (attnDef.Datatype != null) {

                                // need to check the contents of this attribute to make sure
                                // it is valid according to the specified attribute type.
                                CheckValue(reader.Value, attnDef);
                            }
                            if (HasIdentityConstraints) {
                                AttributeIdentityConstraints(reader.LocalName, reader.NamespaceURI, reader.TypedValueObject, reader.Value, attnDef);
                            }
                        }
                        else if (!skipContents) {
                            if (context.ElementDecl == null 
                                && processContents == XmlSchemaContentProcessing.Strict 
                                && attQName.Namespace.Length != 0
                                && schemaInfo.Contains(attQName.Namespace) 
                                ) {
                                SendValidationEvent(Res.Sch_UndeclaredAttribute, attQName.ToString());
                            }
                            else {
                                SendValidationEvent(Res.Sch_NoAttributeSchemaFound, attQName.ToString(), XmlSeverityType.Warning);
                            }
                        }
                    }
                    catch (XmlSchemaException e) {
                        e.SetSource(reader.BaseURI, PositionInfo.LineNumber, PositionInfo.LinePosition);
                        SendValidationEvent(e);
                    }
                } while(reader.MoveToNextAttribute());
                reader.MoveToElement();
            }
        }

        private void ValidateEndStartElement() {
            if (context.ElementDecl.HasDefaultAttribute) {
                for (int i = 0; i < context.ElementDecl.DefaultAttDefs.Count; ++i) {
                    SchemaAttDef attdef = (SchemaAttDef)context.ElementDecl.DefaultAttDefs[i];
                    reader.AddDefaultAttribute(attdef); 
                    // even default attribute i have to move to... but can't exist
                    if (HasIdentityConstraints && !attPresence.Contains(attdef.Name)) {
                        AttributeIdentityConstraints(attdef.Name.Name, attdef.Name.Namespace, UnWrapUnion(attdef.DefaultValueTyped), attdef.DefaultValueRaw, attdef);
                    }
                }
            }

            if (context.ElementDecl.HasRequiredAttribute) {
                try {
                    context.ElementDecl.CheckAttributes(attPresence, reader.StandAlone);
                }
                catch (XmlSchemaException e) {
                    e.SetSource(reader.BaseURI, PositionInfo.LineNumber, PositionInfo.LinePosition);
                    SendValidationEvent(e);
                }

            }
            if (context.ElementDecl.Datatype != null) {
                checkDatatype = true;
                hasSibling = false;
                textString = string.Empty;
                textValue.Length = 0;
            }
        }

            
        [ResourceConsumption(ResourceScope.Machine)]
        [ResourceExposure(ResourceScope.Machine)]
        private void LoadSchemaFromLocation(string uri, string url) {
           
            XmlReader reader = null;
            SchemaInfo schemaInfo = null;

            try {
                Uri ruri = this.XmlResolver.ResolveUri(BaseUri, url);
                Stream stm = (Stream)this.XmlResolver.GetEntity(ruri,null,null);
                reader = new XmlTextReader(ruri.ToString(), stm, NameTable);
                //XmlSchema schema = SchemaCollection.Add(uri, reader, this.XmlResolver);

                Parser parser = new Parser(SchemaType.XSD, NameTable, SchemaNames, EventHandler);
                parser.XmlResolver = this.XmlResolver;
                SchemaType schemaType = parser.Parse(reader, uri);
                
                schemaInfo = new SchemaInfo();
                schemaInfo.SchemaType = schemaType;
                if (schemaType == SchemaType.XSD) {
                    if (SchemaCollection.EventHandler == null) {
			SchemaCollection.EventHandler = this.EventHandler;
                    }			
                    SchemaCollection.Add(uri, schemaInfo, parser.XmlSchema, true);
                }
                //Add to validator's SchemaInfo
                SchemaInfo.Add(schemaInfo, EventHandler);

                while(reader.Read());// wellformness check
            }
            catch(XmlSchemaException e) {
                schemaInfo = null;
                SendValidationEvent(Res.Sch_CannotLoadSchema, new string[] {uri, e.Message}, XmlSeverityType.Error);
            }
            catch(Exception e) {
                schemaInfo = null;
                SendValidationEvent(Res.Sch_CannotLoadSchema, new string[] {uri, e.Message}, XmlSeverityType.Warning);
            }
            finally {
                if (reader != null) {
                    reader.Close();
                }
            }
        }
        
        [ResourceConsumption(ResourceScope.Machine)]
        [ResourceExposure(ResourceScope.Machine)]
        private void LoadSchema(string uri, string url) {
            if (this.XmlResolver == null) {
                return;
            }
            if (SchemaInfo.TargetNamespaces.ContainsKey(uri) && nsManager.LookupPrefix(uri) != null) {
                return;
            }
            
            SchemaInfo schemaInfo = null;
            if (SchemaCollection != null)
                schemaInfo = SchemaCollection.GetSchemaInfo(uri); 
            if (schemaInfo != null) {
                if(schemaInfo.SchemaType != SchemaType.XSD) {
                    throw new XmlException(Res.Xml_MultipleValidaitonTypes, string.Empty, this.PositionInfo.LineNumber, this.PositionInfo.LinePosition);
                }
                SchemaInfo.Add(schemaInfo, EventHandler);
                return;
            }
            if (url != null) {
                LoadSchemaFromLocation(uri, url);
            }
        }

        private bool HasSchema { get { return schemaInfo.SchemaType != SchemaType.None;}}

        public override bool PreserveWhitespace { 
            get { return context.ElementDecl != null ? context.ElementDecl.ContentValidator.PreserveWhitespace : false; }
        }


        void ProcessTokenizedType(
            XmlTokenizedType    ttype,
            string              name
        ) {
            switch(ttype) {
            case XmlTokenizedType.ID:
                if (FindId(name) != null) {
                    SendValidationEvent(Res.Sch_DupId, name);
                }
                else {
                    AddID(name, context.LocalName);
                }
                break;
            case XmlTokenizedType.IDREF:
                object p = FindId(name);
                if (p == null) { // add it to linked list to check it later
                    idRefListHead = new IdRefNode(idRefListHead, name, this.PositionInfo.LineNumber, this.PositionInfo.LinePosition);
                }
                break;
            case XmlTokenizedType.ENTITY:
                ProcessEntity(schemaInfo, name, this, EventHandler, reader.BaseURI, PositionInfo.LineNumber, PositionInfo.LinePosition);
                break;
            default:
                break;
            }
        }

        private void CheckValue(
            string              value,
            SchemaAttDef        attdef
        ) {
            try {
                reader.TypedValueObject = null;
                bool isAttn = attdef != null;
                XmlSchemaDatatype dtype = isAttn ? attdef.Datatype : context.ElementDecl.Datatype;
                if (dtype == null) {
                    return; // no reason to check
                }

                object typedValue = dtype.ParseValue(value, NameTable, nsManager, true);

                // Check special types
                XmlTokenizedType ttype = dtype.TokenizedType;
                if (ttype == XmlTokenizedType.ENTITY || ttype == XmlTokenizedType.ID || ttype == XmlTokenizedType.IDREF) {
                    if (dtype.Variety == XmlSchemaDatatypeVariety.List) {
                        string[] ss = (string[])typedValue;
                        for (int i = 0; i < ss.Length; ++i) {
                            ProcessTokenizedType(dtype.TokenizedType, ss[i]);
                        }
                    }
                    else {
                        ProcessTokenizedType(dtype.TokenizedType, (string)typedValue);
                    }
                }

                SchemaDeclBase decl = isAttn ? (SchemaDeclBase)attdef : (SchemaDeclBase)context.ElementDecl;
                if (!decl.CheckValue(typedValue)) {
                    if (isAttn) {
                        SendValidationEvent(Res.Sch_FixedAttributeValue, attdef.Name.ToString());
                    }
                    else {
                        SendValidationEvent(Res.Sch_FixedElementValue, XmlSchemaValidator.QNameString(context.LocalName, context.Namespace));
                    }
                }
                if (dtype.Variety == XmlSchemaDatatypeVariety.Union) {
                    typedValue = UnWrapUnion(typedValue);
                }
                reader.TypedValueObject = typedValue;
            }
            catch (XmlSchemaException) {
                if (attdef != null) {
                    SendValidationEvent(Res.Sch_AttributeValueDataType, attdef.Name.ToString());
                }
                else {
                    SendValidationEvent(Res.Sch_ElementValueDataType, XmlSchemaValidator.QNameString(context.LocalName, context.Namespace));
                }
            }
        }

 

        internal void AddID(string name, object node) {
            // Note: It used to be true that we only called this if _fValidate was true,
            // but due to the fact that you can now dynamically type somethign as an ID
            // that is no longer true.
            if (IDs == null) {
                IDs = new Hashtable();
            }

            IDs.Add(name, node);
        }

        public override object  FindId(string name) {
            return IDs == null ? null : IDs[name];
        }
        
        public bool IsXSDRoot(string localName, string ns) {
            return Ref.Equal(ns, NsXs) && Ref.Equal(localName, XsdSchema);
        }

        private void Push(XmlQualifiedName elementName) {
            context = (ValidationState)validationStack.Push();
            if (context == null) {
                context = new ValidationState();
                validationStack.AddToTop(context);
            }
            context.LocalName = elementName.Name;
            context.Namespace = elementName.Namespace;
            context.HasMatched = false;
            context.IsNill = false;
            context.ProcessContents = processContents;
            context.NeedValidateChildren = false;
            context.Constr = null; //resetting the constraints to be null incase context != null 
                                   // when pushing onto stack;
        }


        private    void Pop() {
            if (validationStack.Length > 1) {
                validationStack.Pop();
                if (startIDConstraint == validationStack.Length) {
                    startIDConstraint = -1;
                }
                context = (ValidationState)validationStack.Peek();
                processContents = context.ProcessContents;
            }
        }

        private void CheckForwardRefs() {
            IdRefNode next = idRefListHead;
            while (next != null) {
                if(FindId(next.Id) == null) {
                    SendValidationEvent(new XmlSchemaException(Res.Sch_UndeclaredId, next.Id, reader.BaseURI, next.LineNo, next.LinePos));
                }
                IdRefNode ptr = next.Next;
                next.Next = null; // unhook each object so it is cleaned up by Garbage Collector
                next = ptr;
            }
            // not needed any more.
            idRefListHead = null;
        }
        

        private void ValidateStartElementIdentityConstraints() {
            // added on June 15, set the context here, so the stack can have them
            if (context.ElementDecl != null) {
                if (context.ElementDecl.Constraints != null) {
                    AddIdentityConstraints();
                }
                //foreach constraint in stack (including the current one)
                if (HasIdentityConstraints) {
                    ElementIdentityConstraints();
                }
            }
        }

        private bool HasIdentityConstraints {
            get { return startIDConstraint != -1; }
        }

        private void AddIdentityConstraints() {
            context.Constr = new ConstraintStruct[context.ElementDecl.Constraints.Length];
            int id = 0;
            for (int i = 0; i < context.ElementDecl.Constraints.Length; ++i) {
                context.Constr[id++] = new ConstraintStruct (context.ElementDecl.Constraints[i]);
            } // foreach constraint /constraintstruct

            // added on June 19, make connections between new keyref tables with key/unique tables in stack
            // i can't put it in the above loop, coz there will be key on the same level
            for (int i = 0; i < context.Constr.Length; ++i) {
                if ( context.Constr[i].constraint.Role == CompiledIdentityConstraint.ConstraintRole.Keyref ) {
                    bool find = false;
                    // go upwards checking or only in this level
                    for (int level = this.validationStack.Length - 1; level >= ((this.startIDConstraint >= 0) ? this.startIDConstraint : this.validationStack.Length - 1); level --) {
                        // no constraint for this level
                        if (((ValidationState)(this.validationStack[level])).Constr == null) {
                            continue;
                        }
                        // else
                        ConstraintStruct[] constraints = ((ValidationState) this.validationStack[level]).Constr;
                        for (int j = 0; j < constraints.Length; ++j) {
                            if (constraints[j].constraint.name == context.Constr[i].constraint.refer) {
                                find = true;
                                if (constraints[j].keyrefTable == null) {
                                    constraints[j].keyrefTable = new Hashtable();
                                }
                                context.Constr[i].qualifiedTable = constraints[j].keyrefTable;
                                break;
                            }
                        }

                        if (find) {
                            break;
                        }
                    }
                    if (!find) {
                        // didn't find connections, throw exceptions
                        SendValidationEvent(Res.Sch_RefNotInScope, XmlSchemaValidator.QNameString(context.LocalName, context.Namespace));
                    }
                } // finished dealing with keyref

            }  // end foreach

            // initial set
            if (this.startIDConstraint == -1) {
                this.startIDConstraint = this.validationStack.Length - 1;
            }
        }

        private void ElementIdentityConstraints () {
            for (int i = this.startIDConstraint; i < this.validationStack.Length; i ++) {
                // no constraint for this level
                if (((ValidationState)(this.validationStack[i])).Constr == null) {
                    continue;
                }

                // else
                ConstraintStruct[] constraints = ((ValidationState)this.validationStack[i]).Constr;
                for (int j = 0; j < constraints.Length; ++j) {
                    // check selector from here
                    if (constraints[j].axisSelector.MoveToStartElement(reader.LocalName, reader.NamespaceURI)) {
                        // selector selects new node, activate a new set of fields
                        Debug.WriteLine("Selector Match!");
                        Debug.WriteLine("Name: " + reader.LocalName + "\t|\tURI: " + reader.NamespaceURI + "\n");
                        // in which axisFields got updated
                        constraints[j].axisSelector.PushKS(PositionInfo.LineNumber, PositionInfo.LinePosition);
                    }

                    // axisFields is not null, but may be empty
                    for (int k = 0; k < constraints[j].axisFields.Count; ++k) {
                        LocatedActiveAxis laxis = (LocatedActiveAxis)constraints[j].axisFields[k];

                        // check field from here
                        if (laxis.MoveToStartElement(reader.LocalName, reader.NamespaceURI)) {
                            Debug.WriteLine("Element Field Match!");
                            // checking simpleType / simpleContent
                            if (context.ElementDecl != null) {      // nextElement can be null when xml/xsd are not valid
                                if (context.ElementDecl.Datatype == null) {
                                    SendValidationEvent(Res.Sch_FieldSimpleTypeExpected, reader.LocalName);
                                }
                                else {
                                    // can't fill value here, wait till later....
                                    // fill type : xsdType
                                    laxis.isMatched = true;
                                    // since it's simpletyped element, the endchildren will come consequently... don't worry
                                }
                            }
                        }
                    }

                }
            }
        }

        // facilitate modifying
        private void AttributeIdentityConstraints(string name, string ns, object obj, string sobj, SchemaAttDef attdef) {
            for (int ci = this.startIDConstraint; ci < this.validationStack.Length; ci ++) {
                // no constraint for this level
                if (((ValidationState)(this.validationStack[ci])).Constr == null) {
                    continue;
                }

                // else
                ConstraintStruct[] constraints = ((ValidationState)this.validationStack[ci]).Constr;
                for (int i = 0; i < constraints.Length; ++i) {
                    // axisFields is not null, but may be empty
                    for (int j = 0; j < constraints[i].axisFields.Count; ++j) {
                        LocatedActiveAxis laxis = (LocatedActiveAxis)constraints[i].axisFields[j];

                        // check field from here
                        if (laxis.MoveToAttribute(name, ns)) {
                            Debug.WriteLine("Attribute Field Match!");
                            //attribute is only simpletype, so needn't checking...
                            // can fill value here, yeah!!
                            Debug.WriteLine("Attribute Field Filling Value!");
                            Debug.WriteLine("Name: " + name + "\t|\tURI: " + ns + "\t|\tValue: " + obj + "\n");
                            if (laxis.Ks[laxis.Column] != null) {
                                // should be evaluated to either an empty node-set or a node-set with exactly one member
                                // two matches...
                                SendValidationEvent (Res.Sch_FieldSingleValueExpected, name);
                            }
                            else if ((attdef != null) && (attdef.Datatype != null)){
                                laxis.Ks[laxis.Column] = new TypedObject (obj, sobj, attdef.Datatype);
                            }
                        }
                    }
                }
            }
        }

        private object UnWrapUnion(object typedValue) {
            XsdSimpleValue simpleValue = typedValue as XsdSimpleValue;
            if (simpleValue != null) {
                typedValue = simpleValue.TypedValue;
            }
            return typedValue;
        }

        private void EndElementIdentityConstraints() {
            for (int ci = this.validationStack.Length - 1; ci >= this.startIDConstraint; ci --) {
                // no constraint for this level
                if (((ValidationState)(this.validationStack[ci])).Constr == null) {
                    continue;
                }

                // else
                ConstraintStruct[] constraints = ((ValidationState)this.validationStack[ci]).Constr;
                for (int i = 0; i < constraints.Length; ++i) {
                    // EndChildren
                    // axisFields is not null, but may be empty
                    for (int j = 0; j < constraints[i].axisFields.Count; ++j) {
                        LocatedActiveAxis laxis = (LocatedActiveAxis)constraints[i].axisFields[j];
                        // check field from here
                        // isMatched is false when nextElement is null. so needn't change this part.
                        if (laxis.isMatched) {
                            Debug.WriteLine("Element Field Filling Value!");
                            Debug.WriteLine("Name: " + reader.LocalName + "\t|\tURI: " + reader.NamespaceURI + "\t|\tValue: " + reader.TypedValueObject + "\n");
                            // fill value
                            laxis.isMatched = false;
                            if (laxis.Ks[laxis.Column] != null) {
                                // [field...] should be evaluated to either an empty node-set or a node-set with exactly one member
                                // two matches... already existing field value in the table.
                                SendValidationEvent (Res.Sch_FieldSingleValueExpected, reader.LocalName);
                            }
                            else {
                                // for element, reader.Value = "";
                                string stringValue = !hasSibling ? textString : textValue.ToString();  // only for identity-constraint exception reporting
                                if(reader.TypedValueObject != null && stringValue.Length != 0) {
                                    laxis.Ks[laxis.Column] = new TypedObject(reader.TypedValueObject,stringValue,context.ElementDecl.Datatype);
                                }
                            }
                        }
                        // EndChildren
                        laxis.EndElement(reader.LocalName, reader.NamespaceURI);
                    }
                    
                    if (constraints[i].axisSelector.EndElement(reader.LocalName, reader.NamespaceURI)) {
                        // insert key sequence into hash (+ located active axis tuple leave for later)
                        KeySequence ks = constraints[i].axisSelector.PopKS();
                        // unqualified keysequence are not allowed
                        switch (constraints[i].constraint.Role) {
                        case CompiledIdentityConstraint.ConstraintRole.Key:
                            if (! ks.IsQualified()) {
                                //Key's fields can't be null...  if we can return context node's line info maybe it will be better
                                //only keymissing & keyduplicate reporting cases are necessary to be dealt with... 3 places...
                                SendValidationEvent(new XmlSchemaException(Res.Sch_MissingKey, constraints[i].constraint.name.ToString(), reader.BaseURI, ks.PosLine, ks.PosCol));
                            }
                            else if (constraints[i].qualifiedTable.Contains (ks)) {
                                // unique or key checking value confliction
                                // for redundant key, reporting both occurings
                                // doesn't work... how can i retrieve value out??
                                SendValidationEvent(new XmlSchemaException(Res.Sch_DuplicateKey,
                                    new string[2] {ks.ToString(), constraints[i].constraint.name.ToString()},
                                    reader.BaseURI, ks.PosLine, ks.PosCol));
                            }
                            else {
                                constraints[i].qualifiedTable.Add (ks, ks);
                            }
                            break;
                        case CompiledIdentityConstraint.ConstraintRole.Unique:
                            if (! ks.IsQualified()) {
                                continue;
                            }
                            if (constraints[i].qualifiedTable.Contains (ks)) {
                                // unique or key checking confliction
                                SendValidationEvent(new XmlSchemaException(Res.Sch_DuplicateKey,
                                    new string[2] {ks.ToString(), constraints[i].constraint.name.ToString()},
                                    reader.BaseURI, ks.PosLine, ks.PosCol));
                            }
                            else {
                                constraints[i].qualifiedTable.Add (ks, ks);
                            }
                            break;
                        case CompiledIdentityConstraint.ConstraintRole.Keyref:
                            // is there any possibility:
                            // 2 keyrefs: value is equal, type is not
                            // both put in the hashtable, 1 reference, 1 not
                            if (constraints[i].qualifiedTable != null) { //Will be null in cases when the keyref is outside the scope of the key, that is not allowed by our impl
                                if (! ks.IsQualified() || constraints[i].qualifiedTable.Contains (ks)) {
                                    continue;
                                }
                                constraints[i].qualifiedTable.Add (ks, ks);
                            }
                            break;
                        }
                        
                    }
                }
            }

            // current level's constraint struct
            ConstraintStruct[] vcs = ((ValidationState)(this.validationStack[this.validationStack.Length - 1])).Constr;
            if ( vcs != null) {
                // validating all referencing tables...
                for (int i = 0; i < vcs.Length; ++i) {
                    if (( vcs[i].constraint.Role == CompiledIdentityConstraint.ConstraintRole.Keyref)
                        || (vcs[i].keyrefTable == null)) {
                        continue;
                    }
                    foreach (KeySequence ks in vcs[i].keyrefTable.Keys) {
                        if (! vcs[i].qualifiedTable.Contains (ks)) {
                            SendValidationEvent(new XmlSchemaException(Res.Sch_UnresolvedKeyref, new string[2] { ks.ToString(), vcs[i].constraint.name.ToString() },
                                reader.BaseURI, ks.PosLine, ks.PosCol));
                        }
                    }
                }
            }
        }

    }
#pragma warning restore 618
}