Code:
/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Base / System / Windows / DependencyObjectType.cs / 1 / DependencyObjectType.cs
using System; using System.Collections; using System.Diagnostics; using System.Runtime.CompilerServices; using System.Windows.Threading; using MS.Utility; using MS.Internal.WindowsBase; #pragma warning disable 1634, 1691 // suppressing PreSharp warnings namespace System.Windows { ////// Type cache for all DependencyObject derived types /// ////// Every public class DependencyObjectType { ///stores a reference to its DependencyObjectType. /// This is an object that represents a specific system (CLR) Type. /// /// DTypes have 2 purposes: /// ///
///- /// More performant type operations (especially for Expressions that /// rely heavily on type inspection) ///
///- /// Forces static constructors of base types to always run first. This /// consistancy is necessary for components (such as Expressions) that /// rely on static construction order for correctness. ///
////// Retrieve a DependencyObjectType that represents a given system (CLR) type /// /// The system (CLR) type to convert ////// A DependencyObjectType that represents the system (CLR) type (will create /// a new one if doesn't exist) /// public static DependencyObjectType FromSystemType(Type systemType) { if (systemType == null) { throw new ArgumentNullException("systemType"); } if (!typeof(DependencyObject).IsAssignableFrom(systemType)) { #pragma warning suppress 6506 // systemType is obviously not null throw new ArgumentException(SR.Get(SRID.DTypeNotSupportForSystemType, systemType.Name)); } return FromSystemTypeInternal(systemType); } ////// Helper method for the public FromSystemType call but without /// the expensive IsAssignableFrom parameter validation. /// [FriendAccessAllowed] // Built into Base, also used by Framework. internal static DependencyObjectType FromSystemTypeInternal(Type systemType) { Debug.Assert(systemType != null && typeof(DependencyObject).IsAssignableFrom(systemType), "Invalid systemType argument"); DependencyObjectType retVal; lock(_lock) { // Recursive routine to (set up if necessary) and use the // DTypeFromCLRType hashtable that is used for the actual lookup. retVal = FromSystemTypeRecursive( systemType ); } return retVal; } // The caller must wrap this routine inside a locked block. // This recursive routine manipulates the static hashtable DTypeFromCLRType // and it must not be allowed to do this across multiple threads // simultaneously. private static DependencyObjectType FromSystemTypeRecursive(Type systemType) { DependencyObjectType dType; // Map a CLR Type to a DependencyObjectType dType = (DependencyObjectType)DTypeFromCLRType[systemType]; if (dType == null) { // No DependencyObjectType found, create dType = new DependencyObjectType(); // Store CLR type dType._systemType = systemType; // Store reverse mapping DTypeFromCLRType[systemType] = dType; // Establish base DependencyObjectType and base property count if (systemType != typeof(DependencyObject)) { // Get base type dType._baseDType = FromSystemTypeRecursive(systemType.BaseType); } // Store DependencyObjectType zero-based Id dType._id = DTypeCount++; } return dType; } ////// Zero-based unique identifier for constant-time array lookup operations /// ////// There is no guarantee on this value. It can vary between application runs. /// public int Id { get { return _id; } } ////// The system (CLR) type that this DependencyObjectType represents /// public Type SystemType { get { return _systemType; } } ////// The DependencyObjectType of the base class /// public DependencyObjectType BaseType { get { return _baseDType; } } ////// Returns the name of the represented system (CLR) type /// public string Name { get { return SystemType.Name; } } ////// Determines whether the specifed object is an instance of the current DependencyObjectType /// /// The object to compare with the current Type ////// true if the current DependencyObjectType is in the inheritance hierarchy of the /// object represented by the o parameter. false otherwise. /// public bool IsInstanceOfType(DependencyObject dependencyObject) { if (dependencyObject != null) { DependencyObjectType dType = dependencyObject.DependencyObjectType; do { if (dType.Id == Id) { return true; } dType = dType._baseDType; } while (dType != null); } return false; } ////// Determines whether the current DependencyObjectType derives from the /// specified DependencyObjectType /// /// The DependencyObjectType to compare /// with the current DependencyObjectType ////// true if the DependencyObjectType represented by the dType parameter and the /// current DependencyObjectType represent classes, and the class represented /// by the current DependencyObjectType derives from the class represented by /// c; otherwise, false. This method also returns false if dType and the /// current Type represent the same class. /// public bool IsSubclassOf(DependencyObjectType dependencyObjectType) { // Check for null and return false, since this type is never a subclass of null. if (dependencyObjectType != null) { // A DependencyObjectType isn't considered a subclass of itself, so start with base type DependencyObjectType dType = _baseDType; while (dType != null) { if (dType.Id == dependencyObjectType.Id) { return true; } dType = dType._baseDType; } } return false; } ////// Serves as a hash function for a particular type, suitable for use in /// hashing algorithms and data structures like a hash table /// ///The DependencyObjectType's Id public override int GetHashCode() { return _id; } // DTypes may not be constructed outside of FromSystemType private DependencyObjectType() { } private int _id; private Type _systemType; private DependencyObjectType _baseDType; // Synchronized: Covered by DispatcherLock private static Hashtable DTypeFromCLRType = new Hashtable(); // Synchronized: Covered by DispatcherLock private static int DTypeCount = 0; private static object _lock = new object(); } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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