MemberDescriptor.cs source code in C# .NET

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Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / CompMod / System / ComponentModel / MemberDescriptor.cs / 1 / MemberDescriptor.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

/* 
 */ 
namespace System.ComponentModel {
 
    using Microsoft.Win32;
    using System;
    using System.Collections;
    using System.ComponentModel.Design; 
    using System.Diagnostics;
    using System.Reflection; 
    using System.Security.Permissions; 

    ///  
    ///    
    ///       Declares an array of attributes for a member and defines
    ///       the properties and methods that give you access to the attributes in the array.
    ///       All attributes must derive from . 
    ///    
    ///  
    [HostProtection(SharedState = true)] 
    [System.Runtime.InteropServices.ComVisible(true)]
    public abstract class MemberDescriptor { 
        private string name;
        private string displayName;
        private int nameHash;
        private AttributeCollection attributeCollection; 
        private Attribute[] attributes;
        private Attribute[] originalAttributes; 
        private bool attributesFiltered = false; 
        private bool attributesFilled = false;
        private int metadataVersion; 
        private string category;
        private string description;

 
        /// 
        ///     
        ///       Initializes a new instance of the  class with the specified  and no
        ///       attributes. 
        ///    
        /// 
        protected MemberDescriptor(string name) : this(name, null) {
        } 

        ///  
        ///     
        ///       Initializes a new instance of the  class with the specified 
        ///       and  
        ///       array.
        ///    
        /// 
        protected MemberDescriptor(string name, Attribute[] attributes) { 
            try {
                if (name == null || name.Length == 0) { 
                    throw new ArgumentException(SR.GetString(SR.InvalidMemberName)); 
                }
                this.name = name; 
                this.displayName = name;
                this.nameHash = name.GetHashCode();
                if (attributes != null) {
                    this.attributes = attributes; 
                    attributesFiltered = false;
                } 
 
                this.originalAttributes = this.attributes;
            } 
            catch (Exception t) {
                Debug.Fail(t.ToString());
                throw t;
            } 
        }
 
        ///  
        ///    
        ///       Initializes a new instance of the  class with the specified . 
        ///    
        /// 
        protected MemberDescriptor(MemberDescriptor descr) {
            this.name = descr.Name; 
            this.displayName = this.name;
            this.nameHash = name.GetHashCode(); 
 
            this.attributes = new Attribute[descr.Attributes.Count];
            descr.Attributes.CopyTo(this.attributes, 0); 

            attributesFiltered = true;

            this.originalAttributes = this.attributes; 
        }
 
        ///  
        ///    
        ///       Initializes a new instance of the  class with the name in the specified 
        ///     and the attributes
        ///       in both the old  and the  array.
        ///    
        ///  
        protected MemberDescriptor(MemberDescriptor oldMemberDescriptor, Attribute[] newAttributes) {
            this.name = oldMemberDescriptor.Name; 
            this.displayName = oldMemberDescriptor.DisplayName; 
            this.nameHash = name.GetHashCode();
 
            ArrayList newArray = new ArrayList();

            if (oldMemberDescriptor.Attributes.Count != 0) {
                foreach (object o in oldMemberDescriptor.Attributes) { 
                    newArray.Add(o);
                } 
            } 

            if (newAttributes != null) { 
                foreach (object o in newAttributes) {
                    newArray.Add(o);
                }
            } 

            this.attributes = new Attribute[ newArray.Count ]; 
            newArray.CopyTo( this.attributes, 0); 
            attributesFiltered = false;
 
            this.originalAttributes = this.attributes;
        }

        ///  
        ///    
        ///       Gets or sets an array of 
        ///       attributes. 
        ///    
        ///  
        protected virtual Attribute[] AttributeArray {
            get {
                CheckAttributesValid();
                FilterAttributesIfNeeded(); 
                return attributes;
            } 
            set { 
                lock(this) {
                    attributes = value; 
                    originalAttributes = value;
                    attributesFiltered = false;
                    attributeCollection = null;
                } 
            }
        } 
 
        /// 
        ///     
        ///       Gets the collection of attributes for this member.
        ///    
        /// 
        public virtual AttributeCollection Attributes { 
            get {
                CheckAttributesValid(); 
                if (attributeCollection == null) { 
                    attributeCollection = CreateAttributeCollection();
                } 
                return attributeCollection;
            }
        }
 
        /// 
        ///     
        ///       Gets the name of the category that the 
        ///       member
        ///       belongs to, as specified in the . 
        ///    
        /// 
        public virtual string Category {
            get { 
                if (category == null) {
                    category = ((CategoryAttribute)Attributes[typeof(CategoryAttribute)]).Category; 
                } 
                return category;
            } 
        }

        /// 
        ///     
        ///       Gets the description of
        ///       the member as specified in the . 
        ///     
        /// 
        public virtual string Description { 
            get {
                if (description == null) {
                    description = ((DescriptionAttribute) Attributes[typeof(DescriptionAttribute)]).Description;
                } 
                return description;
            } 
        } 

        ///  
        ///    
        ///       Gets a value indicating whether the member is browsable as specified in the
        ///    .
        ///     
        /// 
        public virtual bool IsBrowsable { 
            get { 
                return((BrowsableAttribute)Attributes[typeof(BrowsableAttribute)]).Browsable;
            } 
        }

        /// 
        ///     
        ///       Gets the
        ///       name of the member. 
        ///     
        /// 
        public virtual string Name { 
            get {
                if (name == null) {
                    return "";
                } 
                return name;
            } 
        } 

        ///  
        ///    
        ///       Gets the hash
        ///       code for the name of the member as specified in .
        ///     
        /// 
        protected virtual int NameHashCode { 
            get { 
                return nameHash;
            } 
        }

        /// 
        ///     
        ///       Determines whether this member should be set only at
        ///       design time as specified in the . 
        ///     
        /// 
        public virtual bool DesignTimeOnly { 
            get {
                return(DesignOnlyAttribute.Yes.Equals(Attributes[typeof(DesignOnlyAttribute)]));
            }
        } 

        ///  
        ///     
        ///       Gets the name that can be displayed in a window like a
        ///       properties window. 
        ///    
        /// 
        public virtual string DisplayName {
            get { 
                DisplayNameAttribute displayNameAttr = Attributes[typeof(DisplayNameAttribute)] as DisplayNameAttribute;
                if (displayNameAttr == null || displayNameAttr.IsDefaultAttribute()) { 
                    return displayName; 
                }
                return displayNameAttr.DisplayName; 
            }
        }

        ///  
        ///     Called each time we access the attribtes on
        ///     this member descriptor to give deriving classes 
        ///     a chance to change them on the fly. 
        /// 
        private void CheckAttributesValid() { 
            if (attributesFiltered) {
                if (metadataVersion != TypeDescriptor.MetadataVersion) {
                    attributesFilled = false;
                    attributesFiltered = false; 
                    attributeCollection = null;
                } 
            } 
        }
 
        /// 
        /// 
        ///    
        ///       Creates a collection of attributes using the 
        ///       array of attributes that you passed to the constructor.
        ///     
        ///  
        protected virtual AttributeCollection CreateAttributeCollection() {
            return new AttributeCollection(AttributeArray); 
        }

        /// 
        ///     
        ///       Compares this instance to the specified  to see if they are equivalent.
        ///       NOTE: If you make a change here, you likely need to change GetHashCode() as well. 
        ///     
        /// 
        public override bool Equals(object obj) { 
            if (this == obj) {
                return true;
            }
            if (obj == null) { 
                return false;
            } 
 
            if (obj.GetType() != GetType()) {
                return false; 
            }

            MemberDescriptor mdObj = (MemberDescriptor)obj;
            FilterAttributesIfNeeded(); 
            mdObj.FilterAttributesIfNeeded();
 
            if (mdObj.nameHash != nameHash) { 
                return false;
            } 

            if ((mdObj.category == null) != (category == null) ||
                (category != null && !mdObj.category.Equals(category))) {
                return false; 
            }
 
            if ((mdObj.description == null) != (description == null) || 
                (description != null && !mdObj.category.Equals(description))) {
                return false; 
            }

            if ((mdObj.attributes == null) != (attributes == null)) {
                return false; 
            }
 
            bool sameAttrs = true; 

            if (attributes != null) { 
                if (attributes.Length != mdObj.attributes.Length) {
                    return false;
                }
                for (int i = 0; i < attributes.Length; i++) { 
                    if (!attributes[i].Equals(mdObj.attributes[i])) {
                        sameAttrs = false; 
                        break; 
                    }
                } 
            }
            return sameAttrs;
        }
 
        /// 
        ///     
        ///       In an inheriting class, adds the attributes of the inheriting class to the 
        ///       specified list of attributes in the parent class.  For duplicate attributes,
        ///       the last one added to the list will be kept. 
        ///    
        /// 
        protected virtual void FillAttributes(IList attributeList) {
            if (originalAttributes != null) { 
                foreach (Attribute attr in originalAttributes) {
                    attributeList.Add(attr); 
                } 
            }
        } 

        private void FilterAttributesIfNeeded() {
            if (!attributesFiltered) {
                IList list; 

                if (!attributesFilled) { 
                    list = new ArrayList(); 
                    try {
                        FillAttributes(list); 
                    }
                    catch (Exception e) {
                        Debug.Fail(name + ">>" + e.ToString());
                    } 
                }
                else { 
                    list = new ArrayList(attributes); 
                }
 
                Hashtable hash = new Hashtable(list.Count);

                foreach (Attribute attr in list) {
                    hash[attr.TypeId] = attr; 
                }
 
                Attribute[] newAttributes = new Attribute[hash.Values.Count]; 
                hash.Values.CopyTo(newAttributes, 0);
 
                lock(this) {
                    attributes = newAttributes;
                    attributesFiltered = true;
                    attributesFilled = true; 
                    metadataVersion = TypeDescriptor.MetadataVersion;
                } 
            } 
        }
 
        /// 
        ///    
        ///       Finds the given method through reflection.  This method only looks for public methods.
        ///     
        /// 
        protected static MethodInfo FindMethod(Type componentClass, string name, Type[] args, Type returnType) { 
            return FindMethod(componentClass, name, args, returnType, true); 
        }
 
        /// 
        ///    
        ///       Finds the given method through reflection.
        ///     
        /// 
        protected static MethodInfo FindMethod(Type componentClass, string name, Type[] args, Type returnType, bool publicOnly) { 
            MethodInfo result = null; 

            if (publicOnly) { 
                result = componentClass.GetMethod(name, args);
            }
            else {
                result = componentClass.GetMethod(name, BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic, null, args, null); 
            }
            if (result != null && result.ReturnType != returnType) { 
                result = null; 
            }
            return result; 
        }

        /// 
        ///     Try to keep this reasonable in sync with Equals(). Specifically, 
        ///     if A.Equals(B) returns true, A & B should have the same hash code.
        ///  
        public override int GetHashCode() { 
            return nameHash;
        } 

        /// 
        ///     This method returns the object that should be used during invocation of members.
        ///     Normally the return value will be the same as the instance passed in.  If 
        ///     someone associated another object with this instance, or if the instance is a
        ///     custom type descriptor, GetInvocationTarget may return a different value. 
        ///  
        protected virtual object GetInvocationTarget(Type type, object instance) {
 
            if (type == null)
            {
                throw new ArgumentNullException("type");
            } 

            if (instance == null) 
            { 
                throw new ArgumentNullException("instance");
            } 

            return TypeDescriptor.GetAssociation(type, instance);
        }
 
        /// 
        ///     
        ///       Gets a component site 
        ///       for the given component.
        ///     
        /// 
        protected static ISite GetSite(object component) {
            if (!(component is IComponent)) {
                return null; 
            }
 
            return((IComponent)component).Site; 
        }
 
        /// 
        ///    
        ///       Gets
        ///       the component 
        ///       that a method should be invoked on.
        ///     
        ///  
        [Obsolete("This method has been deprecated. Use GetInvocationTarget instead.  http://go.microsoft.com/fwlink/?linkid=14202")]
        protected static object GetInvokee(Type componentClass, object component) { 

            if (componentClass == null)
            {
                throw new ArgumentNullException("componentClass"); 
            }
 
            if (component == null) 
            {
                throw new ArgumentNullException("component"); 
            }

            return TypeDescriptor.GetAssociation(componentClass, component);
        } 
    }
}

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