AttributeCollection.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / CompMod / System / ComponentModel / AttributeCollection.cs / 1 / AttributeCollection.cs

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

using System.Diagnostics.CodeAnalysis; 
 
/*
 This class has the HostProtectionAttribute. The purpose of this attribute is to enforce host-specific programming model guidelines, not security behavior. 
 Suppress FxCop message - BUT REVISIT IF ADDING NEW SECURITY ATTRIBUTES.
*/
[assembly: SuppressMessage("Microsoft.Security", "CA2112:SecuredTypesShouldNotExposeFields", Scope="type", Target="System.ComponentModel.AttributeCollection")]
[assembly: SuppressMessage("Microsoft.Security", "CA2112:SecuredTypesShouldNotExposeFields", Scope="type", Target="System.ComponentModel.AttributeCollection")] 
[assembly: SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase", Scope="member", Target="System.ComponentModel.AttributeCollection.CopyTo(System.Array,System.Int32):System.Void")]
[assembly: SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase", Scope="member", Target="System.ComponentModel.AttributeCollection.System.Collections.IEnumerable.GetEnumerator():System.Collections.IEnumerator")] 
[assembly: SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase", Scope="member", Target="System.ComponentModel.AttributeCollection.System.Collections.ICollection.get_IsSynchronized():System.Boolean")] 
[assembly: SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase", Scope="member", Target="System.ComponentModel.AttributeCollection.System.Collections.ICollection.get_Count():System.Int32")]
[assembly: SuppressMessage("Microsoft.Security", "CA2123:OverrideLinkDemandsShouldBeIdenticalToBase", Scope="member", Target="System.ComponentModel.AttributeCollection.System.Collections.ICollection.get_SyncRoot():System.Object")] 
[assembly: SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands", Scope="member", Target="System.ComponentModel.AttributeCollection.Contains(System.Attribute):System.Boolean")]
[assembly: SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands", Scope="member", Target="System.ComponentModel.AttributeCollection.CopyTo(System.Array,System.Int32):System.Void")]
[assembly: SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands", Scope="member", Target="System.ComponentModel.AttributeCollection..ctor(System.Attribute[])")]
[assembly: SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands", Scope="member", Target="System.ComponentModel.AttributeCollection.GetEnumerator():System.Collections.IEnumerator")] 
[assembly: SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands", Scope="member", Target="System.ComponentModel.AttributeCollection.get_Item(System.Type):System.Attribute")]
[assembly: SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands", Scope="member", Target="System.ComponentModel.AttributeCollection.get_Item(System.Int32):System.Attribute")] 
[assembly: SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands", Scope="member", Target="System.ComponentModel.AttributeCollection.get_Count():System.Int32")] 

namespace System.ComponentModel 
{

    using System.Reflection;
    using System.Diagnostics; 
    using System.Collections;
 
 
    /// 
    ///     Represents a collection of attributes. 
    /// 
    [System.Runtime.InteropServices.ComVisibleAttribute(true)]
    [System.Security.Permissions.HostProtection(Synchronization=true)]
    public class AttributeCollection : ICollection 
    {
 
        ///  
        ///     An empty AttributeCollection that can used instead of creating a new one.
        ///  
        public static readonly AttributeCollection Empty = new AttributeCollection((Attribute[])null);
        private static Hashtable _defaultAttributes;

        private Attribute[] _attributes; 

        private static object internalSyncObject = new object(); 
 
        private struct AttributeEntry
        { 
            public Type type;
            public int index;
        }
 
        private const int FOUND_TYPES_LIMIT = 5;
 
        private AttributeEntry[] _foundAttributeTypes; 
 		
		private int _index = 0; 

        /// 
        ///     Creates a new AttributeCollection.
        ///  
        public AttributeCollection(params Attribute[] attributes)
        { 
            if (attributes == null) 
            {
                attributes = new Attribute[0]; 
            }
            _attributes = attributes;

            for (int idx = 0; idx < attributes.Length; idx++) 
            {
                if (attributes[idx] == null) 
                { 
                    throw new ArgumentNullException("attributes");
                } 
            }
        }

 
        /// 
        ///     Creates a new AttributeCollection from an existing AttributeCollection 
        ///  
        public static AttributeCollection FromExisting(AttributeCollection existing, params Attribute[] newAttributes)
        { 
            // VSWhidbey #75418
            // This method should be a constructor, but making it one introduces a breaking change.
            //
            if (existing == null) 
            {
                throw new ArgumentNullException("existing"); 
            } 

            if (newAttributes == null) 
            {
                newAttributes = new Attribute[0];
            }
 
            Attribute[] newArray = new Attribute[existing.Count + newAttributes.Length];
            int actualCount = existing.Count; 
            existing.CopyTo(newArray, 0); 

            for (int idx = 0; idx < newAttributes.Length; idx++) 
            {
                if (newAttributes[idx] == null)
                {
                    throw new ArgumentNullException("newAttributes"); 
                }
 
                // We must see if this attribute is already in the existing 
                // array.  If it is, we replace it.
                bool match = false; 
                for (int existingIdx = 0; existingIdx < existing.Count; existingIdx++)
                {
                    if (newArray[existingIdx].TypeId.Equals(newAttributes[idx].TypeId))
                    { 
                        match = true;
                        newArray[existingIdx] = newAttributes[idx]; 
                        break; 
                    }
                } 

                if (!match)
                {
                    newArray[actualCount++] = newAttributes[idx]; 
                }
            } 
 
            // Now, if we collapsed some attributes, create a new array.
            // 

            Attribute[] attributes = null;
            if (actualCount < newArray.Length)
            { 
                attributes = new Attribute[actualCount];
                Array.Copy(newArray, 0, attributes, 0, actualCount); 
            } 
            else
            { 
                attributes = newArray;
            }

            return new AttributeCollection(attributes); 
        }
 
        ///  
        ///     Gets the number of attributes.
        ///  
        public int Count
        {
            get
            { 
                return _attributes.Length;
            } 
        } 

        ///  
        ///     Gets the attribute with the specified index number.
        /// 
        public virtual Attribute this[int index]
        { 
            get
            { 
                return _attributes[index]; 
            }
        } 

        /// 
        ///    Gets the attribute with the specified type.
        ///  
        public virtual Attribute this[Type attributeType]
        { 
            get 
            {
                lock (internalSyncObject) { 
                    // 2 passes here for perf.  Really!  first pass, we just
                    // check equality, and if we don't find it, then we
                    // do the IsAssignableFrom dance.   Turns out that's
                    // a relatively expensive call and we try to avoid it 
                    // since we rarely encounter derived attribute types
                    // and this list is usually short. 
                    // 
                    if (_foundAttributeTypes == null)
                    { 
                        _foundAttributeTypes = new AttributeEntry[FOUND_TYPES_LIMIT];
                    }

                    int ind = 0; 

                    for (; ind < FOUND_TYPES_LIMIT; ind++) 
                    { 
                        if (_foundAttributeTypes[ind].type == attributeType)
                        { 
                           int index = _foundAttributeTypes[ind].index;
                           if (index != -1)
                           {
                               return _attributes[index]; 
                           }
                           else{ 
                               return GetDefaultAttribute(attributeType); 
                           }
                        } 
                        if (_foundAttributeTypes[ind].type == null)
                            break;
                    }
 
                    ind = _index++;
 
                    if (_index >= FOUND_TYPES_LIMIT) 
                    {
    	                _index = 0; 
                    }

                    _foundAttributeTypes[ind].type = attributeType;
 
                    int count = _attributes.Length;
 
 
                    for (int i = 0; i < count; i++)
                    { 
                        Attribute attribute = _attributes[i];
                        Type aType = attribute.GetType();
                        if (aType == attributeType)
                        { 
                            _foundAttributeTypes[ind].index = i;
                            return attribute; 
                        } 
                    }
 
                    // now check the hierarchies.
                    for (int i = 0; i < count; i++)
                    {
                        Attribute attribute = _attributes[i]; 
                        Type aType = attribute.GetType();
                        if (attributeType.IsAssignableFrom(aType)) 
                        { 
                            _foundAttributeTypes[ind].index = i;
                            return attribute; 
                        }
                    }

                    _foundAttributeTypes[ind].index = -1; 
                    return GetDefaultAttribute(attributeType);
                } 
            } 
        }
 
        /// 
        ///     Determines if this collection of attributes has the specified attribute.
        /// 
        public bool Contains(Attribute attribute) 
        {
            Attribute attr = this[attribute.GetType()]; 
            if (attr != null && attr.Equals(attribute)) 
            {
                return true; 
            }
            return false;
        }
 
        /// 
        ///     Determines if this attribute collection contains the all 
        ///     the specified attributes in the attribute array. 
        /// 
        public bool Contains(Attribute[] attributes) 
        {

            if (attributes == null)
            { 
                return true;
            } 
 
            for (int i = 0; i < attributes.Length; i++)
            { 
                if (!Contains(attributes[i]))
                {
                    return false;
                } 
            }
 
            return true; 
        }
 
        /// 
        ///     Returns the default value for an attribute.  This uses the following hurestic:
        ///     1.  It looks for a public static field named "Default".
        ///  
        protected Attribute GetDefaultAttribute(Type attributeType)
        { 
            lock (internalSyncObject) 
            {
                if (_defaultAttributes == null) 
                {
                    _defaultAttributes = new Hashtable();
                }
 
                // If we have already encountered this, use what's in the
                // table. 
                if (_defaultAttributes.ContainsKey(attributeType)) 
                {
                    return(Attribute)_defaultAttributes[attributeType]; 
                }

                Attribute attr = null;
 
                // Nope, not in the table, so do the legwork to discover the default value.
                Type reflect = TypeDescriptor.GetReflectionType(attributeType); 
                System.Reflection.FieldInfo field = reflect.GetField("Default", BindingFlags.Public | BindingFlags.Static | BindingFlags.GetField); 
                if (field != null && field.IsStatic)
                { 
                    attr = (Attribute)field.GetValue(null);
                }
                else
                { 
                    ConstructorInfo ci = reflect.UnderlyingSystemType.GetConstructor(new Type[0]);
                    if (ci != null) 
                    { 
                        attr = (Attribute)ci.Invoke(new object[0]);
 
                        // If we successfully created, verify that it is the
                        // default.  Attributes don't have to abide by this rule.
                        if (!attr.IsDefaultAttribute())
                        { 
                            attr = null;
                        } 
                    } 
                }
 
                _defaultAttributes[attributeType] = attr;
                return attr;
            }
        } 

        ///  
        ///     Gets an enumerator for this collection. 
        /// 
        public IEnumerator GetEnumerator() 
        {
            return _attributes.GetEnumerator();
        }
 
        /// 
        ///     Determines if a specified attribute is the same as an attribute 
        ///     in the collection. 
        /// 
        public bool Matches(Attribute attribute) 
        {
            for (int i = 0; i < _attributes.Length; i++)
            {
                if (_attributes[i].Match(attribute)) 
                {
                    return true; 
                } 
            }
            return false; 
        }

        /// 
        ///     Determines if the attributes in the specified array are 
        ///     the same as the attributes in the collection.
        ///  
        public bool Matches(Attribute[] attributes) 
        {
            for (int i = 0; i < attributes.Length; i++) 
            {
                if (!Matches(attributes[i]))
                {
                    return false; 
                }
            } 
 
            return true;
        } 

        /// 
        int ICollection.Count
        { 
            get
            { 
                return Count; 
            }
        } 


        /// 
        bool ICollection.IsSynchronized 
        {
            get 
            { 
                return false;
            } 
        }

        /// 
        object ICollection.SyncRoot 
        {
            get 
            { 
                return null;
            } 
        }

        /// 
        ///     Copies this collection to an array. 
        /// 
        public void CopyTo(Array array, int index) 
        { 
            Array.Copy(_attributes, 0, array, index, _attributes.Length);
        } 

        /// 
        IEnumerator IEnumerable.GetEnumerator()
        { 
            return GetEnumerator();
        } 
    } 
}
                        

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