IdentityInterner

Interner makes sure there is only one reference of each hash-equally same identity.

IdentityInterner is implementation to IProvider<IIdentity, IIdentity>.

// Create internalizer
IProvider<IIdentity, IIdentity> interner = new IdentityInterner();

Interner can be constructed with custom comparer.

// Create internalizer
IProvider<IIdentity, IIdentity> interner = new IdentityInterner(IdentityComparer.CaseInsensitive);

Interner returns equal and read-only version of the identity, caches it.

// Create identity
IIdentity noninterned = IdentityAccessors.Default.TypeName.Create(typeof(string));
// Internalize
IIdentity interned = interner.Intern(noninterned);

When another identity of equal content is interned, the original cached reference is returned.

// Create assembly qualified type name
string typename = typeof(string).AssemblyQualifiedName;
// Parse
IIdentity noninterned2 = IdentityAccessors.Default.TypeName.MemoryAccessors.Parse(typename.AsMemory());
// Internalize
IIdentity interned2 = interner.Intern(noninterned2);

They are same reference, including the nodes from parent to root.

// Test for reference equality: 'True'
WriteLine(object.ReferenceEquals(interned, interned2));
// 'True'
WriteLine(object.ReferenceEquals(interned.Parent, interned2.Parent));
// 'True'
WriteLine(object.ReferenceEquals(interned.Parent.Parent, interned2.Parent.Parent));

Extension method .InternWith() decorates IIdentityAccessor to apply interner on results.

// Create internalizer
IProvider<IIdentity, IIdentity> interner = new IdentityInterner();
// Create identity accessor
IIdentityAccessor<Type> identityAccessor = IdentityAccessors.Default.TypeNameWithoutAssembly;
// Decorate accessor
identityAccessor = identityAccessor.InternWith(interner);

// Create identity
IIdentity id1 = identityAccessor.Create(typeof(string));
// Create identity
IIdentity id2 = identityAccessor.Create(typeof(string));
// Create identity
IIdentity id3 = identityAccessor.MemoryAccessors.Parse("System.String");

// Compare reference: True
Console.WriteLine(object.ReferenceEquals(id1, id2));
Console.WriteLine(object.ReferenceEquals(id1, id3));

Full Example

Full example

using System;
using Avalanche.Accessor;
using Avalanche.Identity;
using Avalanche.Serialization;
using Avalanche.Utilities;
using Avalanche.Utilities.Provider;
using static System.Console;

class identityinterner
{
    public static void Run()
    {
        {
            // <01>
            // Create internalizer
            IProvider<IIdentity, IIdentity> interner = new IdentityInterner();
            // </01>
            // <02>
            // Create identity
            IIdentity noninterned = IdentityAccessors.Default.TypeName.Create(typeof(string));
            // Internalize
            IIdentity interned = interner.Intern(noninterned);
            // </02>
            // <03>
            // Create assembly qualified type name
            string typename = typeof(string).AssemblyQualifiedName;
            // Parse
            IIdentity noninterned2 = IdentityAccessors.Default.TypeName.MemoryAccessors.Parse(typename.AsMemory());
            // Internalize
            IIdentity interned2 = interner.Intern(noninterned2);
            // </03>
            // <04>
            // Test for reference equality: 'True'
            WriteLine(object.ReferenceEquals(interned, interned2));
            // 'True'
            WriteLine(object.ReferenceEquals(interned.Parent, interned2.Parent));
            // 'True'
            WriteLine(object.ReferenceEquals(interned.Parent.Parent, interned2.Parent.Parent));
            // </04>
        }
        {
            // <01B>
            // Create internalizer
            IProvider<IIdentity, IIdentity> interner = new IdentityInterner(IdentityComparer.CaseInsensitive);
            // </01B>
        }
        {
            // <10>
            // Create internalizer
            IProvider<IIdentity, IIdentity> interner = new IdentityInterner();
            // Create identity accessor
            IIdentityAccessor<Type> identityAccessor = IdentityAccessors.Default.TypeNameWithoutAssembly;
            // Decorate accessor
            identityAccessor = identityAccessor.InternWith(interner);

            // Create identity
            IIdentity id1 = identityAccessor.Create(typeof(string));
            // Create identity
            IIdentity id2 = identityAccessor.Create(typeof(string));
            // Create identity
            IIdentity id3 = identityAccessor.MemoryAccessors.Parse("System.String");

            // Compare reference: True
            Console.WriteLine(object.ReferenceEquals(id1, id2));
            Console.WriteLine(object.ReferenceEquals(id1, id3));
            // </10>
        }
    }
}