CustomModifiers.cs

/*
  The MIT License (MIT) 
  Copyright (C) 2011 Jeroen Frijters
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;
using Managed.Reflection.Emit;
using Managed.Reflection.Reader;

namespace Managed.Reflection
{
    public struct CustomModifiers : IEquatable<CustomModifiers>, IEnumerable<CustomModifiers.Entry>
    {
        // note that FromReqOpt assumes that Initial == ModOpt
        private static Type Initial { get { return MarkerType.ModOpt; } }
        private readonly Type[] types;

        internal CustomModifiers(List<CustomModifiersBuilder.Item> list)
        {
            bool required = Initial == MarkerType.ModReq;
            int count = list.Count;
            foreach (CustomModifiersBuilder.Item item in list)
            {
                if (item.required != required)
                {
                    required = item.required;
                    count++;
                }
            }
            types = new Type[count];
            required = Initial == MarkerType.ModReq;
            int index = 0;
            foreach (CustomModifiersBuilder.Item item in list)
            {
                if (item.required != required)
                {
                    required = item.required;
                    types[index++] = required ? MarkerType.ModReq : MarkerType.ModOpt;
                }
                types[index++] = item.type;
            }
        }

        private CustomModifiers(Type[] types)
        {
            Debug.Assert(types == null || types.Length != 0);
            this.types = types;
        }

        public struct Enumerator : IEnumerator<Entry>
        {
            private readonly Type[] types;
            private int index;
            private bool required;

            internal Enumerator(Type[] types)
            {
                this.types = types;
                this.index = -1;
                this.required = Initial == MarkerType.ModReq;
            }

            void System.Collections.IEnumerator.Reset()
            {
                this.index = -1;
                this.required = Initial == MarkerType.ModReq;
            }

            public Entry Current
            {
                get { return new Entry(types[index], required); }
            }

            public bool MoveNext()
            {
                if (types == null || index == types.Length)
                {
                    return false;
                }
                index++;
                if (index == types.Length)
                {
                    return false;
                }
                else if (types[index] == MarkerType.ModOpt)
                {
                    required = false;
                    index++;
                }
                else if (types[index] == MarkerType.ModReq)
                {
                    required = true;
                    index++;
                }
                return true;
            }

            object System.Collections.IEnumerator.Current
            {
                get { return Current; }
            }

            void IDisposable.Dispose()
            {
            }
        }

        public struct Entry
        {
            private readonly Type type;
            private readonly bool required;

            internal Entry(Type type, bool required)
            {
                this.type = type;
                this.required = required;
            }

            public Type Type
            {
                get { return type; }
            }

            public bool IsRequired
            {
                get { return required; }
            }
        }

        public Enumerator GetEnumerator()
        {
            return new Enumerator(types);
        }

        IEnumerator<Entry> IEnumerable<Entry>.GetEnumerator()
        {
            return GetEnumerator();
        }

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }

        public bool IsEmpty
        {
            get { return types == null; }
        }

        public bool Equals(CustomModifiers other)
        {
            return Util.ArrayEquals(types, other.types);
        }

        public override bool Equals(object obj)
        {
            CustomModifiers? other = obj as CustomModifiers?;
            return other != null && Equals(other.Value);
        }

        public override int GetHashCode()
        {
            return Util.GetHashCode(types);
        }

        public override string ToString()
        {
            if (types == null)
            {
                return string.Empty;
            }
            StringBuilder sb = new StringBuilder();
            string sep = "";
            foreach (Entry e in this)
            {
                sb.Append(sep).Append(e.IsRequired ? "modreq(" : "modopt(").Append(e.Type.FullName).Append(')');
                sep = " ";
            }
            return sb.ToString();
        }

        public bool ContainsMissingType
        {
            get { return Type.ContainsMissingType(types); }
        }

        private Type[] GetRequiredOrOptional(bool required)
        {
            if (types == null)
            {
                return Type.EmptyTypes;
            }
            int count = 0;
            foreach (Entry e in this)
            {
                if (e.IsRequired == required)
                {
                    count++;
                }
            }
            Type[] result = new Type[count];
            foreach (Entry e in this)
            {
                if (e.IsRequired == required)
                {
                    // FXBUG reflection (and ildasm) return custom modifiers in reverse order
                    // while SRE writes them in the specified order
                    result[--count] = e.Type;
                }
            }
            return result;
        }

        internal Type[] GetRequired()
        {
            return GetRequiredOrOptional(true);
        }

        internal Type[] GetOptional()
        {
            return GetRequiredOrOptional(false);
        }

        internal CustomModifiers Bind(IGenericBinder binder)
        {
            if (types == null)
            {
                return this;
            }
            Type[] result = types;
            for (int i = 0; i < types.Length; i++)
            {
                if (types[i] == MarkerType.ModOpt || types[i] == MarkerType.ModReq)
                {
                    continue;
                }
                Type type = types[i].BindTypeParameters(binder);
                if (!ReferenceEquals(type, types[i]))
                {
                    if (result == types)
                    {
                        result = (Type[])types.Clone();
                    }
                    result[i] = type;
                }
            }
            return new CustomModifiers(result);
        }

        internal static CustomModifiers Read(ModuleReader module, ByteReader br, IGenericContext context)
        {
            byte b = br.PeekByte();
            if (!IsCustomModifier(b))
            {
                return new CustomModifiers();
            }
            List<Type> list = new List<Type>();
            Type mode = Initial;
            do
            {
                Type cmod = br.ReadByte() == Signature.ELEMENT_TYPE_CMOD_REQD ? MarkerType.ModReq : MarkerType.ModOpt;
                if (mode != cmod)
                {
                    mode = cmod;
                    list.Add(mode);
                }
                list.Add(Signature.ReadTypeDefOrRefEncoded(module, br, context));
                b = br.PeekByte();
            }
            while (IsCustomModifier(b));
            return new CustomModifiers(list.ToArray());
        }

        internal static void Skip(ByteReader br)
        {
            byte b = br.PeekByte();
            while (IsCustomModifier(b))
            {
                br.ReadByte();
                br.ReadCompressedUInt();
                b = br.PeekByte();
            }
        }

        internal static CustomModifiers FromReqOpt(Type[] req, Type[] opt)
        {
            List<Type> list = null;
            if (opt != null && opt.Length != 0)
            {
                Debug.Assert(Initial == MarkerType.ModOpt);
                list = new List<Type>(opt);
            }
            if (req != null && req.Length != 0)
            {
                if (list == null)
                {
                    list = new List<Type>();
                }
                list.Add(MarkerType.ModReq);
                list.AddRange(req);
            }
            if (list == null)
            {
                return new CustomModifiers();
            }
            else
            {
                return new CustomModifiers(list.ToArray());
            }
        }

        private static bool IsCustomModifier(byte b)
        {
            return b == Signature.ELEMENT_TYPE_CMOD_OPT || b == Signature.ELEMENT_TYPE_CMOD_REQD;
        }

        internal static CustomModifiers Combine(CustomModifiers mods1, CustomModifiers mods2)
        {
            if (mods1.IsEmpty)
            {
                return mods2;
            }
            else if (mods2.IsEmpty)
            {
                return mods1;
            }
            else
            {
                Type[] combo = new Type[mods1.types.Length + mods2.types.Length];
                Array.Copy(mods1.types, combo, mods1.types.Length);
                Array.Copy(mods2.types, 0, combo, mods1.types.Length, mods2.types.Length);
                return new CustomModifiers(combo);
            }
        }
    }
}