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Resolving Symbolic References in a CodeDOM (Part 7)

, 2 Dec 2012
Resolving symbolic references in a CodeDOM.
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// The Nova Project by Ken Beckett.
// Copyright (C) 2007-2012 Inevitable Software, all rights reserved.
// Released under the Common Development and Distribution License, CDDL-1.0: http://opensource.org/licenses/cddl1.php

using System;
using System.Reflection;
using Mono.Cecil;

using Nova.Resolving;

namespace Nova.CodeDOM
{
    /// <summary>
    /// Represents a reference to an <see cref="EnumMemberDecl"/> (a member of an <see cref="EnumDecl"/> type declaration).
    /// </summary>
    public class EnumMemberRef : VariableRef
    {
        #region /* CONSTRUCTORS */

        /// <summary>
        /// Create an <see cref="EnumMemberRef"/>.
        /// </summary>
        public EnumMemberRef(EnumMemberDecl declaration, bool isFirstOnLine)
            : base(declaration, isFirstOnLine)
        { }

        /// <summary>
        /// Create an <see cref="EnumMemberRef"/>.
        /// </summary>
        public EnumMemberRef(EnumMemberDecl declaration)
            : base(declaration, false)
        { }

        /// <summary>
        /// Create an <see cref="EnumMemberRef"/>.
        /// </summary>
        public EnumMemberRef(FieldDefinition fieldDefinition, bool isFirstOnLine)
            : base(fieldDefinition, isFirstOnLine)
        {
            if (!fieldDefinition.IsLiteral || !fieldDefinition.DeclaringType.IsEnum)
                throw new Exception("A FieldDefinition used to construct an EnumMemberRef must represent an enum member.");
        }

        /// <summary>
        /// Create an <see cref="EnumMemberRef"/>.
        /// </summary>
        public EnumMemberRef(FieldDefinition fieldDefinition)
            : this(fieldDefinition, false)
        { }

        /// <summary>
        /// Create an <see cref="EnumMemberRef"/>.
        /// </summary>
        public EnumMemberRef(FieldInfo fieldInfo, bool isFirstOnLine)
            : base(fieldInfo, isFirstOnLine)
        {
            if (!fieldInfo.IsLiteral || (fieldInfo.DeclaringType != null && !fieldInfo.DeclaringType.IsEnum))
                throw new Exception("A FieldInfo used to construct an EnumMemberRef must represent an enum member.");
        }

        /// <summary>
        /// Create an <see cref="EnumMemberRef"/>.
        /// </summary>
        public EnumMemberRef(FieldInfo fieldInfo)
            : this(fieldInfo, false)
        { }

        #endregion

        #region /* PROPERTIES */

        /// <summary>
        /// Always <c>true</c>.
        /// </summary>
        public override bool IsConst
        {
            get { return true; }
        }

        /// <summary>
        /// Always <c>true</c>.
        /// </summary>
        public override bool IsStatic
        {
            get { return true; }
        }

        #endregion

        #region /* STATIC METHODS */

        /// <summary>
        /// Find the enum value with the specified name in the specified <see cref="EnumDecl"/>.
        /// </summary>
        /// <returns>An <see cref="EnumMemberRef"/> to the enum value, or an <see cref="UnresolvedRef"/> if no match was found.</returns>
        public static SymbolicRef Find(EnumDecl enumDecl, string name, bool isFirstOnLine)
        {
            if (enumDecl != null)
            {
                EnumMemberRef enumMemberRef = enumDecl.GetMember(name);
                if (enumMemberRef != null)
                {
                    enumMemberRef.IsFirstOnLine = isFirstOnLine;
                    return enumMemberRef;
                }
            }
            return new UnresolvedRef(name, isFirstOnLine, ResolveCategory.Expression);
        }

        /// <summary>
        /// Find the enum value with the specified name in the specified <see cref="EnumDecl"/>.
        /// </summary>
        /// <returns>An <see cref="EnumMemberRef"/> to the enum value, or an <see cref="UnresolvedRef"/> if no match was found.</returns>
        public static SymbolicRef Find(EnumDecl enumDecl, string name)
        {
            return Find(enumDecl, name, false);
        }

        /// <summary>
        /// Find the enum value with the specified name in the specified enum <see cref="Type"/>.
        /// </summary>
        /// <returns>An <see cref="EnumMemberRef"/> to the enum value, or an <see cref="UnresolvedRef"/> if no match was found.</returns>
        public static SymbolicRef Find(Type type, string valueName, bool isFirstOnLine)
        {
            if (type != null)
            {
                FieldInfo fieldInfo = type.GetField(valueName);
                if (fieldInfo != null)
                    return new EnumMemberRef(fieldInfo, isFirstOnLine);
            }
            return new UnresolvedRef(valueName, isFirstOnLine);
        }

        /// <summary>
        /// Find the enum value with the specified name in the specified enum <see cref="Type"/>.
        /// </summary>
        /// <returns>An <see cref="EnumMemberRef"/> to the enum value, or an <see cref="UnresolvedRef"/> if no match was found.</returns>
        public static SymbolicRef Find(Type type, string valueName)
        {
            return Find(type, valueName, false);
        }

        /// <summary>
        /// Find the enum value with the specified name in the specified <see cref="TypeRefBase"/>.
        /// </summary>
        /// <returns>An <see cref="EnumMemberRef"/> to the enum value, or an <see cref="UnresolvedRef"/> if no match was found.</returns>
        public static SymbolicRef Find(TypeRefBase typeRefBase, string name, bool isFirstOnLine)
        {
            if (typeRefBase is TypeRef && ((TypeRef)typeRefBase).IsEnum)
            {
                if (typeRefBase.Reference is Type)
                    return Find(typeRefBase.Reference as Type, name, isFirstOnLine);
                if (typeRefBase.Reference is EnumDecl)
                    return Find(typeRefBase.Reference as EnumDecl, name, isFirstOnLine);
            }
            return new UnresolvedRef(name, isFirstOnLine, ResolveCategory.Expression);
        }

        /// <summary>
        /// Find the enum value with the specified name in the specified <see cref="TypeRefBase"/>.
        /// </summary>
        /// <returns>An <see cref="EnumMemberRef"/> to the enum value, or an <see cref="UnresolvedRef"/> if no match was found.</returns>
        public static SymbolicRef Find(TypeRefBase typeRefBase, string name)
        {
            return Find(typeRefBase, name, false);
        }

        #endregion

        #region /* METHODS */

        /// <summary>
        /// Get the declaring type of the referenced enum member.
        /// </summary>
        public override TypeRefBase GetDeclaringType()
        {
            TypeRefBase declaringTypeRef = GetDeclaringType(_reference);

            // An enum member reference doesn't store any type arguments for a parent type instance, so any
            // type arguments in any generic declaring type or its parent types will always default to
            // the declared type arguments.  Convert them from OpenTypeParameterRefs to TypeParameterRefs
            // so that they don't show up as Red in the GUI.
            if (declaringTypeRef != null && declaringTypeRef.HasTypeArguments)
                declaringTypeRef.ConvertOpenTypeParameters();

            return declaringTypeRef;
        }

        /// <summary>
        /// Get the declaring type of the specified enum member object.
        /// </summary>
        /// <param name="enumMemberObj">The enum member object (a <see cref="EnumMemberDecl"/> or <see cref="FieldInfo"/>).</param>
        /// <returns>The <see cref="TypeRef"/> of the declaring type, or null if it can't be determined.</returns>
        public static TypeRefBase GetDeclaringType(object enumMemberObj)
        {
            TypeRefBase declaringTypeRef = null;
            if (enumMemberObj is EnumMemberDecl)
            {
                TypeDecl declaringTypeDecl = ((EnumMemberDecl)enumMemberObj).ParentEnumDecl;
                declaringTypeRef = (declaringTypeDecl != null ? declaringTypeDecl.CreateRef() : null);
            }
            else if (enumMemberObj is FieldDefinition)
                declaringTypeRef = TypeRef.Create(((FieldDefinition)enumMemberObj).DeclaringType);
            else if (enumMemberObj is FieldInfo)
                declaringTypeRef = TypeRef.Create(((FieldInfo)enumMemberObj).DeclaringType);
            return declaringTypeRef;
        }

        #endregion

        #region /* RESOLVING */

        /// <summary>
        /// Evaluate the type of the <see cref="Expression"/>.
        /// </summary>
        /// <returns>The resulting <see cref="TypeRef"/> or <see cref="UnresolvedRef"/>.</returns>
        public override TypeRefBase EvaluateType(bool withoutConstants)
        {
            // Get the TypeRef of the enum, using any existing TypeRef on a Dot prefix if possible
            TypeRefBase typeRefBase = null;
            if (_parent is Dot)
            {
                typeRefBase = ((Dot)_parent).Left.EvaluateType(withoutConstants);

                // Convert any aliased enum to the actual enum type
                if (typeRefBase is AliasRef)
                    typeRefBase = ((AliasRef)typeRefBase).Type;
            }

            // Evaluate to a TypeRef that references both the enum type plus the underlying constant value.
            // We have to check for null constant values, because the enum initialization might be unresolved.
            object constantValue = null;
            if (_reference is EnumMemberDecl)
            {
                EnumMemberDecl subEnumDecl = (EnumMemberDecl)_reference;
                // If we had trouble getting the enum type, determine it from the enum member
                if (typeRefBase == null)
                    typeRefBase = subEnumDecl.EvaluateType(withoutConstants);
                if (typeRefBase is TypeRef && !withoutConstants)
                {
                    constantValue = subEnumDecl.GetValue();
                    if (constantValue != null)
                        return new TypeRef((TypeRef)typeRefBase, constantValue);
                }
                return typeRefBase;
            }

            if (_reference is FieldDefinition)
            {
                FieldDefinition fieldDefinition = (FieldDefinition)_reference;
                if (!(typeRefBase is TypeRef))
                    typeRefBase = TypeRef.Create(fieldDefinition.DeclaringType);
                if (!withoutConstants)
                {
                    try { constantValue = fieldDefinition.Constant; }
                    catch { }
                    if (constantValue != null && typeRefBase is TypeRef)
                        return new TypeRef((TypeRef)typeRefBase, constantValue);
                }
                return typeRefBase;
            }
            FieldInfo fieldInfo = (FieldInfo)_reference;
            if (!(typeRefBase is TypeRef))
                typeRefBase = TypeRef.Create(fieldInfo.DeclaringType);
            if (!withoutConstants)
            {
                try { constantValue = fieldInfo.GetRawConstantValue(); }
                catch { }
                if (constantValue != null)
                    return new TypeRef((TypeRef)typeRefBase, constantValue);
            }
            return typeRefBase;
        }

        #endregion
    }
}

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License

This article, along with any associated source code and files, is licensed under The Common Development and Distribution License (CDDL)

About the Author

KenBeckett
Software Developer (Senior)
United States United States
I've been writing software since the late 70's, currently focusing mainly on C#.NET. I also like to travel around the world, and I own a Chocolate Factory (sadly, none of my employees are oompa loompas).

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