FieldExpression.cs :  » Development » Vici-Parser » Vici » Core » Parser » C# / CSharp Open Source

#region License
//=============================================================================
// Vici Core - Productivity Library for .NET 3.5 
//
// Copyright (c) 2008-2010 Philippe Leybaert
//
// 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.
//=============================================================================
#endregion

using System;
using System.Reflection;
using System.Collections.Generic;

namespace Vici.Core.Parser{
    public class FieldExpression : Expression
    {
        private readonly Expression _target;
        private readonly string _member;

        public FieldExpression(TokenPosition position, Expression target, string member) : base(position)
        {
            _target = target;
            _member = member;
        }

        public override ValueExpression Evaluate(IParserContext context)
        {
          return Evaluate(context, null);
        }

    private ValueExpression Evaluate(IParserContext context, object newValue)
      {
        ValueExpression targetValue = _target.Evaluate(context);
        object targetObject;
        Type targetType;

        if (targetValue.Value is ClassName)
        {
          targetType = ((ClassName) targetValue.Value).Type;
          targetObject = null;
        }
        else
        {
          targetType = targetValue.Type;
          targetObject = targetValue.Value;

                if (targetObject == null)
                    return new ValueExpression(TokenPosition, null, targetType);
        }

            if (targetObject is IDynamicObject)
            {
                object value;
                Type type;

                if (((IDynamicObject)targetObject).TryGetValue(_member, out value, out type))
                    return new ValueExpression(TokenPosition, value,type);
            }

        MemberInfo[] members = targetType.GetMember(_member);

        if (members.Length == 0)
        {
                PropertyInfo indexerPropInfo = targetType.GetProperty("Item", new[] { typeof(string) });

                if (indexerPropInfo != null)
                {
                    return new ValueExpression(TokenPosition, indexerPropInfo.GetValue(targetObject, new object[] { _member }), indexerPropInfo.PropertyType);
                }

          throw new UnknownPropertyException("Unknown property " + _member + " for object " + _target + " (type " + targetType.Name + ")", this);
        }

        if (members.Length >= 1 && members[0] is MethodInfo)
        {
          if (targetObject == null)
                    return Exp.Value(TokenPosition, new StaticMethod(targetType, _member));
          else
                    return Exp.Value(TokenPosition, new InstanceMethod(targetType, _member, targetObject));
        }

        MemberInfo member = members[0];

        if (members.Length > 1 && targetObject != null) // CoolStorage, ActiveRecord and Dynamic Proxy frameworks sometimes return > 1 member
        {
          foreach (MemberInfo mi in members)
            if (mi.DeclaringType == targetObject.GetType())
              member = mi;
        }

      if (newValue != null)
      {
        if (member is FieldInfo)
          ((FieldInfo) member).SetValue(targetObject, newValue);

        if (member is PropertyInfo)
          ((PropertyInfo) member).SetValue(targetObject, newValue, null);

        // Fall through to get the new property/field value below
      }

      if (member is FieldInfo)
        return new ValueExpression(TokenPosition, ((FieldInfo) member).GetValue(targetObject), ((FieldInfo) member).FieldType);

      if (member is PropertyInfo)
          return new ValueExpression(TokenPosition, ((PropertyInfo)member).GetValue(targetObject, null), ((PropertyInfo)member).PropertyType);

        throw new ExpressionEvaluationException(_member + " is not a field or property", this);
      }

      public override string ToString()
        {
            return "(" + _target + "." + _member + ")";
        }


      public ValueExpression Assign(IParserContext context, object value)
      {
        return Evaluate(context, value);
      }
    }
}