System.Linq.Dynamic.ExpressionParser.PromoteExpression C# (CSharp) Method

		private Expression PromoteExpression(Expression expr, Type type, bool exact)
		{
			if (expr.Type == type) return expr;
			var ce = expr as ConstantExpression;
			if (ce != null)
			{
				if (ce == NullLiteral)
				{
					if (!type.IsValueType || IsNullableType(type))
						return Expression.Constant(null, type);
				}
				else
				{
					string text;
					if (_literals.TryGetValue(ce, out text))
					{
						Type target = GetNonNullableType(type);
						object value = null;
						switch (Type.GetTypeCode(ce.Type))
						{
							case TypeCode.Int32:
							case TypeCode.UInt32:
							case TypeCode.Int64:
							case TypeCode.UInt64:
								value = ParseNumber(text, target);
								break;
							case TypeCode.Double:
								if (target == typeof(decimal)) value = ParseNumber(text, target);
								break;
							case TypeCode.String:
								value = ParseEnum(text, target);
								break;
						}
						if (value != null)
							return Expression.Constant(value, type);
					}
				}
			}
			if (IsCompatibleWith(expr.Type, type))
			{
				if (type.IsValueType || exact) return Expression.Convert(expr, type);
				return expr;
			}
			if (expr.Type == typeof(char) && type == typeof(string))
			{
				return Expression.Call(expr, "ToString", Type.EmptyTypes);
			}
			return null;
		}