/// <summary>
/// ConstantExpression visit method
/// </summary>
/// <param name="c">The ConstantExpression expression to visit</param>
/// <returns>The visited ConstantExpression expression </returns>
internal override Expression VisitConstant(ConstantExpression c)
{
if (c.Value == null)
{
this.builder.Append(UriHelper.NULL);
return(c);
}
// DEVNOTE:
// Rather than forcing every other codepath to have the 'Try...' pattern for formatting,
// we catch the InvalidOperationException here to change the exception type.
// This is exceedingly rare, and not a scenario where performance is meaningful, so the
// reduced complexity in all other call sites is worth the extra logic here.
string result;
BinaryExpression b = this.parent as BinaryExpression;
MethodCallExpression m = this.parent as MethodCallExpression;
if ((b != null && HasEnumInBinaryExpression(b)) || (m != null && m.Method.Name == "HasFlag"))
{
c = this.ConvertConstantExpressionForEnum(c);
ClientEdmModel model = this.context.Model;
IEdmType edmType = model.GetOrCreateEdmType(c.Type.IsEnum() ? c.Type : c.Type.GetGenericArguments()[0]);
ClientTypeAnnotation typeAnnotation = model.GetClientTypeAnnotation(edmType);
string typeNameInEdm = this.context.ResolveNameFromTypeInternal(typeAnnotation.ElementType);
MemberInfo member = typeAnnotation.ElementType.GetField(c.Value.ToString());
string memberValue = ClientTypeUtil.GetServerDefinedName(member);
ODataEnumValue enumValue = new ODataEnumValue(memberValue, typeNameInEdm ?? typeAnnotation.ElementTypeName);
result = ODataUriUtils.ConvertToUriLiteral(enumValue, CommonUtil.ConvertToODataVersion(this.uriVersion), null);
}
else
{
try
{
result = LiteralFormatter.ForConstants.Format(c.Value);
}
catch (InvalidOperationException)
{
if (this.cantTranslateExpression)
{
// there's already a problem in the parents.
// we should just return here, because caller somewhere up the stack will throw a better exception
return(c);
}
throw new NotSupportedException(Strings.ALinq_CouldNotConvert(c.Value));
}
}
Debug.Assert(result != null, "result != null");
this.builder.Append(result);
return(c);
}
