|
public CreateFieldValueExpression ( |
||
| expression | The expression. | |
| reportedSignatureSupport | A component outlining the supported expression structure of this provider. | |
| return | ||
/// <summary>
/// Converts a <see cref="BinaryExpression"/> to a field predicate expression, if supported and convertible.
/// </summary>
/// <param name="expression">The expression.</param>
/// <param name="structureBinder">The structure binder.</param>
/// <returns></returns>
/// <remarks></remarks>
public static Expression ConvertToFieldPredicate(BinaryExpression expression, AbstractQueryStructureBinder structureBinder)
{
if (IsConvertibleBinary(expression, structureBinder))
{
var left = expression.Left;
// Check if the left had side is a Unary wrapping a DynamicMemberMetadata call just to get the type right
var unaryLeft = left as UnaryExpression;
if (unaryLeft != null)
{
var methodLeft = unaryLeft.Operand as MethodCallExpression;
if (methodLeft != null && methodLeft.Method == DynamicMemberMetadata.GetMemberMethod)
{
left = methodLeft;
}
}
// First assume that the right hand side of the binary is a constant
ConstantExpression right = expression.Right as ConstantExpression;
// If it's not, it might be a unary (e.g. "convert value to object" if it's from DynamicMemberMetadata)
if (right == null)
{
var unary = expression.Right as UnaryExpression;
if (unary != null)
{
// If it was a unary, ignore the operator and just go for the operand (the value)
right = unary.Operand as ConstantExpression;
}
}
BindingSignatureSupport leftBindingSignatureSupport = GetBindingSupport(left, structureBinder);
// Update the ValuePredicateType based on the expression which might reference an operator or a NodeType of NotEqual etc.
UpdateValuePredicateType(leftBindingSignatureSupport, expression);
switch (leftBindingSignatureSupport.SignatureSupportType)
{
case SignatureSupportType.SupportedAsFieldName:
var selectorExpression = GetFieldSelector(left, structureBinder, leftBindingSignatureSupport);
return new FieldPredicateExpression(selectorExpression, new FieldValueExpression(leftBindingSignatureSupport.NodeType, right.Value));
case SignatureSupportType.SupportedAsFieldValue:
var methodCallExpression = ((MethodCallExpression)left);
if (ExpressionHelper.IsMethod(left))
{
var fieldValueExpression = structureBinder
.CreateFieldValueExpression(methodCallExpression, leftBindingSignatureSupport);
var objectOfMethod = methodCallExpression.Object;
var bindingSupportForMethodObject = GetBindingSupport(objectOfMethod, structureBinder);
var fieldSelector = GetFieldSelector(objectOfMethod, structureBinder, bindingSupportForMethodObject);
return new FieldPredicateExpression(fieldSelector, fieldValueExpression);
}
break;
case SignatureSupportType.SupportedAsSchemaAlias:
var schemaSelectorExpression = GetSchemaSelector(left, structureBinder, leftBindingSignatureSupport);
return
new SchemaPredicateExpression(
new SchemaSelectorExpression(schemaSelectorExpression.Name),
new SchemaValueExpression(leftBindingSignatureSupport.NodeType, right.Value));
}
}
return expression;
}
