// This method returns true if the specified argument types match
// the method's parameter types
private static Boolean CompareParamAndArgTypes(
ParameterInfo[] paramTypes,
Type[] argTypes,
CompareParamAndArgTypesFlags flags)
{
// This binder requires that the number of arguments and parameters match
if (paramTypes.Length != argTypes.Length)
{
return(false);
}
Int32 i = 0;
for (; i < paramTypes.Length; i++)
{
// If the argument has a type, compare it against the parameter's type
// This can be null if Type.InvokeMember is passed null for an argument
if (argTypes[i] != null)
{
Type formalType = paramTypes[i].ParameterType;
// If argument and parameter types match exactly, try next pair
if (formalType == argTypes[i])
{
continue;
}
// Compare the primitive, value type, or enumerated type parameter
if (formalType.IsValueType)
{
if (((flags & CompareParamAndArgTypesFlags.CoerceValueTypes) != 0) &&
CanConvertPrimitiveType(argTypes[i], formalType))
{
continue;
}
break; // Can't coerce argument type to parameter type
}
else
{
// Compare the reference type parameter
if (((flags & CompareParamAndArgTypesFlags.AllowBaseTypes) != 0) &&
formalType.IsAssignableFrom(argTypes[i]))
{
continue;
}
break; // Can't implicitly cast argument type to parameter type
}
}
}
// Return true if all argument and parameter types match
return(i == paramTypes.Length);
}
// GetProperty calls this method to select a specific property.
// This code performs uses simple conversion rules to bind.
public override PropertyInfo SelectProperty(
BindingFlags bindingAttr, // Flags to restrict options
PropertyInfo[] properties, // Property subset selected by reflection
Type returnType, // Property's return type
Type[] argTypes, // Set of argument types
ParameterModifier[] modifiers) // Modifiers (usually ignored)
// This ArrayList contains the set of possible properties
{
ArrayList candidates = new ArrayList();
// Build the set of candidate properties removing any property that
// doesn't have the specified number of arguments.
// Only consider properties that have the same number of arguments and type
Int32 argCount = (argTypes == null) ? 0 : argTypes.Length;
foreach (PropertyInfo p in properties)
{
if (GetPropertyParams(p).Length == argCount)
{
// Check the property's type
if ((returnType == null) || (returnType == p.PropertyType))
{
candidates.Add(p);
}
}
}
// If no exact match was found and the caller wants an exact match, throw
Int32 numTests = ((BindingFlags.ExactBinding & bindingAttr) != 0) ? 1 : 3;
for (Int32 test = 0; test < numTests; test++)
{
CompareParamAndArgTypesFlags flags = CompareParamAndArgTypesFlags.Exact;
// Look for properties whose parameter types exactly match the argument types
if (test == 0)
{
flags = CompareParamAndArgTypesFlags.Exact;
}
// Look for properties that can accomodate the parameters passed.
if (test == 1)
{
flags = CompareParamAndArgTypesFlags.AllowBaseTypes;
}
// Check whether any conversion could be applied on primitives as well.
// NOTE: We bind to the first matching property; not the best matching property.
// Look for properties that can accomodate the parameters passed.
if (test == 2)
{
flags = CompareParamAndArgTypesFlags.AllowBaseTypes |
CompareParamAndArgTypesFlags.CoerceValueTypes;
}
// Assume that no property matches the argument's parameters
PropertyInfo match = null;
// Check ALL of the properties
foreach (PropertyInfo p in candidates)
{
if (CompareParamAndArgTypes(GetPropertyParams(p), argTypes, flags))
{
// A matching property was found
// If we found a matching property previously, then we don't know
// how to select one of them.
if (match != null)
{
// Note, when doing an exact match this can occur if multiple
// properties differ only by type
throw new AmbiguousMatchException("Multiple properties match the specified parameter types.");
}
// Save the matching property
match = p;
}
}
// One matching property was found, return it
if (match != null)
{
return(match);
}
}
// No matching property was found, throw
throw new MissingMemberException("Member not found.");
}
// GetMethod calls this method to select a specific method.
// This code performs uses simple conversion rules to bind.
public override MethodBase SelectMethod(
BindingFlags bindingAttr, // Flags to restrict options
MethodBase[] methods, // Method subset selected by reflection
Type[] argTypes, // Set of argument types
ParameterModifier[] modifiers) // Modifiers (usually ignored)
// This ArrayList contains the set of possible methods
{
ArrayList candidates = new ArrayList();
// Build the set of candidate methods removing any method that
// doesn't have the specified number of arguments.
// A more sophisticated binder would have code here to deal with methods
// that accept a variable number of arguments (ParamArrayAttribute) and
// with methods that accept optional arguments and named parameters.
Int32 argCount = argTypes.Length;
foreach (MethodBase m in methods)
{
if (m.GetParameters().Length == argCount)
{
candidates.Add(m);
}
}
// If no exact match was found and the caller wants an exact match, throw
Int32 numTests = ((BindingFlags.ExactBinding & bindingAttr) != 0) ? 1 : 3;
for (Int32 test = 0; test < numTests; test++)
{
CompareParamAndArgTypesFlags flags = CompareParamAndArgTypesFlags.Exact;
// Look for methods whose parameter types exactly match the argument types
if (test == 0)
{
flags = CompareParamAndArgTypesFlags.Exact;
}
// Look for methods that can accomodate the parameters passed.
if (test == 1)
{
flags = CompareParamAndArgTypesFlags.AllowBaseTypes;
}
// Check whether any conversion could be applied on primitives as well.
// NOTE: We bind to the first matching method; not the best matching method.
// Look for methods that can accomodate the parameters passed.
if (test == 2)
{
flags = CompareParamAndArgTypesFlags.AllowBaseTypes |
CompareParamAndArgTypesFlags.CoerceValueTypes;
}
// Assume that no method matches the argument's parameters
MethodBase match = null;
// Check ALL of the methods
foreach (MethodBase m in candidates)
{
if (CompareParamAndArgTypes(m.GetParameters(), argTypes, flags))
{
// A matching method was found
// If we found a matching method previously, then we don't know
// how to select one of them.
if (match != null)
{
// Note, when doing an exact match this can occur if multiple
// methods differ only by return type
throw new AmbiguousMatchException("Multiple methods match the specified parameter types.");
}
// Save the matching method
match = m;
}
}
// One matching method was found, return it
if (match != null)
{
return(match);
}
}
// No matching method was found, throw
throw new MissingMethodException("Member not found.");
}
