Class VisitorPatternHelper<ReturnType>

Helper class for performing a Visitor-type invocation of methods on some node structure

Inheritance

Object

VisitorPatternHelper<ReturnType>

Namespace: SuperOffice.Util

Assembly: SoCore.dll

Syntax

public sealed class VisitorPatternHelper<ReturnType> : Object

Type Parameters

Name	Description
ReturnType	Return type for the visit methods

Remarks

See http://en.wikipedia.org/wiki/Visitor_pattern for a description of the Visitor pattern. Visitor is a fairly abstract pattern and will usually require some thought to follow through.

The class performs the dispatching/invocation of visitor methods, so the client class only needs to provide methods that handle the required types of nodes in the visited structure.

Generally the client class will provide a class instance that contains one or more Visit methods. It will then call the InvokeStrictVisitor(Object[]) or InvokeTolerantVisitor(Object[]) method, giving the root node of some structure to be visited as the input parameter(s).

The VisitorPatternHelper will reflect on the client class and try to find a method whose signature matches the input. If it finds one, it will forward the call to this method, which may recursively call one of the InvokeXXXVisitor methods in turn.

Constructors

VisitorPatternHelper(String, Object)

Initialize the visitor helper with a method prefix and a target class

Declaration

public VisitorPatternHelper(string methodPrefix, object targetClass)

Parameters

Type	Name	Description
String	methodPrefix	The prefix that all visitation methods must be named with
Object	targetClass	The class that contains the visitation methods

Remarks

See http://en.wikipedia.org/wiki/Visitor_pattern for a description of the Visitor pattern. Visitor is a fairly abstract pattern and will usually require some thought to follow through.

The class performs the dispatching/invocation of visitor methods, so the client class only needs to provide methods that handle the required types of nodes in the visited structure.

Generally the client class will provide a class instance that contains one or more Visit methods. It will then call the InvokeStrictVisitor(Object[]) or InvokeTolerantVisitor(Object[]) method, giving the root node of some structure to be visited as the input parameter(s).

The VisitorPatternHelper will reflect on the client class and try to find a method whose signature matches the input. If it finds one, it will forward the call to this method, which may recursively call one of the InvokeXXXVisitor methods in turn.

Methods

InvokeStrictVisitor(Object[])

Invoke the visitor, by finding and calling the method in the target class that has a signature matching the visitorArguments. If no such method is found, an exception is thrown.

Declaration

public ReturnType InvokeStrictVisitor(params object[] visitorArguments)

Parameters

Type	Name	Description
Object[]	visitorArguments	Arguments to the method to be called

Returns

Type	Description
ReturnType	Return value from the visitation method

Remarks

See http://en.wikipedia.org/wiki/Visitor_pattern for a description of the Visitor pattern. Visitor is a fairly abstract pattern and will usually require some thought to follow through.

The class performs the dispatching/invocation of visitor methods, so the client class only needs to provide methods that handle the required types of nodes in the visited structure.

Generally the client class will provide a class instance that contains one or more Visit methods. It will then call the InvokeStrictVisitor(Object[]) or InvokeTolerantVisitor(Object[]) method, giving the root node of some structure to be visited as the input parameter(s).

The VisitorPatternHelper will reflect on the client class and try to find a method whose signature matches the input. If it finds one, it will forward the call to this method, which may recursively call one of the InvokeXXXVisitor methods in turn.

Exceptions

Type	Condition
SoNotImplementedException	Thrown if the target class (given to the constructor) does not contain a method with the given name prefix and parameter signature corresponding to the current set of parameters (visitorArguments)

InvokeTolerantVisitor(Object[])

Invoke the visitor, by finding and calling the method in the target class that has a signature matching the visitorArguments. If no such method is found, no call is made and default(ReturnType) is returned (no exception thrown).

Declaration

public ReturnType InvokeTolerantVisitor(params object[] visitorArguments)

Parameters

Type	Name	Description
Object[]	visitorArguments	Arguments to the method to be called

Returns

Type	Description
ReturnType	Return value from the visitation method

Remarks

See http://en.wikipedia.org/wiki/Visitor_pattern for a description of the Visitor pattern. Visitor is a fairly abstract pattern and will usually require some thought to follow through.

The class performs the dispatching/invocation of visitor methods, so the client class only needs to provide methods that handle the required types of nodes in the visited structure.

Generally the client class will provide a class instance that contains one or more Visit methods. It will then call the InvokeStrictVisitor(Object[]) or InvokeTolerantVisitor(Object[]) method, giving the root node of some structure to be visited as the input parameter(s).

The VisitorPatternHelper will reflect on the client class and try to find a method whose signature matches the input. If it finds one, it will forward the call to this method, which may recursively call one of the InvokeXXXVisitor methods in turn.

InvokeVisitor(Boolean, Object[])

InvokeVisitor checks the in-parameters type against the already existing method dictionary. When the key is found in the array, the key's object method is called.

Declaration

public ReturnType InvokeVisitor(bool failIfMissing, params object[] visitorArguments)

Parameters

Type	Name	Description
Boolean	failIfMissing
Object[]	visitorArguments	arguments as passed to the method. The arguments' type needs to be an exact match of the type implemented in the appropriate target method.

Returns

Type	Description
ReturnType	returns the ReturnType returned from the Invoked target method

Remarks

See http://en.wikipedia.org/wiki/Visitor_pattern for a description of the Visitor pattern. Visitor is a fairly abstract pattern and will usually require some thought to follow through.

The class performs the dispatching/invocation of visitor methods, so the client class only needs to provide methods that handle the required types of nodes in the visited structure.

Generally the client class will provide a class instance that contains one or more Visit methods. It will then call the InvokeStrictVisitor(Object[]) or InvokeTolerantVisitor(Object[]) method, giving the root node of some structure to be visited as the input parameter(s).

The VisitorPatternHelper will reflect on the client class and try to find a method whose signature matches the input. If it finds one, it will forward the call to this method, which may recursively call one of the InvokeXXXVisitor methods in turn.

Exceptions

Type	Condition
SoNotImplementedException	There is no appropriate method to invoke.
SoException	An exception was thrown while trying to invoke the target method

Extension Methods

EnumUtil.MapEnums<From, To>(From)

Converters.MapEnums<From, To>(From)