org.apache.commons.jexl.util.introspection

Class MethodMap

java.lang.Object

org.apache.commons.jexl.util.introspection.MethodMap

public class MethodMap
extends java.lang.Object

Since:

1.0

Version:

$Id: MethodMap.java 398495 2006-05-01 01:33:43Z dion $

Author:

Jason van Zyl, Bob McWhirter, Christoph Reck, Geir Magnusson Jr., Attila Szegedi

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MethodMap.AmbiguousException simple distinguishable exception, used when we run across ambiguous overloading.

Field Summary

Fields

Modifier and Type	Field and Description
private static int	INCOMPARABLE A method doesn't match a previously compared one.
private static int	LESS_SPECIFIC whether a method is less specific than a previously compared one.
protected java.util.Map	methodByNameMap Keep track of all methods with the same name.
private static int	MORE_SPECIFIC whether a method is more specific than a previously compared one.

Constructor Summary

Constructors

Constructor and Description
MethodMap()

Method Summary

Modifier and Type	Method and Description
void	add(java.lang.reflect.Method method) Add a method to a list of methods by name.
java.lang.reflect.Method	find(java.lang.String methodName, java.lang.Object[] args) Find a method.
java.util.List	get(java.lang.String key) Return a list of methods with the same name.
private static java.util.LinkedList	getApplicables(java.util.List methods, java.lang.Class[] classes) Returns all methods that are applicable to actual argument types.
private static java.lang.reflect.Method	getMostSpecific(java.util.List methods, java.lang.Class[] classes) Gets the most specific method from a list.
private static boolean	isApplicable(java.lang.reflect.Method method, java.lang.Class[] classes) Returns true if the supplied method is applicable to actual argument types.
private static boolean	isMethodInvocationConvertible(java.lang.Class formal, java.lang.Class actual) Determines whether a type represented by a class object is convertible to another type represented by a class object using a method invocation conversion, treating object types of primitive types as if they were primitive types (that is, a Boolean actual parameter type matches boolean primitive formal type).
private static boolean	isStrictMethodInvocationConvertible(java.lang.Class formal, java.lang.Class actual) Determines whether a type represented by a class object is convertible to another type represented by a class object using a method invocation conversion, without matching object and primitive types.
private static int	moreSpecific(java.lang.Class[] c1, java.lang.Class[] c2) Determines which method signature (represented by a class array) is more specific.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MORE_SPECIFIC

private static final int MORE_SPECIFIC

whether a method is more specific than a previously compared one.

See Also:

Constant Field Values

LESS_SPECIFIC

private static final int LESS_SPECIFIC

whether a method is less specific than a previously compared one.

See Also:

Constant Field Values

INCOMPARABLE

private static final int INCOMPARABLE

A method doesn't match a previously compared one.

See Also:

Constant Field Values

methodByNameMap

protected java.util.Map methodByNameMap

Keep track of all methods with the same name.

Constructor Detail

MethodMap

public MethodMap()

Method Detail

add

public void add(java.lang.reflect.Method method)

Add a method to a list of methods by name. For a particular class we are keeping track of all the methods with the same name.

Parameters:

method - the method.

get

public java.util.List get(java.lang.String key)

Return a list of methods with the same name.

Parameters:

key - The method name.

Returns:

List list of methods

find

public java.lang.reflect.Method find(java.lang.String methodName,
                                     java.lang.Object[] args)
                              throws MethodMap.AmbiguousException

Find a method. Attempts to find the most specific applicable method using the algorithm described in the JLS section 15.12.2 (with the exception that it can't distinguish a primitive type argument from an object type argument, since in reflection primitive type arguments are represented by their object counterparts, so for an argument of type (say) java.lang.Integer, it will not be able to decide between a method that takes int and a method that takes java.lang.Integer as a parameter.

This turns out to be a relatively rare case where this is needed - however, functionality like this is needed.

Parameters:

methodName - name of method

args - the actual arguments with which the method is called

Returns:

the most specific applicable method, or null if no method is applicable.

Throws:

MethodMap.AmbiguousException - if there is more than one maximally specific applicable method

getMostSpecific

private static java.lang.reflect.Method getMostSpecific(java.util.List methods,
                                                        java.lang.Class[] classes)
                                                 throws MethodMap.AmbiguousException

Gets the most specific method from a list.

Parameters:

methods - list of methods

classes - argument types

Returns:

the most specific method, or null

Throws:

MethodMap.AmbiguousException - if there is more than one specific method

moreSpecific

private static int moreSpecific(java.lang.Class[] c1,
                                java.lang.Class[] c2)

Determines which method signature (represented by a class array) is more specific. This defines a partial ordering on the method signatures.

Parameters:

c1 - first signature to compare

c2 - second signature to compare

Returns:

MORE_SPECIFIC if c1 is more specific than c2, LESS_SPECIFIC if c1 is less specific than c2, INCOMPARABLE if they are incomparable.

getApplicables

private static java.util.LinkedList getApplicables(java.util.List methods,
                                                   java.lang.Class[] classes)

Returns all methods that are applicable to actual argument types.

Parameters:

methods - list of all candidate methods

classes - the actual types of the arguments

Returns:

a list that contains only applicable methods (number of formal and actual arguments matches, and argument types are assignable to formal types through a method invocation conversion).

isApplicable

private static boolean isApplicable(java.lang.reflect.Method method,
                                    java.lang.Class[] classes)

Returns true if the supplied method is applicable to actual argument types.

Parameters:

method - the method to check

classes - possible argument types

Returns:

true if the arguments are applicable to the method.

isMethodInvocationConvertible

private static boolean isMethodInvocationConvertible(java.lang.Class formal,
                                                     java.lang.Class actual)

Determines whether a type represented by a class object is convertible to another type represented by a class object using a method invocation conversion, treating object types of primitive types as if they were primitive types (that is, a Boolean actual parameter type matches boolean primitive formal type). This behavior is because this method is used to determine applicable methods for an actual parameter list, and primitive types are represented by their object duals in reflective method calls.

Parameters:

formal - the formal parameter type to which the actual parameter type should be convertible

actual - the actual parameter type.

Returns:

true if either formal type is assignable from actual type, or formal is a primitive type and actual is its corresponding object type or an object type of a primitive type that can be converted to the formal type.

isStrictMethodInvocationConvertible

private static boolean isStrictMethodInvocationConvertible(java.lang.Class formal,
                                                           java.lang.Class actual)

Determines whether a type represented by a class object is convertible to another type represented by a class object using a method invocation conversion, without matching object and primitive types. This method is used to determine the more specific type when comparing signatures of methods.

Parameters:

formal - the formal parameter type to which the actual parameter type should be convertible

actual - the actual parameter type.

Returns:

true if either formal type is assignable from actual type, or formal and actual are both primitive types and actual can be subject to widening conversion to formal.