fr.umlv.jmmf.matcher
Class PatternMatcher

java.lang.Object
  |
  +--fr.umlv.jmmf.matcher.PatternMatcher

public class PatternMatcher

extends java.lang.Object

This class ease the use of multi-polymorphism. A simple way to use it consist in subclassing the PatternMatcher class. An example on a tree recursive type :

public class Test extends PatternMatcher
{
  interface Tree {}
  static class Leaf implements Tree {
    Leaf(int value) { 
      this.value=value; 
    }
    int value; 
  }
  static class Node implements Tree {
    Node(Tree left,Tree right) { 
      this.left=left; this.right=right; 
    }
    Tree left,right;
  }

  public int sum(Node node)
  { return sum(left)+sum(right); }
  public int sum(Leaf leaf)
  { return value; }

  public int sum(Tree tree)
  { return ((Integer)match("sum",tree)).intValue(); }

  public static void main(String[] args) {
    Tree tree=new Node(new Node(new Leaf(1),new Leaf(3)),new Leaf(7));
    System.out.println("sum "+new Test().sum(tree));
  }
}

Version:

0.4

Author:

Remi Forax

Field Summary

protected java.lang.Object	bean
protected java.util.HashMap	multimethods

Constructor Summary

PatternMatcher()
create a pattern matcher component.

PatternMatcher(java.lang.Object bean)
create a pattern matcher component on a bean object.

Method Summary

java.lang.Object	match(java.lang.String name, java.lang.Object arg) lookup the best method in the multi-method named name and invoke it.
java.lang.Object	match(java.lang.String name, java.lang.Object[] args) lookup the best method in the multi-method named name and invoke it.
java.lang.Object	match(java.lang.String name, java.lang.Object[] args, java.lang.Class[] classes) lookup the best method in the multi-method named name and invoke it.

Methods inherited from class java.lang.Object

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

Field Detail

bean

protected java.lang.Object bean

multimethods

protected java.util.HashMap multimethods

Constructor Detail

PatternMatcher

public PatternMatcher()

create a pattern matcher component. Find all multi-methods in this component and store them.

PatternMatcher

public PatternMatcher(java.lang.Object bean)

create a pattern matcher component on a bean object. Find all multi-methods in the bean component and store them.

Method Detail

match

public java.lang.Object match(java.lang.String name,
                              java.lang.Object arg)

lookup the best method in the multi-method named name and invoke it.

Parameters:

name - name of the multi-method.

arg - first parameter of the multi-method.

Returns:

the result of a call of the best method of the multi-method. if the type of the result is a primitive type, the result is wrapped in the corresponding object (int -> Integer, etc...).

Throws:

NoMatchingMethodException - there is no method that match the parameter arguments.

MultipleMatchingMethodsException - there is no method that match the parameter arguments.

MatchingMethodInvocationException - throws by the target method invoked.

IllegalStateException - is method find isn't accessible, due to an internal error.

See Also:

match(String, Object[], Class[])

match

public java.lang.Object match(java.lang.String name,
                              java.lang.Object[] args)

lookup the best method in the multi-method named name and invoke it.

Parameters:

name - name of the multi-method.

args - parameters of the multi-method.

Returns:

the result of a call of the best method of the multi-method. if the type of the result is a primitive type, the result is wrapped in the corresponding object (int -> Integer, etc...).

Throws:

NoMatchingMethodException - there is no method that match the parameter arguments.

MultipleMatchingMethodsException - there is no method that match the parameter arguments.

MatchingMethodInvocationException - throws by the target method invoked.

IllegalStateException - is method find isn't accessible, due to an internal error.

See Also:

match(String, Object[], Class[])

match

public java.lang.Object match(java.lang.String name,
                              java.lang.Object[] args,
                              java.lang.Class[] classes)

lookup the best method in the multi-method named name and invoke it.

Parameters:

name - name of the multi-method.

args - parameters of the multi-method.

classes - type of the parameter.

Returns:

the result of a call of the best method of the multi-method. if the type of the result is a primitive type, the result is wrapped in the corresponding object (int -> Integer, etc...).

Throws:

NoMatchingMethodException - there is no method that match the parameter arguments.

MultipleMatchingMethodsException - there is no method that match the parameter arguments.

MatchingMethodInvocationException - throws by the target method invoked.

IllegalStateException - is method find isn't accessible, due to an internal error.