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/*
* MultimethodClass.oj
*
* comments here.
*
* @author Michiaki Tatsubori
* @version %VERSION% %DATE%
* @see java.lang.Object
*
* COPYRIGHT 1999 by Michiaki Tatsubori, ALL RIGHTS RESERVED.
*/
package examples.multimethod;
import java.util.*;
import openjava.mop.*;
import openjava.ptree.*;
/**
* The class <code>MultimethodClass</code>
* <p>
* For example
* <pre>
* </pre>
* <p>
*
* @author Michiaki Tatsubori
* @version 1.0
* @since $Id: MultimethodClass.java,v 1.2 2003/02/19 02:55:01 tatsubori Exp $
* @see java.lang.Object
*/
public class MultimethodClass extends OJClass
{
private static final String MULTIFORM = "multiform";
private static final String RUNTIME_EXCEPTION
= "examples.multimethod.NoAddaptableMethodException";
public void translateDefinition() throws MOPException {
Hashtable table = new Hashtable();
OJMethod[] m = getDeclaredMethods();
for (int i = 0; i < m.length; ++i) {
if (! m[i].getModifiers().has( MULTIFORM )) continue;
ParameterSetTree set
= (ParameterSetTree) table.get( makeHashkey( m[i] ) );
if (set != null) {
set.add( m[i] );
} else {
set = new ParameterSetTree( m[i].getParameterTypes(), m[i] );
}
table.put( makeHashkey( m[i] ), set );
}
Enumeration ite = table.elements();
while (ite.hasMoreElements()) {
ParameterSetTree set = (ParameterSetTree) ite.nextElement();
modifyToBeGeneric( set );
System.out.println( set );
}
}
private void modifyToBeGeneric( ParameterSetTree set )
throws MOPException
{
if (! set.hasChildren()) return;
OJMethod method = set.getValue();
if (method == null) addMethod( (method = genSelector( set )) );
StatementList result = new StatementList();
ParameterSetTree[] children = set.getChildren();
for (int i = 0; i < children.length; ++i) {
Expression cond
= makeCond( method, children[i].getParameterTypes() );
StatementList ifbody
= makeQualifiedCall( method, children[i].getParameterTypes() );
result.add( new IfStatement( cond, ifbody ) );
modifyToBeGeneric( children[i] );
}
result.addAll( method.getBody() );
method.addExceptionType( OJClass.forName( RUNTIME_EXCEPTION ) );
method.setBody( result );
}
/* generates a method only for testing params to invoke another */
private OJMethod genSelector( ParameterSetTree set )
throws MOPException
{
/* representer of other features such as throwing exceptions */
OJMethod rep = pickupOne( set );
return new OJMethod(
this, rep.getModifiers(), rep.getReturnType(), rep.getName(),
set.getParameterTypes(), rep.getExceptionTypes(),
makeStatementList( "throw new " + RUNTIME_EXCEPTION + "();" )
);
}
private static Expression makeCond( OJMethod holder, OJClass[] ptypes )
throws MOPException
{
String[] params = holder.getParameters();
StringBuffer strbuf = new StringBuffer();
for (int i = 0; i < ptypes.length; ++i) {
if (i != 0) strbuf.append( " && " );
strbuf.append( "(" );
strbuf.append( params[i] );
strbuf.append( " instanceof " );
strbuf.append( ptypes[i].getName() );
strbuf.append( ")" );
}
return makeExpression( holder.getEnvironment(), strbuf.toString() );
}
private static StatementList
makeQualifiedCall( OJMethod holder, OJClass[] ptypes )
throws MOPException
{
String[] params = holder.getParameters();
StringBuffer strbuf = new StringBuffer();
strbuf.append( "this." ).append( holder.getName() ).append( "( " );
for (int i = 0; i < ptypes.length; ++i) {
if (i != 0) strbuf.append( ", " );
strbuf.append( "(" ).append( ptypes[i].getName() ).append( ") " );
strbuf.append( params[i] );
}
strbuf.append( " )" );
Expression mtdcall
= makeExpression( holder.getEnvironment(), strbuf.toString() );
StatementList result = new StatementList();
if (holder.getReturnType() == OJSystem.VOID) {
result.add( new ExpressionStatement( mtdcall ) );
result.add( new ReturnStatement() );
} else {
result.add( new ReturnStatement( mtdcall ) );
}
return result;
}
private static String makeHashkey( OJMethod method ) {
return method.getReturnType().getName() + "%" + method.getName() +
"%" + method.getParameterTypes().length;
}
private static OJMethod pickupOne( ParameterSetTree set ) {
while (set.getChildren().length != 0) set = set.getChildren()[0];
return set.getValue();
}
/* syntax extension */
public static boolean isRegisteredModifier( String keyword ) {
return keyword.equals( MULTIFORM );
}
/* constructors */
public MultimethodClass( Environment outer_env, OJClass declarer,
ClassDeclaration ptree )
{
super( outer_env, declarer, ptree );
}
public MultimethodClass( Class javaclass, MetaInfo minfo ) {
super( javaclass, minfo );
}
}
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