/*
* Copyright 2004-2010 Brian S O'Neill
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.cojen.classfile;
/**
* A label is used to manipulate a branch instruction's branch location. A
* label has a location address. Branch instructions have origin addresses,
* which contain the address of the opcode that performs the conditional or
* unconditional branch.
*
* <p>Labels are generated by factory methods in the CodeBuilder class.
* If a label has any origin addresses, its location address must be set by
* the time the CodeBuilder's class file is output.
*
* @author Brian S O'Neill
* @see CodeBuilder
*/
public interface Label extends Location {
/**
* Sets the location of a label to be at the current postion in the
* code being generated.
*
* @return the Label itself.
*/
Label setLocation();
/**
* Returns -1 if the location isn't yet fully resolved.
*
* @exception IllegalStateException when the location is unknown because
* the setLocation method was never called.
*/
int getLocation() throws IllegalStateException;
}