/* * 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; }