1 /*
   2  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.nashorn.internal.ir;
  27 
  28 /**
  29  * Interface implemented by AST nodes that either can occur as predecessors of a control flow join, or contain a control
  30  * flow join themselves. JoinPredecessor only provides a getter and setter for a {@link LocalVariableConversion}; the
  31  * semantics of control flow for a particular node implementing the interface are shared between
  32  * {@code LocalVariableTypesCalculator} that creates the conversions, and {@code CodeGenerator} that uses them.
  33  */
  34 public interface JoinPredecessor {
  35     /**
  36      * Set the local variable conversions needed to unify their types at a control flow join point.
  37      * @param lc the current lexical context
  38      * @param conversion the conversions.
  39      * @return this node or a different node representing the change.
  40      */
  41     public JoinPredecessor setLocalVariableConversion(LexicalContext lc, LocalVariableConversion conversion);
  42 
  43     /**
  44      * Returns the local variable conversions needed to unify their types at a control flow join point.
  45      * @return the local variable conversions needed to unify their types at a control flow join point. Can be null.
  46      * Can contain {@link LocalVariableConversion#isLive() dead conversions}.
  47      */
  48     public LocalVariableConversion getLocalVariableConversion();
  49 }