Scala example source code file (FrameNode.java)

This example Scala source code file (FrameNode.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

abstractinsnnode, arraylist, asm, frame, framenode, labelnode, list, map, methodvisitor, object, override

The FrameNode.java Scala example source code

/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package scala.tools.asm.tree;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

import scala.tools.asm.MethodVisitor;
import scala.tools.asm.Opcodes;

/**
 * A node that represents a stack map frame. These nodes are pseudo instruction
 * nodes in order to be inserted in an instruction list. In fact these nodes
 * must(*) be inserted <i>just before</i> any instruction node <b>i</b> that
 * follows an unconditionnal branch instruction such as GOTO or THROW, that is
 * the target of a jump instruction, or that starts an exception handler block.
 * The stack map frame types must describe the values of the local variables and
 * of the operand stack elements <i>just before</i> <b>i</b> is executed. <br>
 * <br>
 * (*) this is mandatory only for classes whose version is greater than or equal
 * to {@link Opcodes#V1_6 V1_6}.
 *
 * @author Eric Bruneton
 */
public class FrameNode extends AbstractInsnNode {

    /**
     * The type of this frame. Must be {@link Opcodes#F_NEW} for expanded
     * frames, or {@link Opcodes#F_FULL}, {@link Opcodes#F_APPEND},
     * {@link Opcodes#F_CHOP}, {@link Opcodes#F_SAME} or
     * {@link Opcodes#F_APPEND}, {@link Opcodes#F_SAME1} for compressed frames.
     */
    public int type;

    /**
     * The types of the local variables of this stack map frame. Elements of
     * this list can be Integer, String or LabelNode objects (for primitive,
     * reference and uninitialized types respectively - see
     * {@link MethodVisitor}).
     */
    public List<Object> local;

    /**
     * The types of the operand stack elements of this stack map frame. Elements
     * of this list can be Integer, String or LabelNode objects (for primitive,
     * reference and uninitialized types respectively - see
     * {@link MethodVisitor}).
     */
    public List<Object> stack;

    private FrameNode() {
        super(-1);
    }

    /**
     * Constructs a new {@link FrameNode}.
     *
     * @param type
     *            the type of this frame. Must be {@link Opcodes#F_NEW} for
     *            expanded frames, or {@link Opcodes#F_FULL},
     *            {@link Opcodes#F_APPEND}, {@link Opcodes#F_CHOP},
     *            {@link Opcodes#F_SAME} or {@link Opcodes#F_APPEND},
     *            {@link Opcodes#F_SAME1} for compressed frames.
     * @param nLocal
     *            number of local variables of this stack map frame.
     * @param local
     *            the types of the local variables of this stack map frame.
     *            Elements of this list can be Integer, String or LabelNode
     *            objects (for primitive, reference and uninitialized types
     *            respectively - see {@link MethodVisitor}).
     * @param nStack
     *            number of operand stack elements of this stack map frame.
     * @param stack
     *            the types of the operand stack elements of this stack map
     *            frame. Elements of this list can be Integer, String or
     *            LabelNode objects (for primitive, reference and uninitialized
     *            types respectively - see {@link MethodVisitor}).
     */
    public FrameNode(final int type, final int nLocal, final Object[] local,
            final int nStack, final Object[] stack) {
        super(-1);
        this.type = type;
        switch (type) {
        case Opcodes.F_NEW:
        case Opcodes.F_FULL:
            this.local = asList(nLocal, local);
            this.stack = asList(nStack, stack);
            break;
        case Opcodes.F_APPEND:
            this.local = asList(nLocal, local);
            break;
        case Opcodes.F_CHOP:
            this.local = Arrays.asList(new Object[nLocal]);
            break;
        case Opcodes.F_SAME:
            break;
        case Opcodes.F_SAME1:
            this.stack = asList(1, stack);
            break;
        }
    }

    @Override
    public int getType() {
        return FRAME;
    }

    /**
     * Makes the given visitor visit this stack map frame.
     *
     * @param mv
     *            a method visitor.
     */
    @Override
    public void accept(final MethodVisitor mv) {
        switch (type) {
        case Opcodes.F_NEW:
        case Opcodes.F_FULL:
            mv.visitFrame(type, local.size(), asArray(local), stack.size(),
                    asArray(stack));
            break;
        case Opcodes.F_APPEND:
            mv.visitFrame(type, local.size(), asArray(local), 0, null);
            break;
        case Opcodes.F_CHOP:
            mv.visitFrame(type, local.size(), null, 0, null);
            break;
        case Opcodes.F_SAME:
            mv.visitFrame(type, 0, null, 0, null);
            break;
        case Opcodes.F_SAME1:
            mv.visitFrame(type, 0, null, 1, asArray(stack));
            break;
        }
    }

    @Override
    public AbstractInsnNode clone(final Map<LabelNode, LabelNode> labels) {
        FrameNode clone = new FrameNode();
        clone.type = type;
        if (local != null) {
            clone.local = new ArrayList<Object>();
            for (int i = 0; i < local.size(); ++i) {
                Object l = local.get(i);
                if (l instanceof LabelNode) {
                    l = labels.get(l);
                }
                clone.local.add(l);
            }
        }
        if (stack != null) {
            clone.stack = new ArrayList<Object>();
            for (int i = 0; i < stack.size(); ++i) {
                Object s = stack.get(i);
                if (s instanceof LabelNode) {
                    s = labels.get(s);
                }
                clone.stack.add(s);
            }
        }
        return clone;
    }

    // ------------------------------------------------------------------------

    private static List<Object> asList(final int n, final Object[] o) {
        return Arrays.asList(o).subList(0, n);
    }

    private static Object[] asArray(final List<Object> l) {
        Object[] objs = new Object[l.size()];
        for (int i = 0; i < objs.length; ++i) {
            Object o = l.get(i);
            if (o instanceof LabelNode) {
                o = ((LabelNode) o).getLabel();
            }
            objs[i] = o;
        }
        return objs;
    }
}