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/*
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 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
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package jdk.internal.org.objectweb.asm.tree;

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

import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.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 just before any instruction node i 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 just before i is executed.

(*) this is mandatory only for classes whose version is greater than or equal to V1_6.
Author:Eric Bruneton
/** * 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 Opcodes.F_NEW for expanded frames, or Opcodes.F_FULL, Opcodes.F_APPEND, Opcodes.F_CHOP, Opcodes.F_SAME or Opcodes.F_APPEND, Opcodes.F_SAME1 for compressed frames.
/** * 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 MethodVisitor).
/** * 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 MethodVisitor).
/** * 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 FrameNode.
Params:
  • type – the type of this frame. Must be Opcodes.F_NEW for expanded frames, or Opcodes.F_FULL, Opcodes.F_APPEND, Opcodes.F_CHOP, Opcodes.F_SAME or Opcodes.F_APPEND, Opcodes.F_SAME1 for compressed frames.
  • nLocal – number of local variables of this stack map frame.
  • 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 MethodVisitor).
  • nStack – number of operand stack elements of this stack map frame.
  • 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 MethodVisitor).
/** * 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.
Params:
  • mv – a method visitor.
/** * 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; } }