// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
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package org.objectweb.asm.tree;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.objectweb.asm.MethodVisitor;
import 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 Opcodes.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}. * * @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.
  • numLocal – 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).
  • numStack – 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 numLocal 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 numStack 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 numLocal, final Object[] local, final int numStack, final Object[] stack) { super(-1); this.type = type; switch (type) { case Opcodes.F_NEW: case Opcodes.F_FULL: this.local = Util.asArrayList(numLocal, local); this.stack = Util.asArrayList(numStack, stack); break; case Opcodes.F_APPEND: this.local = Util.asArrayList(numLocal, local); break; case Opcodes.F_CHOP: this.local = Util.asArrayList(numLocal); break; case Opcodes.F_SAME: break; case Opcodes.F_SAME1: this.stack = Util.asArrayList(1, stack); break; default: throw new IllegalArgumentException(); } } @Override public int getType() { return FRAME; } @Override public void accept(final MethodVisitor methodVisitor) { switch (type) { case Opcodes.F_NEW: case Opcodes.F_FULL: methodVisitor.visitFrame(type, local.size(), asArray(local), stack.size(), asArray(stack)); break; case Opcodes.F_APPEND: methodVisitor.visitFrame(type, local.size(), asArray(local), 0, null); break; case Opcodes.F_CHOP: methodVisitor.visitFrame(type, local.size(), null, 0, null); break; case Opcodes.F_SAME: methodVisitor.visitFrame(type, 0, null, 0, null); break; case Opcodes.F_SAME1: methodVisitor.visitFrame(type, 0, null, 1, asArray(stack)); break; default: throw new IllegalArgumentException(); } } @Override public AbstractInsnNode clone(final Map<LabelNode, LabelNode> clonedLabels) { FrameNode clone = new FrameNode(); clone.type = type; if (local != null) { clone.local = new ArrayList<>(); for (int i = 0, n = local.size(); i < n; ++i) { Object localElement = local.get(i); if (localElement instanceof LabelNode) { localElement = clonedLabels.get(localElement); } clone.local.add(localElement); } } if (stack != null) { clone.stack = new ArrayList<>(); for (int i = 0, n = stack.size(); i < n; ++i) { Object stackElement = stack.get(i); if (stackElement instanceof LabelNode) { stackElement = clonedLabels.get(stackElement); } clone.stack.add(stackElement); } } return clone; } private static Object[] asArray(final List<Object> list) { Object[] array = new Object[list.size()]; for (int i = 0, n = array.length; i < n; ++i) { Object o = list.get(i); if (o instanceof LabelNode) { o = ((LabelNode) o).getLabel(); } array[i] = o; } return array; } }