UneededBoxingRemoverMethodAdapter.java

/*
 * Copyright 2009-2010 MBTE Sweden AB.
 *
 * 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.mbte.groovypp.compiler.asm;

import org.codehaus.groovy.classgen.BytecodeHelper;
import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.mbte.groovypp.runtime.DefaultGroovyPPMethods;

public class UneededBoxingRemoverMethodAdapter extends LdcImproverMethodAdapter implements Opcodes {
    private String boxingDesc = null;
    private static final String DTT  = BytecodeHelper.getClassInternalName(DefaultTypeTransformation.class.getName());
    private static final String DGPP = BytecodeHelper.getClassInternalName(DefaultGroovyPPMethods.class.getName());

    public UneededBoxingRemoverMethodAdapter(MethodVisitor mv) {
        super(mv);
    }

    private void dropBoxing () {
        if (boxingDesc != null) {
            super.visitMethodInsn(Opcodes.INVOKESTATIC, DGPP, "box", boxingDesc);
            boxingDesc = null;
        }
    }

    public void visitInsn(int opcode) {
        if (boxingDesc != null && (opcode == POP || opcode == POP2)) {
            boxingDesc = null;
        }

        dropBoxing ();
        super.visitInsn(opcode);
    }

    public void visitIntInsn(int opcode, int operand) {
        dropBoxing ();
        super.visitIntInsn(opcode, operand);
    }

    public void visitVarInsn(int opcode, int var) {
        dropBoxing ();
        super.visitVarInsn(opcode, var);
    }

    public void visitTypeInsn(int opcode, String desc) {
        if (opcode == CHECKCAST && desc.equals("java/lang/Object"))
           return;

        dropBoxing ();
        super.visitTypeInsn(opcode, desc);
    }

    public void visitFieldInsn(int opcode, String owner, String name, String desc) {
        dropBoxing ();
        super.visitFieldInsn(opcode, owner, name, desc);
    }

    public void visitMethodInsn(int opcode, String owner, String name, String desc) {
        if (boxing(opcode,owner,name)) {
            dropBoxing();
            boxingDesc = desc;
        }
        else {
          if (unboxing(opcode, owner, name)) {
              if (boxingDesc != null) {
                String type = name.substring(0, name.indexOf("Unbox"));
                type = ClassHelper.getWrapper(ClassHelper.make(type)).getNameWithoutPackage();
                String boxingName = boxingDesc.substring(boxingDesc.lastIndexOf('/')+1, boxingDesc.length()-1);
                if (boxingName.equals(type)) {
                    boxingDesc = null;
                }
                else {
                    dropBoxing();
                    super.visitMethodInsn(opcode, owner, name, desc);
                }
              }
              else
                super.visitMethodInsn(opcode, owner, name, desc);
          }
          else {
            dropBoxing();
            super.visitMethodInsn(opcode, owner, name, desc);
          }
        }
    }

    private boolean boxing(int opcode, String owner, String name) {
        return opcode == Opcodes.INVOKESTATIC && owner.equals(DGPP) && name.equals("box");
    }

    private boolean unboxing(int opcode, String owner, String name) {
        return opcode == Opcodes.INVOKESTATIC && owner.equals(DTT) && name.endsWith("Unbox");
    }

    public void visitJumpInsn(int opcode, Label label) {
        dropBoxing ();
        super.visitJumpInsn(opcode, label);
    }

    public void visitLabel(Label label) {
        dropBoxing ();
        super.visitLabel(label);
    }

    public void visitLdcInsn(Object cst) {
        dropBoxing ();
        super.visitLdcInsn(cst);
    }

    public void visitIincInsn(int var, int increment) {
        dropBoxing ();
        super.visitIincInsn(var, increment);
    }

    public void visitTableSwitchInsn(int min, int max, Label dflt, Label labels[]) {
        dropBoxing ();
        super.visitTableSwitchInsn(min, max, dflt, labels);
    }

    public void visitLookupSwitchInsn(Label dflt, int keys[], Label labels[]) {
        dropBoxing ();
        super.visitLookupSwitchInsn(dflt, keys, labels);
    }

    public void visitMultiANewArrayInsn(String desc, int dims) {
        dropBoxing ();
        super.visitMultiANewArrayInsn(desc, dims);
    }

    public void visitTryCatchBlock(Label start, Label end, Label handler, String type) {
        dropBoxing ();
        super.visitTryCatchBlock(start, end, handler, type);
    }
}