com.google.java.contract.core.agent.LineNumberingMethodAdapter.java Source code

Introduction

Here is the source code for com.google.java.contract.core.agent.LineNumberingMethodAdapter.java

Source

/*
 * Copyright 2010 Google Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */
package com.google.java.contract.core.agent;

import com.google.java.contract.Invariant;
import com.google.java.contract.Requires;
import com.google.java.contract.core.util.JavaUtils;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.commons.AdviceAdapter;

import java.util.List;

/**
 * A method adapter that adds {@link #lineNumber} to the beginning of
 * its instructions.
 *
 * @author nhat.minh.le@huoc.org (Nhat Minh L)
 */
@Invariant("lineNumbers == null || " + "ContractMethodSignatures.isLineNumberList(lineNumbers)")
abstract class LineNumberingMethodAdapter extends AdviceAdapter {
    /**
     * The line numbers to add to the method. This implementation always
     * sets this field to {@code null}. Child classes must override this
     * value before the call to {@link #onMethodEnter()} in order to get
     * useful results.
     */
    protected List<Long> lineNumbers;

    /**
     * Constructs a new LineNumberingMethodAdapter.
     *
     * @param mv the MethodVisitor this adapter delegates to
     * @param access the access flags of the method
     * @param name the name of the method
     * @param desc the descriptor of the method
     */
    @Requires({ "mv != null", "name != null", "desc != null" })
    public LineNumberingMethodAdapter(MethodVisitor mv, int access, String name, String desc) {
        super(Opcodes.ASM5, mv, access, name, desc);
        lineNumbers = null;
    }

    @Override
    protected void onMethodEnter() {
        if (lineNumbers != null && !lineNumbers.isEmpty()) {
            Long lineNumber = lineNumbers.get(0);
            if (lineNumber != null) {
                Label methodStart = new Label();
                mark(methodStart);
                mv.visitLineNumber(lineNumber.intValue(), methodStart);
            }
        }
    }

    @Override
    protected void onMethodExit(int opcode) {
    }

    @Override
    public void visitLineNumber(int line, Label start) {
        /* Ignore original line number information. */
    }

    @Override
    public void visitLocalVariable(String name, String desc, String signature, Label start, Label end, int index) {
        if (lineNumbers != null) {
            String prefix = JavaUtils.SUCCESS_VARIABLE_PREFIX + "$";
            if (name.startsWith(prefix)) {
                try {
                    int no = Integer.parseInt(name.substring(prefix.length()));
                    if (no < lineNumbers.size()) {
                        Long lineNumber = lineNumbers.get(no);
                        if (lineNumber != null) {
                            mv.visitLineNumber(lineNumber.intValue(), start);
                        }
                    }
                } catch (NumberFormatException e) {
                    /* Not the variable we are looking for. */
                }
            }
        }
        super.visitLocalVariable(name, desc, signature, start, end, index);
    }
}