src/com/google/inject/util/LineNumbers.java

/**
 * Copyright (C) 2006 Google Inc.
 *
 * 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 com.google.inject.util;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.*;
import java.util.HashMap;
import java.util.Map;
import org.objectweb.asm.*;
import org.objectweb.asm.Type;

public class LineNumbers
{
    private final Class cls;
    private Map<String,Integer> lines = new HashMap<String,Integer>();
    private String source;

    /**
     * Reads line number information from the given class, if available.
     * @throws IllegalArgumentException if the bytecode for the class cannot be found
     */
    public LineNumbers(Class cls) throws IOException {
        this.cls = cls;
        InputStream in = cls.getResourceAsStream("/" + cls.getName().replace('.', '/') + ".class");
        if (in == null)
            throw new IllegalArgumentException("Cannot find bytecode for " + cls);
        new ClassReader(in).accept(new LineNumberReader(), 0);
    }

    /**
     * Get the source file name as read from the bytecode.
     * @return the source file name if available, or null
     */
    public String getSource() {
        return source;
    }

    /**
     * Get the line number associated with the given member.
     * @param member a field, constructor, or method belonging to the class used during construction
     * @return the wrapped line number, or null if not available
     * @throws IllegalArgumentException if the member does not belong to the class used during construction
     */
    public Integer getLineNumber(Member member) {
        if (!cls.equals(member.getDeclaringClass()))
            throw new IllegalArgumentException("Member " + member + " belongs to " + member.getDeclaringClass() + ", not " + cls);
        return lines.get(getKey(member));
    }

    private static String getKey(Member member) {
        if (member instanceof Field) {
            return member.getName();
        } else if (member instanceof Method) {
            return member.getName() + Type.getMethodDescriptor((Method)member);
        } else {
            return "<init>" + Type.getConstructorDescriptor((Constructor)member);
        }
    }

    private class LineNumberReader implements ClassVisitor, MethodVisitor
    {
        private int line = -1;
        private String pendingMethod;
        private String name;
        private boolean inStatic;

        public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
            this.name = name;
        }

        public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
            if ((access & Opcodes.ACC_PRIVATE) != 0)
                return null;
            inStatic = (access & Opcodes.ACC_STATIC) != 0;
            pendingMethod = name + desc;
            line = -1;
            return this;
        }

        public void visitSource(String source, String debug) {
            LineNumbers.this.source = source;
        }

        public void visitLineNumber(int line, Label start) {
            this.line = line;
            if (pendingMethod != null) {
                lines.put(pendingMethod, line);
                pendingMethod = null;
            }
        }

        public void visitFieldInsn(int opcode, String owner, String name, String desc) {
            if (opcode == Opcodes.PUTFIELD && this.name.equals(owner) && !lines.containsKey(name) && line != -1)
                lines.put(name, line);
        }

        public void visitEnd() { }
        public void visitInnerClass(String name, String outerName, String innerName, int access) { }
        public void visitOuterClass(String owner, String name, String desc) { }
        public void visitAttribute(Attribute attr) { }

        public FieldVisitor visitField(int access, String name, String desc, String signature, Object value) { return null; }
        public AnnotationVisitor visitAnnotation(String desc, boolean visible) { return null; }
        public AnnotationVisitor visitAnnotationDefault() { return null; }
        public AnnotationVisitor visitParameterAnnotation(int parameter, String desc, boolean visible) { return null; }

        public void visitCode() { }
        public void visitFrame(int type, int nLocal, Object[] local, int nStack, Object[] stack) { }
        public void visitIincInsn(int var, int increment) { }
        public void visitInsn(int opcode) { }
        public void visitIntInsn(int opcode, int operand) { }
        public void visitJumpInsn(int opcode, Label label) { }
        public void visitLabel(Label label) { }
        public void visitLdcInsn(Object cst) { }
        public void visitLocalVariable(String name, String desc, String signature, Label start, Label end, int index) { }
        public void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels) { }
        public void visitMaxs(int maxStack, int maxLocals) { }
        public void visitMethodInsn(int opcode, String owner, String name, String desc) { }
        public void visitMultiANewArrayInsn(String desc, int dims) { }
        public void visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels) { }
        public void visitTryCatchBlock(Label start, Label end, Label handler, String type) { }
        public void visitTypeInsn(int opcode, String desc) { }
        public void visitVarInsn(int opcode, int var) { }
    }
}