Scala example source code file (JLocalVariableTableAttribute.java)

This example Scala source code file (JLocalVariableTableAttribute.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

entry, entry, io, ioexception, ioexception, iterator, jclass, jconstantpool, jlocalvariabletableattribute, jlocalvariabletableattribute, localvariabletable, string, string, stringbuffer, utf8entry, util

The Scala JLocalVariableTableAttribute.java source code

/* FJBG -- Fast Java Bytecode Generator
 * Copyright 2002-2011 LAMP/EPFL
 * @author  Michel Schinz
 */

package ch.epfl.lamp.fjbg;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.LinkedList;

import ch.epfl.lamp.fjbg.JConstantPool.*;

/**
 * Attribute storing local variables.
 *
 * @author Stephane Micheloud
 * @version 1.0
 */

public class JLocalVariableTableAttribute extends JAttribute {
    /** Constant pool of the current classfile. */
    private JConstantPool pool;

    protected final LinkedList/*<Entry>*/ entries = new LinkedList();
    protected int localVariableIndex = 0;

    public JLocalVariableTableAttribute(FJBGContext context,
                                        JClass clazz,
                                        JCode code) {
        super(context, clazz);
        this.pool = clazz.pool;

        assert code.getOwner().getOwner() == clazz;
    }

    public JLocalVariableTableAttribute(FJBGContext context,
                                        JClass clazz,
                                        Object owner,
                                        String name,
                                        int size,
                                        DataInputStream stream)
        throws IOException {
        super(context, clazz, name);
        this.pool = clazz.pool;

        int count = stream.readShort();
        for (int i = 0; i < count; ++i) {
            int startPc = stream.readShort();
            int length = stream.readShort();
            int nameIndex = stream.readShort();
            int descIndex = stream.readShort();
            int index = stream.readShort();
            addEntry(startPc, length, nameIndex, descIndex, index);
        }

        assert name.equals(getName());
    }

    public void addEntry(int startPc, int length, int nameIndex,
                         int descIndex, int index) {
        entries.add(new Entry(startPc, length, nameIndex, descIndex, index));
    }

    public void addEntry(int startPc, int length, String name,
                         String desc, int index) {
        Entry e = new Entry(startPc, length, name, desc, index);
        Entry other = getEntry(index);
        if (other != null) {
            assert other.nameIndex == e.nameIndex && other.descIndex == e.descIndex
                : e + " already declared as " + other;
        } else
            entries.add(e);
    }

    public void addEntry(int startPc, int length, String name, String desc) {
        entries.add(new Entry(startPc, length, name, desc));
    }

    public String getName() { return "LocalVariableTable"; }

    // Follows javap output format for LocalVariableTable attribute.
    /*@Override*/ public String toString() {
        StringBuffer buf = new StringBuffer("  LocalVariableTable: ");
        buf.append("\n   Start  Length  Slot  Name   Signature");
        for (Iterator it = entries.iterator(); it.hasNext(); ) {
            buf.append("\n   ");
            Entry e = (Entry)it.next();
            Utf8Entry name = (Utf8Entry)pool.lookupEntry(e.nameIndex);
            Utf8Entry sig = (Utf8Entry)pool.lookupEntry(e.descIndex);
            buf.append(e.startPc);
            buf.append("      ");
            buf.append(e.length);
            buf.append("      ");
            buf.append(e.index);
            buf.append("    ");
            buf.append(name.getValue());
            buf.append("       ");
            buf.append(sig.getValue());
        }
        buf.append("\n");
        return buf.toString();
    }

    public int getMaxLocals() {
        return localVariableIndex;
    }

    public int getSize() {
        return 2 + entries.size() * 10;
    }

    protected void writeContentsTo(DataOutputStream stream) throws IOException {
        stream.writeShort(entries.size());
        for (Iterator it = entries.iterator(); it.hasNext(); ) {
            Entry e = (Entry)it.next();
            stream.writeShort(e.startPc);
            stream.writeShort(e.length);
            stream.writeShort(e.nameIndex);
            stream.writeShort(e.descIndex);
            stream.writeShort(e.index);
        }
    }

    private Entry getEntry(int index) {
        Entry e = null;
        try { e = (Entry)entries.get(index); } catch (Exception ex) {}
        return e;
    }

    private class Entry {
        int startPc;
        int length;
        int nameIndex;
        int descIndex;
        int index;

        public Entry(int startPc, int length, int nameIndex, int descIndex, int index) {
            this.startPc = startPc;
            this.length = length;
            this.nameIndex = nameIndex;
            this.descIndex = descIndex;
            this.index = index;
            localVariableIndex += length;
        }

        public Entry(int startPc, int length, String name, String desc, int index) {
            this(startPc, length, pool.addUtf8(name), pool.addUtf8(desc), index);
        }

        public Entry(int startPc, int length, String name, String desc) {
            this(startPc, length, pool.addUtf8(name), pool.addUtf8(desc), localVariableIndex);
        }

        /** Two entries are equal if they refer to the same index.
         */
        public boolean equals(Object other) {
            if (other instanceof Entry) {
                Entry otherEntry = (Entry) other;
                return otherEntry.index == this.index;
            }
            return false;
        }
    }
}