Scala example source code file (JMethod.java)

This example Scala source code file (JMethod.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

io, iterator, jattribute, jclass, jcode, jcodeiterator, jlocalvariable, jlocalvariable, jmethod, jtype, jtype, string, string, stringbuffer, stringbuffer, util

The Scala JMethod.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.IOException;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

/**
 * Representation of a Java method.
 *
 * @author Michel Schinz
 * @version 1.0
 */

public class JMethod extends JFieldOrMethod {
    public final static String CLASS_CONSTRUCTOR_NAME = "<clinit>";
    public final static String INSTANCE_CONSTRUCTOR_NAME = "<init>";

    protected /*final*/ JCode code;
    protected final String[] argNames;

    protected final LinkedList/*<JLocalVariable>*/ localVariables =
        new LinkedList();
    protected int localVariableIndex = 0;


    protected JMethod(FJBGContext context,
                      JClass owner,
                      int accessFlags,
                      String name,
                      JType returnType,
                      JType[] argTypes,
                      String[] argNames) {
        super(context,
              owner,
              accessFlags,
              name,
              new JMethodType(returnType, argTypes));
        this.argNames = argNames;

        assert argTypes.length == argNames.length;

        if (isAbstract() || isNative()) {
            code = null;
        } else {
            code = context.JCode(owner, this);
            addAttribute(context.JCodeAttribute(owner, this));

            if (!isStatic())
                addNewLocalVariable(owner.getType(), "this");

            for (int i = 0; i < argTypes.length; ++i)
                addNewLocalVariable(argTypes[i], argNames[i]);
        }
    }

    protected JMethod(FJBGContext context,
                      JClass owner,
                      DataInputStream stream)
        throws IOException {
        super(context, owner, stream);

        assert isAbstract() || isNative() || code != null;

        int n = 0;
        if (code != null) {
            for (Iterator it = code.getAttributes().iterator(); it.hasNext(); ) {
                JAttribute attr = (JAttribute)it.next();
                if (attr instanceof JLocalVariableTableAttribute)
                   n = ((JLocalVariableTableAttribute)attr).getMaxLocals();
            }
        }
        this.localVariableIndex = n;


        JType[] argTypes = ((JMethodType)getType()).getArgumentTypes();
        argNames = new String[argTypes.length]; // TODO get from attribute
        for (int i = 0; i < argNames.length; ++i)
            argNames[i] = "v"+i;
    }

    public void freeze() throws JCode.OffsetTooBigException {
        if (code != null) code.freeze();
        super.freeze();
    }

    public JType getReturnType() {
        return ((JMethodType)type).getReturnType();
    }

    public JType[] getArgumentTypes() {
        return ((JMethodType)type).getArgumentTypes();
    }

    public int getArgsSize() {
        int size = ((JMethodType)type).getArgsSize();
        if (!isStatic()) size += 1;  // for this
        return size;
    }

    public String[] getArgumentNames() {
        return argNames;
    }

    public JCode getCode() {
        assert !isAbstract();
        return code;
    }

    // Invoked by the JCode constructor
    protected void setCode(JCode code) {
        assert null == this.code;
        this.code = code;
    }

    public JCodeIterator codeIterator() {
        return new JCodeIterator(code);
    }

    // Local variables
    // FIXME : find a better management method for local variables
    public JLocalVariable addNewLocalVariable(JType type, String name) {
        assert !frozen;
        JLocalVariable var =
            context.JLocalVariable(this, type, name, localVariableIndex);
        localVariableIndex += type.getSize();
        localVariables.add(var);
        return var;
    }

    public JLocalVariable getLocalVariable(int index) {
        for (int i = 0; i < localVariables.size(); i++) {
            if (((JLocalVariable)localVariables.get(i)).index == index)
                return (JLocalVariable)localVariables.get(i);
        }
        return null;
    }
 
    public JLocalVariable[] getLocalVariables() {
        return (JLocalVariable[])localVariables
            .toArray(new JLocalVariable[localVariables.size()]);
    }


    public int getMaxLocals() {
        return localVariableIndex;
    }

    // Follows javap output format for methods.
    /*@Override*/ public String toString() {
        StringBuffer buf = new StringBuffer(flagsToString());
        String name = getName();
        if (CLASS_CONSTRUCTOR_NAME.equals(name))
            buf.append("{}");
        else {
            if (INSTANCE_CONSTRUCTOR_NAME.equals(name))
                name = getOwner().getName();
            else {
                buf.append(toExternalName(getReturnType()));
                buf.append(" ");
            }
            buf.append(toExternalName(name));
            buf.append("(");
            JType[] ts = getArgumentTypes();
            for (int i = 0; i < ts.length; ++i) {
                if (i > 0) buf.append(", ");
                buf.append(toExternalName(ts[i]));
            }
            buf.append(")");
        }
        buf.append(";\n");
        Iterator it = attributes.iterator();
        while(it.hasNext()) {
            JAttribute attr = (JAttribute)it.next();
            buf.append(attr);
        }
        return buf.toString();
    }

    private String flagsToString() {
        StringBuffer buf = new StringBuffer();
        if (isPublic()) buf.append("public ");
        else if (isProtected()) buf.append("protected ");
        else if (isPrivate()) buf.append("private ");
        if (isBridge()) buf.append("<bridge> ");
        if (hasVarargs()) buf.append("<varargs> ");
        if (isStatic()) buf.append("static ");
        else if (isNative()) buf.append("native ");
        if (isAbstract()) buf.append("abstract ");
        else if (isFinal()) buf.append("final ");
        return buf.toString();
    }
}