~repos /gdx-studio

/*
 * 03/21/2010
 *
 * Copyright (C) 2010 Robert Futrell
 * robert_futrell at users.sourceforge.net
 * http://fifesoft.com/rsyntaxtextarea
 *
 * This library is distributed under a modified BSD license.  See the included
 * RSTALanguageSupport.License.txt file for details.
 */
package org.fife.rsta.ac.java.classreader;

import java.util.*;

import org.fife.rsta.ac.java.classreader.attributes.Code;


/**
 * A <code>Frame</code> contains information on a method being decompiled,
 * similar to a Frame as defined in 3.6 of the JVM spec.
 *
 * @author Robert Futrell
 * @version 1.0
 */
public class Frame {

  private Stack operandStack;
  private LocalVarInfo[] localVars;


  /**
   * Constructor.
   *
   * @param code The {@link Code} attribute being decompiled.
   */
  public Frame(Code code) {

    operandStack = new Stack();

    localVars = new LocalVarInfo[code.getMaxLocals()];
    int i = 0;
    MethodInfo mi = code.getMethodInfo();

    // Instance methods have an implicit first parameter of "this".
    if (!mi.isStatic()) {
      localVars[i++] = new LocalVarInfo("this", true);
    }

    // Name the passed-in local vars by their types. longs and doubles
    // take up two slots.
    String[] paramTypes = mi.getParameterTypes();
    for (int param_i=0; param_i<paramTypes.length; param_i++) {
      String type = paramTypes[param_i];
      if (type.indexOf('.')>-1) { // Class types.
        type = type.substring(type.lastIndexOf('.')+1);
      }
      String name = "localVar_" + type + "_" + param_i;
      localVars[i] = new LocalVarInfo(name, true);
      i++;
      if ("long".equals(type) || "double".equals(type)) {
        i++; // longs and doubles take up two slots.
      }
    }

    // NOTE: Other local vars will still be "null" here!  We need to
    // infer their types from their usage during disassembly/decompilation.
    System.out.println("NOTE: " + (localVars.length-i) + " unknown localVars slots");

  }


  public LocalVarInfo getLocalVar(int index, String defaultType) {
    LocalVarInfo var = localVars[index];
    if (var==null) {
      String name = "localVar_" + defaultType + "_" + index;
      var = new LocalVarInfo(name, false);
      localVars[index] = var;
    }
    else {
      var.alreadyDeclared = true; // May be redundant
    }
    return var;
  }


  public String pop() {
    return (String)operandStack.pop();
  }


  public void push(String value) {
    operandStack.push(value);
  }


  public static class LocalVarInfo {

    private String value;
    private boolean alreadyDeclared;

    public LocalVarInfo(String value, boolean alreadyDeclared) {
      this.value = value;
      this.alreadyDeclared = alreadyDeclared;
    }

    public String getValue() {
      return value;
    }

    public boolean isAlreadyDeclared() {
      return alreadyDeclared;
    }

  }


}