ContextClassReader.java :  » Scripting » InstantJ » instantj » compile » pizza » Java Open Source

/**
 * InstantJ
 * 
 * Copyright (C) 2002 Nils Meier
 * Additional changes (C) 2002 Andy Thomas 
 * 
 * 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.
 * 
 */
package instantj.compile.pizza;

import instantj.compile.CompilationFailedException;
import instantj.compile.CompiledClass;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.util.Map;

import net.sf.pizzacompiler.compiler.ClassReader;

/**
 * A patched ClassReader that reads resouces from
 * classpath (e.g. class file). This allows to compile
 * classes that reference class-bytes in the current
 * context-classloader but not available through the
 * global classpath
 */
/*package*/  class ContextClassReader extends ClassReader {

  /** the context classloader */
  private ClassLoader cl;
  
  /** the library */
  private Map lib;

  /**
   * Constructor
   */
  /*package*/ ContextClassReader(ClassLoader classloader, Map library) throws CompilationFailedException {
    
    // remember
    cl = classloader;
    lib = library;

  // 20030305 o.k. at this point I don't understand how class-bytes that
  // are not in the classpath can be fed to Pizza. find() seems to be 
  // called for well known java.lang. classes only and classes that I want
  // to load dynamically from classloader/library don't get triggered.
  // Tried to play with loadClass() but am no optimistic :(
  // Won't support library at this point ...
  if (library!=null&&!library.isEmpty()) 
    throw new CompilationFailedException("Pizza integration doesn't support library");
    
//    // publish libary names
//    try {
//      Iterator it = library.getAll().iterator();
//      while (it.hasNext()) {
//        CompiledClass cc = (CompiledClass)it.next();
//        loadClass(Name.fromString(cc.getName()));
//      }
//    } catch (IOException e) {
//      e.printStackTrace();
//    }

    // done
  }
  
//  /**
//   * @see net.sf.pizzacompiler.compiler.ClassReader#loadClass(net.sf.pizzacompiler.compiler.Name)
//   */
//  public ClassSymbol loadClass(Name arg0) throws IOException {
//    System.out.println("Load "+arg0);
//    return super.loadClass(arg0);
//  }

  
  /**
   * Override to find class-bytes in local classpath if available
   * @see instantj.compile.pizza.PizzaSourceCompiler#find(java.lang.String)
   */
  protected InputStream find(String name) {
    
    // patch path
    String s = name.replace('\\','/');
    
    // try to load from classloader
    InputStream result = cl.getResourceAsStream(s);
    if (result!=null) return result;
    
    // Check if the library is sufficient
    if (s.endsWith(".class")) {
      s = s.substring(0, s.lastIndexOf(".class"));
      CompiledClass cc = (CompiledClass)lib.get(s);
      if (cc!=null) return new ByteArrayInputStream(cc.getByteCode());
    }
    
    // super might do
    return super.find(name);
  }

} //InstantClassReader