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Java example source code file (InstructionFactory.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

arithmeticinstruction, arraytype, getstatic, instructionfactory, instructionlist, invalid, methodobject, oops, push, runtimeexception, stackinstruction, string, type

The InstructionFactory.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
package com.sun.org.apache.bcel.internal.generic;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
import com.sun.org.apache.bcel.internal.Constants;

/**
 * Instances of this class may be used, e.g., to generate typed
 * versions of instructions. Its main purpose is to be used as the
 * byte code generating backend of a compiler. You can subclass it to
 * add your own create methods.
 *
 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm
 * @see Constants
 */
public class InstructionFactory
  implements InstructionConstants, java.io.Serializable
{
  protected ClassGen        cg;
  protected ConstantPoolGen cp;

  public InstructionFactory(ClassGen cg, ConstantPoolGen cp) {
    this.cg = cg;
    this.cp = cp;
  }

  /** Initialize with ClassGen object
   */
  public InstructionFactory(ClassGen cg) {
    this(cg, cg.getConstantPool());
  }

  /** Initialize just with ConstantPoolGen object
   */
  public InstructionFactory(ConstantPoolGen cp) {
    this(null, cp);
  }

  /** Create an invoke instruction.
   *
   * @param class_name name of the called class
   * @param name name of the called method
   * @param ret_type return type of method
   * @param arg_types argument types of method
   * @param kind how to invoke, i.e., INVOKEINTERFACE, INVOKESTATIC, INVOKEVIRTUAL,
   * or INVOKESPECIAL
   * @see Constants
   */
  public InvokeInstruction createInvoke(String class_name, String name, Type ret_type,
                                        Type[] arg_types, short kind) {
    int    index;
    int    nargs      = 0;
    String signature  = Type.getMethodSignature(ret_type, arg_types);

    for(int i=0; i < arg_types.length; i++) // Count size of arguments
      nargs += arg_types[i].getSize();

    if(kind == Constants.INVOKEINTERFACE)
      index = cp.addInterfaceMethodref(class_name, name, signature);
    else
      index = cp.addMethodref(class_name, name, signature);

    switch(kind) {
    case Constants.INVOKESPECIAL:   return new INVOKESPECIAL(index);
    case Constants.INVOKEVIRTUAL:   return new INVOKEVIRTUAL(index);
    case Constants.INVOKESTATIC:    return new INVOKESTATIC(index);
    case Constants.INVOKEINTERFACE: return new INVOKEINTERFACE(index, nargs + 1);
    default:
      throw new RuntimeException("Oops: Unknown invoke kind:" + kind);
    }
  }

  /** Create a call to the most popular System.out.println() method.
   *
   * @param s the string to print
   */
  public InstructionList createPrintln(String s) {
    InstructionList il      = new InstructionList();
    int             out     = cp.addFieldref("java.lang.System", "out",
                                             "Ljava/io/PrintStream;");
    int             println = cp.addMethodref("java.io.PrintStream", "println",
                                              "(Ljava/lang/String;)V");

    il.append(new GETSTATIC(out));
    il.append(new PUSH(cp, s));
    il.append(new INVOKEVIRTUAL(println));

    return il;
  }

  /** Uses PUSH to push a constant value onto the stack.
   * @param value must be of type Number, Boolean, Character or String
   */
  public Instruction createConstant(Object value) {
    PUSH push;

    if(value instanceof Number)
      push = new PUSH(cp, (Number)value);
    else if(value instanceof String)
      push = new PUSH(cp, (String)value);
    else if(value instanceof Boolean)
      push = new PUSH(cp, (Boolean)value);
    else if(value instanceof Character)
      push = new PUSH(cp, (Character)value);
    else
      throw new ClassGenException("Illegal type: " + value.getClass());

    return push.getInstruction();
  }

  private static class MethodObject {
    Type[]   arg_types;
    Type     result_type;
    String[] arg_names;
    String   class_name;
    String   name;
    int      access;

    MethodObject(String c, String n, Type r, Type[] a, int acc) {
      class_name  = c;
      name        = n;
      result_type = r;
      arg_types   = a;
      access      = acc;
    }
  }

  private InvokeInstruction createInvoke(MethodObject m, short kind) {
    return createInvoke(m.class_name, m.name, m.result_type, m.arg_types, kind);
  }

  private static MethodObject[] append_mos = {
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER,
                     new Type[] { Type.STRING }, Constants.ACC_PUBLIC),
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER,
                     new Type[] { Type.OBJECT }, Constants.ACC_PUBLIC),
    null, null, // indices 2, 3
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER,
                     new Type[] { Type.BOOLEAN }, Constants.ACC_PUBLIC),
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER,
                     new Type[] { Type.CHAR }, Constants.ACC_PUBLIC),
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER,
                     new Type[] { Type.FLOAT }, Constants.ACC_PUBLIC),
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER,
                     new Type[] { Type.DOUBLE }, Constants.ACC_PUBLIC),
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER,
                     new Type[] { Type.INT }, Constants.ACC_PUBLIC),
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER, // No append(byte)
                     new Type[] { Type.INT }, Constants.ACC_PUBLIC),
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER, // No append(short)
                     new Type[] { Type.INT }, Constants.ACC_PUBLIC),
    new MethodObject("java.lang.StringBuffer", "append", Type.STRINGBUFFER,
                     new Type[] { Type.LONG }, Constants.ACC_PUBLIC)
  };

  private static final boolean isString(Type type) {
    return ((type instanceof ObjectType) &&
            ((ObjectType)type).getClassName().equals("java.lang.String"));
  }

  public Instruction createAppend(Type type) {
    byte t = type.getType();

    if(isString(type))
      return createInvoke(append_mos[0], Constants.INVOKEVIRTUAL);

    switch(t) {
    case Constants.T_BOOLEAN:
    case Constants.T_CHAR:
    case Constants.T_FLOAT:
    case Constants.T_DOUBLE:
    case Constants.T_BYTE:
    case Constants.T_SHORT:
    case Constants.T_INT:
    case Constants.T_LONG
      :   return createInvoke(append_mos[t], Constants.INVOKEVIRTUAL);
    case Constants.T_ARRAY:
    case Constants.T_OBJECT:
      return createInvoke(append_mos[1], Constants.INVOKEVIRTUAL);
    default:
      throw new RuntimeException("Oops: No append for this type? " + type);
    }
  }

  /** Create a field instruction.
   *
   * @param class_name name of the accessed class
   * @param name name of the referenced field
   * @param type  type of field
   * @param kind how to access, i.e., GETFIELD, PUTFIELD, GETSTATIC, PUTSTATIC
   * @see Constants
   */
  public FieldInstruction createFieldAccess(String class_name, String name, Type type, short kind) {
    int    index;
    String signature  = type.getSignature();

    index = cp.addFieldref(class_name, name, signature);

    switch(kind) {
    case Constants.GETFIELD:  return new GETFIELD(index);
    case Constants.PUTFIELD:  return new PUTFIELD(index);
    case Constants.GETSTATIC: return new GETSTATIC(index);
    case Constants.PUTSTATIC: return new PUTSTATIC(index);

    default:
      throw new RuntimeException("Oops: Unknown getfield kind:" + kind);
    }
  }

  /** Create reference to `this'
   */
  public static Instruction createThis() {
    return new ALOAD(0);
  }

  /** Create typed return
   */
  public static ReturnInstruction createReturn(Type type) {
    switch(type.getType()) {
    case Constants.T_ARRAY:
    case Constants.T_OBJECT:  return ARETURN;
    case Constants.T_INT:
    case Constants.T_SHORT:
    case Constants.T_BOOLEAN:
    case Constants.T_CHAR:
    case Constants.T_BYTE:    return IRETURN;
    case Constants.T_FLOAT:   return FRETURN;
    case Constants.T_DOUBLE:  return DRETURN;
    case Constants.T_LONG:    return LRETURN;
    case Constants.T_VOID:    return RETURN;

    default:
      throw new RuntimeException("Invalid type: " + type);
    }
  }

  private static final ArithmeticInstruction createBinaryIntOp(char first, String op) {
    switch(first) {
    case '-' : return ISUB;
    case '+' : return IADD;
    case '%' : return IREM;
    case '*' : return IMUL;
    case '/' : return IDIV;
    case '&' : return IAND;
    case '|' : return IOR;
    case '^' : return IXOR;
    case '<' : return ISHL;
    case '>' : return op.equals(">>>")? (ArithmeticInstruction)IUSHR :
      (ArithmeticInstruction)ISHR;
    default: throw new RuntimeException("Invalid operand " + op);
    }
  }

  private static final ArithmeticInstruction createBinaryLongOp(char first, String op) {
    switch(first) {
    case '-' : return LSUB;
    case '+' : return LADD;
    case '%' : return LREM;
    case '*' : return LMUL;
    case '/' : return LDIV;
    case '&' : return LAND;
    case '|' : return LOR;
    case '^' : return LXOR;
    case '<' : return LSHL;
    case '>' : return op.equals(">>>")? (ArithmeticInstruction)LUSHR :
      (ArithmeticInstruction)LSHR;
    default: throw new RuntimeException("Invalid operand " + op);
    }
  }

  private static final ArithmeticInstruction createBinaryFloatOp(char op) {
    switch(op) {
    case '-' : return FSUB;
    case '+' : return FADD;
    case '*' : return FMUL;
    case '/' : return FDIV;
    default: throw new RuntimeException("Invalid operand " + op);
    }
  }

  private static final ArithmeticInstruction createBinaryDoubleOp(char op) {
    switch(op) {
    case '-' : return DSUB;
    case '+' : return DADD;
    case '*' : return DMUL;
    case '/' : return DDIV;
    default: throw new RuntimeException("Invalid operand " + op);
    }
  }

  /**
   * Create binary operation for simple basic types, such as int and float.
   *
   * @param op operation, such as "+", "*", "<<", etc.
   */
  public static ArithmeticInstruction createBinaryOperation(String op, Type type) {
    char first = op.toCharArray()[0];

    switch(type.getType()) {
    case Constants.T_BYTE:
    case Constants.T_SHORT:
    case Constants.T_INT:
    case Constants.T_CHAR:    return createBinaryIntOp(first, op);
    case Constants.T_LONG:    return createBinaryLongOp(first, op);
    case Constants.T_FLOAT:   return createBinaryFloatOp(first);
    case Constants.T_DOUBLE:  return createBinaryDoubleOp(first);
    default:        throw new RuntimeException("Invalid type " + type);
    }
  }

  /**
   * @param size size of operand, either 1 (int, e.g.) or 2 (double)
   */
  public static StackInstruction createPop(int size) {
    return (size == 2)? (StackInstruction)POP2 :
      (StackInstruction)POP;
  }

  /**
   * @param size size of operand, either 1 (int, e.g.) or 2 (double)
   */
  public static StackInstruction createDup(int size) {
    return (size == 2)? (StackInstruction)DUP2 :
      (StackInstruction)DUP;
  }

  /**
   * @param size size of operand, either 1 (int, e.g.) or 2 (double)
   */
  public static StackInstruction createDup_2(int size) {
    return (size == 2)? (StackInstruction)DUP2_X2 :
      (StackInstruction)DUP_X2;
  }

  /**
   * @param size size of operand, either 1 (int, e.g.) or 2 (double)
   */
  public static StackInstruction createDup_1(int size) {
    return (size == 2)? (StackInstruction)DUP2_X1 :
      (StackInstruction)DUP_X1;
  }

  /**
   * @param index index of local variable
   */
  public static LocalVariableInstruction createStore(Type type, int index) {
    switch(type.getType()) {
    case Constants.T_BOOLEAN:
    case Constants.T_CHAR:
    case Constants.T_BYTE:
    case Constants.T_SHORT:
    case Constants.T_INT:    return new ISTORE(index);
    case Constants.T_FLOAT:  return new FSTORE(index);
    case Constants.T_DOUBLE: return new DSTORE(index);
    case Constants.T_LONG:   return new LSTORE(index);
    case Constants.T_ARRAY:
    case Constants.T_OBJECT: return new ASTORE(index);
    default:       throw new RuntimeException("Invalid type " + type);
    }
  }

  /**
   * @param index index of local variable
   */
  public static LocalVariableInstruction createLoad(Type type, int index) {
    switch(type.getType()) {
    case Constants.T_BOOLEAN:
    case Constants.T_CHAR:
    case Constants.T_BYTE:
    case Constants.T_SHORT:
    case Constants.T_INT:    return new ILOAD(index);
    case Constants.T_FLOAT:  return new FLOAD(index);
    case Constants.T_DOUBLE: return new DLOAD(index);
    case Constants.T_LONG:   return new LLOAD(index);
    case Constants.T_ARRAY:
    case Constants.T_OBJECT: return new ALOAD(index);
    default:       throw new RuntimeException("Invalid type " + type);
    }
  }

  /**
   * @param type type of elements of array, i.e., array.getElementType()
   */
  public static ArrayInstruction createArrayLoad(Type type) {
    switch(type.getType()) {
    case Constants.T_BOOLEAN:
    case Constants.T_BYTE:   return BALOAD;
    case Constants.T_CHAR:   return CALOAD;
    case Constants.T_SHORT:  return SALOAD;
    case Constants.T_INT:    return IALOAD;
    case Constants.T_FLOAT:  return FALOAD;
    case Constants.T_DOUBLE: return DALOAD;
    case Constants.T_LONG:   return LALOAD;
    case Constants.T_ARRAY:
    case Constants.T_OBJECT: return AALOAD;
    default:       throw new RuntimeException("Invalid type " + type);
    }
  }

  /**
   * @param type type of elements of array, i.e., array.getElementType()
   */
  public static ArrayInstruction createArrayStore(Type type) {
    switch(type.getType()) {
    case Constants.T_BOOLEAN:
    case Constants.T_BYTE:   return BASTORE;
    case Constants.T_CHAR:   return CASTORE;
    case Constants.T_SHORT:  return SASTORE;
    case Constants.T_INT:    return IASTORE;
    case Constants.T_FLOAT:  return FASTORE;
    case Constants.T_DOUBLE: return DASTORE;
    case Constants.T_LONG:   return LASTORE;
    case Constants.T_ARRAY:
    case Constants.T_OBJECT: return AASTORE;
    default:       throw new RuntimeException("Invalid type " + type);
    }
  }


  /** Create conversion operation for two stack operands, this may be an I2C, instruction, e.g.,
   * if the operands are basic types and CHECKCAST if they are reference types.
   */
  public Instruction createCast(Type src_type, Type dest_type) {
    if((src_type instanceof BasicType) && (dest_type instanceof BasicType)) {
      byte dest = dest_type.getType();
      byte src  = src_type.getType();

      if(dest == Constants.T_LONG && (src == Constants.T_CHAR || src == Constants.T_BYTE ||
                                      src == Constants.T_SHORT))
        src = Constants.T_INT;

      String[] short_names = { "C", "F", "D", "B", "S", "I", "L" };

      String name = "com.sun.org.apache.bcel.internal.generic." + short_names[src - Constants.T_CHAR] +
        "2" + short_names[dest - Constants.T_CHAR];

      Instruction i = null;
      try {
        i = (Instruction)java.lang.Class.forName(name).newInstance();
      } catch(Exception e) {
        throw new RuntimeException("Could not find instruction: " + name);
      }

      return i;
    } else if((src_type instanceof ReferenceType) && (dest_type instanceof ReferenceType)) {
      if(dest_type instanceof ArrayType)
        return new CHECKCAST(cp.addArrayClass((ArrayType)dest_type));
      else
        return new CHECKCAST(cp.addClass(((ObjectType)dest_type).getClassName()));
    }
    else
      throw new RuntimeException("Can not cast " + src_type + " to " + dest_type);
  }

  public GETFIELD createGetField(String class_name, String name, Type t) {
    return new GETFIELD(cp.addFieldref(class_name, name, t.getSignature()));
  }

  public GETSTATIC createGetStatic(String class_name, String name, Type t) {
    return new GETSTATIC(cp.addFieldref(class_name, name, t.getSignature()));
  }

  public PUTFIELD createPutField(String class_name, String name, Type t) {
    return new PUTFIELD(cp.addFieldref(class_name, name, t.getSignature()));
  }

  public PUTSTATIC createPutStatic(String class_name, String name, Type t) {
    return new PUTSTATIC(cp.addFieldref(class_name, name, t.getSignature()));
  }

  public CHECKCAST createCheckCast(ReferenceType t) {
    if(t instanceof ArrayType)
      return new CHECKCAST(cp.addArrayClass((ArrayType)t));
    else
      return new CHECKCAST(cp.addClass((ObjectType)t));
  }

  public INSTANCEOF createInstanceOf(ReferenceType t) {
    if(t instanceof ArrayType)
      return new INSTANCEOF(cp.addArrayClass((ArrayType)t));
    else
      return new INSTANCEOF(cp.addClass((ObjectType)t));
  }

  public NEW createNew(ObjectType t) {
    return new NEW(cp.addClass(t));
  }

  public NEW createNew(String s) {
    return createNew(new ObjectType(s));
  }

  /** Create new array of given size and type.
   * @return an instruction that creates the corresponding array at runtime, i.e. is an AllocationInstruction
   */
  public Instruction createNewArray(Type t, short dim) {
    if(dim == 1) {
      if(t instanceof ObjectType)
        return new ANEWARRAY(cp.addClass((ObjectType)t));
      else if(t instanceof ArrayType)
        return new ANEWARRAY(cp.addArrayClass((ArrayType)t));
      else
        return new NEWARRAY(((BasicType)t).getType());
    } else {
      ArrayType at;

      if(t instanceof ArrayType)
        at = (ArrayType)t;
      else
        at = new ArrayType(t, dim);

      return new MULTIANEWARRAY(cp.addArrayClass(at), dim);
    }
  }

  /** Create "null" value for reference types, 0 for basic types like int
   */
  public static Instruction createNull(Type type) {
    switch(type.getType()) {
    case Constants.T_ARRAY:
    case Constants.T_OBJECT:  return ACONST_NULL;
    case Constants.T_INT:
    case Constants.T_SHORT:
    case Constants.T_BOOLEAN:
    case Constants.T_CHAR:
    case Constants.T_BYTE:    return ICONST_0;
    case Constants.T_FLOAT:   return FCONST_0;
    case Constants.T_DOUBLE:  return DCONST_0;
    case Constants.T_LONG:    return LCONST_0;
    case Constants.T_VOID:    return NOP;

    default:
      throw new RuntimeException("Invalid type: " + type);
    }
  }

  /** Create branch instruction by given opcode, except LOOKUPSWITCH and TABLESWITCH.
   * For those you should use the SWITCH compound instruction.
   */
  public static BranchInstruction createBranchInstruction(short opcode, InstructionHandle target) {
    switch(opcode) {
    case Constants.IFEQ:      return new IFEQ(target);
    case Constants.IFNE:      return new IFNE(target);
    case Constants.IFLT:      return new IFLT(target);
    case Constants.IFGE:      return new IFGE(target);
    case Constants.IFGT:      return new IFGT(target);
    case Constants.IFLE:      return new IFLE(target);
    case Constants.IF_ICMPEQ: return new IF_ICMPEQ(target);
    case Constants.IF_ICMPNE: return new IF_ICMPNE(target);
    case Constants.IF_ICMPLT: return new IF_ICMPLT(target);
    case Constants.IF_ICMPGE: return new IF_ICMPGE(target);
    case Constants.IF_ICMPGT: return new IF_ICMPGT(target);
    case Constants.IF_ICMPLE: return new IF_ICMPLE(target);
    case Constants.IF_ACMPEQ: return new IF_ACMPEQ(target);
    case Constants.IF_ACMPNE: return new IF_ACMPNE(target);
    case Constants.GOTO:      return new GOTO(target);
    case Constants.JSR:       return new JSR(target);
    case Constants.IFNULL:    return new IFNULL(target);
    case Constants.IFNONNULL: return new IFNONNULL(target);
    case Constants.GOTO_W:    return new GOTO_W(target);
    case Constants.JSR_W:     return new JSR_W(target);
    default:
        throw new RuntimeException("Invalid opcode: " + opcode);
    }
  }

  public void            setClassGen(ClassGen c)            { cg = c; }
  public ClassGen        getClassGen()                      { return cg; }
  public void            setConstantPool(ConstantPoolGen c) { cp = c; }
  public ConstantPoolGen getConstantPool()                  { return cp; }
}

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