findpattern.java

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  /**
   * @return number of matched instructions, or -1 if the match did not succeed
   */
  public final int getMatchLength() { return match_length; }

  /**
   * @return the matched piece of code as an array of instruction (handles)
   */
  public final InstructionHandle[] getMatch() {
    if(match_length == -1)
      throw new ClassGenException("Nothing matched.");

    InstructionHandle[] match = new InstructionHandle[match_length];
    System.arraycopy(handles, matched_from, match, 0, match_length);

    return match;
  }

  /**
   * Defines a new instruction list. Automatically calls
   * <a href="#reread()">reread()</a> to update the object.
   *
   * @param il the new instuction list
   */
  public final void setInstructionList(InstructionList il) {
    this.il = il;
    reread();
  }

  /**
   * Internal debugging routines.
   */
  private static final String pattern2string(String pattern) {
    return pattern2string(pattern, true);
  }

  private static final String pattern2string(String pattern, boolean make_string) {
    StringBuffer buf = new StringBuffer();

    for(int i=0; i < pattern.length(); i++) {
      char ch = pattern.charAt(i);

      if(ch >= OFFSET) {
	if(make_string)
	  buf.append(Constants.OPCODE_NAMES[ch - OFFSET]);
	else
	  buf.append((int)(ch - OFFSET));
      }
      else
	buf.append(ch);
    }

    return buf.toString();
  }


  /* Static initializer.
   */
  static {

    String instruction_pattern, binstruction_pattern, if_icmp_pattern, if_pattern,
      push_pattern, iload_pattern, aload_pattern, fload_pattern,
      dload_pattern, lload_pattern, istore_pattern, astore_pattern,
      fstore_pattern, dstore_pattern, lstore_pattern, invoke_pattern, return_pattern,
      if_pattern2;
    
    StringBuffer buf;

    /* Make instruction string
     */
    buf = new StringBuffer("(");
    
    for(short i=0; i < NO_OPCODES; i++) {
      if(Constants.NO_OF_OPERANDS[i] != Constants.UNDEFINED) { // Not an invalid opcode
	buf.append(makeChar(i));

	if(i < NO_OPCODES - 1)
	  buf.append('|');
      }
    }
    buf.append(')');

    instruction_pattern = buf.toString();

    /* Make BranchInstruction string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.IFEQ, Constants.LOOKUPSWITCH);
    buf.append('|');
    appendPatterns(buf, Constants.IFNULL, Constants.JSR_W);
    buf.append(')');
    binstruction_pattern = buf.toString();
 
    /* Make IF_ICMP__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.IF_ICMPEQ, Constants.IF_ICMPLE);
    buf.append(')');
    if_icmp_pattern = buf.toString();

    /* Make IF__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.IFEQ, Constants.IFLE);
    buf.append(')');
    if_pattern = buf.toString();

    /* Make PUSH pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.ACONST_NULL,Constants. LDC2_W);
    buf.append(')');
    push_pattern = buf.toString();

    /* Make ILOAD__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.ILOAD_0, Constants.ILOAD_3);
    buf.append('|');
    buf.append(makeChar(Constants.ILOAD));
    buf.append(')');
    iload_pattern = buf.toString();

    /* Make ALOAD__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.ALOAD_0, Constants.ALOAD_3);
    buf.append('|');
    buf.append(makeChar(Constants.ALOAD));
    buf.append(')');
    aload_pattern = buf.toString();

    /* Make FLOAD__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.FLOAD_0, Constants.FLOAD_3);
    buf.append('|');
    buf.append(makeChar(Constants.FLOAD));
    buf.append(')');
    fload_pattern = buf.toString();

    /* Make DLOAD__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.DLOAD_0, Constants.DLOAD_3);
    buf.append('|');
    buf.append(makeChar(Constants.DLOAD));
    buf.append(')');
    dload_pattern = buf.toString();

    /* Make LLOAD__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.LLOAD_0, Constants.LLOAD_3);
    buf.append('|');
    buf.append(makeChar(Constants.LLOAD));
    buf.append(')');
    lload_pattern = buf.toString();

    /* Make ISTORE__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.ISTORE_0, Constants.ISTORE_3);
    buf.append('|');
    buf.append(makeChar(Constants.ISTORE));
    buf.append(')');
    istore_pattern = buf.toString();

    /* Make ASTORE__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.ASTORE_0, Constants.ASTORE_3);
    buf.append('|');
    buf.append(makeChar(Constants.ASTORE));
    buf.append(')');
    astore_pattern = buf.toString();

    /* Make FSTORE__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.FSTORE_0, Constants.FSTORE_3);
    buf.append('|');
    buf.append(makeChar(Constants.FSTORE));
    buf.append(')');
    fstore_pattern = buf.toString();

    /* Make DSTORE__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.DSTORE_0, Constants.DSTORE_3);
    buf.append('|');
    buf.append(makeChar(Constants.DSTORE));
    buf.append(')');
    dstore_pattern = buf.toString();

    /* Make LSTORE__ pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.LSTORE_0, Constants.LSTORE_3);
    buf.append('|');
    buf.append(makeChar(Constants.LSTORE));
    buf.append(')');
    lstore_pattern = buf.toString();

    /* Make INVOKE pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.INVOKEVIRTUAL, Constants.INVOKEINTERFACE);
    buf.append(')');
    invoke_pattern = buf.toString();

    /* Make RETURN pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.IRETURN, Constants.RETURN);
    buf.append(')');
    return_pattern = buf.toString();

    /* Make IfInstruction pattern string
     */
    appendPatterns(buf = new StringBuffer("("), Constants.IFEQ, Constants.IF_ACMPNE);
    buf.append('|');
    buf.append(makeChar(Constants.IFNULL));
    buf.append('|');
    buf.append(makeChar(Constants.IFNONNULL));
    buf.append(')');
    if_pattern2 = buf.toString();

    pattern_map = new String[] {
      instruction_pattern, binstruction_pattern, if_icmp_pattern, if_pattern,
      push_pattern, iload_pattern, aload_pattern, fload_pattern,
      dload_pattern, lload_pattern, istore_pattern, astore_pattern,
      fstore_pattern, dstore_pattern, lstore_pattern, invoke_pattern, return_pattern,
      if_pattern2
    };
  }

  /**
   * Convert opcode number to char.
   */
  private static final char makeChar(short opcode) {
    return (char)(opcode + OFFSET);
  }

  /**
   * Append instructions characters starting from `start' to `to'.
   */
  private final static void appendPatterns(StringBuffer buf, short from, short to) {
    for(short i=from; i <= to; i++) {
      buf.append(makeChar(i));

      if(i < to)
	buf.append('|');
    }
  }

  /**
   * @return the inquired instruction list
   */
  public final InstructionList getInstructionList() { return il; }
}