/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2005 INRIA, France Telecom
 * 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. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS 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 COPYRIGHT OWNER OR 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.
 */
package org.mvel2.asm.signature;

/**
 * A signature visitor that generates signatures in string format.
 *
 * @author Thomas Hallgren
 * @author Eric Bruneton
 */
public class SignatureWriter implements SignatureVisitor {

  /**
   * Buffer used to construct the signature.
   */
  private final StringBuffer buf = new StringBuffer();

  /**
   * Indicates if the signature contains formal type parameters.
   */
  private boolean hasFormals;

  /**
   * Indicates if the signature contains method parameter types.
   */
  private boolean hasParameters;

  /**
   * Stack used to keep track of class types that have arguments. Each element
   * of this stack is a boolean encoded in one bit. The top of the stack is
   * the lowest order bit. Pushing false = *2, pushing true = *2+1, popping =
   * /2.
   */
  private int argumentStack;

  /**
   * Constructs a new {@link SignatureWriter} object.
   */
  public SignatureWriter() {
  }

  // ------------------------------------------------------------------------
  // Implementation of the SignatureVisitor interface
  // ------------------------------------------------------------------------

  public void visitFormalTypeParameter(final String name) {
    if (!hasFormals) {
      hasFormals = true;
      buf.append('<');
    }
    buf.append(name);
    buf.append(':');
  }

  public SignatureVisitor visitClassBound() {
    return this;
  }

  public SignatureVisitor visitInterfaceBound() {
    buf.append(':');
    return this;
  }

  public SignatureVisitor visitSuperclass() {
    endFormals();
    return this;
  }

  public SignatureVisitor visitInterface() {
    return this;
  }

  public SignatureVisitor visitParameterType() {
    endFormals();
    if (!hasParameters) {
      hasParameters = true;
      buf.append('(');
    }
    return this;
  }

  public SignatureVisitor visitReturnType() {
    endFormals();
    if (!hasParameters) {
      buf.append('(');
    }
    buf.append(')');
    return this;
  }

  public SignatureVisitor visitExceptionType() {
    buf.append('^');
    return this;
  }

  public void visitBaseType(final char descriptor) {
    buf.append(descriptor);
  }

  public void visitTypeVariable(final String name) {
    buf.append('T');
    buf.append(name);
    buf.append(';');
  }

  public SignatureVisitor visitArrayType() {
    buf.append('[');
    return this;
  }

  public void visitClassType(final String name) {
    buf.append('L');
    buf.append(name);
    argumentStack *= 2;
  }

  public void visitInnerClassType(final String name) {
    endArguments();
    buf.append('.');
    buf.append(name);
    argumentStack *= 2;
  }

  public void visitTypeArgument() {
    if (argumentStack % 2 == 0) {
      ++argumentStack;
      buf.append('<');
    }
    buf.append('*');
  }

  public SignatureVisitor visitTypeArgument(final char wildcard) {
    if (argumentStack % 2 == 0) {
      ++argumentStack;
      buf.append('<');
    }
    if (wildcard != '=') {
      buf.append(wildcard);
    }
    return this;
  }

  public void visitEnd() {
    endArguments();
    buf.append(';');
  }

  /**
   * Returns the signature that was built by this signature writer.
   *
   * @return the signature that was built by this signature writer.
   */
  public String toString() {
    return buf.toString();
  }

  // ------------------------------------------------------------------------
  // Utility methods
  // ------------------------------------------------------------------------

  /**
   * Ends the formal type parameters section of the signature.
   */
  private void endFormals() {
    if (hasFormals) {
      hasFormals = false;
      buf.append('>');
    }
  }

  /**
   * Ends the type arguments of a class or inner class type.
   */
  private void endArguments() {
    if (argumentStack % 2 != 0) {
      buf.append('>');
    }
    argumentStack /= 2;
  }
}