/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2007 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 alterrs.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;
	}
}