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	/*
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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 General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file:
	*
	* ASM: a very small and fast Java bytecode manipulation framework
	* Copyright (c) 2000-2011 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 jdk.internal.org.objectweb.asm.signature;

	import jdk.internal.org.objectweb.asm.Opcodes;

	/**
	* A SignatureVisitor that generates signature literals, as defined in the Java Virtual Machine
	* Specification (JVMS).
	*
	* @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.9.1">JVMS
	* 4.7.9.1</a>
	* @author Thomas Hallgren
	* @author Eric Bruneton
	*/
	public class SignatureWriter extends SignatureVisitor {

	/** The builder used to construct the visited signature. */
	private final StringBuilder stringBuilder = new StringBuilder();

	/** Whether the visited signature contains formal type parameters. */
	private boolean hasFormals;

	/** Whether the visited signature contains method parameter types. */
	private boolean hasParameters;

	/**
	* The 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 least significant bit. Pushing false
	* = 2, pushing true = 2+1, popping = /2.
	*
	* <p>Class type arguments must be surrounded with '<' and '>' and, because
	*
	* <ol>
	* <li>class types can be nested (because type arguments can themselves be class types),
	* <li>SignatureWriter always returns 'this' in each visit* method (to avoid allocating new
	* SignatureWriter instances),
	* </ol>
	*
	* <p>we need a stack to properly balance these 'parentheses'. A new element is pushed on this
	* stack for each new visited type, and popped when the visit of this type ends (either is
	* visitEnd, or because visitInnerClassType is called).
	*/
	private int argumentStack;

	/** Constructs a new {@link SignatureWriter}. */
	public SignatureWriter() {
	super(/* latest api =*/ Opcodes.ASM8);
	}

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

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

	@Override
	public SignatureVisitor visitClassBound() {
	return this;
	}

	@Override
	public SignatureVisitor visitInterfaceBound() {
	stringBuilder.append(':');
	return this;
	}

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

	@Override
	public SignatureVisitor visitInterface() {
	return this;
	}

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

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

	@Override
	public SignatureVisitor visitExceptionType() {
	stringBuilder.append('^');
	return this;
	}

	@Override
	public void visitBaseType(final char descriptor) {
	stringBuilder.append(descriptor);
	}

	@Override
	public void visitTypeVariable(final String name) {
	stringBuilder.append('T');
	stringBuilder.append(name);
	stringBuilder.append(';');
	}

	@Override
	public SignatureVisitor visitArrayType() {
	stringBuilder.append('[');
	return this;
	}

	@Override
	public void visitClassType(final String name) {
	stringBuilder.append('L');
	stringBuilder.append(name);
	// Pushes 'false' on the stack, meaning that this type does not have type arguments (as far as
	// we can tell at this point).
	argumentStack *= 2;
	}

	@Override
	public void visitInnerClassType(final String name) {
	endArguments();
	stringBuilder.append('.');
	stringBuilder.append(name);
	// Pushes 'false' on the stack, meaning that this type does not have type arguments (as far as
	// we can tell at this point).
	argumentStack *= 2;
	}

	@Override
	public void visitTypeArgument() {
	// If the top of the stack is 'false', this means we are visiting the first type argument of the
	// currently visited type. We therefore need to append a '<', and to replace the top stack
	// element with 'true' (meaning that the current type does have type arguments).
	if (argumentStack % 2 == 0) {
	argumentStack \|= 1;
	stringBuilder.append('<');
	}
	stringBuilder.append('*');
	}

	@Override
	public SignatureVisitor visitTypeArgument(final char wildcard) {
	// If the top of the stack is 'false', this means we are visiting the first type argument of the
	// currently visited type. We therefore need to append a '<', and to replace the top stack
	// element with 'true' (meaning that the current type does have type arguments).
	if (argumentStack % 2 == 0) {
	argumentStack \|= 1;
	stringBuilder.append('<');
	}
	if (wildcard != '=') {
	stringBuilder.append(wildcard);
	}
	return this;
	}

	@Override
	public void visitEnd() {
	endArguments();
	stringBuilder.append(';');
	}

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

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

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

	/** Ends the type arguments of a class or inner class type. */
	private void endArguments() {
	// If the top of the stack is 'true', this means that some type arguments have been visited for
	// the type whose visit is now ending. We therefore need to append a '>', and to pop one element
	// from the stack.
	if (argumentStack % 2 == 1) {
	stringBuilder.append('>');
	}
	argumentStack /= 2;
	}
	}

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