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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;

	/**
	* A parser for signature literals, as defined in the Java Virtual Machine Specification (JVMS), to
	* visit them with a SignatureVisitor.
	*
	* @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 SignatureReader {

	/** The JVMS signature to be read. */
	private final String signatureValue;

	/**
	* Constructs a {@link SignatureReader} for the given signature.
	*
	* @param signature A <i>JavaTypeSignature</i>, <i>ClassSignature</i> or <i>MethodSignature</i>.
	*/
	public SignatureReader(final String signature) {
	this.signatureValue = signature;
	}

	/**
	* Makes the given visitor visit the signature of this {@link SignatureReader}. This signature is
	* the one specified in the constructor (see {@link #SignatureReader}). This method is intended to
	* be called on a {@link SignatureReader} that was created using a <i>ClassSignature</i> (such as
	* the <code>signature</code> parameter of the {@link jdk.internal.org.objectweb.asm.ClassVisitor#visit}
	* method) or a <i>MethodSignature</i> (such as the <code>signature</code> parameter of the {@link
	* jdk.internal.org.objectweb.asm.ClassVisitor#visitMethod} method).
	*
	* @param signatureVistor the visitor that must visit this signature.
	*/
	public void accept(final SignatureVisitor signatureVistor) {
	String signature = this.signatureValue;
	int length = signature.length();
	int offset; // Current offset in the parsed signature (parsed from left to right).
	char currentChar; // The signature character at 'offset', or just before.

	// If the signature starts with '<', it starts with TypeParameters, i.e. a formal type parameter
	// identifier, followed by one or more pair ':',ReferenceTypeSignature (for its class bound and
	// interface bounds).
	if (signature.charAt(0) == '<') {
	// Invariant: offset points to the second character of a formal type parameter name at the
	// beginning of each iteration of the loop below.
	offset = 2;
	do {
	// The formal type parameter name is everything between offset - 1 and the first ':'.
	int classBoundStartOffset = signature.indexOf(':', offset);
	signatureVistor.visitFormalTypeParameter(
	signature.substring(offset - 1, classBoundStartOffset));

	// If the character after the ':' class bound marker is not the start of a
	// ReferenceTypeSignature, it means the class bound is empty (which is a valid case).
	offset = classBoundStartOffset + 1;
	currentChar = signature.charAt(offset);
	if (currentChar == 'L' \|\| currentChar == '[' \|\| currentChar == 'T') {
	offset = parseType(signature, offset, signatureVistor.visitClassBound());
	}

	// While the character after the class bound or after the last parsed interface bound
	// is ':', we need to parse another interface bound.
	while ((currentChar = signature.charAt(offset++)) == ':') {
	offset = parseType(signature, offset, signatureVistor.visitInterfaceBound());
	}

	// At this point a TypeParameter has been fully parsed, and we need to parse the next one
	// (note that currentChar is now the first character of the next TypeParameter, and that
	// offset points to the second character), unless the character just after this
	// TypeParameter signals the end of the TypeParameters.
	} while (currentChar != '>');
	} else {
	offset = 0;
	}

	// If the (optional) TypeParameters is followed by '(' this means we are parsing a
	// MethodSignature, which has JavaTypeSignature type inside parentheses, followed by a Result
	// type and optional ThrowsSignature types.
	if (signature.charAt(offset) == '(') {
	offset++;
	while (signature.charAt(offset) != ')') {
	offset = parseType(signature, offset, signatureVistor.visitParameterType());
	}
	// Use offset + 1 to skip ')'.
	offset = parseType(signature, offset + 1, signatureVistor.visitReturnType());
	while (offset < length) {
	// Use offset + 1 to skip the first character of a ThrowsSignature, i.e. '^'.
	offset = parseType(signature, offset + 1, signatureVistor.visitExceptionType());
	}
	} else {
	// Otherwise we are parsing a ClassSignature (by hypothesis on the method input), which has
	// one or more ClassTypeSignature for the super class and the implemented interfaces.
	offset = parseType(signature, offset, signatureVistor.visitSuperclass());
	while (offset < length) {
	offset = parseType(signature, offset, signatureVistor.visitInterface());
	}
	}
	}

	/**
	* Makes the given visitor visit the signature of this {@link SignatureReader}. This signature is
	* the one specified in the constructor (see {@link #SignatureReader}). This method is intended to
	* be called on a {@link SignatureReader} that was created using a <i>JavaTypeSignature</i>, such
	* as the <code>signature</code> parameter of the {@link
	* jdk.internal.org.objectweb.asm.ClassVisitor#visitField} or {@link
	* jdk.internal.org.objectweb.asm.MethodVisitor#visitLocalVariable} methods.
	*
	* @param signatureVisitor the visitor that must visit this signature.
	*/
	public void acceptType(final SignatureVisitor signatureVisitor) {
	parseType(signatureValue, 0, signatureVisitor);
	}

	/**
	* Parses a JavaTypeSignature and makes the given visitor visit it.
	*
	* @param signature a string containing the signature that must be parsed.
	* @param startOffset index of the first character of the signature to parsed.
	* @param signatureVisitor the visitor that must visit this signature.
	* @return the index of the first character after the parsed signature.
	*/
	private static int parseType(
	final String signature, final int startOffset, final SignatureVisitor signatureVisitor) {
	int offset = startOffset; // Current offset in the parsed signature.
	char currentChar = signature.charAt(offset++); // The signature character at 'offset'.

	// Switch based on the first character of the JavaTypeSignature, which indicates its kind.
	switch (currentChar) {
	case 'Z':
	case 'C':
	case 'B':
	case 'S':
	case 'I':
	case 'F':
	case 'J':
	case 'D':
	case 'V':
	// Case of a BaseType or a VoidDescriptor.
	signatureVisitor.visitBaseType(currentChar);
	return offset;

	case '[':
	// Case of an ArrayTypeSignature, a '[' followed by a JavaTypeSignature.
	return parseType(signature, offset, signatureVisitor.visitArrayType());

	case 'T':
	// Case of TypeVariableSignature, an identifier between 'T' and ';'.
	int endOffset = signature.indexOf(';', offset);
	signatureVisitor.visitTypeVariable(signature.substring(offset, endOffset));
	return endOffset + 1;

	case 'L':
	// Case of a ClassTypeSignature, which ends with ';'.
	// These signatures have a main class type followed by zero or more inner class types
	// (separated by '.'). Each can have type arguments, inside '<' and '>'.
	int start = offset; // The start offset of the currently parsed main or inner class name.
	boolean visited = false; // Whether the currently parsed class name has been visited.
	boolean inner = false; // Whether we are currently parsing an inner class type.
	// Parses the signature, one character at a time.
	while (true) {
	currentChar = signature.charAt(offset++);
	if (currentChar == '.' \|\| currentChar == ';') {
	// If a '.' or ';' is encountered, this means we have fully parsed the main class name
	// or an inner class name. This name may already have been visited it is was followed by
	// type arguments between '<' and '>'. If not, we need to visit it here.
	if (!visited) {
	String name = signature.substring(start, offset - 1);
	if (inner) {
	signatureVisitor.visitInnerClassType(name);
	} else {
	signatureVisitor.visitClassType(name);
	}
	}
	// If we reached the end of the ClassTypeSignature return, otherwise start the parsing
	// of a new class name, which is necessarily an inner class name.
	if (currentChar == ';') {
	signatureVisitor.visitEnd();
	break;
	}
	start = offset;
	visited = false;
	inner = true;
	} else if (currentChar == '<') {
	// If a '<' is encountered, this means we have fully parsed the main class name or an
	// inner class name, and that we now need to parse TypeArguments. First, we need to
	// visit the parsed class name.
	String name = signature.substring(start, offset - 1);
	if (inner) {
	signatureVisitor.visitInnerClassType(name);
	} else {
	signatureVisitor.visitClassType(name);
	}
	visited = true;
	// Now, parse the TypeArgument(s), one at a time.
	while ((currentChar = signature.charAt(offset)) != '>') {
	switch (currentChar) {
	case '*':
	// Unbounded TypeArgument.
	++offset;
	signatureVisitor.visitTypeArgument();
	break;
	case '+':
	case '-':
	// Extends or Super TypeArgument. Use offset + 1 to skip the '+' or '-'.
	offset =
	parseType(
	signature, offset + 1, signatureVisitor.visitTypeArgument(currentChar));
	break;
	default:
	// Instanceof TypeArgument. The '=' is implicit.
	offset = parseType(signature, offset, signatureVisitor.visitTypeArgument('='));
	break;
	}
	}
	}
	}
	return offset;

	default:
	throw new IllegalArgumentException();
	}
	}
	}

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