1 /*
   2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.  Oracle designates this
   7  * particular file as subject to the "Classpath" exception as provided
   8  * by Oracle in the LICENSE file that accompanied this code.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
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  24 
  25 /*
  26  * This file is available under and governed by the GNU General Public
  27  * License version 2 only, as published by the Free Software Foundation.
  28  * However, the following notice accompanied the original version of this
  29  * file:
  30  *
  31  * ASM: a very small and fast Java bytecode manipulation framework
  32  * Copyright (c) 2000-2011 INRIA, France Telecom
  33  * All rights reserved.
  34  *
  35  * Redistribution and use in source and binary forms, with or without
  36  * modification, are permitted provided that the following conditions
  37  * are met:
  38  * 1. Redistributions of source code must retain the above copyright
  39  *    notice, this list of conditions and the following disclaimer.
  40  * 2. Redistributions in binary form must reproduce the above copyright
  41  *    notice, this list of conditions and the following disclaimer in the
  42  *    documentation and/or other materials provided with the distribution.
  43  * 3. Neither the name of the copyright holders nor the names of its
  44  *    contributors may be used to endorse or promote products derived from
  45  *    this software without specific prior written permission.
  46  *
  47  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  48  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  50  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  51  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  52  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  53  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  54  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  55  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  56  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  57  * THE POSSIBILITY OF SUCH DAMAGE.
  58  */
  59 package jdk.internal.org.objectweb.asm.signature;
  60 
  61 /**
  62  * A parser for signature literals, as defined in the Java Virtual Machine Specification (JVMS), to
  63  * visit them with a SignatureVisitor.
  64  *
  65  * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.9.1">JVMS
  66  *     4.7.9.1</a>
  67  * @author Thomas Hallgren
  68  * @author Eric Bruneton
  69  */
  70 public class SignatureReader {
  71 
  72     /** The JVMS signature to be read. */
  73     private final String signatureValue;
  74 
  75     /**
  76       * Constructs a {@link SignatureReader} for the given signature.
  77       *
  78       * @param signature A <i>JavaTypeSignature</i>, <i>ClassSignature</i> or <i>MethodSignature</i>.
  79       */
  80     public SignatureReader(final String signature) {
  81         this.signatureValue = signature;
  82     }
  83 
  84     /**
  85       * Makes the given visitor visit the signature of this {@link SignatureReader}. This signature is
  86       * the one specified in the constructor (see {@link #SignatureReader}). This method is intended to
  87       * be called on a {@link SignatureReader} that was created using a <i>ClassSignature</i> (such as
  88       * the <code>signature</code> parameter of the {@link jdk.internal.org.objectweb.asm.ClassVisitor#visit}
  89       * method) or a <i>MethodSignature</i> (such as the <code>signature</code> parameter of the {@link
  90       * jdk.internal.org.objectweb.asm.ClassVisitor#visitMethod} method).
  91       *
  92       * @param signatureVistor the visitor that must visit this signature.
  93       */
  94     public void accept(final SignatureVisitor signatureVistor) {
  95         String signature = this.signatureValue;
  96         int length = signature.length();
  97         int offset; // Current offset in the parsed signature (parsed from left to right).
  98         char currentChar; // The signature character at 'offset', or just before.
  99 
 100         // If the signature starts with '<', it starts with TypeParameters, i.e. a formal type parameter
 101         // identifier, followed by one or more pair ':',ReferenceTypeSignature (for its class bound and
 102         // interface bounds).
 103         if (signature.charAt(0) == '<') {
 104             // Invariant: offset points to the second character of a formal type parameter name at the
 105             // beginning of each iteration of the loop below.
 106             offset = 2;
 107             do {
 108                 // The formal type parameter name is everything between offset - 1 and the first ':'.
 109                 int classBoundStartOffset = signature.indexOf(':', offset);
 110                 signatureVistor.visitFormalTypeParameter(
 111                         signature.substring(offset - 1, classBoundStartOffset));
 112 
 113                 // If the character after the ':' class bound marker is not the start of a
 114                 // ReferenceTypeSignature, it means the class bound is empty (which is a valid case).
 115                 offset = classBoundStartOffset + 1;
 116                 currentChar = signature.charAt(offset);
 117                 if (currentChar == 'L' || currentChar == 'Q' || currentChar == '[' || currentChar == 'T') {
 118                     offset = parseType(signature, offset, signatureVistor.visitClassBound());
 119                 }
 120 
 121                 // While the character after the class bound or after the last parsed interface bound
 122                 // is ':', we need to parse another interface bound.
 123                 while ((currentChar = signature.charAt(offset++)) == ':') {
 124                     offset = parseType(signature, offset, signatureVistor.visitInterfaceBound());
 125                 }
 126 
 127                 // At this point a TypeParameter has been fully parsed, and we need to parse the next one
 128                 // (note that currentChar is now the first character of the next TypeParameter, and that
 129                 // offset points to the second character), unless the character just after this
 130                 // TypeParameter signals the end of the TypeParameters.
 131             } while (currentChar != '>');
 132         } else {
 133             offset = 0;
 134         }
 135 
 136         // If the (optional) TypeParameters is followed by '(' this means we are parsing a
 137         // MethodSignature, which has JavaTypeSignature type inside parentheses, followed by a Result
 138         // type and optional ThrowsSignature types.
 139         if (signature.charAt(offset) == '(') {
 140             offset++;
 141             while (signature.charAt(offset) != ')') {
 142                 offset = parseType(signature, offset, signatureVistor.visitParameterType());
 143             }
 144             // Use offset + 1 to skip ')'.
 145             offset = parseType(signature, offset + 1, signatureVistor.visitReturnType());
 146             while (offset < length) {
 147                 // Use offset + 1 to skip the first character of a ThrowsSignature, i.e. '^'.
 148                 offset = parseType(signature, offset + 1, signatureVistor.visitExceptionType());
 149             }
 150         } else {
 151             // Otherwise we are parsing a ClassSignature (by hypothesis on the method input), which has
 152             // one or more ClassTypeSignature for the super class and the implemented interfaces.
 153             offset = parseType(signature, offset, signatureVistor.visitSuperclass());
 154             while (offset < length) {
 155                 offset = parseType(signature, offset, signatureVistor.visitInterface());
 156             }
 157         }
 158     }
 159 
 160     /**
 161       * Makes the given visitor visit the signature of this {@link SignatureReader}. This signature is
 162       * the one specified in the constructor (see {@link #SignatureReader}). This method is intended to
 163       * be called on a {@link SignatureReader} that was created using a <i>JavaTypeSignature</i>, such
 164       * as the <code>signature</code> parameter of the {@link
 165       * jdk.internal.org.objectweb.asm.ClassVisitor#visitField} or {@link
 166       * jdk.internal.org.objectweb.asm.MethodVisitor#visitLocalVariable} methods.
 167       *
 168       * @param signatureVisitor the visitor that must visit this signature.
 169       */
 170     public void acceptType(final SignatureVisitor signatureVisitor) {
 171         parseType(signatureValue, 0, signatureVisitor);
 172     }
 173 
 174     /**
 175       * Parses a JavaTypeSignature and makes the given visitor visit it.
 176       *
 177       * @param signature a string containing the signature that must be parsed.
 178       * @param startOffset index of the first character of the signature to parsed.
 179       * @param signatureVisitor the visitor that must visit this signature.
 180       * @return the index of the first character after the parsed signature.
 181       */
 182     private static int parseType(
 183             final String signature, final int startOffset, final SignatureVisitor signatureVisitor) {
 184         int offset = startOffset; // Current offset in the parsed signature.
 185         char currentChar = signature.charAt(offset++); // The signature character at 'offset'.
 186 
 187         // Switch based on the first character of the JavaTypeSignature, which indicates its kind.
 188         switch (currentChar) {
 189             case 'Z':
 190             case 'C':
 191             case 'B':
 192             case 'S':
 193             case 'I':
 194             case 'F':
 195             case 'J':
 196             case 'D':
 197             case 'V':
 198                 // Case of a BaseType or a VoidDescriptor.
 199                 signatureVisitor.visitBaseType(currentChar);
 200                 return offset;
 201 
 202             case '[':
 203                 // Case of an ArrayTypeSignature, a '[' followed by a JavaTypeSignature.
 204                 return parseType(signature, offset, signatureVisitor.visitArrayType());
 205 
 206             case 'T':
 207                 // Case of TypeVariableSignature, an identifier between 'T' and ';'.
 208                 int endOffset = signature.indexOf(';', offset);
 209                 signatureVisitor.visitTypeVariable(signature.substring(offset, endOffset));
 210                 return endOffset + 1;
 211 
 212             case 'L':
 213                 // Case of a ClassTypeSignature, which ends with ';'.
 214                 // These signatures have a main class type followed by zero or more inner class types
 215                 // (separated by '.'). Each can have type arguments, inside '<' and '>'.
 216                 int start = offset; // The start offset of the currently parsed main or inner class name.
 217                 boolean visited = false; // Whether the currently parsed class name has been visited.
 218                 boolean inner = false; // Whether we are currently parsing an inner class type.
 219                 // Parses the signature, one character at a time.
 220                 while (true) {
 221                     currentChar = signature.charAt(offset++);
 222                     if (currentChar == '.' || currentChar == ';') {
 223                         // If a '.' or ';' is encountered, this means we have fully parsed the main class name
 224                         // or an inner class name. This name may already have been visited it is was followed by
 225                         // type arguments between '<' and '>'. If not, we need to visit it here.
 226                         if (!visited) {
 227                             String name = signature.substring(start, offset - 1);
 228                             if (inner) {
 229                                 signatureVisitor.visitInnerClassType(name);
 230                             } else {
 231                                 signatureVisitor.visitClassType(name);
 232                             }
 233                         }
 234                         // If we reached the end of the ClassTypeSignature return, otherwise start the parsing
 235                         // of a new class name, which is necessarily an inner class name.
 236                         if (currentChar == ';') {
 237                             signatureVisitor.visitEnd();
 238                             break;
 239                         }
 240                         start = offset;
 241                         visited = false;
 242                         inner = true;
 243                     } else if (currentChar == '<') {
 244                         // If a '<' is encountered, this means we have fully parsed the main class name or an
 245                         // inner class name, and that we now need to parse TypeArguments. First, we need to
 246                         // visit the parsed class name.
 247                         String name = signature.substring(start, offset - 1);
 248                         if (inner) {
 249                             signatureVisitor.visitInnerClassType(name);
 250                         } else {
 251                             signatureVisitor.visitClassType(name);
 252                         }
 253                         visited = true;
 254                         // Now, parse the TypeArgument(s), one at a time.
 255                         while ((currentChar = signature.charAt(offset)) != '>') {
 256                             switch (currentChar) {
 257                                 case '*':
 258                                     // Unbounded TypeArgument.
 259                                     ++offset;
 260                                     signatureVisitor.visitTypeArgument();
 261                                     break;
 262                                 case '+':
 263                                 case '-':
 264                                     // Extends or Super TypeArgument. Use offset + 1 to skip the '+' or '-'.
 265                                     offset =
 266                                             parseType(
 267                                                     signature, offset + 1, signatureVisitor.visitTypeArgument(currentChar));
 268                                     break;
 269                                 default:
 270                                     // Instanceof TypeArgument. The '=' is implicit.
 271                                     offset = parseType(signature, offset, signatureVisitor.visitTypeArgument('='));
 272                                     break;
 273                             }
 274                         }
 275                     }
 276                 }
 277                 return offset;
 278 
 279             default:
 280                 throw new IllegalArgumentException();
 281         }
 282     }
 283 }