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.
  23  */
  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 import jdk.internal.org.objectweb.asm.Opcodes;
  62 
  63 /**
  64  * A signature visitor that generates signatures in string format.
  65  *
  66  * @author Thomas Hallgren
  67  * @author Eric Bruneton
  68  */
  69 public class SignatureWriter extends SignatureVisitor {
  70 
  71     /**
  72      * Builder used to construct the signature.
  73      */
  74     private final StringBuilder buf = new StringBuilder();
  75 
  76     /**
  77      * Indicates if the signature contains formal type parameters.
  78      */
  79     private boolean hasFormals;
  80 
  81     /**
  82      * Indicates if the signature contains method parameter types.
  83      */
  84     private boolean hasParameters;
  85 
  86     /**
  87      * Stack used to keep track of class types that have arguments. Each element
  88      * of this stack is a boolean encoded in one bit. The top of the stack is
  89      * the lowest order bit. Pushing false = *2, pushing true = *2+1, popping =
  90      * /2.
  91      */
  92     private int argumentStack;
  93 
  94     /**
  95      * Constructs a new {@link SignatureWriter} object.
  96      */
  97     public SignatureWriter() {
  98         super(Opcodes.ASM6);
  99     }
 100 
 101     // ------------------------------------------------------------------------
 102     // Implementation of the SignatureVisitor interface
 103     // ------------------------------------------------------------------------
 104 
 105     @Override
 106     public void visitFormalTypeParameter(final String name) {
 107         if (!hasFormals) {
 108             hasFormals = true;
 109             buf.append('<');
 110         }
 111         buf.append(name);
 112         buf.append(':');
 113     }
 114 
 115     @Override
 116     public SignatureVisitor visitClassBound() {
 117         return this;
 118     }
 119 
 120     @Override
 121     public SignatureVisitor visitInterfaceBound() {
 122         buf.append(':');
 123         return this;
 124     }
 125 
 126     @Override
 127     public SignatureVisitor visitSuperclass() {
 128         endFormals();
 129         return this;
 130     }
 131 
 132     @Override
 133     public SignatureVisitor visitInterface() {
 134         return this;
 135     }
 136 
 137     @Override
 138     public SignatureVisitor visitParameterType() {
 139         endFormals();
 140         if (!hasParameters) {
 141             hasParameters = true;
 142             buf.append('(');
 143         }
 144         return this;
 145     }
 146 
 147     @Override
 148     public SignatureVisitor visitReturnType() {
 149         endFormals();
 150         if (!hasParameters) {
 151             buf.append('(');
 152         }
 153         buf.append(')');
 154         return this;
 155     }
 156 
 157     @Override
 158     public SignatureVisitor visitExceptionType() {
 159         buf.append('^');
 160         return this;
 161     }
 162 
 163     @Override
 164     public void visitBaseType(final char descriptor) {
 165         buf.append(descriptor);
 166     }
 167 
 168     @Override
 169     public void visitTypeVariable(final String name) {
 170         buf.append('T');
 171         buf.append(name);
 172         buf.append(';');
 173     }
 174 
 175     @Override
 176     public SignatureVisitor visitArrayType() {
 177         buf.append('[');
 178         return this;
 179     }
 180 
 181     @Override
 182     public void visitClassType(final String name) {
 183         buf.append('L');
 184         buf.append(name);
 185         argumentStack *= 2;
 186     }
 187 
 188     @Override
 189     public void visitInnerClassType(final String name) {
 190         endArguments();
 191         buf.append('.');
 192         buf.append(name);
 193         argumentStack *= 2;
 194     }
 195 
 196     @Override
 197     public void visitTypeArgument() {
 198         if (argumentStack % 2 == 0) {
 199             ++argumentStack;
 200             buf.append('<');
 201         }
 202         buf.append('*');
 203     }
 204 
 205     @Override
 206     public SignatureVisitor visitTypeArgument(final char wildcard) {
 207         if (argumentStack % 2 == 0) {
 208             ++argumentStack;
 209             buf.append('<');
 210         }
 211         if (wildcard != '=') {
 212             buf.append(wildcard);
 213         }
 214         return this;
 215     }
 216 
 217     @Override
 218     public void visitEnd() {
 219         endArguments();
 220         buf.append(';');
 221     }
 222 
 223     /**
 224      * Returns the signature that was built by this signature writer.
 225      *
 226      * @return the signature that was built by this signature writer.
 227      */
 228     @Override
 229     public String toString() {
 230         return buf.toString();
 231     }
 232 
 233     // ------------------------------------------------------------------------
 234     // Utility methods
 235     // ------------------------------------------------------------------------
 236 
 237     /**
 238      * Ends the formal type parameters section of the signature.
 239      */
 240     private void endFormals() {
 241         if (hasFormals) {
 242             hasFormals = false;
 243             buf.append('>');
 244         }
 245     }
 246 
 247     /**
 248      * Ends the type arguments of a class or inner class type.
 249      */
 250     private void endArguments() {
 251         if (argumentStack % 2 != 0) {
 252             buf.append('>');
 253         }
 254         argumentStack /= 2;
 255     }
 256 }