1 /*
   2  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package java.lang.constant;
  26 
  27 import java.lang.invoke.MethodHandles;
  28 
  29 import static java.lang.constant.ConstantUtils.dropFirstAndLastChar;
  30 import static java.lang.constant.ConstantUtils.internalToBinary;
  31 import static java.util.Objects.requireNonNull;
  32 
  33 /**
  34  * A <a href="package-summary.html#nominal">nominal descriptor</a> for a class,
  35  * interface, or array type.  A {@linkplain ReferenceClassDescImpl} corresponds to a
  36  * {@code Constant_Class_info} entry in the constant pool of a classfile.
  37  */
  38 final class ReferenceClassDescImpl implements ClassDesc {
  39     private final String descriptor;
  40 
  41     /**
  42      * Creates a {@linkplain ClassDesc} from a descriptor string for a class or
  43      * interface type
  44      *
  45      * @param descriptor a field descriptor string for a class or interface type
  46      * @throws IllegalArgumentException if the descriptor string is not a valid
  47      * field descriptor string, or does not describe a class or interface type
  48      * @jvms 4.3.2 Field Descriptors
  49      */
  50     ReferenceClassDescImpl(String descriptor) {
  51         requireNonNull(descriptor);
  52         int len = ConstantUtils.matchSig(descriptor, 0, descriptor.length());
  53         if (len == 0 || len == 1
  54             || len != descriptor.length())
  55             throw new IllegalArgumentException(String.format("not a valid reference type descriptor: %s", descriptor));
  56         this.descriptor = descriptor;
  57     }
  58 
  59     @Override
  60     public String descriptorString() {
  61         return descriptor;
  62     }
  63 
  64     @Override
  65     public Class<?> resolveConstantDesc(MethodHandles.Lookup lookup)
  66             throws ReflectiveOperationException {
  67         ClassDesc c = this;
  68         int depth = ConstantUtils.arrayDepth(descriptorString());
  69         for (int i=0; i<depth; i++)
  70             c = c.componentType();
  71 
  72         if (c.isPrimitive())
  73             return lookup.findClass(descriptorString());
  74         else {
  75             Class<?> clazz = lookup.findClass(internalToBinary(dropFirstAndLastChar(c.descriptorString())));
  76             for (int i = 0; i < depth; i++)
  77                 clazz = clazz.arrayType();
  78             return clazz;
  79         }
  80     }
  81 
  82     /**
  83      * Returns {@code true} if this {@linkplain ReferenceClassDescImpl} is
  84      * equal to another {@linkplain ReferenceClassDescImpl}.  Equality is
  85      * determined by the two class descriptors having equal class descriptor
  86      * strings.
  87      *
  88      * @param o the {@code ClassDesc} to compare to this
  89      *       {@code ClassDesc}
  90      * @return {@code true} if the specified {@code ClassDesc} is
  91      *      equals to this {@code ClassDesc}.
  92      */
  93     @Override
  94     public boolean equals(Object o) {
  95         if (this == o) return true;
  96         if (o == null || getClass() != o.getClass()) return false;
  97 
  98         ClassDesc constant = (ClassDesc) o;
  99         return descriptor.equals(constant.descriptorString());
 100     }
 101 
 102     @Override
 103     public int hashCode() {
 104         return descriptor.hashCode();
 105     }
 106 
 107     @Override
 108     public String toString() {
 109         return String.format("ClassDesc[%s]", displayName());
 110     }
 111 }