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 import java.util.Optional;
  29 
  30 import static java.lang.constant.ConstantUtils.dropFirstAndLastChar;
  31 import static java.lang.constant.ConstantUtils.internalToBinary;
  32 import static java.util.Objects.requireNonNull;
  33 
  34 /**
  35  * A <a href="package-summary.html#nominal">nominal descriptor</a> for a class,
  36  * interface, or array type.  A {@linkplain ReferenceClassDescImpl} corresponds to a
  37  * {@code Constant_Class_info} entry in the constant pool of a classfile.
  38  */
  39 final class ReferenceClassDescImpl implements ClassDesc {
  40     private final String descriptor;
  41 
  42     /**
  43      * Create a {@linkplain ClassDesc} from a descriptor string for a class or
  44      * interface type
  45      *
  46      * @param descriptor a field descriptor string for a class or interface type,
  47      *                   as per JVMS 4.3.2
  48      * @throws IllegalArgumentException if the descriptor string is not a valid
  49      * field descriptor string, or does not describe a class or interface type
  50      * @jvms 4.3.2 Field Descriptors
  51      */
  52     ReferenceClassDescImpl(String descriptor) {
  53         requireNonNull(descriptor);
  54         int len = ConstantUtils.matchSig(descriptor, 0, descriptor.length());
  55         if (len == 0 || len == 1
  56             || len != descriptor.length())
  57             throw new IllegalArgumentException(String.format("not a valid reference type descriptor: %s", descriptor));
  58         this.descriptor = descriptor;
  59     }
  60 
  61     @Override
  62     public String descriptorString() {
  63         return descriptor;
  64     }
  65 
  66     @Override
  67     public Class<?> resolveConstantDesc(MethodHandles.Lookup lookup)
  68             throws ReflectiveOperationException {
  69         ClassDesc c = this;
  70         int depth = ConstantUtils.arrayDepth(descriptorString());
  71         for (int i=0; i<depth; i++)
  72             c = c.componentType();
  73 
  74         if (c.isPrimitive())
  75             return lookup.findClass(descriptorString());
  76         else {
  77             Class<?> clazz = lookup.findClass(internalToBinary(dropFirstAndLastChar(c.descriptorString())));
  78             for (int i = 0; i < depth; i++)
  79                 clazz = clazz.arrayType();
  80             return clazz;
  81         }
  82     }
  83 
  84     @Override
  85     public Optional<? extends ConstantDesc<ConstantDesc<Class<?>>>> describeConstable() {
  86         return Optional.of(DynamicConstantDesc.ofSymbolic(this));
  87     }
  88 
  89     @Override
  90     public boolean equals(Object o) {
  91         if (this == o) return true;
  92         if (o == null || getClass() != o.getClass()) return false;
  93 
  94         ClassDesc constant = (ClassDesc) o;
  95         return descriptor.equals(constant.descriptorString());
  96     }
  97 
  98     @Override
  99     public int hashCode() {
 100         return descriptor.hashCode();
 101     }
 102 
 103     @Override
 104     public String toString() {
 105         return String.format("ClassDesc[%s]", displayName());
 106     }
 107 }