1 /*
   2  * Copyright (c) 2018, 2019, 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 java.lang.invoke.MethodHandles;
  30 import java.util.Optional;
  31 
  32 import static java.lang.constant.ConstantDescs.BSM_INVOKE;
  33 import static java.lang.constant.ConstantUtils.dropFirstAndLastChar;
  34 import static java.lang.constant.ConstantUtils.internalToBinary;
  35 import static java.util.Objects.requireNonNull;
  36 
  37 /**
  38  * A <a href="package-summary.html#nominal">nominal descriptor</a> for a class,
  39  * interface, or array type.  A {@linkplain ReferenceClassDescImpl} corresponds to a
  40  * {@code Constant_Class_info} entry in the constant pool of a classfile.
  41  */
  42 final class ReferenceClassDescImpl implements ClassDesc {
  43     private final String descriptor;
  44 
  45     /**
  46      * Creates a {@linkplain ClassDesc} from a descriptor string for a class or
  47      * interface type
  48      *
  49      * @param descriptor a field descriptor string for a class or interface type
  50      * @throws IllegalArgumentException if the descriptor string is not a valid
  51      * field descriptor string, or does not describe a class or interface type
  52      * @jvms 4.3.2 Field Descriptors
  53      */
  54     ReferenceClassDescImpl(String descriptor) {
  55         requireNonNull(descriptor);
  56         int len = ConstantUtils.skipOverFieldSignature(descriptor, 0, descriptor.length(), false);
  57         if (len == 0 || len == 1
  58             || len != descriptor.length())
  59             throw new IllegalArgumentException(String.format("not a valid reference type descriptor: %s", descriptor));
  60         this.descriptor = descriptor;
  61     }
  62 
  63     @Override
  64     public String descriptorString() {
  65         return descriptor;
  66     }
  67 
  68     @Override
  69     public Class<?> resolveConstantDesc(MethodHandles.Lookup lookup)
  70             throws ReflectiveOperationException {
  71         ClassDesc c = this;
  72         int depth = ConstantUtils.arrayDepth(descriptorString());
  73         for (int i=0; i<depth; i++)
  74             c = c.componentType();
  75 
  76         if (c.isPrimitive())
  77             return lookup.findClass(descriptorString());
  78         else {
  79             Class<?> clazz = lookup.findClass(internalToBinary(dropFirstAndLastChar(c.descriptorString())));
  80             for (int i = 0; i < depth; i++)
  81                 clazz = clazz.arrayType();
  82             return clazz;
  83         }
  84     }
  85 
  86     /**
  87      * Returns {@code true} if this {@linkplain ReferenceClassDescImpl} is
  88      * equal to another {@linkplain ReferenceClassDescImpl}.  Equality is
  89      * determined by the two class descriptors having equal class descriptor
  90      * strings.
  91      *
  92      * @param o the {@code ClassDesc} to compare to this
  93      *       {@code ClassDesc}
  94      * @return {@code true} if the specified {@code ClassDesc} is
  95      *      equals to this {@code ClassDesc}.
  96      */
  97     @Override
  98     public boolean equals(Object o) {
  99         if (this == o) return true;
 100         if (o == null || getClass() != o.getClass()) return false;
 101 
 102         ClassDesc constant = (ClassDesc) o;
 103         return descriptor.equals(constant.descriptorString());
 104     }
 105 
 106     @Override
 107     public int hashCode() {
 108         return descriptor.hashCode();
 109     }
 110 
 111     @Override
 112     public String toString() {
 113         return String.format("ClassDesc[%s]", displayName());
 114     }
 115 
 116     @Override
 117     public Optional<? extends ConstantDesc> describeConstable() {
 118         return Optional.empty();
 119     }
 120 }