java/10 : java.base/sun/reflect/generics/reflectiveObjects/WildcardTypeImpl.java

WildcardTypeImpl
https://openjdk.java.net/
GPLv2 + Classpath Exception
/*
 * Copyright (c) 2003, 2016, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.reflect.generics.reflectiveObjects;


import java.lang.reflect.Type;
import java.lang.reflect.WildcardType;
import sun.reflect.generics.factory.GenericsFactory;
import sun.reflect.generics.tree.FieldTypeSignature;
import sun.reflect.generics.visitor.Reifier;
import java.util.Arrays;
import java.util.StringJoiner;


Implementation of WildcardType interface for core reflection.
/**
 * Implementation of WildcardType interface for core reflection.
 */
public class WildcardTypeImpl extends LazyReflectiveObjectGenerator
    implements WildcardType {

    /*
     * We are required to evaluate the bounds lazily, so we store them as ASTs
     * until we are first asked for them.  This also neatly solves the problem
     * with F-bounds - you can't reify them before the formal is defined.
     */

    The upper bounds.  Lazily converted from FieldTypeSignature[] to Type[]. /** The upper bounds.  Lazily converted from FieldTypeSignature[] to Type[]. */
    private volatile Object[] upperBounds;

    The lower bounds.  Lazily converted from FieldTypeSignature[] to Type[]. /** The lower bounds.  Lazily converted from FieldTypeSignature[] to Type[]. */
    private volatile Object[] lowerBounds;

    // constructor is private to enforce access through static factory
    private WildcardTypeImpl(FieldTypeSignature[] ubs,
                             FieldTypeSignature[] lbs,
                             GenericsFactory f) {
        super(f);
        upperBounds = ubs;
        lowerBounds = lbs;
    }

    Factory method.
Params: ubs – - an array of ASTs representing the upper bounds for the type
variable to be created
lbs – - an array of ASTs representing the lower bounds for the type
variable to be created
f – - a factory that can be used to manufacture reflective
objects that represent the bounds of this wildcard type
Returns: a wild card type with the requested bounds and factory/**
     * Factory method.
     * @param ubs - an array of ASTs representing the upper bounds for the type
     * variable to be created
     * @param lbs - an array of ASTs representing the lower bounds for the type
     * variable to be created
     * @param f - a factory that can be used to manufacture reflective
     * objects that represent the bounds of this wildcard type
     * @return a wild card type with the requested bounds and factory
     */
    public static WildcardTypeImpl make(FieldTypeSignature[] ubs,
                                        FieldTypeSignature[] lbs,
                                        GenericsFactory f) {
        return new WildcardTypeImpl(ubs, lbs, f);
    }

    Returns an array of Type objects representing the upper bound(s) of this type variable. Note that if no upper bound is explicitly declared, the upper bound is Object. For each upper bound B :

 if B is a parameterized type or a type variable, it is created, (see ParameterizedType for the details of the creation process for parameterized types). 
Otherwise, B is resolved.

Throws:  {@code TypeNotPresentException} if any of the
 –    bounds refers to a non-existent type declaration
 {@code MalformedParameterizedTypeException} if any of the
 –    bounds refer to a parameterized type that cannot be instantiated
    for any reason
Returns: an array of Types representing the upper bound(s) of this
    type variable/**
     * Returns an array of {@code Type} objects representing the upper
     * bound(s) of this type variable.  Note that if no upper bound is
     * explicitly declared, the upper bound is {@code Object}.
     *
     * <p>For each upper bound B :
     * <ul>
     *  <li>if B is a parameterized type or a type variable, it is created,
     *  (see {@link #ParameterizedType} for the details of the creation
     *  process for parameterized types).
     *  <li>Otherwise, B is resolved.
     * </ul>
     *
     * @return an array of Types representing the upper bound(s) of this
     *     type variable
     * @throws {@code TypeNotPresentException} if any of the
     *     bounds refers to a non-existent type declaration
     * @throws {@code MalformedParameterizedTypeException} if any of the
     *     bounds refer to a parameterized type that cannot be instantiated
     *     for any reason
     */
    public Type[] getUpperBounds() {
        Object[] value = upperBounds;
        if (value instanceof FieldTypeSignature[]) {
            value = reifyBounds((FieldTypeSignature[])value);
            upperBounds = value;
        }
        return (Type[])value.clone();
    }

    Returns an array of Type objects representing the lower bound(s) of this type variable. Note that if no lower bound is explicitly declared, the lower bound is the type of null. In this case, a zero length array is returned. For each lower bound B :

  if B is a parameterized type or a type variable, it is created, (see ParameterizedType for the details of the creation process for parameterized types). 
Otherwise, B is resolved.

Throws:  {@code TypeNotPresentException} if any of the
 –    bounds refers to a non-existent type declaration
 {@code MalformedParameterizedTypeException} if any of the
 –    bounds refer to a parameterized type that cannot be instantiated
    for any reason
Returns: an array of Types representing the lower bound(s) of this
    type variable/**
     * Returns an array of {@code Type} objects representing the
     * lower bound(s) of this type variable.  Note that if no lower bound is
     * explicitly declared, the lower bound is the type of {@code null}.
     * In this case, a zero length array is returned.
     *
     * <p>For each lower bound B :
     * <ul>
     *   <li>if B is a parameterized type or a type variable, it is created,
     *   (see {@link #ParameterizedType} for the details of the creation
     *   process for parameterized types).
     *   <li>Otherwise, B is resolved.
     * </ul>
     *
     * @return an array of Types representing the lower bound(s) of this
     *     type variable
     * @throws {@code TypeNotPresentException} if any of the
     *     bounds refers to a non-existent type declaration
     * @throws {@code MalformedParameterizedTypeException} if any of the
     *     bounds refer to a parameterized type that cannot be instantiated
     *     for any reason
     */
    public Type[] getLowerBounds() {
        Object[] value = lowerBounds;
        if (value instanceof FieldTypeSignature[]) {
            value = reifyBounds((FieldTypeSignature[])value);
            lowerBounds = value;
        }
        return (Type[])value.clone();
    }

    public String toString() {
        Type[] lowerBounds = getLowerBounds();
        Type[] bounds = lowerBounds;
        StringBuilder sb = new StringBuilder();

        if (lowerBounds.length > 0)
            sb.append("? super ");
        else {
            Type[] upperBounds = getUpperBounds();
            if (upperBounds.length > 0 && !upperBounds[0].equals(Object.class) ) {
                bounds = upperBounds;
                sb.append("? extends ");
            } else
                return "?";
        }

        assert bounds.length > 0;

        StringJoiner sj = new StringJoiner(" & ");
        for(Type bound: bounds) {
            sj.add(bound.getTypeName());
        }
        sb.append(sj.toString());

        return sb.toString();
    }

    @Override
    public boolean equals(Object o) {
        if (o instanceof WildcardType) {
            WildcardType that = (WildcardType) o;
            return
                Arrays.equals(this.getLowerBounds(),
                              that.getLowerBounds()) &&
                Arrays.equals(this.getUpperBounds(),
                              that.getUpperBounds());
        } else
            return false;
    }

    @Override
    public int hashCode() {
        Type [] lowerBounds = getLowerBounds();
        Type [] upperBounds = getUpperBounds();

        return Arrays.hashCode(lowerBounds) ^ Arrays.hashCode(upperBounds);
    }
}
Params:	ubs – - an array of ASTs representing the upper bounds for the type variable to be created lbs – - an array of ASTs representing the lower bounds for the type variable to be created f – - a factory that can be used to manufacture reflective objects that represent the bounds of this wildcard type
Returns:	a wild card type with the requested bounds and factory
Throws:	{@code TypeNotPresentException} if any of the – bounds refers to a non-existent type declaration {@code MalformedParameterizedTypeException} if any of the – bounds refer to a parameterized type that cannot be instantiated for any reason
Returns:	an array of Types representing the upper bound(s) of this type variable
/

java/ 10/ java.base/sun/reflect/generics/reflectiveObjects/WildcardTypeImpl.java
