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 * Copyright (c) 2018, 2019, 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

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package java.lang.constant;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodType;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.Arrays;

import java.util.List;

import static java.util.Objects.requireNonNull;

/**

 * A <a href="package-summary.html#nominal">nominal descriptor</a> for a

 * {@link MethodType}.  A {@linkplain MethodTypeDescImpl} corresponds to a

 * {@code Constant_MethodType_info} entry in the constant pool of a classfile.

 */

final class MethodTypeDescImpl implements MethodTypeDesc {

    private final ClassDesc returnType;

    private final ClassDesc[] argTypes;

    /**

     * Constructs a {@linkplain MethodTypeDesc} with the specified return type

     * and parameter types

     *

     * @param returnType a {@link ClassDesc} describing the return type

     * @param argTypes {@link ClassDesc}s describing the parameter types

     */

    MethodTypeDescImpl(ClassDesc returnType, ClassDesc[] argTypes) {

        this.returnType = requireNonNull(returnType);

        this.argTypes = requireNonNull(argTypes);

        for (ClassDesc cr : argTypes)

            if (cr.isPrimitive() && cr.descriptorString().equals("V"))

                throw new IllegalArgumentException("Void parameters not permitted");

    }

    /**

     * Creates a {@linkplain MethodTypeDescImpl} given a method descriptor string.

     *

     * @param descriptor the method descriptor string

     * @return a {@linkplain MethodTypeDescImpl} describing the desired method type

     * @throws IllegalArgumentException if the descriptor string is not a valid

     * method descriptor

     * @jvms 4.3.3 Method Descriptors

     */

    static MethodTypeDescImpl ofDescriptor(String descriptor) {

        requireNonNull(descriptor);

        List<String> types = ConstantUtils.parseMethodDescriptor(descriptor);

        ClassDesc[] paramTypes = types.stream().skip(1).map(ClassDesc::ofDescriptor).toArray(ClassDesc[]::new);

        return new MethodTypeDescImpl(ClassDesc.ofDescriptor(types.get(0)), paramTypes);

    }

    @Override

    public ClassDesc returnType() {

        return returnType;

    }

    @Override

    public int parameterCount() {

        return argTypes.length;

    }

    @Override

    public ClassDesc parameterType(int index) {

        return argTypes[index];

    }

    @Override

    public List<ClassDesc> parameterList() {

        return List.of(argTypes);

    }

    @Override

    public ClassDesc[] parameterArray() {

        return argTypes.clone();

    }

    @Override

    public MethodTypeDesc changeReturnType(ClassDesc returnType) {

        return MethodTypeDesc.of(returnType, argTypes);

    }

    @Override

    public MethodTypeDesc changeParameterType(int index, ClassDesc paramType) {

        ClassDesc[] newArgs = argTypes.clone();

        newArgs[index] = paramType;

        return MethodTypeDesc.of(returnType, newArgs);

    }

    @Override

    public MethodTypeDesc dropParameterTypes(int start, int end) {

        if (start < 0 || start >= argTypes.length || end < 0 || end > argTypes.length || start > end)

            throw new IndexOutOfBoundsException();

        ClassDesc[] newArgs = new ClassDesc[argTypes.length - (end - start)];

        System.arraycopy(argTypes, 0, newArgs, 0, start);

        System.arraycopy(argTypes, end, newArgs, start, argTypes.length - end);

        return MethodTypeDesc.of(returnType, newArgs);

    }

    @Override

    public MethodTypeDesc insertParameterTypes(int pos, ClassDesc... paramTypes) {

        if (pos < 0 || pos > argTypes.length)

            throw new IndexOutOfBoundsException(pos);

        ClassDesc[] newArgs = new ClassDesc[argTypes.length + paramTypes.length];

        System.arraycopy(argTypes, 0, newArgs, 0, pos);

        System.arraycopy(paramTypes, 0, newArgs, pos, paramTypes.length);

        System.arraycopy(argTypes, pos, newArgs, pos+paramTypes.length, argTypes.length - pos);

        return MethodTypeDesc.of(returnType, newArgs);

    }

    @Override

    public MethodType resolveConstantDesc(MethodHandles.Lookup lookup) throws ReflectiveOperationException {

        MethodType mtype = AccessController.doPrivileged(new PrivilegedAction<>() {

            @Override

            public MethodType run() {

                return MethodType.fromMethodDescriptorString(descriptorString(),

                                                             lookup.lookupClass().getClassLoader());

            }

        });

        // let's check that the lookup has access to all the types in the method type

        lookup.accessClass(mtype.returnType());

        for (Class<?> paramType: mtype.parameterArray()) {

            lookup.accessClass(paramType);

        }

        return mtype;

    }

    /**

     * Returns {@code true} if this {@linkplain MethodTypeDescImpl} is

     * equal to another {@linkplain MethodTypeDescImpl}.  Equality is

     * determined by the two descriptors having equal return types and argument

     * types.

     *

     * @param o the {@code MethodTypeDescImpl} to compare to this

     *       {@code MethodTypeDescImpl}

     * @return {@code true} if the specified {@code MethodTypeDescImpl} is

     *      equals to this {@code MethodTypeDescImpl}.

     */

    @Override

    public boolean equals(Object o) {

        if (this == o) return true;

        if (o == null || getClass() != o.getClass()) return false;

        MethodTypeDescImpl constant = (MethodTypeDescImpl) o;

        return returnType.equals(constant.returnType)

               && Arrays.equals(argTypes, constant.argTypes);

    }

    @Override

    public int hashCode() {

        int result = returnType.hashCode();

        result = 31 * result + Arrays.hashCode(argTypes);

        return result;

    }

    @Override

    public String toString() {

        return String.format("MethodTypeDesc[%s]", displayDescriptor());

    }

}