GuardedInvocationComponent.java

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/*
 * This file is available under and governed by the GNU General Public
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 * However, the following notice accompanied the original version of this
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/*
   Copyright 2009-2013 Attila Szegedi

   Licensed under both the Apache License, Version 2.0 (the "Apache License")
   and the BSD License (the "BSD License"), with licensee being free to
   choose either of the two at their discretion.

   You may not use this file except in compliance with either the Apache
   License or the BSD License.

   If you choose to use this file in compliance with the Apache License, the
   following notice applies to you:

       You may obtain a copy of the Apache License at

           http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software
       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
       implied. See the License for the specific language governing
       permissions and limitations under the License.

   If you choose to use this file in compliance with the BSD License, the
   following notice applies to you:

       Redistribution and use in source and binary forms, with or without
       modification, are permitted provided that the following conditions are
       met:
       * Redistributions of source code must retain the above copyright
         notice, this list of conditions and the following disclaimer.
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         notice, this list of conditions and the following disclaimer in the
         documentation and/or other materials provided with the distribution.
       * Neither the name of the copyright holder nor the names of
         contributors may be used to endorse or promote products derived from
         this software without specific prior written permission.

       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
       IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
       TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
       PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
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*/

package jdk.internal.dynalink.beans;

import java.lang.invoke.MethodHandle;
import jdk.internal.dynalink.linker.GuardedInvocation;

/**
 * Represents one component for a GuardedInvocation of a potentially composite operation of an
 * {@link AbstractJavaLinker}. In addition to holding a guarded invocation, it holds semantic information about its
 * guard. All guards produced in the AbstractJavaLinker are either "Class.isInstance()" or "getClass() == clazz"
 * expressions. This allows choosing the most restrictive guard as the guard for the composition of two components.
 * @author Attila Szegedi
 * @version $Id: $
 */
class GuardedInvocationComponent {
    enum ValidationType {
        NONE, // No guard; the operation can be linked unconditionally (quite rare); least strict.
        INSTANCE_OF, // "validatorClass.isInstance(obj)" guard
        EXACT_CLASS, // "obj.getClass() == validatorClass" guard; most strict.
        IS_ARRAY, // "obj.getClass().isArray()"
    }

    private final GuardedInvocation guardedInvocation;
    private final Validator validator;

    GuardedInvocationComponent(final MethodHandle invocation) {
        this(invocation, null, ValidationType.NONE);
    }

    GuardedInvocationComponent(final MethodHandle invocation, final MethodHandle guard, final ValidationType validationType) {
        this(invocation, guard, null, validationType);
    }

    GuardedInvocationComponent(final MethodHandle invocation, final MethodHandle guard, final Class<?> validatorClass,
            final ValidationType validationType) {
        this(invocation, guard, new Validator(validatorClass, validationType));
    }

    GuardedInvocationComponent(final GuardedInvocation guardedInvocation, final Class<?> validatorClass,
            final ValidationType validationType) {
        this(guardedInvocation, new Validator(validatorClass, validationType));
    }

    GuardedInvocationComponent replaceInvocation(final MethodHandle newInvocation) {
        return replaceInvocation(newInvocation, guardedInvocation.getGuard());
    }

    GuardedInvocationComponent replaceInvocation(final MethodHandle newInvocation, final MethodHandle newGuard) {
        return new GuardedInvocationComponent(guardedInvocation.replaceMethods(newInvocation,
                newGuard), validator);
    }

    private GuardedInvocationComponent(final MethodHandle invocation, final MethodHandle guard, final Validator validator) {
        this(new GuardedInvocation(invocation, guard), validator);
    }

    private GuardedInvocationComponent(final GuardedInvocation guardedInvocation, final Validator validator) {
        this.guardedInvocation = guardedInvocation;
        this.validator = validator;
    }

    GuardedInvocation getGuardedInvocation() {
        return guardedInvocation;
    }

    Class<?> getValidatorClass() {
        return validator.validatorClass;
    }

    ValidationType getValidationType() {
        return validator.validationType;
    }

    GuardedInvocationComponent compose(final MethodHandle compositeInvocation, final MethodHandle otherGuard,
            final Class<?> otherValidatorClass, final ValidationType otherValidationType) {
        final Validator compositeValidator = validator.compose(new Validator(otherValidatorClass, otherValidationType));
        final MethodHandle compositeGuard = compositeValidator == validator ? guardedInvocation.getGuard() : otherGuard;
        return new GuardedInvocationComponent(compositeInvocation, compositeGuard, compositeValidator);
    }

    private static class Validator {
        /*private*/ final Class<?> validatorClass;
        /*private*/ final ValidationType validationType;

        Validator(final Class<?> validatorClass, final ValidationType validationType) {
            this.validatorClass = validatorClass;
            this.validationType = validationType;
        }

        Validator compose(final Validator other) {
            if(other.validationType == ValidationType.NONE) {
                return this;
            }
            switch(validationType) {
                case NONE:
                    return other;
                case INSTANCE_OF:
                    switch(other.validationType) {
                        case INSTANCE_OF:
                            if(isAssignableFrom(other)) {
                                return other;
                            } else if(other.isAssignableFrom(this)) {
                                return this;
                            }
                            break;
                        case EXACT_CLASS:
                            if(isAssignableFrom(other)) {
                                return other;
                            }
                            break;
                        case IS_ARRAY:
                            if(validatorClass.isArray()) {
                                return this;
                            }
                            break;
                        default:
                            throw new AssertionError();
                    }
                    break;
                case EXACT_CLASS:
                    switch(other.validationType) {
                        case INSTANCE_OF:
                            if(other.isAssignableFrom(this)) {
                                return this;
                            }
                            break;
                        case EXACT_CLASS:
                            if(validatorClass == other.validatorClass) {
                                return this;
                            }
                            break;
                        case IS_ARRAY:
                            if(validatorClass.isArray()) {
                                return this;
                            }
                            break;
                        default:
                            throw new AssertionError();
                    }
                    break;
                case IS_ARRAY:
                    switch(other.validationType) {
                        case INSTANCE_OF:
                        case EXACT_CLASS:
                            if(other.validatorClass.isArray()) {
                                return other;
                            }
                            break;
                        case IS_ARRAY:
                            return this;
                        default:
                            throw new AssertionError();
                    }
                    break;
                default:
                    throw new AssertionError();
            }
            throw new AssertionError("Incompatible composition " + this + " vs " + other);
        }

        private boolean isAssignableFrom(final Validator other) {
            return validatorClass.isAssignableFrom(other.validatorClass);
        }

        @Override
        public String toString() {
            return "Validator[" + validationType + (validatorClass == null ? "" : (" " + validatorClass.getName())) + "]";
        }
    }
}