ApplicableOverloadedMethods.java

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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.

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   License or the BSD License.

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   following notice applies to you:

       You may obtain a copy of the Apache License at

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

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       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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   following notice applies to you:

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       modification, are permitted provided that the following conditions are
       met:
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         notice, this list of conditions and the following disclaimer.
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       IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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package jdk.internal.dynalink.beans;

import java.lang.invoke.MethodType;
import java.util.LinkedList;
import java.util.List;
import jdk.internal.dynalink.support.TypeUtilities;

/**
 * Represents overloaded methods applicable to a specific call site signature.
 *
 * @author Attila Szegedi
 */
class ApplicableOverloadedMethods {
    private final List<SingleDynamicMethod> methods;
    private final boolean varArgs;

    /**
     * Creates a new ApplicableOverloadedMethods instance
     *
     * @param methods a list of all overloaded methods with the same name for a class.
     * @param callSiteType the type of the call site
     * @param test applicability test. One of {@link #APPLICABLE_BY_SUBTYPING},
     * {@link #APPLICABLE_BY_METHOD_INVOCATION_CONVERSION}, or {@link #APPLICABLE_BY_VARIABLE_ARITY}.
     */
    ApplicableOverloadedMethods(final List<SingleDynamicMethod> methods, final MethodType callSiteType,
            final ApplicabilityTest test) {
        this.methods = new LinkedList<>();
        for(final SingleDynamicMethod m: methods) {
            if(test.isApplicable(callSiteType, m)) {
                this.methods.add(m);
            }
        }
        varArgs = test == APPLICABLE_BY_VARIABLE_ARITY;
    }

    /**
     * Retrieves all the methods this object holds.
     *
     * @return list of all methods.
     */
    List<SingleDynamicMethod> getMethods() {
        return methods;
    }

    /**
     * Returns a list of all methods in this objects that are maximally specific.
     *
     * @return a list of maximally specific methods.
     */
    List<SingleDynamicMethod> findMaximallySpecificMethods() {
        return MaximallySpecific.getMaximallySpecificMethods(methods, varArgs);
    }

    abstract static class ApplicabilityTest {
        abstract boolean isApplicable(MethodType callSiteType, SingleDynamicMethod method);
    }

    /**
     * Implements the applicability-by-subtyping test from JLS 15.12.2.2.
     */
    static final ApplicabilityTest APPLICABLE_BY_SUBTYPING = new ApplicabilityTest() {
        @Override
        boolean isApplicable(final MethodType callSiteType, final SingleDynamicMethod method) {
            final MethodType methodType = method.getMethodType();
            final int methodArity = methodType.parameterCount();
            if(methodArity != callSiteType.parameterCount()) {
                return false;
            }
            // 0th arg is receiver; it doesn't matter for overload
            // resolution.
            for(int i = 1; i < methodArity; ++i) {
                if(!TypeUtilities.isSubtype(callSiteType.parameterType(i), methodType.parameterType(i))) {
                    return false;
                }
            }
            return true;
        }
    };

    /**
     * Implements the applicability-by-method-invocation-conversion test from JLS 15.12.2.3.
     */
    static final ApplicabilityTest APPLICABLE_BY_METHOD_INVOCATION_CONVERSION = new ApplicabilityTest() {
        @Override
        boolean isApplicable(final MethodType callSiteType, final SingleDynamicMethod method) {
            final MethodType methodType = method.getMethodType();
            final int methodArity = methodType.parameterCount();
            if(methodArity != callSiteType.parameterCount()) {
                return false;
            }
            // 0th arg is receiver; it doesn't matter for overload
            // resolution.
            for(int i = 1; i < methodArity; ++i) {
                if(!TypeUtilities.isMethodInvocationConvertible(callSiteType.parameterType(i),
                        methodType.parameterType(i))) {
                    return false;
                }
            }
            return true;
        }
    };

    /**
     * Implements the applicability-by-variable-arity test from JLS 15.12.2.4.
     */
    static final ApplicabilityTest APPLICABLE_BY_VARIABLE_ARITY = new ApplicabilityTest() {
        @Override
        boolean isApplicable(final MethodType callSiteType, final SingleDynamicMethod method) {
            if(!method.isVarArgs()) {
                return false;
            }
            final MethodType methodType = method.getMethodType();
            final int methodArity = methodType.parameterCount();
            final int fixArity = methodArity - 1;
            final int callSiteArity = callSiteType.parameterCount();
            if(fixArity > callSiteArity) {
                return false;
            }
            // 0th arg is receiver; it doesn't matter for overload
            // resolution.
            for(int i = 1; i < fixArity; ++i) {
                if(!TypeUtilities.isMethodInvocationConvertible(callSiteType.parameterType(i),
                        methodType.parameterType(i))) {
                    return false;
                }
            }
            final Class<?> varArgType = methodType.parameterType(fixArity).getComponentType();
            for(int i = fixArity; i < callSiteArity; ++i) {
                if(!TypeUtilities.isMethodInvocationConvertible(callSiteType.parameterType(i), varArgType)) {
                    return false;
                }
            }
            return true;
        }
    };
}