ConversionComparator.java

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/*
   Copyright 2009-2013 Attila Szegedi

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package jdk.dynalink.linker;


/**
 * Optional interface to be implemented by {@link GuardingTypeConverterFactory}
 * implementers. Language-specific conversions can cause increased overloaded
 * method resolution ambiguity, as many methods can become applicable because of
 * additional conversions. The static way of selecting the "most specific"
 * method will fail more often, because there will be multiple maximally
 * specific method with unrelated signatures. In these cases, language runtimes
 * can be asked to resolve the ambiguity by expressing preferences for one
 * conversion over the other.
 */
public interface ConversionComparator {
    /**
     * Enumeration of possible outcomes of comparing one conversion to another.
     */
    enum Comparison {
        /** The conversions cannot be compared. **/
        INDETERMINATE,
        /** The first conversion is better than the second one. **/
        TYPE_1_BETTER,
        /** The second conversion is better than the first one. **/
        TYPE_2_BETTER,
    }

    /**
     * Determines which of the two target types is the preferred conversion
     * target from a source type.
     * @param sourceType the source type.
     * @param targetType1 one potential target type
     * @param targetType2 another potential target type.
     * @return one of Comparison constants that establish which - if any - of
     * the target types is preferred for the conversion.
     */
    public Comparison compareConversion(Class<?> sourceType, Class<?> targetType1, Class<?> targetType2);
}