ArityException.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * accompanied this code).
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package com.oracle.truffle.api.interop;

import com.oracle.truffle.api.CompilerDirectives;

/**
 * An exception thrown if a foreign function or method invocation provides the wrong number of
 * arguments.
 *
 * @since 0.11
 */
public final class ArityException extends InteropException {

    private static final long serialVersionUID = 1857745390734085182L;

    private final int expectedArity;
    private final int actualArity;

    private ArityException(int expectedArity, int actualArity) {
        super("Arity error - expected: " + expectedArity + " actual: " + actualArity);
        this.expectedArity = expectedArity;
        this.actualArity = actualArity;
    }

    /**
     * Returns the number of arguments that the foreign object expects.
     *
     * @return the number of expected arguments
     * @since 0.11
     */
    public int getExpectedArity() {
        return expectedArity;
    }

    /**
     * Returns the actual number of arguments provided by the foreign access.
     *
     * @return the number of provided arguments
     * @since 0.11
     */
    public int getActualArity() {
        return actualArity;
    }

    /**
     * Raises an {@link ArityException}, hidden as a {@link RuntimeException}, which allows throwing
     * it without an explicit throws declaration. The {@link ForeignAccess} methods (e.g.
     * <code> ForeignAccess.sendRead </code>) catch the exceptions and re-throw them as checked
     * exceptions.
     *
     * @param expectedArity the number of arguments expected by the foreign object
     * @param actualArity the number of provided by the foreign access
     *
     * @return the exception
     * @since 0.11
     */
    public static RuntimeException raise(int expectedArity, int actualArity) {
        CompilerDirectives.transferToInterpreter();
        return silenceException(RuntimeException.class, new ArityException(expectedArity, actualArity));
    }

}