Arity.java

/*
 * The MIT License
 *
 * Copyright 2024 Edgar Asatryan <nstdio@gmail.com>.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
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package cz.jirutka.rsql.parser.ast;

/**
 * The arity of an operator.
 *
 * @since 2.3.0
 */
public interface Arity {

    /**
     * The minimum number of arguments operator can receive.
     *
     * @return The minimum number of arguments operator can receive. Positive or zero.
     * @apiNote The minimum values is always less than or equal to {@linkplain #max()}
     */
    int min();

    /**
     * The maximum number of arguments operator can receive.
     *
     * @return The maximum number of arguments operator can receive. Positive or zero.
     * @apiNote The maximum values is always greater than or equal to {@linkplain #min()}. For practically unlimited
     *     arity the implementations should return {@link Integer#MAX_VALUE}.
     */
    int max();

    /**
     * Compares this object with the specified object for equality. Two objects are considered equal if they represent
     * the same Arity, meaning their min and max are equal.
     *
     * @param o The object to be compared for equality with this object.
     * @return {@code true} if the specified object is equal to this object; {@code false} otherwise.
     */
    @Override
    boolean equals(Object o);

    /**
     * Returns the hash code value for this object. The hash code is computed based on the properties of the object and
     * ensures that equal objects have the same hash code.
     *
     * @return The hash code value for this object.
     */
    @Override
    int hashCode();

    /**
     * Creates arity with given {@code min} and {@code max}.
     *
     * @param min The minimum number of arguments. Must be zero or positive.
     * @param max The maximum number of arguments. Must be zero or positive and greater than or equal to {@code min}.
     * @return the created arity
     */
    static Arity of(int min, int max) {
        return min == max ? nary(min) : new DynamicArity(min, max);
    }

    /**
     * Creates N-ary object.
     *
     * @param n The N.
     * @return the created arity
     */
    static Arity nary(int n) {
        return new NAry(n);
    }
}