/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
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 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Other licenses:
 * -----------------------------------------------------------------------------
 * Commercial licenses for this work are available. These replace the above
 * ASL 2.0 and offer limited warranties, support, maintenance, and commercial
 * database integrations.
 *
 * For more information, please visit: http://www.jooq.org/licenses
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package org.jooq;

import org.jooq.impl.DSL;

/**
 * A comparator to be used in conditions to form comparison predicates.
 * <p>
 * Comparison operators listed here can be used to compare {@link Field} or
 * {@link Row} values with other {@link Field} or {@link Row} values, or with
 * {@link Select} or {@link QuantifiedSelect} values.
 * <p>
 * The following flags indicate whether the comparator can be used as:
 * <ul>
 * <li>a quantified comparison operator: {@link #supportsQuantifier()}. Example:
 * <code>X = ANY (A, B, C)</code></li>
 * <li>a subselect comparison operator: {@link #supportsSubselect()}. Example:
 * <code>X = (SELECT A)</code></li>
 * </ul>
 *
 * @author Lukas Eder
 */
public enum Comparator {

    @Support
    IN("in", false, true),

    @Support
    NOT_IN("not in", false, true),

    @Support
    EQUALS("=", true, true),

    @Support
    NOT_EQUALS("<>", true, true),

    @Support
    LESS("<", true, true),

    @Support
    LESS_OR_EQUAL("<=", true, true),

    @Support
    GREATER(">", true, true),

    @Support
    GREATER_OR_EQUAL(">=", true, true),

    @Support
    IS_DISTINCT_FROM("is distinct from", false, false),

    @Support
    IS_NOT_DISTINCT_FROM("is not distinct from", false, false),

    @Support
    LIKE("like", false, false),

    @Support
    NOT_LIKE("not like", false, false),

    @Support
    LIKE_IGNORE_CASE("ilike", false, false),

    @Support
    NOT_LIKE_IGNORE_CASE("not ilike", false, false),

    ;

    private final String  sql;
    private final Keyword keyword;
    private final boolean supportsQuantifier;
    private final boolean supportsSubselect;

    private Comparator(String sql, boolean supportsQuantifier, boolean supportsSubselect) {
        this.sql = sql;
        this.keyword = DSL.keyword(sql);
        this.supportsQuantifier = supportsQuantifier;
        this.supportsSubselect = supportsSubselect;
    }

    /**
     * A SQL rendition of this comparator.
     */
    public String toSQL() {
        return sql;
    }

    /**
     * A keyword rendition of this comparator.
     */
    public Keyword toKeyword() {
        return keyword;
    }

    /**
     * Whether this comparator supports quantifiers on the right-hand side.
     */
    public boolean supportsQuantifier() {
        return supportsQuantifier;
    }

    /**
     * Whether this comparator supports subselects on the right-hand side.
     */
    public boolean supportsSubselect() {
        return supportsSubselect;
    }
}