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Advanced and thread-safe Java Redis client for synchronous, asynchronous, and reactive usage. Supports Cluster, Sentinel, Pipelining, Auto-Reconnect, Codecs and much more.
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/*
 * Copyright 2024, Redis Ltd. and Contributors
 * All rights reserved.
 *
 * Licensed under the MIT License.
 */

package io.lettuce.core.json;

/**
 * Describes a path to a certain {@link JsonValue} inside a JSON document.
 * 
 * 

 * The Redis server implements its own JSONPath implementation, based on existing technologies. The generic rules to build a
 * path string are:
 * 

 * $ - The root (outermost JSON element), starts the path.
 * . or [] - Selects a child element.
 * .. - Recursively descends through the JSON document.
 * * - Wildcard, returns all elements.
 * [] - Subscript operator, accesses an array element.
 * [,]] - Union, selects multiple elements.
 * [start:end:step] - Array slice where start, end, and step are indexes.
 * ?() - Filters a JSON object or array. Supports comparison operators (==, !=, <, <=, >, >=, =~), logical
 * operators (&&, ||), and parenthesis ((, )).
 * () - Script expression.
 * @ - The current element, used in filter or script expressions.
 * 
 * 
 * For example, given the following JSON document:
 * 
 * 
 * {
 *     "inventory": {
 *         "mountain_bikes": [
 *             {
 *                 "id": "bike:1",
 *                 "model": "Phoebe",
 *                 "description": "This is a mid-travel trail slayer that is a fantastic daily...",
 *                 "price": 1920,
 *                 "specs": {"material": "carbon", "weight": 13.1},
 *                 "colors": ["black", "silver"],
 *             },
 *             ...
 *         }
 *     }
 *}
 * 
 * 
 * To get a list of all the {@code mountain_bikes} inside the {@code inventory} you would write something like:
 * 

 * {@code JSON.GET store '$.inventory["mountain_bikes"]' }
 *
 * @author Tihomir Mateev
 * @since 6.5
 * @see JSON Path in Redis docs
 */
public class JsonPath {

    /**
     * The root path {@code $} as defined by the second version of the RedisJSON implementation.
     * 
     * 
     * @since 6.5
     */
    public static final JsonPath ROOT_PATH = new JsonPath("$");

    /**
     * The legacy root path {@code .} as defined by the first version of the RedisJSON implementation.
     * 
     * @deprecated since 6.5, use {@link #ROOT_PATH} instead.
     */
    public static final JsonPath ROOT_PATH_LEGACY = new JsonPath(".");

    private final String path;

    /**
     * Create a new {@link JsonPath} given a path string.
     *
     * @param pathString the path string, must not be {@literal null} or empty.
     */
    public JsonPath(final String pathString) {

        if (pathString == null) {
            throw new IllegalArgumentException("Path cannot be null.");
        }

        if (pathString.isEmpty()) {
            throw new IllegalArgumentException("Path cannot be empty.");
        }

        this.path = pathString;
    }

    @Override
    public String toString() {
        return path;
    }

    /**
     * Create a new {@link JsonPath} given a path string.
     *
     * @param path the path string, must not be {@literal null} or empty.
     * @return the {@link JsonPath}.
     */
    public static JsonPath of(final String path) {
        return new JsonPath(path);
    }

    @Override
    public boolean equals(Object obj) {
        return this.path.equals(obj);
    }

    @Override
    public int hashCode() {
        return path.hashCode();
    }

    public boolean isRootPath() {
        return ROOT_PATH.toString().equals(path) || ROOT_PATH_LEGACY.toString().equals(path);
    }

}