src/paimon/common/data/variant/variant_path_segment.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#pragma once

#include <cstdint>
#include <string>
#include <vector>

#include "paimon/result.h"

namespace paimon {

/// A path segment for variant get, representing either an object key access or an array index
/// access.
struct VariantPathSegment {
    enum class Kind { kObjectExtraction, kArrayExtraction };

    Kind kind;
    /// The object key when `kind` is `kObjectExtraction`.
    std::string key;
    /// The array index when `kind` is `kArrayExtraction`.
    int32_t index = 0;

    static VariantPathSegment ObjectExtraction(std::string key) {
        VariantPathSegment segment;
        segment.kind = Kind::kObjectExtraction;
        segment.key = std::move(key);
        return segment;
    }

    static VariantPathSegment ArrayExtraction(int32_t index) {
        VariantPathSegment segment;
        segment.kind = Kind::kArrayExtraction;
        segment.index = index;
        return segment;
    }

    /// Parses a path starting with `$`. Supported segments after the root are `.key`, `['key']`,
    /// `["key"]` and `[index]`, e.g. `$.user.addresses[0]['city']`.
    static Result<std::vector<VariantPathSegment>> Parse(const std::string& path);
};

}  // namespace paimon