doris/be/src/exprs/json_functions.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 <fmt/core.h>
#include <rapidjson/document.h>

#include <sstream>

#include "udf/udf.h"

namespace doris {

enum JsonFunctionType {
    JSON_FUN_INT = 0,
    JSON_FUN_DOUBLE,
    JSON_FUN_STRING,

    JSON_FUN_UNKNOWN //The last
};

class Expr;
class OpcodeRegistry;
class TupleRow;

struct JsonPath {
    std::string key; // key of a json object
    int idx;         // array index of a json array, -1 means not set, -2 means *
    bool is_valid;   // true if the path is successfully parsed

    JsonPath(const std::string& key_, int idx_, bool is_valid_)
            : key(key_), idx(idx_), is_valid(is_valid_) {}

    JsonPath(std::string&& key_, int idx_, bool is_valid_)
            : key(std::move(key_)), idx(idx_), is_valid(is_valid_) {}

    std::string to_string() const {
        std::stringstream ss;
        if (!is_valid) {
            return "INVALID";
        }
        if (!key.empty()) {
            ss << key;
        }
        if (idx == -2) {
            ss << "[*]";
        } else if (idx > -1) {
            ss << "[" << idx << "]";
        }
        return ss.str();
    }

    std::string to_simdjson_pointer(bool* valid) const {
        std::stringstream ss;
        if (!is_valid) {
            *valid = false;
            return "";
        }
        ss << "/";
        if (!key.empty()) {
            ss << key;
        }
        if (idx == -2) {
            // not support [*]
            *valid = false;
            return "";
        } else if (idx > -1) {
            ss << "/" << idx;
        }
        return ss.str();
    }

    std::string debug_string() const {
        return fmt::format("key:{}, idx:{}, valid:{}", key, idx, is_valid);
    }
};

struct JsonState {
    std::vector<JsonPath> json_paths;
    rapidjson::Document document;
};

class JsonFunctions {
public:
    static void init();
    static doris_udf::IntVal get_json_int(doris_udf::FunctionContext* context,
                                          const doris_udf::StringVal& json_str,
                                          const doris_udf::StringVal& path);
    static doris_udf::StringVal get_json_string(doris_udf::FunctionContext* context,
                                                const doris_udf::StringVal& json_str,
                                                const doris_udf::StringVal& path);
    static doris_udf::DoubleVal get_json_double(doris_udf::FunctionContext* context,
                                                const doris_udf::StringVal& json_str,
                                                const doris_udf::StringVal& path);

    static rapidjson::Value* get_json_object(FunctionContext* context, std::string_view json_string,
                                             std::string_view path_string,
                                             const JsonFunctionType& fntype,
                                             rapidjson::Document* document);

    static doris_udf::StringVal json_array(doris_udf::FunctionContext* context, int num_args,
                                           const doris_udf::StringVal* json_str);
    static doris_udf::StringVal json_object(doris_udf::FunctionContext* context, int num_args,
                                            const doris_udf::StringVal* json_str);
    static doris_udf::StringVal json_quote(doris_udf::FunctionContext* context,
                                           const doris_udf::StringVal& json_str);

    /**
     * The `document` parameter must be has parsed.
     * return Value Is Array object
     * wrap_explicitly is set to true when the returned Array is wrapped actively.
     */
    static rapidjson::Value* get_json_array_from_parsed_json(
            const std::vector<JsonPath>& parsed_paths, rapidjson::Value* document,
            rapidjson::Document::AllocatorType& mem_allocator, bool* wrap_explicitly);

    // this is only for test, it will parse the json path inside,
    // so that we can easily pass a json path as string.
    static rapidjson::Value* get_json_array_from_parsed_json(
            const std::string& jsonpath, rapidjson::Value* document,
            rapidjson::Document::AllocatorType& mem_allocator, bool* wrap_explicitly);

    static rapidjson::Value* get_json_object_from_parsed_json(
            const std::vector<JsonPath>& parsed_paths, rapidjson::Value* document,
            rapidjson::Document::AllocatorType& mem_allocator);

    static void json_path_prepare(doris_udf::FunctionContext*,
                                  doris_udf::FunctionContext::FunctionStateScope);

    static void json_path_close(doris_udf::FunctionContext*,
                                doris_udf::FunctionContext::FunctionStateScope);

    static void parse_json_paths(const std::string& path_strings,
                                 std::vector<JsonPath>* parsed_paths);

private:
    static rapidjson::Value* match_value(const std::vector<JsonPath>& parsed_paths,
                                         rapidjson::Value* document,
                                         rapidjson::Document::AllocatorType& mem_allocator,
                                         bool is_insert_null = false);
    static void get_parsed_paths(const std::vector<std::string>& path_exprs,
                                 std::vector<JsonPath>* parsed_paths);
    static rapidjson::Value parse_str_with_flag(const StringVal& arg, const StringVal& flag,
                                                const int num,
                                                rapidjson::Document::AllocatorType& allocator);
};
} // namespace doris