How to Operate With Json List In Cmake?

To operate with a JSON list in CMake, you can use the jsoncpp library which provides functionality for parsing and manipulating JSON data. By including the library in your CMake project and using its API, you can easily read and write JSON lists in your CMake scripts. This allows you to interact with JSON data structures, such as arrays and objects, and extract the information you need for your build process. With the jsoncpp library, you can iterate over JSON lists, access individual elements, and perform various operations on the data. This can be helpful when working with JSON configuration files or exchanging data between different parts of your CMake project.

What is the syntax for accessing elements in a JSON list in CMake?

To access elements in a JSON formatted list in CMake, you can use the following syntax:

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json_value(<VARIABLE> <KEY> JSON <JSON_STRING>)

For example, considering a JSON list like this:

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{
  "key": [1, 2, 3, 4, 5]
}

You can access elements of the list like this:

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json_value(LIST_ELEMENT "key[0]" JSON {"key": [1, 2, 3, 4, 5]})
message("First element: ${LIST_ELEMENT}")

This will output First element: 1, which corresponds to the first element of the list.

What is the syntax for removing elements from a JSON list in CMake?

In CMake, you can remove elements from a JSON list using the json_list(REMOVE) function. The syntax for removing elements from a JSON list in CMake is as follows:

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json_list(REMOVE <list> <index>)

Where:

• is the name of the JSON list variable.
• is the index of the element to remove from the list.

For example, to remove the element at index 1 from a JSON list variable called myList, you can use the following syntax:

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json_list(REMOVE myList 1)

This will remove the element at index 1 from the JSON list variable myList.

How to use libraries or tools to simplify operations with JSON lists in CMake?

There are several CMake libraries that can simplify operations with JSON lists:

1. jsoncpp: This is a popular C++ library for working with JSON data. You can integrate jsoncpp into your CMake projects by adding it as a dependency in your CMakeLists.txt file.

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find_package(jsoncpp REQUIRED)

Then, you can use the library in your C++ code to parse and manipulate JSON data.

1. nlohmann/json: Another widely used C++ library for working with JSON data. You can add nlohmann/json to your CMake project by cloning the GitHub repository and including the header files in your source code.

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#include <nlohmann/json.hpp>

Then, you can use the library to interact with JSON data structures in your C++ code.

1. Command line tools: If you prefer using command line tools, you can use jq, a lightweight and flexible command-line JSON processor. You can install jq on your system and call it from within your CMake scripts to manipulate JSON lists.

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execute_process(COMMAND jq . input.json OUTPUT_FILE output.json)

These are just a few examples of libraries and tools that can help simplify operations with JSON lists in CMake. Depending on your specific requirements, there may be other libraries or tools that are better suited for your needs.

How to parse a JSON list received from an API in CMake?

To parse a JSON list received from an API in CMake, you can use a CMake module called RapidJSON. Here's a step-by-step guide on how to do this:

1. Download RapidJSON library and include it in your CMake project. You can download RapidJSON from its official GitHub repository: https://github.com/Tencent/rapidjson
2. Include RapidJSON in your CMakeLists.txt file by adding the following lines:

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#include rapidjson.cmake
include_directories(path/to/rapidjson/include)

1. Write a C++ program that will parse the JSON list. Here's an example code snippet to get you started:

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#include <iostream>
#include <rapidjson/document.h>
#include <rapidjson/writer.h>
#include <rapidjson/stringbuffer.h>

int main() {
    const char* json = "{\"colors\": [\"red\", \"blue\", \"green\"]}";

    rapidjson::Document doc;
    doc.Parse(json);

    const rapidjson::Value& colors = doc["colors"];

    for (rapidjson::SizeType i = 0; i < colors.Size(); i++) {
        std::cout << colors[i].GetString() << std::endl;
    }

    return 0;
}

1. Add the C++ source file to your CMakeLists.txt file:

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add_executable(parse_json_list parse_json_list.cpp)

1. Compile and run your CMake project. The program should parse the JSON list and output the individual elements ("red", "blue", "green").

By following these steps, you should be able to parse a JSON list received from an API in CMake using the RapidJSON library.