Panini is a header-only library for generating C++ code written in C++17. The library uses a write-only approach to code generation, which means output is only ever appended and never rolled back. Panini is very fast in run-time execution because it does not need to track many state variables. Unlike most code generation solutions for C++, Panini does not use a scripting language. Its "scripts" are written in C++, which means there's no overhead from a virtual machine. You can even step through your code as it's being output by attaching a debugger to your executable. Panini can be easily integrated into your existing C++ codebase because it can use the same tools for retrieving and processing data as the rest of your code. But just because Panini is fast doesn't mean you have to compromise on generating readable code! The library automatically handles whitespace in your generated code with commands for adding a new line and pushing and popping the indentation level so that you can focus on more important things. While Panini is best suited for generating C++, you can use it to generate code for any language, including JavaScript, TypeScript, XML, or even Python. The library uses the C++ Standard Template Library (STL) and has no other external dependencies. We built Panini using test-driven development and validated its functions with 100+ unit and integration tests. # Example ```cpp #include int main(int argc, char** argv) { using namespace panini; ConsoleWriter writer; writer << Include("iostream", IncludeStyle::AngularBrackets) << NextLine(); writer << NextLine(); writer << Scope("int main(int argc, char** argv)", [](WriterBase& writer) { writer << R"(std::cout << "Hello, World!" << std::endl;)" << NextLine(); writer << NextLine(); writer << "return 0;" << NextLine(); }) << NextLine(); return 0; } ``` Which will output the following to the console: ```cpp #include int main(int argc, char** argv) { std::cout << "Hello, World!" << std::endl; return 0; } ``` # Installation Panini comes with a `CMakeLists.txt` configuration file. Although you should refer to the [CMake documentation](https://cmake.org/) for your specific configuration, as an example, you can use the following command to generate a solution for Visual Studio 2017 in the `build` directory: cmake -G "Visual Studio 15 2017 Win64" -S . -B build # Philosophy We designed Panini to output code with as little processing as possible on the input. You cannot undo already written output because we wrote it to be _write-only_. This allows for very fast execution because there is only minimal state to track while running the program. Panini does not do any string processing, but we can recommend the [fmt](https://github.com/fmtlib/fmt) library for this task. | Type | Description | | ------------- | --------------------------------------------------------------- | | Chunk | Strings of characters after input processing | | Command | Modifies the state of chunks and adds them to the active writer | | Writer | Writes chunks to the output and processes commands | | WriterConfig | Output settings for the writer | # Writing custom commands Commands range from the humble `NextLine`, which adds a new line chunk, to the more involved `Braces`, which adds opening and closing braces to the output based on the brace breaking style. Create your own commands by inheriting from the `panini::Command` class and implementing its pure virtual methods. No other registration is required. Because you cannot undo output after writing it, we **strongly advise** not to end your commands with a `NextLine()` instruction. # Configuring writers Code generation is always started by declaring an instance of `panini::ConfiguredWriter` and optionally giving it a `panini::WriterConfig` specific to that writer. Panini includes several writer implementations out of the box. The configuration instance allows you to change the indentation style (tabs or spaces), new line style (Unix or Windows), where to place opening and closing braces, and other properties that may be specific to your writer. ```cpp FileWriterConfig config; config.indentChunk = " "; FileWriter writer("taxes.csv", config); ``` Create your own writer by inheriting from `panini::ConfiguredWriter` and implementing its pure virtual methods. No other registration is required. If your writer has configurable properties, create a new struct that inherits from `panini::WriterConfig`. See `panini::FileWriterConfig` for an example.