Overview

What is LuaFormatter?

LuaFormatter is a code formatter for Lua scripts inspired by clang-format. It also integrates easily in various code editors.

Project Idea

LuaFormatter formats the Lua scripts according to an user defined configuration file. Before this project, LuaFormatter didn’t check if the configuration values made sense before using it. The following configuration was valid:

• column_limit : -5
• column_table_limit : 0
• indent_width : -2
• single_quote_to_double_quote : true and double_quote_to_single_quote : true

So initially the project was aimed at the following:

• Building the Validators for each of the configuration fields.
• Implement feature to add configuration field value through command-line flags.
• Enhancement of configuration field with more features and solve existing bugs.

Initially, the Formatter workflow was simple as:

Project Implementation

The project started with fixing the existing issues and implemented some enhancement features in it. The project was completed in three phases:

Phase1

This phase starts with adding test case for space_before_call feature. It was later followed by adding the column_table_limit feature in the configuration. This feature helps the user to set the column limit of the table independently of column_limit config value. If the user will not provide the value of column_table_limit then the formatter automatically sets the column_table_limit value as same as column_limit. The test case and documentation are added along with this feature. Also, the align_parameter feature was fixed in this phase.

Phase2

The codebase workflow (HACKING.md) of the project was initiated in this phase. This is the working documentation of the program. In continuation with HACKING.md, the feature implementation of configuration setting through command-line flags is started. In this feature, the user can set the configuration value of each field through command-line flags. Also, the Unit-test and documentation for the feature are added.

./lua-format file.lua --column-limit 20 --use-tab --no-align-parameter --tab-width 4 --extra-sep-at-table-end --table-sep ; --keep-simple-function-one-line

Configuration through command-line flags

Phase3

Now the validators for the configuration fields are implemented. The values of each configuration field are passed through their corresponding validators. In case of an error in the configuration values, the validators throw the error and the program gets terminated. Validators are implemented for domain error, logic error, and conflicting error with the value of other configuration fields. At last workflow of all the implemented features was updated in HACKING.md

Finally, after completion of the project the workflow of the Formatter is:

Technologies involved

The technologies which I learned and used in the project are given below:

• Used Args parser and group validator to set configuration flags.
• Std::map are used to store the configuration value from command-line flags and validators of the configuration field.
• Used std::any for storing values of every configuration field in a single map which later processed by std::any_cast.
• Used lambda function to implement the validator.
• Used generic programming to keep the project in a standard layout.
• Implemented unit-test for various features.
• Get knowledge about various git commands and used it for maintaining the PRs and git log.

My Code Contributions

The following PRs include the work for the above-mentioned highlights and also other miscellaneous works and bug fixes during the GSoC period.

All PRs : LuaFormatter

Further Work

The GSoC project is completed successfully and all the features are ready to use by the users. After this, I have some plan which can be implemented after Google Summer of Code.

• Some more fields will be added in the configuration for formatting.
• Existing bugs will be resolved.
• Enhancement of some existing features like chop_down_parameter will be done.
• Continue to work on the project along with fixing issues and helping other developers and users.

Acknowledgments

I would like to thank my mentor for his continuous guidance throughout the summer and for giving me the best experience of my life. The motivation and guidance I got from him will definitely help me in the days to come.

Time flew and brought us close to the end. However, the best things deserve to be a special part of our life and LabLua had already made its place in my heart long back. Loads of 💖 to my LabLua family.

We will keep improving the user as well as developer experience in the coming days. Cheers to a new beginning.✌