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https://github.com/lucasamonrc/retfsm
A CLI application that converts regular expression to its Finite State Machine (FSM) graph representation.
https://github.com/lucasamonrc/retfsm
cli cs236 graphviz regex
Last synced: about 2 months ago
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A CLI application that converts regular expression to its Finite State Machine (FSM) graph representation.
- Host: GitHub
- URL: https://github.com/lucasamonrc/retfsm
- Owner: lucasamonrc
- License: mit
- Created: 2024-09-28T23:00:21.000Z (4 months ago)
- Default Branch: main
- Last Pushed: 2024-09-28T23:07:20.000Z (4 months ago)
- Last Synced: 2024-10-02T07:41:43.615Z (4 months ago)
- Topics: cli, cs236, graphviz, regex
- Language: Go
- Homepage:
- Size: 1.24 MB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# 🎰 RegEx to Finite State Machine: `retfsm`
During my sophomore year in college I took a class called "Discrete Structures". We spent a great deal of the first quarter of that class talking about regular expression and their FSM counterparts. A lot of my homework involved of taking language grammars (usually represented through regular expressions) and converting them to FSM by hand. This tool is a gift to my past self.
`retfsm` is a CLI application that converts regular expression to its Finite State Machine (FSM) graph representation. Output to `.dot`, `.svg`, `.png`, and `.jpg` files. Run `retfsm` as a REPL or as command with `retfsm draw`. Input can be passed by stdin redirection, file, or literal strings. Output, if not specified, defaults to a `.dot` file.
### Example
```sh
$ retfsm draw "ab*c" # Creates `a.dot` file in the current directory
$ echo "ab*c" | retfsm draw # Creates `a.dot` file in the current directory
$ retfsm draw "ab*c" out.png # Creates `out.png` file in the current directory
```
Alternatively you can run `retfsm` as a REPL.
```sh
$ refsm
retfsm> ab*c
# The DOT output will be printed to stdout
```
You can also pass text files and redirect `stdin`. Note that any multi-line inputs will produce one output for each line.
## ⚙️ Installation
You must have go installed in your system. This application depends on Go version `1.23.0`. If Go is installed, you can simply run the command below:
```sh
go install github.com/lucasamonrc/retfsm@latest
```
You can check if everything works by running the `help` command:
```sh
retfsm help
```
## 🧠 The RegEx Engine
This projects implements a very simple RegEx engine with symbols and operators that are only applicable to languages that can be expressed as FSMs.
### Current Support
- **Alphanumeric literals:** literal characters `a-z`, `A-Z`, and `0-9`
- **Kleene star:** special character `*`, to indicate that the previous character can be repeated 0 or more times
### Future Support
- **Kleene plus:** special character `+`, to indicate that the previous character (or group) can be repeated 1 or more times
- **Grouping**: special characters `(` and `)`, to logically constraint a sequence of characters together
### Beyond the scope
- **Dot operator**: special character `.` to match any alphanumeric character
- **Character escaping:** using `\` in front of a special character to indicate that it should be used as a literal
- **Or operator:** using `|` between two characters to match one or the other
## 🚀 Technology Stack
This project mostly relies on Go's standard libraries that are included with the version `1.23.0`. Some other important dependencies:
- [graphviz](https://graphviz.org/): Graphviz is open source graph visualization software
- [go-graphviz](https://github.com/goccy/go-graphviz): Provides Go bindings for the `graphviz` package
- [DOT Language](https://graphviz.org/doc/info/lang.html): A simple DSL for defining `graphviz` nodes, edges, and graphs
## 🧑💻 Authors
- Lucas Castro ([@lucasamonrc](https://github.com/lucasamonrc)) | [lucasamonrc.dev](https://lucasamonrc.dev)