Melody

<p align="center"> <img alt="Melody Logo" height="250px" src="https://user-images.githubusercontent.com/14347895/159069215-7da8f087-65d5-4982-9592-639c1d81e7f1.svg#gh-dark-mode-only"> <img alt="Melody Logo" height="250px" src="https://user-images.githubusercontent.com/14347895/159069181-53bce5b3-a831-43f1-8c14-af6c6ed7b92b.svg#gh-light-mode-only"> </p> <p align="center"> <a href="https://github.com/yoav-lavi/melody/actions/workflows/rust.yml"> <img alt="Rust CI" src="https://github.com/yoav-lavi/melody/actions/workflows/rust.yml/badge.svg"> </a> <a href="https://crates.io/crates/melody_compiler"> <img alt="Crates.io" src="https://img.shields.io/crates/v/melody_compiler?label=compiler"> </a> <a href="https://crates.io/crates/melody_cli"> <img alt="Crates.io" src="https://img.shields.io/crates/v/melody_cli?label=cli"> </a> <a href="https://melody-playground.vercel.app"> <img alt="melody playground" src="https://img.shields.io/badge/melody-playground-brightgreen"> </a> <a href="https://yoav-lavi.github.io/melody/book/"> <img alt="melody playground" src="https://img.shields.io/badge/melody-book-blue"> </a> </p> <p align="center"> Melody is a language that compiles to ECMAScript regular expressions, while aiming to be more readable and maintainable. </p> <p align="center"> <img width="400" alt="code example" src="https://user-images.githubusercontent.com/14347895/154124756-ddbd3c84-f8b2-45bd-b624-2c510482c4e2.png"> </p>

Examples

Note: these are for the currently supported syntax and may change

Batman Theme  _{^{<a href="https://melody-playground.vercel.app?content=MTYlMjBvZiUyMCUyMm5hJTIyJTNCJTBBJTBBMiUyMG9mJTIwbWF0Y2glMjAlN0IlMEElMjAlMjAlM0NzcGFjZSUzRSUzQiUwQSUyMCUyMCUyMmJhdG1hbiUyMiUzQiUwQSU3RCUwQSUwQSUyRiUyRiUyMCVGMCU5RiVBNiU4NyVGMCU5RiVBNiVCOCVFMiU4MCU4RCVFMiU5OSU4MiVFRiVCOCU4Rg==">try in playground</a>}}

16 of "na";

2 of match {
  <space>;
  "batman";
}

// 🦇🦸‍♂️

Turns into

(?:na){16}(?: batman){2}

Twitter Hashtag  _{^{<a href="https://melody-playground.vercel.app?content=JTIyJTIzJTIyJTNCJTBBc29tZSUyMG9mJTIwJTNDd29yZCUzRSUzQiUwQSUwQSUyRiUyRiUyMCUyM21lbG9keQ==">try in playground</a>}}

"#";
some of <word>;

// #melody

Turns into

#\w+

Introductory Courses  _{^{<a href="https://melody-playground.vercel.app?content=c29tZSUyMG9mJTIwJTNDYWxwaGFiZXRpYyUzRSUzQiUwQSUzQ3NwYWNlJTNFJTNCJTBBJTIyMSUyMiUzQiUwQTIlMjBvZiUyMCUzQ2RpZ2l0JTNFJTNCJTBBJTBBJTJGJTJGJTIwY2xhc3NuYW1lJTIwMXh4">try in playground</a>}}

some of <alphabetic>;
<space>;
"1";
2 of <digit>;

// classname 1xx

Turns into

[a-zA-Z]+ 1\d{2}

Indented Code (2 spaces)  _{^{<a href="https://melody-playground.vercel.app?content=c29tZSUyMG9mJTIwbWF0Y2glMjAlN0IlMEElMjAlMjAyJTIwb2YlMjAlM0NzcGFjZSUzRSUzQiUwQSU3RCUwQSUwQXNvbWUlMjBvZiUyMCUzQ2NoYXIlM0UlM0IlMEElMjIlM0IlMjIlM0IlMEElMEElMkYlMkYlMjBsZXQlMjB2YWx1ZSUyMCUzRCUyMDUlM0I=">try in playground</a>}}

some of match {
  2 of <space>;
}

some of <char>;
";";

// let value = 5;

Turns into

(?: {2})+.+;

Semantic Versions  _{^{<a href="https://melody-playground.vercel.app?content=JTNDc3RhcnQlM0UlM0IlMEElMEFvcHRpb24lMjBvZiUyMCUyMnYlMjIlM0IlMEElMEFjYXB0dXJlJTIwbWFqb3IlMjAlN0IlMEElMjAlMjBzb21lJTIwb2YlMjAlM0NkaWdpdCUzRSUzQiUwQSU3RCUwQSUwQSUyMi4lMjIlM0IlMEElMEFjYXB0dXJlJTIwbWlub3IlMjAlN0IlMEElMjAlMjBzb21lJTIwb2YlMjAlM0NkaWdpdCUzRSUzQiUwQSU3RCUwQSUwQSUyMi4lMjIlM0IlMEElMEFjYXB0dXJlJTIwcGF0Y2glMjAlN0IlMEElMjAlMjBzb21lJTIwb2YlMjAlM0NkaWdpdCUzRSUzQiUwQSU3RCUwQSUwQSUzQ2VuZCUzRSUzQiUwQSUwQSUyRiUyRiUyMHYxLjAuMA==">try in playground</a>}}

<start>;

option of "v";

capture major {
  some of <digit>;
}

".";

capture minor {
  some of <digit>;
}

".";

capture patch {
  some of <digit>;
}

<end>;

// v1.0.0

Turns into

^v?(?<major>\d+)\.(?<minor>\d+)\.(?<patch>\d+)$

Playground

You can try Melody in your browser using the playground

Book

Read the book here

Install

Cargo

cargo install melody_cli

From Source

git clone https://github.com/yoav-lavi/melody.git
cd melody
cargo install --path crates/melody_cli

Binary

• macOS binaries (aarch64 and x86_64) can be downloaded from the release page

Community

• Brew (macOS and Linux)

  <details><summary>Installation instructions</summary>

  brew install melody
  

  </details>

• Arch Linux (maintained by @ilai-deutel)

  <details><summary>Installation instructions</summary>

  1. Installation with an AUR helper, for instance using paru:

     paru -Syu melody
     

  2. Install manually with makepkg:

     git clone https://aur.archlinux.org/melody.git
     cd melody
     makepkg -si
     

  </details>

• NixOS (maintained by @jyooru)

  <details><summary>Installation instructions</summary>

  1. Declarative installation using /etc/nixos/configuration.nix:

     { pkgs, ... }:
     {
       environment.systemPackages = with pkgs; [
         melody
       ];
     }
     

  2. Imperative installation using nix-env:

     nix-env -iA nixos.melody
     

  </details>

CLI Usage

USAGE:
    melody [OPTIONS] [INPUT_FILE_PATH]

ARGS:
    <INPUT_FILE_PATH>    Read from a file
                         Use '-' and or pipe input to read from stdin

OPTIONS:
    -f, --test-file <TEST_FILE>
            Test the compiled regex against the contents of a file

        --generate-completions <COMPLETIONS>
            Outputs completions for the selected shell
            To use, write the output to the appropriate location for your shell

    -h, --help
            Print help information

    -n, --no-color
            Print output with no color

    -o, --output <OUTPUT_FILE_PATH>
            Write to a file

    -r, --repl
            Start the Melody REPL

    -t, --test <TEST>
            Test the compiled regex against a string

    -V, --version
            Print version information

Changelog

See the changelog here or in the release page

Syntax

Quantifiers

• ... of - used to express a specific amount of a pattern. equivalent to regex {5} (assuming 5 of ...)
• ... to ... of - used to express an amount within a range of a pattern. equivalent to regex {5,9} (assuming 5 to 9 of ...)
• over ... of - used to express more than an amount of a pattern. equivalent to regex {6,} (assuming over 5 of ...)
• some of - used to express 1 or more of a pattern. equivalent to regex +
• any of - used to express 0 or more of a pattern. equivalent to regex *
• option of - used to express 0 or 1 of a pattern. equivalent to regex ?

All quantifiers can be preceded by lazy to match the least amount of characters rather than the most characters (greedy). Equivalent to regex +?, *?, etc.

Symbols

• <char> - matches any single character. equivalent to regex .
• <space> - matches a space character. equivalent to regex
• <whitespace> - matches any kind of whitespace character. equivalent to regex \s or [ \t\n\v\f\r]
• <newline> - matches a newline character. equivalent to regex \n
• <tab> - matches a tab character. equivalent to regex \t
• <return> - matches a carriage return character. equivalent to regex \r
• <feed> - matches a form feed character. equivalent to regex \f
• <null> - matches a null characther. equivalent to regex \0
• <digit> - matches any single digit. equivalent to regex \d or [0-9]
• <vertical> - matches a vertical tab character. equivalent to regex \v
• <word> - matches a word character (any latin letter, any digit or an underscore). equivalent to regex \w or [a-zA-Z0-9_]
• <alphabetic> - matches any single latin letter. equivalent to regex [a-zA-Z]
• <alphanumeric> - matches any single latin letter or any single digit. equivalent to regex [a-zA-Z0-9]
• <boundary> - Matches a character between a character matched by <word> and a character not matched by <word> without consuming the character. equivalent to regex \b
• <backspace> - matches a backspace control character. equivalent to regex [\b]

All symbols can be preceeded with not to match any character other than the symbol

Special Symbols

• <start> - matches the start of the string. equivalent to regex ^
• <end> - matches the end of the string. equivalent to regex $

Unicode Categories

Note: these are not supported when testing in the CLI (-t or -f) as the regex engine used does not support unicode categories. These require using the u flag.

• <category::letter> - any kind of letter from any language
  • <category::lowercase_letter> - a lowercase letter that has an uppercase variant
  • <category::uppercase_letter> - an uppercase letter that has a lowercase variant.
  • <category::titlecase_letter> - a letter that appears at the start of a word when only the first letter of the word is capitalized
  • <category::cased_letter> - a letter that exists in lowercase and uppercase variants
  • <category::modifier_letter> - a special character that is used like a letter
  • <category::other_letter> - a letter or ideograph that does not have lowercase and uppercase variants
• <category::mark> - a character intended to be combined with another character (e.g. accents, umlauts,