/melody

Melody is a language that compiles to regular expressions and aims to be more easily readable and maintainable

Primary LanguageRustMIT LicenseMIT

code example

Melody is a language designed to compile to and maintain a 1-1 relationship with regular expressions, while being more readable and maintainable.

The current goal is supporting the JavaScript implementation of regular expressions.

⚠️ Melody is very new and is unstable at the moment ⚠️

Examples

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

Batman Theme

16 of "na";

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

// 🦇🦸‍♂️

Turns into

/(?:na){16}(?:\sbatman){2}/

Twitter Hashtag

"#";
some of <word>;

// #melody

Turns into

/#\w+/

Introductory Courses

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

// classname 1xx

Turns into

/\w+\s1\d{2}/

Indented Code (2 spaces)

some of match {
  2 of <space>;
}

some of char;
";";

//  let value = 5;

Turns into

/(?:\s{2})+.+;/

Playground

You can try Melody in your browser using the playground

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

CLI Usage

melody [OPTIONS] <PATH>

OPTIONS:
  -f, --file <FILE>    write to an output file
  -n, --no-color       print output with no color
  -V, --version        print version information
  -h, --help           print help information

Keywords

  • of - used after a number or a range and before a sequence to be matched, e.g. 5 of "A";, equivalent to regex {5}
  • to - used to create a range (either as a quantifier or as a character range), e.g. 5 to 9, equivalent to regex {5,9} if before an of or [5-9] otherwise
  • capture - used to open a capture or named capture block, equivalent to regex (...)
  • match - used to open a match block, equivalent to regex (?:...)
  • start - matches the start of the string, equivalent to regex ^
  • end - matches the end of the string, equivalent to regex $
  • char - matches a single character, equivalent to regex .
  • some - used with of to express 1 or more of a pattern, equivalent to regex +
  • over - used with of to express more than an amount of a pattern, equivalent to regex {6,} (assuming over 5 of ...)

Symbols

  • <space> - equivalent to regex \s
  • <newline> - equivalent to regex \n
  • <tab> - equivalent to regex \t
  • <return> - equivalent to regex \r
  • <feed> - equivalent to regex \f
  • <null> - equivalent to regex \0
  • <digit> - equivalent to regex \d
  • <vertical> - equivalent to regex \v
  • <word> - equivalent to regex \w

Concepts

  • "..." or '...' - used to mark a literal part of the match

Extras

  • // - used to mark comments

File Extension

The Melody file extension is .mdy

Crates

  • melody_compiler - The Melody compiler 📦 📖
  • melody_cli - A CLI wrapping the Melody compiler 📦 📖
  • melody_wasm - WASM binding for the Melody compiler

Extensions

Feature Status

✅ - Implemented

🐣 - Partially implemented

❌ - Not implemented

❓ - Unclear whether this will be implemented

❔ - Unclear what the syntax will be

Melody Regex Status
5 of "hello"; (?:hello){5} ✅
5 to 7 of "A"; A{5,7} ✅
capture { ... } (...) ✅
capture name { ... } (?<name>...) ✅
match { ... } (?:...) ✅
<space>; \s ✅
A to Z; [A-Z] ✅
a to z; [a-z] ✅
0 to 9; [0-9] ✅
// comment ✅
start; ^ ✅
end; $ ✅
<newline>; \n ✅
<tab>; \t ✅
<return>; \r ✅
<feed>; \f ✅
<null>; \0 ✅
<digit>; \d ✅
<vertical>; \v ✅
<word>; \w ✅
"..."; (raw) ... ✅
'...'; (raw) ... ✅
'\''; ' ✅
"\""; " ✅
support non alphanumeric characters ✅
output to file ✅
no color output ✅
char . ✅
some of + ✅
syntax highlighting extension ✅
over 5 of "A"; A{6,} ✅
WASM binding ✅
Rust crate ✅
enforce group close 🐣
tests 🐣
not <space>; \S ❌
not <digit>; \D ❌
not <word>; \W ❌
<backspace> [\b] ❌
file watcher ❌
nested groups (...(...)) ❌
multiple ranges [a-zA-Z0-9] ❌
general cleanup and modules ❌
auto escape for non Melody patterns ❌
TS / JS build step ❌
more robust parsing mechanism (ast) ❌
not "A"; [^A] ❔
flags: global, multiline, ... /.../gm... ❔
/* comment */ ❔
maybe of ? ❔
maybe some of * ❔
either of ..., ... | ❔
any of "a", "b", "c" [abc] ❔
... not before ... ...(?!...) ❔
... not after ... ...(?<!...) ❔
... before ... ...(?=...) ❔
... after ... ...(?<=...) ❔
(?) *? ❔
(?) \# ❔
(?) \k<name> ❔
(?) \p{...} ❔
(?) \P{...} ❔
(?) \uYYYY ❔
(?) \xYY ❔
(?) \ddd ❔
(?) \cY ❔
(?) \b ❔
(?) \B ❔
(?) $1 ❔
(?) $` ❔
(?) $& ❔
(?) x20 ❔
(?) x{06fa} ❔
variables / macros ❓
regex optimization ❓
standard library / patterns ❓
reverse compiler ❓

Acknowledgments

Melody uses: