refactory_string 0.1.0

A library to modify a string using original indices. Useful for Source Code transformations.


A library to modify a string using original indices, inspired by Rich Harris' MagicString (see here).

Suppose you have some source code and you want to modify it. If the source code that you're using doesn't have a lossless AST parser and writer, you won't be able to parse it, update it, then save it back. This is where RefactoryString comes in handy; it allows you to modify a text content using its original indices. It is also very fast.

For example, you may want to replace the variable name i in the following code:

let i = 1;
println!("{}", i + 5);

One struggle is to do the transformation in order, and you need to reparse the AST everytime you add something new. With RefactoryString you don't need to worry about it; just overwrite, append or prepend to the left or right of indices in the original string, and serialize to string;

fn do_it() -> Result<(), refactory_string::Error> {
    let example = String::from(r#"let i = 1;\nprintln!("{}", i + 5);"#);
    let mut rs = RefactoryString::new(&example);


    assert_eq!(&rs.to_string()?, r#"let new_var_name = 1;\nprintln!("{}", new_var_name + 5);"#);



The RefactoryString type deals with strings, but this crate also export a type that can deal with binary data; RefactoryBuffer. This is the same structure but replaces to_string() with to_bytes(), which returns a Vec<u8>.


See our issue list here.