refactory_string 0.1.4

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). Downloads GitHub Workflow Status rustc ^1.38.0

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 with new_var_name in the following code:

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

One struggle is to do the transformation in the appropriate order (so you have to queue all changes), 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);

    rs.overwrite(4, 5, "new_var_name")?;
    rs.overwrite(27, 28, "new_var_name")?;  // Using indices in the original content.

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


Documentation can be found here and is always improving.


See our issue list here.