Cursors

A Rust library that lets you edit String like in a modern editor (Vim, VS Code, etc.)

🔥 WIP 🔥

Features to support

Multiple cursors
Multiple selections
Move semantics for cursors
Select by regex
Copy, paste, replace semantics
Iterators over selections and cursor

Usage scenarios

Manipulate document-like strings
Multi-substring replacement
Regex based replacement

Examples

Regex substitution

#include <stdlib>
#include <stdio>

int main(){
  return 0;
}

We want to replace all headers with (header).h, i.e. we expect the result to be:

#include <stdlib.h>
#include <stdio.h>

int main(){
  return 0;
}

It's possible to use the powerful regex library to implement this. (replace_all)

If we are in a modern editor like VS Code, we can do this by: search by regex, select all text that matches, move cursor to the end of the selections, and type .h.

To do this in an elegant way, we can create some cursors like you as if you are in a modern editor.

Sample code:

fn rep(s: String) -> String {
  let mut doc = Doc::from(s);
  doc.select_regex_all("#include <(.*?)>") // Select all that matches the regex
    .add_cursor_right() // Add cursors to the right for each selection
    .insert(".h") // Insert `.h` to all selections
    .content() // Return the content
}

Insert vertically

1 + 1 <
2 + 2 =
10 + 10 >

We want to add ? to the end of each line, i.e. we expect

1 + 1 < ?
2 + 2 = ?
10 + 10 > ?

Sample code:

fn rep(s: String) -> String {
  let mut doc = Doc::from(s);
  let lines = doc.lines();
  doc.cursors()
    .add(0) // Create a cursor at the beginning of the string
    .duplicate_down(lines - 1) // Duplicate cursors
    .move_it(CursorMove::EndOfLine) // Move to the end
    .insert(String::from(" ?")); // Insert ` ?` to all cursors
    .content() // Return the content
}

Issues

It seems it's not very suitable to implement this by using Rc<RefCell> because it has runtime overhead.

linsyking / cursors