crates/rust-analyzer/src/diff.rs

   1 //! Generate minimal `TextEdit`s from different text versions
   2 use dissimilar::Chunk;
   3 use ide::{TextEdit, TextRange, TextSize};
   4
   5 pub(crate) fn diff(left: &str, right: &str) -> TextEdit {
   6     let chunks = dissimilar::diff(left, right);
   7     textedit_from_chunks(chunks)
   8 }
   9
  10 fn textedit_from_chunks(chunks: Vec<dissimilar::Chunk>) -> TextEdit {
  11     let mut builder = TextEdit::builder();
  12     let mut pos = TextSize::default();
  13
  14     let mut chunks = chunks.into_iter().peekable();
  15     while let Some(chunk) = chunks.next() {
  16         if let (Chunk::Delete(deleted), Some(&Chunk::Insert(inserted))) = (chunk, chunks.peek()) {
  17             chunks.next().unwrap();
  18             let deleted_len = TextSize::of(deleted);
  19             builder.replace(TextRange::at(pos, deleted_len), inserted.into());
  20             pos += deleted_len;
  21             continue;
  22         }
  23
  24         match chunk {
  25             Chunk::Equal(text) => {
  26                 pos += TextSize::of(text);
  27             }
  28             Chunk::Delete(deleted) => {
  29                 let deleted_len = TextSize::of(deleted);
  30                 builder.delete(TextRange::at(pos, deleted_len));
  31                 pos += deleted_len;
  32             }
  33             Chunk::Insert(inserted) => {
  34                 builder.insert(pos, inserted.into());
  35             }
  36         }
  37     }
  38     builder.finish()
  39 }
  40
  41 #[cfg(test)]
  42 mod tests {
  43     use super::*;
  44
  45     #[test]
  46     fn diff_applies() {
  47         let mut original = String::from("fn foo(a:u32){\n}");
  48         let result = "fn foo(a: u32) {}";
  49         let edit = diff(&original, result);
  50         edit.apply(&mut original);
  51         assert_eq!(original, result);
  52     }
  53 }