🐛 merge view diff bug for appended text with new line

v6
1

the reproducible bug code and example can be viewed here online.

issue

  • I want to show diff view for two texts; the new text only append some text with new line in it.
  • the diff view is expected to show only one added green new line without deleted red old line

unexpected diff view with deleted line
unexpected diff view with deleted line1496×866 45 KB

  • Could you please update the diff algorithm to correct this?
const doc = `line11
line12
line13
line14
line15
examples are strings with op
new line after will highlight current line`;

const docAppended = doc+'\nSix';

 const editor = new EditorView({
      extensions: [
        basicSetup,
        unifiedMergeView({
          original: doc,
          gutter: true,
          highlightChanges: false,
          syntaxHighlightDeletions: true,
          mergeControls: false,
        }),
      ],
      doc: docAppended,
      parent: document.body
    });
2

This is intentional behavior. Our changed chunk representation cannot have one side of the chunk’s range be outside of the document, and since there’s no valid document position beyond that last line, we must include that line (see this issue).

3

  • this issue seems to only happen at the last line in the diff view. I never have this problem in the middle of diff view

    • If so, we can keep the diff algorithm logic unchanged and only change the render logic to make the diff view visually correct

  • :bulb: I have an idea,

    • in state field deletedChunks.update , when buildDeletedChunks, ignore the last chunk to hide the unexpected red deleted line (the line above line7 in pic)
    • in view plugin decorateChunks.update, when iterating change chunks, if it’s the second-to-last chunk, ignore buildChunkDeco for it to hide the unexpected green background ( line7 in pic) because it’s unchanged visually

  • :thinking: What do you think of my solution?