acmefs: pardes --fs serves acme's control filesystem over raw Linux FUSE

1 files changed, 25 insertions, 1 deletions

diff --git a/src/file_pane.zig b/src/file_pane.zig
index 80c31edb..be3ff201 100644
--- a/src/file_pane.zig
+++ b/src/file_pane.zig
@@ -388,9 +388,33 @@ pub fn deinit(p: *Pardes, pane: *Pane, file: *State) void {
     for (file.redo[0..file.redo_len]) |snap| p.gpa.free(snap.content);
 }
 
+/// TELL A SCRIPT WHAT CHANGED, when one is listening.
+///
+/// acme reports edits from the two places that make them — `textinsert` and
+/// `textdelete`, which already know their range — so a replacement arrives as
+/// a `D` record and then an `I`. pardes has no such pair: every edit lands
+/// here as a whole new buffer, so the range is recovered by DIFFING, and
+/// `acmefs.noteReplace` owns both the diff and the D-then-I order.
+///
+/// The cost is two vectorised scans of the content, and it is paid only while
+/// a script holds an `event` file open (`p.fs.listeners`); the editor nobody
+/// is scripting does one branch. The pane lookup is a walk of at most
+/// MAX_PANES slots comparing the FILE pointer — a file pane's state is stored
+/// inline in its pane, so that identifies the pane exactly.
+fn reportEdit(p: *Pardes, f: *State, new: []const u8) void {
+    if (p.fs.listeners == 0) return;
+    const id = for (p.panes, 0..) |slot, i| {
+        const pane = slot orelse continue;
+        if (pane.file) |*state| if (state == f) break i;
+    } else return;
+    pardes.acmefs.noteReplace(p, id, false, f.content, new);
+}
+
 /// The ONE content swap. Everything that edits a file pane lands here, which
-/// is what lets the line index above have a single invalidation point.
+/// is what lets the line index above have a single invalidation point — and
+/// is why one diff HERE is every body edit a script can be told about.
 pub fn setContent(p: *Pardes, f: *State, new: []u8) void {
+    reportEdit(p, f, new);
     p.gpa.free(f.content);
     f.content = new;
     f.revision +%= 1;