From 9fe9c0f99c109a39588d9fe20a3bd80fae05acf1 Mon Sep 17 00:00:00 2001
From: ath3 <ha05190@protonmail.com>
Date: Thu, 11 Nov 2021 17:14:26 +0100
Subject: [PATCH] Implement "Goto last modification" command

---
 book/src/keymap.md          |  1 +
 helix-core/src/history.rs   | 26 ++++++++++++++++++++++++++
 helix-term/src/commands.rs  | 14 ++++++++++++++
 helix-term/src/keymap.rs    |  1 +
 helix-term/src/ui/editor.rs |  2 +-
 helix-view/src/document.rs  |  5 +++++
 6 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/book/src/keymap.md b/book/src/keymap.md
index 901c84711c72d..1da59cccf6e60 100644
--- a/book/src/keymap.md
+++ b/book/src/keymap.md
@@ -162,6 +162,7 @@ active language server for the file to work.
 | `a`   | Go to the last accessed/alternate file           | `goto_last_accessed_file`  |
 | `n`   | Go to next buffer                                | `goto_next_buffer`         |
 | `p`   | Go to previous buffer                            | `goto_previous_buffer`     |
+| `.`   | Go to last modification in current file          | `goto_last_modification`   |
 
 #### Match mode
 
diff --git a/helix-core/src/history.rs b/helix-core/src/history.rs
index b53c01fe759df..8359baa9048b6 100644
--- a/helix-core/src/history.rs
+++ b/helix-core/src/history.rs
@@ -133,6 +133,32 @@ impl History {
         Some(&self.revisions[last_child.get()].transaction)
     }
 
+    // Get the position of last change
+    pub fn last_edit_pos(&self) -> Option<usize> {
+        let current_revision = &self.revisions[self.current];
+        let mut primary_selection = 0;
+        if let Some(tsel) = current_revision.transaction.selection() {
+            if let Some(isel) = current_revision.inversion.selection() {
+                if isel.len() <= tsel.len() {
+                    primary_selection = isel.primary_index();
+                }
+            }
+        }
+        if let Some((pos, _, _)) = &current_revision
+            .transaction
+            .changes_iter()
+            .nth(primary_selection)
+        {
+            let mpos = current_revision
+                .transaction
+                .changes()
+                .map_pos(*pos, crate::Assoc::After);
+            Some(mpos)
+        } else {
+            None
+        }
+    }
+
     fn lowest_common_ancestor(&self, mut a: usize, mut b: usize) -> usize {
         use std::collections::HashSet;
         let mut a_path_set = HashSet::new();
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 738621b0466f8..6d985e752c8a2 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -259,6 +259,7 @@ impl Command {
         goto_window_middle, "Goto window middle",
         goto_window_bottom, "Goto window bottom",
         goto_last_accessed_file, "Goto last accessed file",
+        goto_last_modification, "Goto last modification",
         goto_line, "Goto line",
         goto_last_line, "Goto last line",
         goto_first_diag, "Goto first diagnostic",
@@ -3196,6 +3197,19 @@ fn goto_last_accessed_file(cx: &mut Context) {
     }
 }
 
+fn goto_last_modification(cx: &mut Context) {
+    let (view, doc) = current!(cx.editor);
+    let pos = doc.history().unwrap().last_edit_pos();
+    let text = doc.text().slice(..);
+    if let Some(pos) = pos {
+        let selection = doc
+            .selection(view.id)
+            .clone()
+            .transform(|range| range.put_cursor(text, pos, doc.mode == Mode::Select));
+        doc.set_selection(view.id, selection);
+    }
+}
+
 fn select_mode(cx: &mut Context) {
     let (view, doc) = current!(cx.editor);
     let text = doc.text().slice(..);
diff --git a/helix-term/src/keymap.rs b/helix-term/src/keymap.rs
index b2b865e434c57..547f3817412cd 100644
--- a/helix-term/src/keymap.rs
+++ b/helix-term/src/keymap.rs
@@ -509,6 +509,7 @@ impl Default for Keymaps {
                 "a" => goto_last_accessed_file,
                 "n" => goto_next_buffer,
                 "p" => goto_previous_buffer,
+                "." => goto_last_modification,
             },
             ":" => command_mode,
 
diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index 90f09e9c9db15..5f53ca58e5f4a 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -741,7 +741,7 @@ impl EditorView {
                     std::num::NonZeroUsize::new(cxt.editor.count.map_or(i, |c| c.get() * 10 + i));
             }
             // special handling for repeat operator
-            key!('.') => {
+            key!('.') if self.keymaps.pending().is_empty() => {
                 // first execute whatever put us into insert mode
                 self.last_insert.0.execute(cxt);
                 // then replay the inputs
diff --git a/helix-view/src/document.rs b/helix-view/src/document.rs
index 80f6a740f81aa..8bd5a69566629 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -782,6 +782,11 @@ impl Document {
         success
     }
 
+    // Get reference to history
+    pub fn history(&self) -> Option<&History> {
+        unsafe { self.history.as_ptr().as_ref() }
+    }
+
     /// Commit pending changes to history
     pub fn append_changes_to_history(&mut self, view_id: ViewId) {
         if self.changes.is_empty() {