From 35c974c9c49f9127da3798c9a8e49795b3c4aadc Mon Sep 17 00:00:00 2001
From: ath3 <45574139+ath3@users.noreply.github.com>
Date: Sun, 14 Nov 2021 16:11:53 +0100
Subject: [PATCH] Implement "Goto last modification" command (#1067)

---
 book/src/keymap.md          |  1 +
 helix-core/src/history.rs   | 30 +++++++++++++++++++++++++++++-
 helix-term/src/commands.rs  | 14 ++++++++++++++
 helix-term/src/keymap.rs    |  1 +
 helix-term/src/ui/editor.rs |  2 +-
 helix-view/src/document.rs  |  2 +-
 6 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/book/src/keymap.md b/book/src/keymap.md
index c544a472..6155e553 100644
--- a/book/src/keymap.md
+++ b/book/src/keymap.md
@@ -165,6 +165,7 @@ Jumps to various locations.
 | `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 b53c01fe..bf2624e2 100644
--- a/helix-core/src/history.rs
+++ b/helix-core/src/history.rs
@@ -1,4 +1,4 @@
-use crate::{ChangeSet, Rope, State, Transaction};
+use crate::{Assoc, ChangeSet, Rope, State, Transaction};
 use once_cell::sync::Lazy;
 use regex::Regex;
 use std::num::NonZeroUsize;
@@ -133,6 +133,34 @@ impl History {
         Some(&self.revisions[last_child.get()].transaction)
     }
 
+    // Get the position of last change
+    pub fn last_edit_pos(&self) -> Option<usize> {
+        if self.current == 0 {
+            return None;
+        }
+        let current_revision = &self.revisions[self.current];
+        let primary_selection = current_revision
+            .inversion
+            .selection()
+            .expect("inversion always contains a selection")
+            .primary();
+        let (_from, to, _fragment) = current_revision
+            .transaction
+            .changes_iter()
+            // find a change that matches the primary selection
+            .find(|(from, to, _fragment)| {
+                crate::Range::new(*from, *to).overlaps(&primary_selection)
+            })
+            // or use the first change
+            .or_else(|| current_revision.transaction.changes_iter().next())
+            .unwrap();
+        let pos = current_revision
+            .transaction
+            .changes()
+            .map_pos(to, Assoc::After);
+        Some(pos)
+    }
+
     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 d5a48c5f..e37265a8 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -257,6 +257,7 @@ 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",
@@ -3195,6 +3196,19 @@ 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.get_mut().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 e3e01995..b14b1a6f 100644
--- a/helix-term/src/keymap.rs
+++ b/helix-term/src/keymap.rs
@@ -525,6 +525,7 @@ 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 dcf87203..bcd9f8f0 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -743,7 +743,7 @@ 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 6b429151..76b19a07 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -98,7 +98,7 @@ pub struct Document {
     // It can be used as a cell where we will take it out to get some parts of the history and put
     // it back as it separated from the edits. We could split out the parts manually but that will
     // be more troublesome.
-    history: Cell<History>,
+    pub history: Cell<History>,
 
     pub savepoint: Option<Transaction>,