From 35c974c9c49f9127da3798c9a8e49795b3c4aadc Mon Sep 17 00:00:00 2001
From: ath3
Date: Sun, 14 Nov 2021 16:11:53 +0100
Subject: Implement "Goto last modification" command (#1067)

---
 helix-core/src/history.rs | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

(limited to 'helix-core/src')

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();
-- 
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