Add trim_selections command (#1092)

4 files changed, 40 insertions, 2 deletions

diff --git a/book/src/keymap.md b/book/src/keymap.md
index 9f1714f6..69f5f02c 100644
--- a/book/src/keymap.md
+++ b/book/src/keymap.md
@@ -88,6 +88,7 @@
 | `s`      | Select all regex matches inside selections                        | `select_regex`                       |
 | `S`      | Split selection into subselections on regex matches               | `split_selection`                    |
 | `Alt-s`  | Split selection on newlines                                       | `split_selection_on_newline`         |
+| `_`      | Trim whitespace from the selection                                | `trim_selections`                    |
 | `;`      | Collapse selection onto a single cursor                           | `collapse_selection`                 |
 | `Alt-;`  | Flip selection cursor and anchor                                  | `flip_selections`                    |
 | `,`      | Keep only the primary selection                                   | `keep_primary_selection`             |
diff --git a/helix-core/src/movement.rs b/helix-core/src/movement.rs
index 9e85bd21..01a8f890 100644
--- a/helix-core/src/movement.rs
+++ b/helix-core/src/movement.rs
@@ -168,7 +168,7 @@ pub fn backwards_skip_while<F>(slice: RopeSlice, pos: usize, fun: F) -> Option<u
 where
     F: Fn(char) -> bool,
 {
-    let mut chars_starting_from_next = slice.chars_at(pos + 1);
+    let mut chars_starting_from_next = slice.chars_at(pos);
     let mut backwards = iter::from_fn(|| chars_starting_from_next.prev()).enumerate();
     backwards.find_map(|(i, c)| {
         if !fun(c) {
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index ebacb377..56cc02a2 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -272,6 +272,7 @@ impl Command {
         // TODO: different description ?
         goto_line_end_newline, "Goto line end",
         goto_first_nonwhitespace, "Goto first non-blank in line",
+        trim_selections, "Trim whitespace from selections",
         extend_to_line_start, "Extend to line start",
         extend_to_line_end, "Extend to line end",
         extend_to_line_end_newline, "Extend to line end",
@@ -584,6 +585,42 @@ fn goto_first_nonwhitespace(cx: &mut Context) {
     doc.set_selection(view.id, selection);
 }
 
+fn trim_selections(cx: &mut Context) {
+    let (view, doc) = current!(cx.editor);
+    let text = doc.text().slice(..);
+
+    let ranges: SmallVec<[Range; 1]> = doc
+        .selection(view.id)
+        .iter()
+        .filter_map(|range| {
+            if range.is_empty() || range.fragment(text).chars().all(|ch| ch.is_whitespace()) {
+                return None;
+            }
+            let mut start = range.from();
+            let mut end = range.to();
+            start = movement::skip_while(text, start, |x| x.is_whitespace()).unwrap_or(start);
+            end = movement::backwards_skip_while(text, end, |x| x.is_whitespace()).unwrap_or(end);
+            if range.anchor < range.head {
+                Some(Range::new(start, end))
+            } else {
+                Some(Range::new(end, start))
+            }
+        })
+        .collect();
+
+    if !ranges.is_empty() {
+        let primary = doc.selection(view.id).primary();
+        let idx = ranges
+            .iter()
+            .position(|range| range.overlaps(&primary))
+            .unwrap_or(ranges.len() - 1);
+        doc.set_selection(view.id, Selection::new(ranges, idx));
+    } else {
+        collapse_selection(cx);
+        keep_primary_selection(cx);
+    };
+}
+
 fn goto_window(cx: &mut Context, align: Align) {
     let (view, doc) = current!(cx.editor);
 
diff --git a/helix-term/src/keymap.rs b/helix-term/src/keymap.rs
index 3280f0f8..fc9fd590 100644
--- a/helix-term/src/keymap.rs
+++ b/helix-term/src/keymap.rs
@@ -603,7 +603,7 @@ impl Default for Keymaps {
             // "Q" => replay_macro,
 
             // & align selections
-            // _ trim selections
+            "_" => trim_selections,
 
             "(" => rotate_selections_backward,
             ")" => rotate_selections_forward,