WIP: auto indent on insert_at_line_start

helix-term/src/commands.rs

@@ -15,7 +15,9 @@ use helix_core::{
     history::UndoKind,
     increment, indent,
     indent::IndentStyle,
-    line_ending::{get_line_ending_of_str, line_end_char_index, str_is_line_ending},
+    line_ending::{
+        get_line_ending_of_str, line_end_char_index, line_without_line_ending, str_is_line_ending,
+    },
     match_brackets,
     movement::{self, move_vertically_visual, Direction},
     object, pos_at_coords,
@@ -2659,9 +2661,85 @@ fn last_picker(cx: &mut Context) {
 }
 
 // I inserts at the first nonwhitespace character of each line with a selection
+// If the line is empty, automatically indent
 fn insert_at_line_start(cx: &mut Context) {
-    goto_first_nonwhitespace(cx);
     enter_insert_mode(cx);
+
+    let (view, doc) = current!(cx.editor);
+
+    let text = doc.text().slice(..);
+    let contents = doc.text();
+    let selection = doc.selection(view.id);
+
+    let language_config = doc.language_config();
+    let syntax = doc.syntax();
+    let tab_width = doc.tab_width();
+
+    let mut ranges = SmallVec::with_capacity(selection.len());
+    let mut offs = 0;
+
+    let mut transaction = Transaction::change_by_selection(contents, selection, |range| {
+        let cursor = range.from();
+        let cursor_line = text.char_to_line(cursor);
+
+        let doc_end = contents.len_chars();
+        if range.from() == doc_end {
+            ranges.push(Range::point(doc_end + offs));
+            return (doc_end, doc_end, None);
+        }
+
+        let line_content = line_without_line_ending(&text, cursor_line);
+        if line_content.len_chars() == 0 {
+            // line is empty => auto indent
+            let (line_end_index, line_end_offset_width) = if cursor_line == 0 {
+                (0, 0)
+            } else {
+                (
+                    line_end_char_index(&doc.text().slice(..), cursor_line),
+                    doc.line_ending.len_chars(),
+                )
+            };
+
+            let indent = indent::indent_for_newline(
+                language_config,
+                syntax,
+                &doc.indent_style,
+                tab_width,
+                text,
+                cursor_line,
+                line_end_index,
+                cursor_line,
+            );
+
+            let indent_len = indent.len();
+            let mut text = String::with_capacity(indent_len);
+            text.push_str(&indent);
+
+            // calculate new selection ranges
+            let pos = offs + line_end_index + line_end_offset_width;
+            ranges.push(Range::point((pos + indent_len).saturating_sub(1)));
+
+            offs += text.chars().count();
+            (line_end_index, line_end_index, Some(text.into()))
+        } else {
+            // move cursor to the first non-whitespace character of the current line
+            let first_non_ws = line_content
+                .chars()
+                .enumerate()
+                .find_map(|(i, c)| if !c.is_whitespace() { Some(i) } else { None })
+                .unwrap_or_default();
+
+            let pos = offs + text.line_to_char(cursor_line) + first_non_ws;
+            ranges.push(Range::point(pos));
+            (pos, pos, None)
+        }
+    });
+
+    transaction = transaction.with_selection(Selection::new(ranges, selection.primary_index()));
+    doc.apply(&transaction, view.id);
+
+    // goto_first_nonwhitespace(cx);
+    // enter_insert_mode(cx);
 }
 
 // A inserts at the end of each line with a selection