Smart tab (aka tabout)

book/src/configuration.md

@@ -347,3 +347,11 @@ max-wrap = 25 # increase value to reduce forced mid-word wrapping
 max-indent-retain = 0
 wrap-indicator = ""  # set wrap-indicator to "" to hide it
 ```
+
+### `[editor.smart-tab]` Section
+
+
+| Key        | Description | Default |
+|------------|-------------|---------|
+| `enable` | If set to true, then when the cursor is in a position with non-whitespace to its left, instead of inserting a tab, it will run `move_parent_node_end`. If there is only whitespace to the left, then it inserts a tab as normal. With the default bindings, to explicitly insert a tab character, press Shift-tab. | `true` |
+| `supersede-menu` | Normally, when a menu is on screen, such as when auto complete is triggered, the tab key is bound to cycling through the items. This means when menus are on screen, one cannot use the tab key to trigger the `smart-tab` command. If this option is set to true, the `smart-tab` command always takes precedence, which means one cannot use the tab key to cycle through menu items. One of the other bindings must be used instead, such as arrow keys or `C-n`/`C-p`. | `false` |

helix-core/src/movement.rs

@@ -16,7 +16,7 @@ use crate::{
     syntax::LanguageConfiguration,
     text_annotations::TextAnnotations,
     textobject::TextObject,
-    visual_offset_from_block, Range, RopeSlice,
+    visual_offset_from_block, Range, RopeSlice, Selection, Syntax,
 };
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
@@ -556,6 +556,85 @@ pub fn goto_treesitter_object(
     last_range
 }
 
+fn find_parent_start(mut node: Node) -> Option<Node> {
+    let start = node.start_byte();
+
+    while node.start_byte() >= start || !node.is_named() {
+        node = node.parent()?;
+    }
+
+    Some(node)
+}
+
+pub fn move_parent_node_end(
+    syntax: &Syntax,
+    text: RopeSlice,
+    selection: Selection,
+    dir: Direction,
+    movement: Movement,
+) -> Selection {
+    let tree = syntax.tree();
+
+    selection.transform(|range| {
+        let start_from = text.char_to_byte(range.from());
+        let start_to = text.char_to_byte(range.to());
+
+        let mut node = match tree
+            .root_node()
+            .named_descendant_for_byte_range(start_from, start_to)
+        {
+            Some(node) => node,
+            None => {
+                log::debug!(
+                    "no descendant found for byte range: {} - {}",
+                    start_from,
+                    start_to
+                );
+                return range;
+            }
+        };
+
+        let mut end_head = match dir {
+            // moving forward, we always want to move one past the end of the
+            // current node, so use the end byte of the current node, which is an exclusive
+            // end of the range
+            Direction::Forward => text.byte_to_char(node.end_byte()),
+
+            // moving backward, we want the cursor to land on the start char of
+            // the current node, or if it is already at the start of a node, to traverse up to
+            // the parent
+            Direction::Backward => {
+                let end_head = text.byte_to_char(node.start_byte());
+
+                // if we're already on the beginning, look up to the parent
+                if end_head == range.cursor(text) {
+                    node = find_parent_start(node).unwrap_or(node);
+                    text.byte_to_char(node.start_byte())
+                } else {
+                    end_head
+                }
+            }
+        };
+
+        if movement == Movement::Move {
+            // preserve direction of original range
+            if range.direction() == Direction::Forward {
+                Range::new(end_head, end_head + 1)
+            } else {
+                Range::new(end_head + 1, end_head)
+            }
+        } else {
+            // if we end up with a forward range, then adjust it to be one past
+            // where we want
+            if end_head >= range.anchor {
+                end_head += 1;
+            }
+
+            Range::new(range.anchor, end_head)
+        }
+    })
+}
+
 #[cfg(test)]
 mod test {
     use ropey::Rope;

helix-term/src/application.rs

@@ -33,12 +33,9 @@ use crate::{
 };
 
 use log::{debug, error, warn};
-use std::{
-    collections::btree_map::Entry,
-    io::{stdin, stdout},
-    path::Path,
-    sync::Arc,
-};
+#[cfg(not(feature = "integration"))]
+use std::io::stdout;
+use std::{collections::btree_map::Entry, io::stdin, path::Path, sync::Arc};
 
 use anyhow::{Context, Error};
 

helix-term/src/commands.rs

@@ -247,6 +247,8 @@ impl MappableCommand {
         move_prev_long_word_start, "Move to start of previous long word",
         move_next_long_word_end, "Move to end of next long word",
         move_prev_long_word_end, "Move to end of previous long word",
+        move_parent_node_end, "Move to end of the parent node",
+        move_parent_node_start, "Move to beginning of the parent node",
         extend_next_word_start, "Extend to start of next word",
         extend_prev_word_start, "Extend to start of previous word",
         extend_next_word_end, "Extend to end of next word",
@@ -255,6 +257,8 @@ impl MappableCommand {
         extend_prev_long_word_start, "Extend to start of previous long word",
         extend_next_long_word_end, "Extend to end of next long word",
         extend_prev_long_word_end, "Extend to end of prev long word",
+        extend_parent_node_end, "Extend to end of the parent node",
+        extend_parent_node_start, "Extend to beginning of the parent node",
         find_till_char, "Move till next occurrence of char",
         find_next_char, "Move to next occurrence of char",
         extend_till_char, "Extend till next occurrence of char",
@@ -361,6 +365,7 @@ impl MappableCommand {
         extend_to_line_end, "Extend to line end",
         extend_to_line_end_newline, "Extend to line end",
         signature_help, "Show signature help",
+        smart_tab, "Insert tab if all cursors have all whitespace to their left; otherwise, run a separate command.",
         insert_tab, "Insert tab char",
         insert_newline, "Insert newline char",
         delete_char_backward, "Delete previous char",
@@ -2517,6 +2522,10 @@ fn insert_mode(cx: &mut Context) {
         .transform(|range| Range::new(range.to(), range.from()));
 
     doc.set_selection(view.id, selection);
+
+    // [TODO] temporary workaround until we're not using the idle timer to
+    //        trigger auto completions any more
+    cx.editor.clear_idle_timer();
 }
 
 // inserts at the end of each selection
@@ -3440,6 +3449,7 @@ pub mod insert {
     }
 
     use helix_core::auto_pairs;
+    use helix_view::editor::SmartTabConfig;
 
     pub fn insert_char(cx: &mut Context, c: char) {
         let (view, doc) = current_ref!(cx.editor);
@@ -3465,6 +3475,31 @@ pub mod insert {
         }
     }
 
+    pub fn smart_tab(cx: &mut Context) {
+        let (view, doc) = current_ref!(cx.editor);
+        let view_id = view.id;
+
+        if matches!(
+            cx.editor.config().smart_tab,
+            Some(SmartTabConfig { enable: true, .. })
+        ) {
+            let cursors_after_whitespace = doc.selection(view_id).ranges().iter().all(|range| {
+                let cursor = range.cursor(doc.text().slice(..));
+                let current_line_num = doc.text().char_to_line(cursor);
+                let current_line_start = doc.text().line_to_char(current_line_num);
+                let left = doc.text().slice(current_line_start..cursor);
+                left.chars().all(|c| c.is_whitespace())
+            });
+
+            if !cursors_after_whitespace {
+                move_parent_node_end(cx);
+                return;
+            }
+        }
+
+        insert_tab(cx);
+    }
+
     pub fn insert_tab(cx: &mut Context) {
         let (view, doc) = current!(cx.editor);
         // TODO: round out to nearest indentation level (for example a line with 3 spaces should
@@ -4605,6 +4640,49 @@ fn select_prev_sibling(cx: &mut Context) {
     select_sibling_impl(cx, &|node| Node::prev_sibling(&node))
 }
 
+fn move_node_bound_impl(cx: &mut Context, dir: Direction, movement: Movement) {
+    let motion = move |editor: &mut Editor| {
+        let (view, doc) = current!(editor);
+
+        if let Some(syntax) = doc.syntax() {
+            let text = doc.text().slice(..);
+            let current_selection = doc.selection(view.id);
+
+            let selection = movement::move_parent_node_end(
+                syntax,
+                text,
+                current_selection.clone(),
+                dir,
+                movement,
+            );
+
+            doc.set_selection(view.id, selection);
+
+            // [TODO] temporary workaround until we're not using the idle timer to
+            //        trigger auto completions any more
+            editor.clear_idle_timer();
+        }
+    };
+
+    cx.editor.apply_motion(motion);
+}
+
+pub fn move_parent_node_end(cx: &mut Context) {
+    move_node_bound_impl(cx, Direction::Forward, Movement::Move)
+}
+
+pub fn move_parent_node_start(cx: &mut Context) {
+    move_node_bound_impl(cx, Direction::Backward, Movement::Move)
+}
+
+pub fn extend_parent_node_end(cx: &mut Context) {
+    move_node_bound_impl(cx, Direction::Forward, Movement::Extend)
+}
+
+pub fn extend_parent_node_start(cx: &mut Context) {
+    move_node_bound_impl(cx, Direction::Backward, Movement::Extend)
+}
+
 fn match_brackets(cx: &mut Context) {
     let (view, doc) = current!(cx.editor);
     let is_select = cx.editor.mode == Mode::Select;

helix-term/src/config.rs

@@ -109,6 +109,7 @@ impl Config {
                     )?,
                 }
             }
+
             // these are just two io errors return the one for the global config
             (Err(err), Err(_)) => return Err(err),
         };

helix-term/src/keymap/default.rs

@@ -88,6 +88,8 @@ pub fn default() -> HashMap<Mode, KeyTrie> {
         "A-i" | "A-down" => shrink_selection,
         "A-p" | "A-left" => select_prev_sibling,
         "A-n" | "A-right" => select_next_sibling,
+        "A-e" => move_parent_node_end,
+        "A-b" => move_parent_node_start,
 
         "%" => select_all,
         "x" => extend_line_below,
@@ -336,6 +338,9 @@ pub fn default() -> HashMap<Mode, KeyTrie> {
         "B" => extend_prev_long_word_start,
         "E" => extend_next_long_word_end,
 
+        "A-e" => extend_parent_node_end,
+        "A-b" => extend_parent_node_start,
+
         "n" => extend_search_next,
         "N" => extend_search_prev,
 
@@ -368,7 +373,8 @@ pub fn default() -> HashMap<Mode, KeyTrie> {
         "C-h" | "backspace" | "S-backspace" => delete_char_backward,
         "C-d" | "del" => delete_char_forward,
         "C-j" | "ret" => insert_newline,
-        "tab" => insert_tab,
+        "tab" => smart_tab,
+        "S-tab" => insert_tab,
 
         "up" => move_visual_line_up,
         "down" => move_visual_line_down,

helix-term/src/ui/menu.rs

@@ -11,7 +11,7 @@ pub use tui::widgets::{Cell, Row};
 use fuzzy_matcher::skim::SkimMatcherV2 as Matcher;
 use fuzzy_matcher::FuzzyMatcher;
 
-use helix_view::{graphics::Rect, Editor};
+use helix_view::{editor::SmartTabConfig, graphics::Rect, Editor};
 use tui::layout::Constraint;
 
 pub trait Item {
@@ -247,6 +247,21 @@ impl<T: Item + 'static> Component for Menu<T> {
             compositor.pop();
         }));
 
+        // Ignore tab key when supertab is turned on in order not to interfere
+        // with it. (Is there a better way to do this?)
+        if (event == key!(Tab) || event == shift!(Tab))
+            && cx.editor.config().auto_completion
+            && matches!(
+                cx.editor.config().smart_tab,
+                Some(SmartTabConfig {
+                    enable: true,
+                    supersede_menu: true,
+                })
+            )
+        {
+            return EventResult::Ignored(None);
+        }
+
         match event {
             // esc or ctrl-c aborts the completion and closes the menu
             key!(Esc) | ctrl!('c') => {

helix-term/tests/test/commands.rs

@@ -2,6 +2,7 @@ use helix_term::application::Application;
 
 use super::*;
 
+mod movement;
 mod write;
 
 #[tokio::test(flavor = "multi_thread")]