Indent draft, linewise paste

7 files changed, 209 insertions, 12 deletions

diff --git a/helix-core/src/indent.rs b/helix-core/src/indent.rs
new file mode 100644
index 00000000..c1a4fd6c
--- /dev/null
+++ b/helix-core/src/indent.rs
@@ -0,0 +1,111 @@
+use crate::{
+    syntax::Syntax,
+    tree_sitter::{Node, Tree},
+    Rope, RopeSlice, State,
+};
+
+const TAB_WIDTH: usize = 4;
+
+fn indent_level_for_line(line: RopeSlice) -> usize {
+    let mut len = 0;
+    for ch in line.chars() {
+        match ch {
+            '\t' => len += TAB_WIDTH,
+            ' ' => len += 1,
+            _ => break,
+        }
+    }
+
+    len / TAB_WIDTH
+}
+
+/// Find the highest syntax node at position.
+/// This is to identify the column where this node (e.g., an HTML closing tag) ends.
+fn get_highest_syntax_node_at_bytepos(syntax: &Syntax, pos: usize) -> Option<Node> {
+    let tree = syntax.root_layer.tree.as_ref().unwrap();
+
+    let mut node = match tree.root_node().named_descendant_for_byte_range(pos, pos) {
+        Some(node) => node,
+        None => return None,
+    };
+
+    while let Some(parent) = node.parent() {
+        if parent.start_byte() == node.start_byte() {
+            node = parent
+        } else {
+            break;
+        }
+    }
+
+    Some(node)
+}
+
+fn walk(node: Option<Node>) -> usize {
+    let node = match node {
+        Some(node) => node,
+        None => return 0,
+    };
+
+    let parent = match node.parent() {
+        Some(node) => node,
+        None => return 0,
+    };
+
+    let mut increment = 0;
+
+    let not_first_or_last_sibling = node.next_sibling().is_some() && node.prev_sibling().is_some();
+    let is_scope = true;
+
+    if not_first_or_last_sibling && is_scope {
+        increment += 1;
+    }
+
+    walk(Some(parent)) + increment
+}
+
+// for_line_at_col
+fn suggested_indent_for_line(state: &State, line_num: usize) -> usize {
+    let line = state.doc.line(line_num);
+    let current = indent_level_for_line(line);
+
+    let mut byte_start = state.doc.line_to_byte(line_num);
+
+    // find first non-whitespace char
+    for ch in line.chars() {
+        // TODO: could use memchr with chunks?
+        if ch != ' ' && ch != '\t' {
+            break;
+        }
+        byte_start += 1;
+    }
+
+    if let Some(syntax) = &state.syntax {
+        let node = get_highest_syntax_node_at_bytepos(state.syntax.as_ref().unwrap(), byte_start);
+
+        // let indentation = walk()
+        // special case for comments
+
+        // if preserve_leading_whitespace
+
+        unimplemented!()
+    } else {
+        // TODO: case for non-tree sitter grammars
+        0
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn indent_level() {
+        let line = Rope::from("        fn new"); // 8 spaces
+        assert_eq!(indent_level_for_line(line.slice(..)), 2);
+        let line = Rope::from("\t\t\tfn new"); // 3 tabs
+        assert_eq!(indent_level_for_line(line.slice(..)), 3);
+        // mixed indentation
+        let line = Rope::from("\t    \tfn new"); // 1 tab, 4 spaces, tab
+        assert_eq!(indent_level_for_line(line.slice(..)), 3);
+    }
+}
diff --git a/helix-core/src/lib.rs b/helix-core/src/lib.rs
index 4a7a2dd4..ccdc7297 100644
--- a/helix-core/src/lib.rs
+++ b/helix-core/src/lib.rs
@@ -1,6 +1,7 @@
 #![allow(unused)]
 pub mod graphemes;
 mod history;
+mod indent;
 pub mod macros;
 mod position;
 pub mod register;
diff --git a/helix-core/src/selection.rs b/helix-core/src/selection.rs
index bc677330..d3806cf3 100644
--- a/helix-core/src/selection.rs
+++ b/helix-core/src/selection.rs
@@ -110,7 +110,6 @@ impl Range {
 
     #[inline]
     pub fn fragment<'a>(&'a self, text: &'a RopeSlice) -> Cow<'a, str> {
-        // end inclusive
         Cow::from(text.slice(self.from()..self.to() + 1))
     }
 }
diff --git a/helix-core/src/state.rs b/helix-core/src/state.rs
index fde6a866..7035b27c 100644
--- a/helix-core/src/state.rs
+++ b/helix-core/src/state.rs
@@ -47,6 +47,7 @@ impl State {
     #[must_use]
     pub fn new(doc: Rope) -> Self {
         let changes = ChangeSet::new(&doc);
+        let old_state = Some((doc.clone(), Selection::single(0, 0)));
 
         Self {
             path: None,
@@ -56,7 +57,7 @@ impl State {
             restore_cursor: false,
             syntax: None,
             changes,
-            old_state: None,
+            old_state,
         }
     }
 
diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index 3e5927e5..290f2652 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -146,7 +146,7 @@ pub struct Syntax {
 
     config: Arc<HighlightConfiguration>,
 
-    root_layer: LanguageLayer,
+    pub(crate) root_layer: LanguageLayer,
 }
 
 impl Syntax {
@@ -309,7 +309,7 @@ pub struct LanguageLayer {
     // mode
     // grammar
     // depth
-    tree: Option<Tree>,
+    pub(crate) tree: Option<Tree>,
 }
 
 use crate::state::coords_at_pos;
diff --git a/helix-view/src/commands.rs b/helix-view/src/commands.rs
index e5e3244d..56e1c5db 100644
--- a/helix-view/src/commands.rs
+++ b/helix-view/src/commands.rs
@@ -241,7 +241,7 @@ pub fn select_line(view: &mut View, _count: usize) {
     let text = view.state.doc();
     let line = text.char_to_line(pos.head);
     let start = text.line_to_char(line);
-    let end = text.line_to_char(line + 1);
+    let end = text.line_to_char(line + 1).saturating_sub(1);
 
     // TODO: use a transaction
     view.state.selection = Selection::single(start, end);
@@ -249,7 +249,7 @@ pub fn select_line(view: &mut View, _count: usize) {
 
 pub fn delete_selection(view: &mut View, _count: usize) {
     let transaction =
-        Transaction::change_by_selection(&view.state, |range| (range.from(), range.to(), None));
+        Transaction::change_by_selection(&view.state, |range| (range.from(), range.to() + 1, None));
     transaction.apply(&mut view.state);
 
     append_changes_to_history(view);
@@ -267,6 +267,13 @@ pub fn collapse_selection(view: &mut View, _count: usize) {
         .transform(|range| Range::new(range.head, range.head))
 }
 
+pub fn flip_selections(view: &mut View, _count: usize) {
+    view.state.selection = view
+        .state
+        .selection
+        .transform(|range| Range::new(range.head, range.anchor))
+}
+
 fn enter_insert_mode(view: &mut View) {
     view.state.mode = Mode::Insert;
 
@@ -463,7 +470,7 @@ pub fn delete_char_forward(view: &mut View, count: usize) {
 pub fn undo(view: &mut View, _count: usize) {
     view.history.undo(&mut view.state);
 
-    // TODO: each command should simply return a Option<transaction>, then the higher level handles storing it?
+    // TODO: each command could simply return a Option<transaction>, then the higher level handles storing it?
 }
 
 pub fn redo(view: &mut View, _count: usize) {
@@ -481,11 +488,15 @@ pub fn yank(view: &mut View, _count: usize) {
         .map(|cow| cow.into_owned())
         .collect();
 
-    register::set('"', values);
+    // TODO: allow specifying reg
+    let reg = '"';
+    register::set(reg, values);
 }
 
 pub fn paste(view: &mut View, _count: usize) {
-    if let Some(values) = register::get('"') {
+    // TODO: allow specifying reg
+    let reg = '"';
+    if let Some(values) = register::get(reg) {
         let repeat = std::iter::repeat(
             values
                 .last()
@@ -493,13 +504,74 @@ pub fn paste(view: &mut View, _count: usize) {
                 .unwrap(),
         );
 
+        // TODO: if any of values ends \n it's linewise paste
+        //
+        // p => paste after
+        // P => paste before
+        // alt-p => paste every yanked selection after selected text
+        // alt-P => paste every yanked selection before selected text
+        // R => replace selected text with yanked text
+        // alt-R => replace selected text with every yanked text
+        //
+        // append => insert at next line
+        // insert => insert at start of line
+        // replace => replace
+        // default insert
+
+        let linewise = values.iter().any(|value| value.ends_with('\n'));
+
         let mut values = values.into_iter().map(Tendril::from).chain(repeat);
 
-        let transaction = Transaction::change_by_selection(&view.state, |range| {
-            (range.head + 1, range.head + 1, Some(values.next().unwrap()))
-        });
+        let transaction = if linewise {
+            // paste on the next line
+            // TODO: can simply take a range + modifier and compute the right pos without ifs
+            let text = view.state.doc();
+            Transaction::change_by_selection(&view.state, |range| {
+                let line_end = text.line_to_char(text.char_to_line(range.head) + 1);
+                (line_end, line_end, Some(values.next().unwrap()))
+            })
+        } else {
+            Transaction::change_by_selection(&view.state, |range| {
+                (range.head + 1, range.head + 1, Some(values.next().unwrap()))
+            })
+        };
 
         transaction.apply(&mut view.state);
         append_changes_to_history(view);
     }
 }
+
+const TAB_WIDTH: usize = 4;
+
+pub fn indent(view: &mut View, _count: usize) {
+    let mut lines = Vec::new();
+
+    // Get all line numbers
+    for range in view.state.selection.ranges() {
+        let start = view.state.doc.char_to_line(range.from());
+        let end = view.state.doc.char_to_line(range.to());
+
+        for line in start..=end {
+            lines.push(line)
+        }
+    }
+    lines.sort_unstable(); // sorting by usize so _unstable is preferred
+    lines.dedup();
+
+    // Indent by one level
+    let indent = Tendril::from(" ".repeat(TAB_WIDTH));
+
+    let transaction = Transaction::change(
+        &view.state,
+        lines.into_iter().map(|line| {
+            let pos = view.state.doc.line_to_char(line);
+            (pos, pos, Some(indent.clone()))
+        }),
+    );
+    transaction.apply(&mut view.state);
+    append_changes_to_history(view);
+}
+
+pub fn unindent(view: &mut View, _count: usize) {
+    unimplemented!()
+}
diff --git a/helix-view/src/keymap.rs b/helix-view/src/keymap.rs
index 8c53b403..1d7505d2 100644
--- a/helix-view/src/keymap.rs
+++ b/helix-view/src/keymap.rs
@@ -117,6 +117,15 @@ macro_rules! ctrl {
     };
 }
 
+macro_rules! alt {
+    ($ch:expr) => {
+        Key {
+            code: KeyCode::Char($ch),
+            modifiers: Modifiers::ALT,
+        }
+    };
+}
+
 pub fn default() -> Keymaps {
     hashmap!(
         state::Mode::Normal =>
@@ -145,11 +154,15 @@ pub fn default() -> Keymaps {
                 vec![key!('c')] => commands::change_selection,
                 vec![key!('s')] => commands::split_selection_on_newline,
                 vec![key!(';')] => commands::collapse_selection,
+                // TODO should be alt(;)
+                vec![key!('%')] => commands::flip_selections,
                 vec![key!('x')] => commands::select_line,
                 vec![key!('u')] => commands::undo,
                 vec![shift!('U')] => commands::redo,
                 vec![key!('y')] => commands::yank,
                 vec![key!('p')] => commands::paste,
+                vec![key!('>')] => commands::indent,
+                vec![key!('<')] => commands::unindent,
                 vec![Key {
                     code: KeyCode::Esc,
                     modifiers: Modifiers::NONE