Add home-end keymaps, (as kakoune/vim do) (#83)

* add home-end keymaps

* implement extend methods for extend_line_start, extend_line_end

* add home-end mappings to keymaps.md

* add ^-$ extend mappings for extend mode

* pass cargo linter

3 files changed, 55 insertions, 4 deletions

diff --git a/book/src/keymap.md b/book/src/keymap.md
index 234766ca..003d0845 100644
--- a/book/src/keymap.md
+++ b/book/src/keymap.md
@@ -17,6 +17,8 @@
 | f   | find next char |
 | T   | find 'till previous char |
 | F   | find previous char |
+| Home   | move to the start of the line |
+| End   | move to the end of the line |
 | m   | Jump to matching bracket | 
 | PageUp | Move page up |
 | PageDown | Move page down |
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 796493ea..bc11d0fe 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -573,6 +573,37 @@ pub fn extend_line_down(cx: &mut Context) {
     doc.set_selection(view.id, selection);
 }
 
+pub fn extend_line_end(cx: &mut Context) {
+    let (view, doc) = cx.current();
+
+    let selection = doc.selection(view.id).transform(|range| {
+        let text = doc.text();
+        let line = text.char_to_line(range.head);
+
+        // Line end is pos at the start of next line - 1
+        // subtract another 1 because the line ends with \n
+        let pos = text.line_to_char(line + 1).saturating_sub(2);
+        Range::new(range.anchor, pos)
+    });
+
+    doc.set_selection(view.id, selection);
+}
+
+pub fn extend_line_start(cx: &mut Context) {
+    let (view, doc) = cx.current();
+
+    let selection = doc.selection(view.id).transform(|range| {
+        let text = doc.text();
+        let line = text.char_to_line(range.head);
+
+        // adjust to start of the line
+        let pos = text.line_to_char(line);
+        Range::new(range.anchor, pos)
+    });
+
+    doc.set_selection(view.id, selection);
+}
+
 pub fn select_all(cx: &mut Context) {
     let (view, doc) = cx.current();
 
diff --git a/helix-term/src/keymap.rs b/helix-term/src/keymap.rs
index b1d8428b..7376cd03 100644
--- a/helix-term/src/keymap.rs
+++ b/helix-term/src/keymap.rs
@@ -61,8 +61,8 @@ use std::collections::HashMap;
 //          in kakoune these are alt-h alt-l / gh gl
 //                              select from curs to begin end / move curs to begin end
 //          0 = start of line
-//          ^ = start of line (first non blank char)
-//          $ = end of line
+//          ^ = start of line(first non blank char) || Home  = start of line(first non blank char)
+//          $ = end of line                         || End   = end of line
 //
 //          z = save selections
 //          Z = restore selections
@@ -153,6 +153,16 @@ pub fn default() -> Keymaps {
         //
         key!('r') => commands::replace,
 
+        KeyEvent {
+            code: KeyCode::Home,
+            modifiers: KeyModifiers::NONE
+        } => commands::move_line_start,
+
+        KeyEvent {
+            code: KeyCode::End,
+            modifiers: KeyModifiers::NONE
+        } => commands::move_line_end,
+
         key!('w') => commands::move_next_word_start,
         key!('b') => commands::move_prev_word_start,
         key!('e') => commands::move_next_word_end,
@@ -306,13 +316,21 @@ pub fn default() -> Keymaps {
 
             key!('t') => commands::extend_till_char,
             key!('f') => commands::extend_next_char,
+
             key!('T') => commands::extend_till_prev_char,
             key!('F') => commands::extend_prev_char,
-
+            KeyEvent {
+                code: KeyCode::Home,
+                modifiers: KeyModifiers::NONE
+            } => commands::extend_line_start,
+            KeyEvent {
+                code: KeyCode::End,
+                modifiers: KeyModifiers::NONE
+            } => commands::extend_line_end,
             KeyEvent {
                 code: KeyCode::Esc,
                 modifiers: KeyModifiers::NONE
-            } => commands::exit_select_mode as Command,
+            } => commands::exit_select_mode,
         )
         .into_iter(),
     );