Add modal keyboard motion mode

This implements a basic mode for navigating inside of Alacritty's
history with keyboard bindings. They're bound by default to vi's motion
shortcuts but are fully customizable. Since this relies on key bindings
only single key bindings are currently supported (so no `ge`, or
repetition).

Other than navigating the history and moving the viewport, this mode
should enable making use of all available selection modes to copy
content to the clipboard and launch URLs below the cursor.

This also changes the rendering of the block cursor at the side of
selections, since previously it could be inverted to be completely
invisible. Since that would have caused some troubles with this keyboard
selection mode, the block cursor now is no longer inverted when it is at
the edges of a selection.

Fixes #262.

2 files changed, 22 insertions, 12 deletions

diff --git a/alacritty_terminal/src/config/colors.rs b/alacritty_terminal/src/config/colors.rs
index 35c03684..5c057619 100644
--- a/alacritty_terminal/src/config/colors.rs
+++ b/alacritty_terminal/src/config/colors.rs
@@ -12,6 +12,8 @@ pub struct Colors {
     #[serde(deserialize_with = "failure_default")]
     pub cursor: CursorColors,
     #[serde(deserialize_with = "failure_default")]
+    pub vi_mode_cursor: CursorColors,
+    #[serde(deserialize_with = "failure_default")]
     pub selection: SelectionColors,
     #[serde(deserialize_with = "failure_default")]
     normal: NormalColors,
diff --git a/alacritty_terminal/src/config/mod.rs b/alacritty_terminal/src/config/mod.rs
index da95391c..df8d37bd 100644
--- a/alacritty_terminal/src/config/mod.rs
+++ b/alacritty_terminal/src/config/mod.rs
@@ -28,7 +28,7 @@ mod scrolling;
 mod visual_bell;
 mod window;
 
-use crate::ansi::{Color, CursorStyle, NamedColor};
+use crate::ansi::{CursorStyle, NamedColor};
 
 pub use crate::config::colors::Colors;
 pub use crate::config::debug::Debug;
@@ -170,16 +170,28 @@ impl<T> Config<T> {
         self.dynamic_title.0
     }
 
-    /// Cursor foreground color
+    /// Cursor foreground color.
     #[inline]
     pub fn cursor_text_color(&self) -> Option<Rgb> {
         self.colors.cursor.text
     }
 
-    /// Cursor background color
+    /// Cursor background color.
     #[inline]
-    pub fn cursor_cursor_color(&self) -> Option<Color> {
-        self.colors.cursor.cursor.map(|_| Color::Named(NamedColor::Cursor))
+    pub fn cursor_cursor_color(&self) -> Option<NamedColor> {
+        self.colors.cursor.cursor.map(|_| NamedColor::Cursor)
+    }
+
+    /// Vi mode cursor foreground color.
+    #[inline]
+    pub fn vi_mode_cursor_text_color(&self) -> Option<Rgb> {
+        self.colors.vi_mode_cursor.text
+    }
+
+    /// Vi mode cursor background color.
+    #[inline]
+    pub fn vi_mode_cursor_cursor_color(&self) -> Option<Rgb> {
+        self.colors.vi_mode_cursor.cursor
     }
 
     #[inline]
@@ -230,20 +242,16 @@ impl Default for EscapeChars {
 }
 
 #[serde(default)]
-#[derive(Copy, Clone, Debug, Deserialize, PartialEq, Eq)]
+#[derive(Deserialize, Copy, Clone, Debug, Default, PartialEq, Eq)]
 pub struct Cursor {
     #[serde(deserialize_with = "failure_default")]
     pub style: CursorStyle,
+    #[serde(deserialize_with = "option_explicit_none")]
+    pub vi_mode_style: Option<CursorStyle>,
     #[serde(deserialize_with = "failure_default")]
     unfocused_hollow: DefaultTrueBool,
 }
 
-impl Default for Cursor {
-    fn default() -> Self {
-        Self { style: Default::default(), unfocused_hollow: Default::default() }
-    }
-}
-
 impl Cursor {
     pub fn unfocused_hollow(self) -> bool {
         self.unfocused_hollow.0