Adding dynamic_title property to configuration (#819)

This logic is applied in Term's ansi::Handler implementation
to avoid unnecessary allocations.

alacritty.yml

@@ -204,6 +204,8 @@ mouse:
 selection:
   semantic_escape_chars: ",│`|:\"' ()[]{}<>"
 
+dynamic_title: true
+
 hide_cursor_when_typing: false
 
 # Style of the cursor

alacritty_macos.yml

@@ -185,6 +185,8 @@ mouse:
 selection:
   semantic_escape_chars: ",│`|:\"' ()[]{}<>"
 
+dynamic_title: true
+
 hide_cursor_when_typing: false
 
 # Style of the cursor

src/config.rs

@@ -307,6 +307,10 @@ pub struct Config {
     #[serde(default)]
     visual_bell: VisualBellConfig,
 
+    /// Use dynamic title
+    #[serde(default="true_bool")]
+    dynamic_title: bool,
+
     /// Hide cursor when typing
     #[serde(default)]
     hide_cursor_when_typing: bool,
@@ -371,6 +375,7 @@ impl Default for Config {
             env: Default::default(),
             hide_cursor_when_typing: Default::default(),
             cursor_style: Default::default(),
+            dynamic_title: Default::default(),
             live_config_reload: true,
             window: Default::default(),
         }
@@ -1240,6 +1245,11 @@ impl Config {
         self.live_config_reload
     }
 
+    #[inline]
+    pub fn dynamic_title(&self) -> bool {
+        self.dynamic_title
+    }
+
     pub fn load_from<P: Into<PathBuf>>(path: P) -> Result<Config> {
         let path = path.into();
         let raw = Config::read_file(path.as_path())?;

src/term/mod.rs

@@ -703,6 +703,8 @@ pub struct Term {
 
     /// Default style for resetting the cursor
     default_cursor_style: CursorStyle,
+
+    dynamic_title: bool,
 }
 
 /// Terminal size info
@@ -806,6 +808,7 @@ impl Term {
             semantic_escape_chars: config.selection().semantic_escape_chars.clone(),
             cursor_style: None,
             default_cursor_style: config.cursor_style(),
+            dynamic_title: config.dynamic_title(),
         }
     }
 
@@ -831,6 +834,7 @@ impl Term {
         }
         self.visual_bell.update_config(config);
         self.default_cursor_style = config.cursor_style();
+        self.dynamic_title = config.dynamic_title();
     }
 
     #[inline]
@@ -1159,8 +1163,10 @@ impl ansi::Handler for Term {
     /// Set the window title
     #[inline]
     fn set_title(&mut self, title: &str) {
+        if self.dynamic_title {
             self.next_title = Some(title.to_owned());
         }
+    }
 
     /// A character to be displayed
     #[inline]