Add *_maybe helper methods for TextInput

widget/src/text_input.rs

@@ -137,13 +137,37 @@ where
         self
     }
 
+    /// Sets the message that should be produced when some text is typed into
+    /// the [`TextInput`], if `Some`.
+    ///
+    /// If `None`, the [`TextInput`] will be disabled.
+    pub fn on_input_maybe<F>(mut self, callback: Option<F>) -> Self
+    where
+        F: 'a + Fn(String) -> Message,
+    {
+        self.on_input = match callback {
+            Some(c) => Some(Box::new(c)),
+            None => None,
+        };
+        self
+    }
+
     /// Sets the message that should be produced when the [`TextInput`] is
     /// focused and the enter key is pressed.
     pub fn on_submit(mut self, message: Message) -> Self {
         self.on_submit = Some(message);
         self
     }
 
+    /// Sets the message that should be produced when the [`TextInput`] is
+    /// focused and the enter key is pressed, if `Some`.
+    ///
+    /// If `None` the [`TextInput`] nothing will happen.
+    pub fn on_submit_maybe(mut self, on_submit: Option<Message>) -> Self {
+        self.on_submit = on_submit;
+        self
+    }
+
     /// Sets the message that should be produced when some text is pasted into
     /// the [`TextInput`].
     pub fn on_paste(
@@ -154,6 +178,21 @@ where
         self
     }
 
+    /// Sets the message that should be produced when some text is pasted into
+    /// the [`TextInput`], if `Some`.
+    ///
+    /// If `None` nothing will happen.
+    pub fn on_paste_maybe(
+        mut self,
+        on_paste: Option<impl Fn(String) -> Message + 'a>,
+    ) -> Self {
+        self.on_paste = match on_paste {
+            Some(func) => Some(Box::new(func)),
+            None => None,
+        };
+        self
+    }
+
     /// Sets the [`Font`] of the [`TextInput`].
     ///
     /// [`Font`]: text::Renderer::Font