Add text input operations

native/src/widget/operation/text_input.rs

@@ -0,0 +1,131 @@
+//! Operate on widgets that have text input.
+use crate::widget::operation::Operation;
+use crate::widget::Id;
+
+/// The internal state of a widget that has text input.
+pub trait TextInput {
+    /// Moves the cursor of the text input to the front of the input text.
+    fn move_cursor_to_front(&mut self);
+    /// Moves the cursor of the text input to the end of the input text.
+    fn move_cursor_to_end(&mut self);
+    /// Moves the cursor of the text input to an arbitrary location.
+    fn move_cursor_to(&mut self, position: usize);
+    /// Selects all the content of the text input.
+    fn select_all(&mut self);
+}
+
+/// Produces an [`Operation`] that moves the cursor of the widget with the given [`Id`] to the
+/// front.
+pub fn move_cursor_to_front<T>(target: Id) -> impl Operation<T> {
+    struct MoveCursor {
+        target: Id,
+    }
+
+    impl<T> Operation<T> for MoveCursor {
+        fn text_input(&mut self, state: &mut dyn TextInput, id: Option<&Id>) {
+            match id {
+                Some(id) if id == &self.target => {
+                    state.move_cursor_to_front();
+                }
+                _ => {}
+            }
+        }
+
+        fn container(
+            &mut self,
+            _id: Option<&Id>,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+        ) {
+            operate_on_children(self)
+        }
+    }
+
+    MoveCursor { target }
+}
+
+/// Produces an [`Operation`] that moves the cursor of the widget with the given [`Id`] to the
+/// end.
+pub fn move_cursor_to_end<T>(target: Id) -> impl Operation<T> {
+    struct MoveCursor {
+        target: Id,
+    }
+
+    impl<T> Operation<T> for MoveCursor {
+        fn text_input(&mut self, state: &mut dyn TextInput, id: Option<&Id>) {
+            match id {
+                Some(id) if id == &self.target => {
+                    state.move_cursor_to_end();
+                }
+                _ => {}
+            }
+        }
+
+        fn container(
+            &mut self,
+            _id: Option<&Id>,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+        ) {
+            operate_on_children(self)
+        }
+    }
+
+    MoveCursor { target }
+}
+
+/// Produces an [`Operation`] that moves the cursor of the widget with the given [`Id`] to the
+/// provided position.
+pub fn move_cursor_to<T>(target: Id, position: usize) -> impl Operation<T> {
+    struct MoveCursor {
+        target: Id,
+        position: usize,
+    }
+
+    impl<T> Operation<T> for MoveCursor {
+        fn text_input(&mut self, state: &mut dyn TextInput, id: Option<&Id>) {
+            match id {
+                Some(id) if id == &self.target => {
+                    state.move_cursor_to(self.position);
+                }
+                _ => {}
+            }
+        }
+
+        fn container(
+            &mut self,
+            _id: Option<&Id>,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+        ) {
+            operate_on_children(self)
+        }
+    }
+
+    MoveCursor { target, position }
+}
+
+/// Produces an [`Operation`] that selects all the content of the widget with the given [`Id`].
+pub fn select_all<T>(target: Id) -> impl Operation<T> {
+    struct MoveCursor {
+        target: Id,
+    }
+
+    impl<T> Operation<T> for MoveCursor {
+        fn text_input(&mut self, state: &mut dyn TextInput, id: Option<&Id>) {
+            match id {
+                Some(id) if id == &self.target => {
+                    state.select_all();
+                }
+                _ => {}
+            }
+        }
+
+        fn container(
+            &mut self,
+            _id: Option<&Id>,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+        ) {
+            operate_on_children(self)
+        }
+    }
+
+    MoveCursor { target }
+}