feat(widget): add table widget

src/widget/table/model/selection.rs

@@ -0,0 +1,115 @@
+// Copyright 2022 System76 <info@system76.com>
+// SPDX-License-Identifier: MPL-2.0
+
+//! Describes logic specific to the single-select and multi-select modes of a model.
+
+use super::{
+    category::{ItemCategory, ItemInterface},
+    Entity, Model,
+};
+use std::collections::HashSet;
+
+/// Describes a type that has selectable items.
+pub trait Selectable {
+    /// Activate an item.
+    fn activate(&mut self, id: Entity);
+
+    /// Deactivate an item.
+    fn deactivate(&mut self, id: Entity);
+
+    /// Checks if the item is active.
+    fn is_active(&self, id: Entity) -> bool;
+}
+
+/// [`Model<SingleSelect>`] Ensures that only one key may be selected.
+#[derive(Debug, Default)]
+pub struct SingleSelect {
+    pub active: Entity,
+}
+
+impl<Item: ItemInterface<Category>, Category: ItemCategory> Selectable
+    for Model<SingleSelect, Item, Category>
+{
+    fn activate(&mut self, id: Entity) {
+        if !self.items.contains_key(id) {
+            return;
+        }
+
+        self.selection.active = id;
+    }
+
+    fn deactivate(&mut self, id: Entity) {
+        if id == self.selection.active {
+            self.selection.active = Entity::default();
+        }
+    }
+
+    fn is_active(&self, id: Entity) -> bool {
+        self.selection.active == id
+    }
+}
+
+impl<Item: ItemInterface<Category>, Category: ItemCategory> Model<SingleSelect, Item, Category> {
+    /// Get an immutable reference to the data associated with the active item.
+    #[must_use]
+    pub fn active_data<Data: 'static>(&self) -> Option<&Data> {
+        self.data(self.active())
+    }
+
+    /// Get a mutable reference to the data associated with the active item.
+    #[must_use]
+    pub fn active_data_mut<Data: 'static>(&mut self) -> Option<&mut Data> {
+        self.data_mut(self.active())
+    }
+
+    /// Deactivates the active item.
+    pub fn deactivate(&mut self) {
+        Selectable::deactivate(self, Entity::default());
+    }
+
+    /// The ID of the active item.
+    #[must_use]
+    pub fn active(&self) -> Entity {
+        self.selection.active
+    }
+}
+
+/// [`Model<MultiSelect>`] permits multiple keys to be active at a time.
+#[derive(Debug, Default)]
+pub struct MultiSelect {
+    pub active: HashSet<Entity>,
+}
+
+impl<Item: ItemInterface<Category>, Category: ItemCategory> Selectable
+    for Model<MultiSelect, Item, Category>
+{
+    fn activate(&mut self, id: Entity) {
+        if !self.items.contains_key(id) {
+            return;
+        }
+
+        if !self.selection.active.insert(id) {
+            self.selection.active.remove(&id);
+        }
+    }
+
+    fn deactivate(&mut self, id: Entity) {
+        self.selection.active.remove(&id);
+    }
+
+    fn is_active(&self, id: Entity) -> bool {
+        self.selection.active.contains(&id)
+    }
+}
+
+impl<Item: ItemInterface<Category>, Category: ItemCategory> Model<MultiSelect, Item, Category> {
+    /// Deactivates the item in the model.
+    pub fn deactivate(&mut self, id: Entity) {
+        Selectable::deactivate(self, id);
+    }
+
+    /// The IDs of the active items.
+    pub fn active(&self) -> impl Iterator<Item = Entity> + '_ {
+        self.selection.active.iter().copied()
+    }
+}