Add simple implementation of a KeyBindingsManager + match tests

src/KeyBindingsManager.ts

@@ -0,0 +1,102 @@
+import { isMac } from "./Keyboard";
+
+export enum KeyBindingContext {
+
+}
+
+export enum KeyAction {
+    None = 'None',
+}
+
+/**
+ * Represent a key combination.
+ * 
+ * The combo is evaluated strictly, i.e. the KeyboardEvent must match the exactly what is specified in the KeyCombo.
+ */
+export type KeyCombo = {
+    /** Currently only one `normal` key is supported */
+    keys: string[];
+
+    /** On PC: ctrl is pressed; on Mac: meta is pressed */
+    ctrlOrCmd?: boolean;
+
+    altKey?: boolean;
+    ctrlKey?: boolean;
+    metaKey?: boolean;
+    shiftKey?: boolean;
+}
+
+export type KeyBinding = {
+    keyCombo: KeyCombo;
+    action: KeyAction;
+}
+
+/**
+ * Helper method to check if a KeyboardEvent matches a KeyCombo
+ * 
+ * Note, this method is only exported for testing.
+ */
+export function isKeyComboMatch(ev: KeyboardEvent, combo: KeyCombo, onMac: boolean): boolean {
+    if (combo.keys.length > 0 && ev.key !== combo.keys[0]) {
+        return false;
+    }
+
+    const comboCtrl = combo.ctrlKey ?? false;
+    const comboAlt = combo.altKey ?? false;
+    const comboShift = combo.shiftKey ?? false;
+    const comboMeta = combo.metaKey ?? false;
+    // When ctrlOrCmd is set, the keys need do evaluated differently on PC and Mac
+    if (combo.ctrlOrCmd) {
+        if (onMac) {
+            if (!ev.metaKey
+                || ev.ctrlKey !== comboCtrl
+                || ev.altKey !== comboAlt
+                || ev.shiftKey !== comboShift) {
+                return false;
+            }
+        } else {
+            if (!ev.ctrlKey
+                || ev.metaKey !== comboMeta
+                || ev.altKey !== comboAlt
+                || ev.shiftKey !== comboShift) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    if (ev.metaKey !== comboMeta
+        || ev.ctrlKey !== comboCtrl
+        || ev.altKey !== comboAlt
+        || ev.shiftKey !== comboShift) {
+        return false;
+    }
+
+    return true;
+}
+
+export class KeyBindingsManager {
+    contextBindings: Record<KeyBindingContext, KeyBinding[]> = {};
+
+    /**
+     * Finds a matching KeyAction for a given KeyboardEvent
+     */
+    getAction(context: KeyBindingContext, ev: KeyboardEvent): KeyAction {
+        const bindings = this.contextBindings[context];
+        if (!bindings) {
+            return KeyAction.None;
+        }
+        const binding = bindings.find(it => isKeyComboMatch(ev, it.keyCombo, isMac));
+        if (binding) {
+            return binding.action;
+        }
+
+        return KeyAction.None;
+    }
+}
+
+const manager = new KeyBindingsManager();
+
+export function getKeyBindingsManager(): KeyBindingsManager {
+    return manager;
+}