1 files changed, 99 insertions, 0 deletions
diff --git a/src/shared/utils/keys.ts b/src/shared/utils/keys.ts
new file mode 100644
index 0000000..e9b0365
--- /dev/null
+++ b/src/shared/utils/keys.ts
@@ -0,0 +1,99 @@
+export interface Key {
+    key: string;
+    shiftKey: boolean | undefined;
+    ctrlKey: boolean | undefined;
+    altKey: boolean | undefined;
+    metaKey: boolean | undefined;
+}
+
+const modifiedKeyName = (name: string): string => {
+  if (name === ' ') {
+    return 'Space';
+  }
+  if (name.length === 1) {
+    return name;
+  } else if (name === 'Escape') {
+    return 'Esc';
+  }
+  return name;
+};
+
+const fromKeyboardEvent = (e: KeyboardEvent): Key => {
+  let key = modifiedKeyName(e.key);
+  let shift = e.shiftKey;
+  if (key.length === 1 && key.toUpperCase() === key.toLowerCase()) {
+    // make shift false for symbols to enable key bindings by symbold keys.
+    // But this limits key bindings by symbol keys with Shift (such as Shift+$>.
+    shift = false;
+  }
+
+  return {
+    key: modifiedKeyName(e.key),
+    shiftKey: shift,
+    ctrlKey: e.ctrlKey,
+    altKey: e.altKey,
+    metaKey: e.metaKey,
+  };
+};
+
+const fromMapKey = (key: string): Key => {
+  if (key.startsWith('<') && key.endsWith('>')) {
+    let inner = key.slice(1, -1);
+    let shift = inner.includes('S-');
+    let base = inner.slice(inner.lastIndexOf('-') + 1);
+    if (shift && base.length === 1) {
+      base = base.toUpperCase();
+    } else if (!shift && base.length === 1) {
+      base = base.toLowerCase();
+    }
+    return {
+      key: base,
+      shiftKey: inner.includes('S-'),
+      ctrlKey: inner.includes('C-'),
+      altKey: inner.includes('A-'),
+      metaKey: inner.includes('M-'),
+    };
+  }
+  return {
+    key: key,
+    shiftKey: key.toLowerCase() !== key,
+    ctrlKey: false,
+    altKey: false,
+    metaKey: false,
+  };
+};
+
+const fromMapKeys = (keys: string): Key[] => {
+  const fromMapKeysRecursive = (
+    remainings: string, mappedKeys: Key[],
+  ): Key[] => {
+    if (remainings.length === 0) {
+      return mappedKeys;
+    }
+
+    let nextPos = 1;
+    if (remainings.startsWith('<')) {
+      let ltPos = remainings.indexOf('>');
+      if (ltPos > 0) {
+        nextPos = ltPos + 1;
+      }
+    }
+
+    return fromMapKeysRecursive(
+      remainings.slice(nextPos),
+      mappedKeys.concat([fromMapKey(remainings.slice(0, nextPos))])
+    );
+  };
+
+  return fromMapKeysRecursive(keys, []);
+};
+
+const equals = (e1: Key, e2: Key): boolean => {
+  return e1.key === e2.key &&
+    e1.ctrlKey === e2.ctrlKey &&
+    e1.metaKey === e2.metaKey &&
+    e1.altKey === e2.altKey &&
+    e1.shiftKey === e2.shiftKey;
+};
+
+export { fromKeyboardEvent, fromMapKey, fromMapKeys, equals };