implement some GEO commands, improve scan generic transformer, expose RPUSHX

lib/commands/GEOPOS.ts

@@ -0,0 +1,27 @@
+export const FIRST_KEY_INDEX = 1;
+
+export const IS_READ_ONLY = true;
+
+export function transformArguments(key: string, member: string | Array<string>): Array<string> {
+    const args = ['GEOPOS', key];
+
+    if (typeof member === 'string') {
+        args.push(member);
+    } else {
+        args.push(...member);
+    }
+
+    return args;
+}
+
+interface GeoCoordinates {
+    longitude: string;
+    latitude: string;
+}
+
+export function transformReply(reply: Array<[string, string] | null>): Array<GeoCoordinates | null> {
+    return reply.map(coordinates => coordinates === null ? null : {
+        longitude: coordinates[0],
+        latitude: coordinates[1]
+    });
+}