Initial implementation of APKINDEX, fetching, reading, parsing, & merging

Sources/dpk-cli/Subcommands/DpkUpgradeCommand.swift

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: Apache-2.0
+
+import ArgumentParser
+
+struct DpkUpgradeCommand: ParsableCommand {
+  static let configuration = CommandConfiguration(
+    commandName: "upgrade",
+    abstract: "Upgrade installed packages.",
+    aliases: [ "U" ])
+
+  @Argument(help: "Optionally specify packages to upgrade. Otherwise upgrade all packages installed on the system.")
+  var packages: [String] = []
+
+  func run() throws {
+    if packages.isEmpty {
+      print("upgrading system")
+    } else {
+      print("upgrading invidual packages: \"\(packages.joined(separator: "\", \""))\"")
+    }
+  }
+}