From 062ffaa571168da02b132785cd6fe697b1089088 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Botond=20D=C3=A9nes?= <bdenes@scylladb.com>
Date: Fri, 7 Jan 2022 08:18:15 +0200
Subject: [PATCH] tools/utils: add positional-argument based overload of
 get_selected_operation()

As opposed to the current one, which expects the operation to be given
with the --operation syntax, this new overload expects it as the first
positional argument. If found and valid, it is extracted from the
arglist and returned. Otherwise exit() is invoked to simplify error
handling.
---
 tools/utils.hh | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/utils.hh b/tools/utils.hh
index 907d29b062..e6fb73b86e 100644
--- a/tools/utils.hh
+++ b/tools/utils.hh
@@ -35,6 +35,39 @@ concept Operation = requires(Op op) {
     { op.name() }; // returns some string
 };
 
+// Extract the operation from the argv.
+//
+// The operation is expected to be at argv[1].If found, it is shifted out to the
+// end (effectively removed) and the corresponding Op* is returned.
+// If not found or unrecognized an error is logged and exit() is called.
+template <Operation Op>
+const Op& get_selected_operation(int& ac, char**& av, const std::vector<Op>& operations, std::string_view alias) {
+    if (ac < 2) {
+        fmt::print(std::cerr, "error: missing mandatory {} argument\n", alias);
+        exit(1);
+    }
+
+    const Op* found_operation = nullptr;
+    for (const auto& op : operations) {
+        if (av[1] == op.name()) {
+            found_operation = &op;
+            break;
+        }
+    }
+    if (found_operation) {
+        --ac;
+        for (int i = 1; i < ac; ++i) {
+            std::swap(av[i], av[i + 1]);
+        }
+        return *found_operation;
+    }
+
+    const auto all_operation_names = boost::algorithm::join(operations | boost::adaptors::transformed([] (const Op& op) { return op.name(); } ), ", ");
+
+    fmt::print(std::cerr, "error: unrecognized {} argument: expected one of ({}), got {}\n", alias, all_operation_names, av[1]);
+    exit(1);
+}
+
 template <Operation Op>
 const Op& get_selected_operation(boost::program_options::variables_map& app_config, const std::vector<Op>& operations, std::string_view alias) {
     std::vector<const Op*> found_operations;