uhd: Add discoverable_features API

The "discoverable features" API handles how clients access the myriad
features we offer, without simply adding a million has_FOO and do_FOO
methods to radio_control and multi_usrp. discoverable_features allows
clients to query the existance of, enumerate, and ultimately they get
(by enum or by type) an object which implements their wanted feature.

1 files changed, 111 insertions, 0 deletions

diff --git a/host/tests/discoverable_feature_test.cpp b/host/tests/discoverable_feature_test.cpp
new file mode 100644
index 000000000..b75cb76f3
--- /dev/null
+++ b/host/tests/discoverable_feature_test.cpp
@@ -0,0 +1,111 @@
+//
+// Copyright 2020 Ettus Research, a National Instruments Brand
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#include <uhd/features/discoverable_feature_getter_iface.hpp>
+#include <boost/test/unit_test.hpp>
+#include <iostream>
+
+using namespace uhd::features;
+
+class test_feature0 : public discoverable_feature
+{
+public:
+    static discoverable_feature::feature_id_t get_feature_id()
+    {
+        return discoverable_feature::RESERVED0;
+    }
+
+    std::string get_feature_name() const override
+    {
+        return "test_feature0";
+    }
+};
+
+class test_feature1 : public discoverable_feature
+{
+public:
+    static discoverable_feature::feature_id_t get_feature_id()
+    {
+        return discoverable_feature::RESERVED1;
+    }
+
+    std::string get_feature_name() const override
+    {
+        return "test_feature1";
+    }
+};
+
+class test_feature_getter : public discoverable_feature_getter_iface
+{
+public:
+    test_feature_getter(bool feature0_enabled, bool feature1_enabled)
+    {
+        if (feature0_enabled)
+            _test_feature0.reset(new test_feature0());
+        if (feature1_enabled)
+            _test_feature1.reset(new test_feature1);
+    }
+
+    std::vector<std::string> enumerate_features() override
+    {
+        std::vector<std::string> features;
+        if (_test_feature0)
+            features.push_back(_test_feature0->get_feature_name());
+        if (_test_feature1)
+            features.push_back(_test_feature1->get_feature_name());
+        return features;
+    }
+
+private:
+    discoverable_feature::sptr get_feature_ptr(
+        discoverable_feature::feature_id_t feature_id) override
+    {
+        switch (feature_id) {
+            case discoverable_feature::RESERVED0:
+                return _test_feature0;
+            case discoverable_feature::RESERVED1:
+                return _test_feature1;
+            default:
+                return discoverable_feature::sptr();
+        };
+    }
+
+    discoverable_feature::sptr _test_feature0;
+    discoverable_feature::sptr _test_feature1;
+};
+
+BOOST_AUTO_TEST_CASE(test_has_feature_works)
+{
+    test_feature_getter feature_getter(true, false);
+    BOOST_CHECK_EQUAL(feature_getter.has_feature<test_feature0>(), true);
+    BOOST_CHECK_EQUAL(feature_getter.has_feature<test_feature1>(), false);
+}
+
+BOOST_AUTO_TEST_CASE(test_enumerate_feature_works)
+{
+    test_feature_getter feature_getter(true, true);
+    const auto features = feature_getter.enumerate_features();
+
+    // Note that ordering isn't strictly a requirement of the interface,
+    // we just leverage that here to demonstrate API usage concisely.
+    BOOST_CHECK_EQUAL(features[0], "test_feature0");
+    BOOST_CHECK_EQUAL(features[1], "test_feature1");
+}
+
+BOOST_AUTO_TEST_CASE(test_get_feature_works)
+{
+    test_feature_getter feature_getter(true, true);
+    const auto f0 = feature_getter.get_feature<test_feature0>();
+    const auto f1 = feature_getter.get_feature<test_feature1>();
+    BOOST_CHECK_EQUAL(f0.get_feature_name(), "test_feature0");
+    BOOST_CHECK_EQUAL(f1.get_feature_name(), "test_feature1");
+}
+
+BOOST_AUTO_TEST_CASE(test_get_feature_throws)
+{
+    test_feature_getter feature_getter(false, true);
+    BOOST_CHECK_THROW(feature_getter.get_feature<test_feature0>(), std::exception);
+}