FTL: Add variadic concatenation
For now, the arguments can only be integers, string literals, and
truncated string views, as this will mainly be used for tracing.
Bug: 185536303
Test: ftl_test
Change-Id: I3141992c6c9438710f04b056e67a5e8811d39f78
diff --git a/libs/ftl/concat_test.cpp b/libs/ftl/concat_test.cpp
new file mode 100644
index 0000000..8ecb1b2
--- /dev/null
+++ b/libs/ftl/concat_test.cpp
@@ -0,0 +1,55 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <ftl/concat.h>
+#include <gtest/gtest.h>
+
+namespace android::test {
+
+// Keep in sync with example usage in header file.
+TEST(Concat, Example) {
+ std::string_view name = "Volume";
+ ftl::Concat string(ftl::truncated<3>(name), ": ", -3, " dB");
+
+ EXPECT_EQ(string.str(), "Vol: -3 dB");
+ EXPECT_EQ(string.c_str()[string.size()], '\0');
+}
+
+namespace {
+
+static_assert(ftl::Concat{"foo"}.str() == "foo");
+static_assert(ftl::Concat{ftl::truncated<3>("foobar")}.str() == "foo");
+
+constexpr ftl::Concat kConcat{"po", "trz", "ebie"};
+
+static_assert(kConcat.size() == 9);
+static_assert(kConcat.max_size() == 9);
+static_assert(kConcat.str() == "potrzebie");
+static_assert(kConcat.str() == std::string_view(kConcat.c_str()));
+
+constexpr auto concat() {
+ return ftl::Concat{ftl::truncated<1>("v???"), ftl::truncated<2>("ee??"),
+ ftl::truncated<3>("ble?"), ftl::truncated<4>("fetz"),
+ ftl::truncated<90>("er")};
+}
+
+static_assert(concat().size() == 12);
+static_assert(concat().max_size() == 100);
+static_assert(concat().str() == "veeblefetzer");
+static_assert(concat().str() == std::string_view(concat().c_str()));
+
+} // namespace
+} // namespace android::test