util/str: Add string concatentation methods

Change-Id: I5caf8e0731eb9ac0f18b84d25256ea0068fab03c
Signed-off-by: William A. Kennington III <wak@google.com>

2 files changed, 58 insertions, 0 deletions

diff --git a/src/meson.build b/src/meson.build
index a6e82b9..aadb68d 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -31,4 +31,5 @@ install_headers(
 
 install_headers(
   'stdplus/util/cexec.hpp',
+  'stdplus/util/string.hpp',
   subdir: 'stdplus/util')
diff --git a/src/stdplus/util/string.hpp b/src/stdplus/util/string.hpp
new file mode 100644
index 0000000..4e37e3b
--- /dev/null
+++ b/src/stdplus/util/string.hpp
@@ -0,0 +1,57 @@
+#pragma once
+#include <cstring>
+#include <string>
+#include <string_view>
+#include <utility>
+
+namespace stdplus
+{
+namespace util
+{
+namespace detail
+{
+
+template <typename... Views>
+void strAppendViews(std::string& dst, Views... views)
+{
+    dst.reserve((dst.size() + ... + views.size()));
+    (dst.append(views), ...);
+}
+
+} // namespace detail
+
+/** @brief Appends multiple strings to the end of the destination string
+ *         in the most optimal way for the given inputs.
+ *
+ *  @param[in, out] dst - The string being appended to
+ *  @param[in] ...strs  - An arbitrary number of strings to concatenate
+ */
+template <typename... Strs>
+void strAppend(std::string& dst, const Strs&... strs)
+{
+    detail::strAppendViews(dst, std::string_view(strs)...);
+}
+
+/** @brief Concatenates multiple strings together in the most optimal
+ *         way for the given inputs.
+ *
+ *  @param[in] ...strs - An arbitrary number of strings to concatenate
+ *  @return The concatenated result string
+ */
+template <typename... Strs>
+std::string strCat(const Strs&... strs)
+{
+    std::string ret;
+    strAppend(ret, strs...);
+    return ret;
+}
+template <typename... Strs>
+std::string strCat(std::string&& in, const Strs&... strs)
+{
+    std::string ret = std::move(in);
+    strAppend(ret, strs...);
+    return ret;
+}
+
+} // namespace util
+} // namespace stdplus