[cmake] Add FindUtfcpp.cmake

it will look for utfcpp in the standard system paths, UTFCPP_PATH,
and lib/utfcpp/v2_0/source.

This allows the use of utfcpp in:

  * standard locations such as /usr/include on distributions shipping
  utfcpp

  * custom locations for users via UTFCPP_PATH

  * the source tree using the default location of the utfcpp
    git submodule, .i.e lib/utfcpp/v2_0

Signed-off-by: Alexis Hildebrandt <afh@surryhill.net>

1 files changed, 30 insertions, 0 deletions

diff --git a/cmake/FindUtfcpp.cmake b/cmake/FindUtfcpp.cmake
new file mode 100644
index 00000000..185a8d88
--- /dev/null
+++ b/cmake/FindUtfcpp.cmake
@@ -0,0 +1,30 @@
+# - Try to find utfcpp
+# Once done, this will define
+#
+#  UTFCPP_FOUND        - system has utfcpp's utf8.h
+#  UTFCPP_PATH         - the utfcpp include directories
+
+include(CheckCXXSourceCompiles)
+
+set(UTFCPP_FOUND FALSE)
+
+find_path(UTFCPP_INCLUDE_DIR
+    NAMES utf8.h
+    HINTS  "${UTFCPP_PATH}" "${PROJECT_SOURCE_DIR}/lib/utfcpp/v2_0/source"
+)
+
+if (UTFCPP_INCLUDE_DIR)
+  set(CMAKE_REQUIRED_INCLUDES "${UTFCPP_INCLUDE_DIR}")
+  set(UTFCPP_FOUND TRUE)
+endif()
+
+check_cxx_source_compiles("
+#include <string>
+#include \"utf8.h\"
+
+int main(int argc, char** argv) {
+    std::string input = std::string(\"utfcpp\");
+    const char * p = input.c_str();
+    std::size_t len = input.length();
+    utf8::is_valid(p, p + len);
+}" HAVE_WORKING_UTFCPP)