Add an option to enable/disable sqlite backend

Currently you can't disable it since sqlite is the only
supported backend and you must have at least one enabled
and available on the system. This will be needed for later.

meson_options.txt

@@ -1,3 +1,4 @@
 option('base_url', type: 'string', value: 'https://api.originsro.org')
 option('def_sqlite_db_name', type: 'string', value: 'originsro.db3')
 option('tests', type: 'feature', value: 'enabled')
+option('with_sqlite', type: 'feature', value: 'auto')

src/config.hpp.in

@@ -29,4 +29,6 @@ constexpr const unsigned short int g_version_major = @PROJECT_VERSION_MAJOR@;
 constexpr const unsigned short int g_version_minor = @PROJECT_VERSION_MINOR@;
 constexpr const unsigned short int g_version_patch = @PROJECT_VERSION_PATCH@;
 
+#mesondefine OROTOOL_WITH_SQLITE
+
 } //namespace duck

src/meson.build

@@ -6,9 +6,14 @@ restc_cpp_dep = dependency('restc-cpp', version: '>=0.1.1',
   ],
 )
 
-sqlitecpp_dep = dependency('sqlitecpp', version: '>=3.0.0',
-  fallback: ['SQLiteCpp', 'sqlitecpp_dep'],
-)
+if not get_option('with_sqlite').disabled()
+  sqlitecpp_dep = dependency('sqlitecpp', version: '>=3.0.0',
+	fallback: ['SQLiteCpp', 'sqlitecpp_dep'],
+	required: get_option('with_sqlite'),
+  )
+else
+  sqlitecpp_dep = disabler()
+endif
 
 ev_dep = dependency('libev', version: '>=4.31')
 threads_dep = dependency('threads')
@@ -33,6 +38,7 @@ version_arr = meson.project_version().split('.')
 conf.set('PROJECT_VERSION_MAJOR', version_arr[0])
 conf.set('PROJECT_VERSION_MINOR', version_arr[1])
 conf.set('PROJECT_VERSION_PATCH', version_arr[2])
+conf.set('OROTOOL_WITH_SQLITE', sqlitecpp_dep.found())
 project_config_file = configure_file(
 	input: 'config.hpp.in',
 	output: meson.project_name() + '_config.hpp',
@@ -43,13 +49,24 @@ gnulib_conf = configuration_data()
 gnulib_conf.set('_GL_ATTRIBUTE_CONST', '__attribute__ ((__const__))')
 configure_file(output : 'config.h', configuration : gnulib_conf)
 
+backend_libs = [
+  sqlitecpp_dep,
+]
+
+backends_selected = false
+foreach backend_lib : backend_libs
+  backends_selected = backends_selected or backend_lib.found()
+endforeach
+if not backends_selected
+  error('No backend was enabled or none of the enabled backend dependencies could be located')
+endif
+
 lib_deps = [
   restc_cpp_dep,
-  sqlitecpp_dep,
   ev_dep,
   threads_dep,
   boost_dep,
-]
+] + backend_libs
 
 executable(meson.project_name(),
   'main.cpp',

src/oro/originsdb.cpp

@@ -15,6 +15,9 @@
  * along with Orotool.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "orotool_config.hpp"
+#if defined(OROTOOL_WITH_SQLITE)
+
 #include "originsdb.hpp"
 #include "SQLiteCpp/Database.h"
 #include "SQLiteCpp/Statement.h"
@@ -557,3 +560,5 @@ Timestamp OriginsDB::next_access_time (DBOperation op) const {
 }
 
 } //namespace oro
+
+#endif