Add `string::translate()` and `settings::language` for getting translated strings depending on language.

adapters/standalone.cpp

@@ -179,6 +179,7 @@ int main(int argc, char* argv[]) {
 			exit(1);
 		}
 	}
+	string::init();
 
 	// Check existence of the system res/ directory
 	std::string resDir = asset::system("res");

include/settings.hpp

@@ -27,6 +27,8 @@ extern bool isPlugin;
 
 // Persistent state, serialized to settings.json.
 
+/** ISO 639-1 language code for string translations. */
+extern std::string language;
 /** Launches Rack without loading plugins or the autosave patch. Always set to false when settings are saved. */
 extern bool safeMode;
 /** vcvrack.com user token */

include/string.hpp

@@ -131,5 +131,10 @@ struct Version {
 };
 
 
+std::string translate(const std::string& id);
+std::string translate(const std::string& id, const std::string& language);
+void init();
+
+
 } // namespace string
 } // namespace rack

src/settings.cpp

@@ -20,6 +20,7 @@ bool devMode = false;
 bool headless = false;
 bool isPlugin = false;
 
+std::string language = "en";
 bool safeMode = false;
 std::string token;
 bool windowMaximized = false;
@@ -126,6 +127,8 @@ void destroy() {
 json_t* toJson() {
 	json_t* rootJ = json_object();
 
+	json_object_set_new(rootJ, "language", json_string(language.c_str()));
+
 	// Always disable safe mode when settings are saved.
 	json_object_set_new(rootJ, "safeMode", json_boolean(false));
 
@@ -281,6 +284,10 @@ json_t* toJson() {
 }
 
 void fromJson(json_t* rootJ) {
+	json_t* languageJ = json_object_get(rootJ, "language");
+	if (languageJ)
+		language = json_string_value(languageJ);
+
 	json_t* safeModeJ = json_object_get(rootJ, "safeMode");
 	if (safeModeJ) {
 		// If safe mode is enabled (e.g. by command line flag), don't disable it when loading.

src/string.cpp

@@ -3,6 +3,7 @@
 #include <ctime>
 #include <cctype> // for tolower and toupper
 #include <algorithm> // for transform and equal
+#include <map>
 #include <libgen.h> // for dirname and basename
 #include <stdarg.h>
 
@@ -11,6 +12,9 @@
 #endif
 
 #include <string.hpp>
+#include <settings.hpp>
+#include <system.hpp>
+#include <asset.hpp>
 
 
 namespace rack {
@@ -322,6 +326,76 @@ bool Version::operator<(const Version& other) {
 }
 
 
+/** {language: {id: string}} */
+static std::map<std::string, std::map<std::string, std::string>> translations;
+
+
+static void loadTranslations() {
+	translations.clear();
+	std::string translationsDir = asset::system("translations");
+
+	for (std::string filename : system::getEntries(translationsDir)) {
+		if (system::getExtension(filename) != ".json")
+			continue;
+		std::string language = system::getStem(filename);
+		std::string path = system::join(translationsDir, filename);
+
+		INFO("Loading translation %s from %s", language.c_str(), path.c_str());
+		FILE* file = std::fopen(path.c_str(), "r");
+		if (!file) {
+			WARN("Cannot open translation file %s", path.c_str());
+			continue;
+		}
+		DEFER({std::fclose(file);});
+
+		json_error_t error;
+		json_t* rootJ = json_loadf(file, 0, &error);
+		if (!rootJ) {
+			WARN("Translation file has invalid JSON at %d:%d %s", error.line, error.column, error.text);
+			continue;
+		}
+		DEFER({json_decref(rootJ);});
+
+		auto& translation = translations[language];
+
+		// Load JSON
+		const char* id;
+		json_t* strJ;
+		json_object_foreach(rootJ, id, strJ) {
+			std::string s(json_string_value(strJ), json_string_length(strJ));
+			translation[id] = s;
+		}
+	}
+}
+
+
+std::string translate(const std::string& id) {
+	std::string s = translate(id, settings::language);
+	if (!s.empty())
+		return s;
+
+	// English fallback
+	if (settings::language != "en") {
+		return translate(id, "en");
+	}
+	return "";
+}
+
+
+std::string translate(const std::string& id, const std::string& language) {
+	auto it = translations.find(language);
+	if (it == translations.end())
+		return "";
+
+	const auto& translation = it->second;
+	return get(translation, id, "");
+}
+
+
+void init() {
+	loadTranslations();
+}
+
 
 } // namespace string
 } // namespace rack

translations/en.json

@@ -0,0 +1,3 @@
+{
+	"language": "English"
+}