spa: add i18n interface

The interface can be used to get translated strings.

spa/include/spa/support/i18n.h

@@ -0,0 +1,93 @@
+/* Simple Plugin API
+ *
+ * Copyright © 2021 Wim Taymans
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef SPA_I18N_H
+#define SPA_I18N_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <spa/utils/hook.h>
+#include <spa/utils/defs.h>
+
+#define SPA_TYPE_INTERFACE_I18N		SPA_TYPE_INFO_INTERFACE_BASE "I18N"
+
+#define SPA_VERSION_I18N		0
+struct spa_i18n { struct spa_interface iface; };
+
+struct spa_i18n_methods {
+#define SPA_VERSION_I18N_METHODS	0
+        uint32_t version;
+
+	/**
+	 * Translate a message
+         *
+         * \param object the i18n interface
+         * \param msgid the message
+         * \return a translated message
+	 */
+	const char *(*text) (void *object, const char *msgid);
+
+	/**
+	 * Translate a message for a number
+         *
+         * \param object the i18n interface
+         * \param msgid the message to translate
+         * \param msgid_plural the plural form of \a msgid
+         * \param n a number
+         * \return a translated message for the number \a n
+	 */
+	const char *(*ntext) (void *object, const char *msgid,
+			const char *msgid_plural, unsigned long int n);
+};
+
+static inline const char *
+spa_i18n_gettext(struct spa_i18n *i18n, const char *msgid)
+{
+	const char *res = msgid;
+	if (SPA_LIKELY(i18n != NULL))
+		spa_interface_call_res(&i18n->iface,
+	                        struct spa_i18n_methods, res,
+				text, 0, msgid);
+	return res;
+}
+
+static inline const char *
+spa_i18n_ngettext(struct spa_i18n *i18n, const char *msgid,
+		const char *msgid_plural, unsigned long int n)
+{
+	const char *res = n == 1 ? msgid : msgid_plural;
+	if (SPA_LIKELY(i18n != NULL))
+		spa_interface_call_res(&i18n->iface,
+	                        struct spa_i18n_methods, res,
+				ntext, 0, msgid, msgid_plural, n);
+	return res;
+}
+
+#ifdef __cplusplus
+}  /* extern "C" */
+#endif
+
+#endif /* SPA_I18N_H */