rtsp-server: Add builder API for RTSPToken for consistency with Structure

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1421>

examples/src/bin/rtsp-server-custom-auth.rs

@@ -138,7 +138,11 @@ mod auth {
                     if let Some(authorization) = auth_credentials.authorization() {
                         if let Some(user) = self.external_auth(authorization) {
                             // Update context token with authenticated username
-                            ctx.set_token(gst_rtsp_server::RTSPToken::new(&[("user", &user)]));
+                            ctx.set_token(
+                                gst_rtsp_server::RTSPToken::builder()
+                                    .field("user", user)
+                                    .build(),
+                            );
                             return true;
                         }
                     }

examples/src/bin/rtsp-server-record.rs

@@ -45,10 +45,9 @@ fn main_loop() -> Result<(), Error> {
     // Here we configure a method of authentication that we want the
     // server to require from clients.
     let auth = gst_rtsp_server::RTSPAuth::new();
-    let token = gst_rtsp_server::RTSPToken::new(&[(
+    let token = gst_rtsp_server::RTSPToken::builder()
-        gst_rtsp_server::RTSP_TOKEN_MEDIA_FACTORY_ROLE,
+        .field(gst_rtsp_server::RTSP_TOKEN_MEDIA_FACTORY_ROLE, "user")
-        &"user",
+        .build();
-    )]);
     let basic = gst_rtsp_server::RTSPAuth::make_basic("user", "password");
     // For proper authentication, we want to use encryption. And there's no
     // encryption without a certificate!

gstreamer-rtsp-server/src/rtsp_token.rs

@@ -2,7 +2,7 @@
 
 use std::fmt;
 
-use glib::{translate::*, value::ToSendValue};
+use glib::{translate::*, SendValue};
 
 gst::mini_object_wrapper!(RTSPToken, RTSPTokenRef, ffi::GstRTSPToken, || {
     ffi::gst_rtsp_token_get_type()
@@ -15,18 +15,19 @@ impl RTSPToken {
         unsafe { from_glib_full(ffi::gst_rtsp_token_new_empty()) }
     }
 
-    pub fn new(values: &[(&str, &(dyn ToSendValue + Sync))]) -> Self {
+    #[doc(alias = "gst_rtsp_token_new")]
+    pub fn builder() -> Builder {
+        skip_assert_initialized!();
+        Builder::new()
+    }
+
+    #[allow(clippy::should_implement_trait)]
+    pub fn from_iter(iter: impl IntoIterator<Item = (impl IntoGStr, SendValue)>) -> RTSPToken {
         skip_assert_initialized!();
         let mut token = RTSPToken::new_empty();
 
-        {
+        let s = token.get_mut().unwrap().structure_mut();
-            let token = token.get_mut().unwrap();
+        iter.into_iter().for_each(|(f, v)| s.set_value(f, v));
-            let structure = token.structure_mut();
-
-            for &(f, v) in values {
-                structure.set_value(f, v.to_send_value());
-            }
-        }
 
         token
     }
@@ -82,3 +83,32 @@ impl fmt::Debug for RTSPTokenRef {
             .finish()
     }
 }
+
+#[derive(Debug)]
+#[must_use = "The builder must be built to be used"]
+pub struct Builder {
+    token: RTSPToken,
+}
+
+impl Builder {
+    fn new() -> Self {
+        skip_assert_initialized!();
+        Builder {
+            token: RTSPToken::new_empty(),
+        }
+    }
+
+    pub fn field(mut self, name: impl IntoGStr, value: impl Into<glib::Value> + Send) -> Self {
+        self.token
+            .get_mut()
+            .unwrap()
+            .structure_mut()
+            .set(name, value);
+        self
+    }
+
+    #[must_use = "Building the structure without using it has no effect"]
+    pub fn build(self) -> RTSPToken {
+        self.token
+    }
+}