Remove context refernce from Chatlist

See #476 aka a0b5e32f98 for full
rationale.  Tl;dr it allows us to evolve the Rust API while keeping
the FFI API identical.

deltachat-ffi/src/lib.rs

@@ -405,19 +405,17 @@ pub unsafe extern "C" fn dc_maybe_network(context: *mut dc_context_t) {
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn dc_get_chatlist<'a>(
+pub unsafe extern "C" fn dc_get_chatlist(
     context: *mut dc_context_t,
     flags: libc::c_int,
     query_str: *mut libc::c_char,
     query_id: u32,
-) -> *mut dc_chatlist_t<'a> {
+) -> *mut dc_chatlist_t {
     if context.is_null() {
         eprintln!("ignoring careless call to dc_get_chatlist()");
         return ptr::null_mut();
     }
-
     let context = &*context;
-
     let qs = if query_str.is_null() {
         None
     } else {
@@ -425,7 +423,10 @@ pub unsafe extern "C" fn dc_get_chatlist<'a>(
     };
     let qi = if query_id == 0 { None } else { Some(query_id) };
     match chatlist::Chatlist::try_load(context, flags as usize, qs, qi) {
-        Ok(list) => Box::into_raw(Box::new(list)),
+        Ok(list) => {
+            let ffi_list = ChatlistWrapper { context, list };
+            Box::into_raw(Box::new(ffi_list))
+        }
         Err(_) => std::ptr::null_mut(),
     }
 }
@@ -1633,8 +1634,20 @@ pub unsafe fn dc_array_is_independent(
 
 // dc_chatlist_t
 
+/// FFI struct for [dc_chatlist_t]
+///
+/// This is the structure behind [dc_chatlist_t] which is the opaque
+/// structure representing a chatlist in the FFI API.  It exists
+/// because the FFI API has a refernce from the message to the
+/// context, but the Rust API does not, so the FFI layer needs to glue
+/// these together.
+pub struct ChatlistWrapper {
+    context: *const dc_context_t,
+    list: chatlist::Chatlist,
+}
+
 #[no_mangle]
-pub type dc_chatlist_t<'a> = chatlist::Chatlist<'a>;
+pub type dc_chatlist_t = ChatlistWrapper;
 
 #[no_mangle]
 pub unsafe extern "C" fn dc_chatlist_unref(chatlist: *mut dc_chatlist_t) {
@@ -1642,7 +1655,6 @@ pub unsafe extern "C" fn dc_chatlist_unref(chatlist: *mut dc_chatlist_t) {
         eprintln!("ignoring careless call to dc_chatlist_unref()");
         return;
     }
-
     Box::from_raw(chatlist);
 }
 
@@ -1652,9 +1664,8 @@ pub unsafe extern "C" fn dc_chatlist_get_cnt(chatlist: *mut dc_chatlist_t) -> li
         eprintln!("ignoring careless call to dc_chatlist_get_cnt()");
         return 0;
     }
-
+    let ffi_list = &*chatlist;
-    let list = &*chatlist;
+    ffi_list.list.len() as libc::size_t
-    list.len() as libc::size_t
 }
 
 #[no_mangle]
@@ -1666,9 +1677,8 @@ pub unsafe extern "C" fn dc_chatlist_get_chat_id(
         eprintln!("ignoring careless call to dc_chatlist_get_chat_id()");
         return 0;
     }
-
+    let ffi_list = &*chatlist;
-    let list = &*chatlist;
+    ffi_list.list.get_chat_id(index as usize)
-    list.get_chat_id(index as usize)
 }
 
 #[no_mangle]
@@ -1680,9 +1690,8 @@ pub unsafe extern "C" fn dc_chatlist_get_msg_id(
         eprintln!("ignoring careless call to dc_chatlist_get_msg_id()");
         return 0;
     }
-
+    let ffi_list = &*chatlist;
-    let list = &*chatlist;
+    ffi_list.list.get_msg_id(index as usize)
-    list.get_msg_id(index as usize)
 }
 
 #[no_mangle]
@@ -1701,8 +1710,10 @@ pub unsafe extern "C" fn dc_chatlist_get_summary(
         let ffi_chat = &*chat;
         Some(&ffi_chat.chat)
     };
-    let list = &*chatlist;
+    let ffi_list = &*chatlist;
-    let lot = list.get_summary(index as usize, maybe_chat);
+    let lot = ffi_list
+        .list
+        .get_summary(&*ffi_list.context, index as usize, maybe_chat);
     Box::into_raw(Box::new(lot))
 }
 
@@ -1714,10 +1725,8 @@ pub unsafe extern "C" fn dc_chatlist_get_context(
         eprintln!("ignoring careless call to dc_chatlist_get_context()");
         return ptr::null_mut();
     }
-
+    let ffi_list = &*chatlist;
-    let list = &*chatlist;
+    ffi_list.context
-
-    list.get_context() as *const _
 }
 
 // dc_chat_t

examples/repl/cmdline.rs

@@ -592,7 +592,7 @@ pub unsafe fn dc_cmdline(context: &Context, line: &str) -> Result<(), failure::E
                         temp_subtitle,
                         chat::get_fresh_msg_cnt(context, chat.get_id()),
                     );
-                    let lot = chatlist.get_summary(i, Some(&chat));
+                    let lot = chatlist.get_summary(context, i, Some(&chat));
                     let statestr = if chat.is_archived() {
                         " [Archived]"
                     } else {

examples/simple.rs

@@ -101,7 +101,7 @@ fn main() {
         let chats = Chatlist::try_load(&ctx, 0, None, None).unwrap();
 
         for i in 0..chats.len() {
-            let summary = chats.get_summary(0, None);
+            let summary = chats.get_summary(&ctx, 0, None);
             let text1 = summary.get_text1();
             let text2 = summary.get_text2();
             println!("chat: {} - {:?} - {:?}", i, text1, text2,);

src/chatlist.rs

@@ -31,17 +31,12 @@ use crate::stock::StockMessage;
 /// first entry and only present on new messages, there is the rough idea that it can be optionally always
 /// present and sorted into the list by date. Rendering the deaddrop in the described way
 /// would not add extra work in the UI then.
-pub struct Chatlist<'a> {
+pub struct Chatlist {
-    context: &'a Context,
     /// Stores pairs of `chat_id, message_id`
     ids: Vec<(u32, u32)>,
 }
 
-impl<'a> Chatlist<'a> {
+impl Chatlist {
-    pub fn get_context(&self) -> &Context {
-        self.context
-    }
-
     /// Get a list of chats.
     /// The list can be filtered by query parameters.
     ///
@@ -85,7 +80,7 @@ impl<'a> Chatlist<'a> {
     /// `query_contact_id`: An optional contact ID for filtering the list. Only chats including this contact ID
     ///     are returned.
     pub fn try_load(
-        context: &'a Context,
+        context: &Context,
         listflags: usize,
         query: Option<&str>,
         query_contact_id: Option<u32>,
@@ -200,7 +195,7 @@ impl<'a> Chatlist<'a> {
             ids.push((DC_CHAT_ID_ARCHIVED_LINK, 0));
         }
 
-        Ok(Chatlist { context, ids })
+        Ok(Chatlist { ids })
     }
 
     /// Find out the number of chats.
@@ -247,7 +242,7 @@ impl<'a> Chatlist<'a> {
     /// - dc_lot_t::timestamp: the timestamp of the message.  0 if not applicable.
     /// - dc_lot_t::state: The state of the message as one of the DC_STATE_* constants (see #dc_msg_get_state()).
     //    0 if not applicable.
-    pub fn get_summary(&self, index: usize, chat: Option<&Chat>) -> Lot {
+    pub fn get_summary(&self, context: &Context, index: usize, chat: Option<&Chat>) -> Lot {
         // The summary is created by the chat, not by the last message.
         // This is because we may want to display drafts here or stuff as
         // "is typing".
@@ -263,7 +258,7 @@ impl<'a> Chatlist<'a> {
         let chat = if let Some(chat) = chat {
             chat
         } else {
-            if let Ok(chat) = Chat::load_from_db(self.context, self.ids[index].0) {
+            if let Ok(chat) = Chat::load_from_db(context, self.ids[index].0) {
                 chat_loaded = chat;
                 &chat_loaded
             } else {
@@ -275,11 +270,11 @@ impl<'a> Chatlist<'a> {
         let mut lastcontact = None;
 
         let lastmsg = if 0 != lastmsg_id {
-            if let Ok(lastmsg) = dc_msg_load_from_db(self.context, lastmsg_id) {
+            if let Ok(lastmsg) = dc_msg_load_from_db(context, lastmsg_id) {
                 if lastmsg.from_id != 1 as libc::c_uint
                     && (chat.typ == Chattype::Group || chat.typ == Chattype::VerifiedGroup)
                 {
-                    lastcontact = Contact::load_from_db(self.context, lastmsg.from_id).ok();
+                    lastcontact = Contact::load_from_db(context, lastmsg.from_id).ok();
                 }
 
                 Some(lastmsg)
@@ -294,14 +289,9 @@ impl<'a> Chatlist<'a> {
             ret.text2 = None;
         } else if lastmsg.is_none() || lastmsg.as_ref().unwrap().from_id == DC_CONTACT_ID_UNDEFINED
         {
-            ret.text2 = Some(self.context.stock_str(StockMessage::NoMessages).to_string());
+            ret.text2 = Some(context.stock_str(StockMessage::NoMessages).to_string());
         } else {
-            ret.fill(
+            ret.fill(&mut lastmsg.unwrap(), chat, lastcontact.as_ref(), context);
-                &mut lastmsg.unwrap(),
-                chat,
-                lastcontact.as_ref(),
-                self.context,
-            );
         }
 
         ret