Add a ClientCreate and ClientClose hook

As discussed in #2830.
Closes #2500.

doc/pages/hooks.asciidoc

@@ -140,6 +140,13 @@ name. Hooks with no description will always use an empty string.
     executed when a fifo buffer closes its fifo file descriptor either
     because the buffer is being deleted or the writing end has been closed
 
+*ClientCreate* `client name`::
+    executed when a new client is created.
+
+*ClientClose* `client name`::
+    executed when a client is closed, after it was removed from the client
+    list.
+
 *RuntimeError* `error message`::
     an error was encountered while executing a user command
 

src/client_manager.cc

@@ -64,7 +64,9 @@ Client* ClientManager::create_client(std::unique_ptr<UserInterface>&& ui, int pi
 
     try
     {
-        CommandManager::instance().execute(init_cmds, client->context());
+        auto& context = client->context();
+        context.hooks().run_hook(Hook::ClientCreate, context.name(), context);
+        CommandManager::instance().execute(init_cmds, context);
     }
     catch (Kakoune::runtime_error& error)
     {
@@ -116,10 +118,14 @@ void ClientManager::remove_client(Client& client, bool graceful, int status)
         kak_assert(contains(m_client_trash, &client));
         return;
     }
+
     client.exit(status);
     m_client_trash.push_back(std::move(*it));
     m_clients.erase(it);
 
+    auto& context = client.context();
+    context.hooks().run_hook(Hook::ClientClose, context.name(), context);
+
     if (not graceful and m_clients.empty())
         BufferManager::instance().backup_modified_buffers();
 }

src/hook_manager.hh

@@ -28,6 +28,8 @@ enum class Hook
     BufCloseFifo,
     BufReadFifo,
     BufSetOption,
+    ClientCreate,
+    ClientClose,
     InsertBegin,
     InsertChar,
     InsertDelete,
@@ -60,7 +62,7 @@ enum class Hook
 
 constexpr auto enum_desc(Meta::Type<Hook>)
 {
-    return make_array<EnumDesc<Hook>, 39>({
+    return make_array<EnumDesc<Hook>, 41>({
         {Hook::BufCreate, "BufCreate"},
         {Hook::BufNewFile, "BufNewFile"},
         {Hook::BufOpenFile, "BufOpenFile"},
@@ -72,6 +74,8 @@ constexpr auto enum_desc(Meta::Type<Hook>)
         {Hook::BufCloseFifo, "BufCloseFifo"},
         {Hook::BufReadFifo, "BufReadFifo"},
         {Hook::BufSetOption, "BufSetOption"},
+        {Hook::ClientCreate, "ClientCreate"},
+        {Hook::ClientClose, "ClientClose"},
         {Hook::InsertBegin, "InsertBegin"},
         {Hook::InsertChar, "InsertChar"},
         {Hook::InsertDelete, "InsertDelete"},