Add User hook support

doc/pages/changelog.asciidoc

@@ -5,6 +5,8 @@ released versions.
 
 == Development version
 
+* Introduce `User` hook support.
+
 * The `bold` and `italic` faces are no longer built-in. Highlighters
   are expected to use face attributes (`+b` and `+i`, respectively) to
   decorate text.

doc/pages/commands.asciidoc

@@ -210,6 +210,10 @@ of the file onto the filesystem
     remove every hooks in *scope* that are part of the given *group*
     (See <<hooks#,`:doc hooks`>> and <<scopes#,`:doc scopes`>>)
 
+*trigger-user-hook* <param>::
+    trigger the `User` hook with the given *param* as filter string in
+    the current context. (See <<hooks#,`:doc hooks`>>)
+
 == Display
 
 *echo* [<switches>] <text>::

doc/pages/hooks.asciidoc

@@ -178,6 +178,10 @@ name. Hooks with no description will always use an empty string.
 *ModuleLoaded* `module`::
     Triggered after a module is evaluated by the first `require-module` call
 
+*User* `param`::
+    Triggered  via the `trigger-user-hook` command. Provides a way for plugins
+    to introduce custom hooks by specifying what *param* would be.
+
 Note that some hooks will not consider underlying scopes depending on what
 context they are bound to be run into, e.g. the `BufWritePost` hook is a buffer
 hook, and will not consider the `window` scope.

src/commands.cc

@@ -1093,6 +1093,20 @@ const CommandDesc remove_hook_cmd = {
     }
 };
 
+const CommandDesc trigger_user_hook_cmd = {
+    "trigger-user-hook",
+    nullptr,
+    "trigger-user-hook <param>: run 'User' hook with <param> as filter string",
+    single_param,
+    CommandFlags::None,
+    CommandHelper{},
+    CommandCompleter{},
+    [](const ParametersParser& parser, Context& context, const ShellContext&)
+    {
+        context.hooks().run_hook(Hook::User, parser[0], context);
+    }
+};
+
 Vector<String> params_to_shell(const ParametersParser& parser)
 {
     Vector<String> vars;
@@ -2635,6 +2649,7 @@ void register_commands()
     register_command(remove_highlighter_cmd);
     register_command(add_hook_cmd);
     register_command(remove_hook_cmd);
+    register_command(trigger_user_hook_cmd);
     register_command(define_command_cmd);
     register_command(alias_cmd);
     register_command(unalias_cmd);

src/hook_manager.hh

@@ -54,7 +54,8 @@ enum class Hook
     WinDisplay,
     WinResize,
     WinSetOption,
-    ModuleLoaded
+    ModuleLoaded,
+    User
 };
 
 constexpr auto enum_desc(Meta::Type<Hook>)
@@ -97,7 +98,8 @@ constexpr auto enum_desc(Meta::Type<Hook>)
         {Hook::WinDisplay, "WinDisplay"},
         {Hook::WinResize, "WinResize"},
         {Hook::WinSetOption, "WinSetOption"},
-        {Hook::ModuleLoaded, "ModuleLoaded"}
+        {Hook::ModuleLoaded, "ModuleLoaded"},
+        {Hook::User, "User"}
     });
 }