Add an unmap command to remove key mappings

README.asciidoc

@@ -1402,6 +1402,15 @@ a single key name and `keys` a list of keys.
 `user` mode allows for user mapping behind the `,` key. Keys will be executed in
 normal mode.
 
+Mappings can be removed with the unmap command
+
+----------------------------------------
+:unmap <scope> <mode> <key> [<expected>]
+----------------------------------------
+
+If `<expected>` is specified, unmapping will only proceed if the current
+mapping matches the expected keys.
+
 Defining Commands
 ~~~~~~~~~~~~~~~~~
 

doc/manpages/commands.asciidoc

@@ -113,8 +113,17 @@ command *q!* has to be used).
 	define a new command (c.f. the 'Declaring new commands' section below)
 
 *map* <scope> <mode> <key> <keys>::
-	bind a combination of keys to another one (c.f. the 'commands'
+	make *key* behave as if *keys* were typed. with *scope*
-	documentation page)
+	being one of *global*, *buffer* or *window*, *mode* being
+	*insert*, *normal*, *prompt*, *menu* or *user*.
+
+	*user* mode allows for user mapping behind the *,* key. Keys
+	will be executed in normal mode.
+
+*unmap* <scope> <mode> <key> [<expected>]::
+	remove the mapping of *key* in given *scope* and *mode*, if
+	expected is specified, only remove the mapping it if matches
+	the expected keys.
 
 *hook* [-group <group>] <scope> <hook_name> <filtering_regex> <command>::
 	execute a command whenever an event is triggered (c.f. the 'hooks'

src/array_view.hh

@@ -73,6 +73,25 @@ private:
 template<typename T>
 using ConstArrayView = ArrayView<const T>;
 
+template<typename T>
+bool operator==(ArrayView<T> lhs, ArrayView<T> rhs)
+{
+    if (lhs.size() != rhs.size())
+        return false;
+    for (int i = 0; i < lhs.size(); ++i)
+    {
+        if (lhs[i] != rhs[i])
+            return false;
+    }
+    return true;
+}
+
+template<typename T>
+bool operator!=(ArrayView<T> lhs, ArrayView<T> rhs)
+{
+    return not (lhs == rhs);
+}
+
 }
 
 #endif // array_view_hh_INCLUDED

src/commands.cc

@@ -1328,6 +1328,23 @@ KeymapMode parse_keymap_mode(const String& str)
     throw runtime_error(format("unknown keymap mode '{}'", str));
 }
 
+auto map_key_completer =
+    [](const Context& context, CompletionFlags flags,
+       CommandParameters params, size_t token_to_complete,
+       ByteCount pos_in_token) -> Completions
+    {
+        if (token_to_complete == 0)
+            return { 0_byte, params[0].length(),
+                     complete(params[0], pos_in_token, scopes) };
+        if (token_to_complete == 1)
+        {
+            constexpr const char* modes[] = { "normal", "insert", "menu", "prompt", "goto", "view", "user", "object" };
+            return { 0_byte, params[1].length(),
+                     complete(params[1], pos_in_token, modes) };
+        }
+        return {};
+    };
+
 const CommandDesc map_key_cmd = {
     "map",
     nullptr,
@@ -1344,21 +1361,7 @@ const CommandDesc map_key_cmd = {
     ParameterDesc{{}, ParameterDesc::Flags::None, 4, 4},
     CommandFlags::None,
     CommandHelper{},
-    [](const Context& context, CompletionFlags flags,
+    map_key_completer,
-       CommandParameters params, size_t token_to_complete,
-       ByteCount pos_in_token) -> Completions
-    {
-        if (token_to_complete == 0)
-            return { 0_byte, params[0].length(),
-                     complete(params[0], pos_in_token, scopes) };
-        if (token_to_complete == 1)
-        {
-            constexpr const char* modes[] = { "normal", "insert", "menu", "prompt", "goto", "view", "user", "object" };
-            return { 0_byte, params[1].length(),
-                     complete(params[1], pos_in_token, modes) };
-        }
-        return {};
-    },
     [](const ParametersParser& parser, Context& context, const ShellContext&)
     {
         KeymapManager& keymaps = get_scope(parser[0], context).keymaps();
@@ -1373,6 +1376,41 @@ const CommandDesc map_key_cmd = {
     }
 };
 
+const CommandDesc unmap_key_cmd = {
+    "unmap",
+    nullptr,
+    "unmap <scope> <mode> <key> [<expected-keys>]: unmap <key> from given mode in <scope>.\n"
+    "If <expected> is specified, remove the mapping only if its value is <expected>\n"
+    "<mode> can be:\n"
+    "    normal\n"
+    "    insert\n"
+    "    menu\n"
+    "    prompt\n"
+    "    goto\n"
+    "    view\n"
+    "    user\n"
+    "    object\n",
+    ParameterDesc{{}, ParameterDesc::Flags::None, 4, 4},
+    CommandFlags::None,
+    CommandHelper{},
+    map_key_completer,
+    [](const ParametersParser& parser, Context& context, const ShellContext&)
+    {
+        KeymapManager& keymaps = get_scope(parser[0], context).keymaps();
+        KeymapMode keymap_mode = parse_keymap_mode(parser[1]);
+
+        KeyList key = parse_keys(parser[2]);
+        if (key.size() != 1)
+            throw runtime_error("only a single key can be mapped");
+
+        if (keymaps.is_mapped(key[0], keymap_mode) and
+            (parser.positional_count() < 4 or
+             (keymaps.get_mapping(key[0], keymap_mode) ==
+              ConstArrayView<Key>{parse_keys(parser[3])})))
+            keymaps.unmap_key(key[0], keymap_mode);
+    }
+};
+
 const ParameterDesc context_wrap_params = {
     { { "client",     { true,  "run in given client context" } },
       { "try-client", { true,  "run in given client context if it exists, or else in the current one" } },
@@ -2001,6 +2039,7 @@ void register_commands()
     register_command(unset_option_cmd);
     register_command(declare_option_cmd);
     register_command(map_key_cmd);
+    register_command(unmap_key_cmd);
     register_command(exec_string_cmd);
     register_command(eval_string_cmd);
     register_command(prompt_cmd);