Add wezterm.gui.default_key_tables()

This provides a means for more easily extending the default key
tables without forcing the user to recreate the entire config
for themselves.

wezterm.gui.default_keys is also added by this, but it is likely
not as useful.

config/src/lib.rs

@@ -700,6 +700,13 @@ impl ConfigHandle {
     pub fn generation(&self) -> usize {
         self.generation
     }
+
+    pub fn default_config() -> Self {
+        Self {
+            config: Arc::new(Config::default_config()),
+            generation: 0,
+        }
+    }
 }
 
 impl std::ops::Deref for ConfigHandle {

docs/changelog.md

@@ -11,6 +11,11 @@ usually the best available version.
 
 As features stabilize some brief notes about them will accumulate here.
 
+#### New
+* [wezterm.gui.default_key_tables](config/lua/wezterm.gui/default_key_tables.md)
+  and [wezterm.gui.default_keys](config/lua/wezterm.gui/default_keys.md) for
+  more conveniently copying and extending the default configuration.
+
 #### Fixed
 * Wayland: key repeat gets stuck after pressing two keys in quick succession.
   Thanks to [@unrelentingtech](https://github.com/unrelentingtech)!

docs/config/lua/wezterm.gui/default_key_tables.md

@@ -0,0 +1,32 @@
+# `wezterm.gui.default_key_tables()`
+
+*Since: nightly builds only*
+
+Returns a table holding the effective default set of `key_tables`.  That is the
+set of keys that is used as a base if there was no configuration file.
+
+This is useful in cases where you want to override a key table assignment
+without replacing the entire set of key tables.
+
+This example shows how to add a key assignment for `Backspace` to `copy_mode`,
+without having to manually specify the entire key table:
+
+```lua
+local wezterm = require 'wezterm'
+local act = wezterm.action
+
+local copy_mode = nil
+if wezterm.gui then
+  copy_mode = wezterm.gui.default_key_tables().copy_mode
+  table.insert(
+    copy_mode,
+    { key = 'Backspace', mods = 'NONE', action = act.CopyMode 'MoveLeft' }
+  )
+end
+
+return {
+  key_tables = {
+    copy_mode = copy_mode,
+  },
+}
+```

docs/config/lua/wezterm.gui/default_keys.md

@@ -0,0 +1,8 @@
+# `wezterm.gui.default_keys()`
+
+*Since: nightly builds only*
+
+Returns a table holding the effective default values for key assignments.  That
+is the set of keys that is used as a base if there was no configuration file.
+
+

docs/copymode.md

@@ -75,8 +75,14 @@ reassignable.
 
 The key assignments for copy mode are specified by the `copy_mode` [Key Table](config/key-tables.md).
 
-You may provide your own definition of this key table if you wish to customize it.
-There isn't a way to override portions of the key table, only to replace the entire table.
+You may provide your own definition of this key table if you wish to customize
+it.
+
+You may use
+[wezterm.gui.default_key_tables](config/lua/wezterm.gui/default_key_tables.md)
+to obtain the defaults and extend them. In earlier versions of wezterm there
+wasn't a way to override portions of the key table, only to replace the entire
+table.
 
 The default configuration at the time that these docs were built (which
 may be more recent than your version of wezterm) is shown below.

docs/scrollback.md

@@ -91,8 +91,11 @@ When the search overlay is active the behavior of wezterm changes:
 
 The key assignments for copy mode are specified by the `search_mode` [Key Table](config/key-tables.md).
 
-You may provide your own definition of this key table if you wish to customize it.
-There isn't a way to override portions of the key table, only to replace the entire table.
+You may use
+[wezterm.gui.default_key_tables](config/lua/wezterm.gui/default_key_tables.md)
+to obtain the defaults and extend them. In earlier versions of wezterm there
+wasn't a way to override portions of the key table, only to replace the entire
+table.
 
 The default configuration at the time that these docs were built (which
 may be more recent than your version of wezterm) is shown below.

wezterm-gui/src/inputmap.rs

@@ -17,6 +17,11 @@ pub struct InputMap {
 }
 
 impl InputMap {
+    pub fn default_input_map() -> Self {
+        let config = ConfigHandle::default_config();
+        Self::new(&config)
+    }
+
     pub fn new(config: &ConfigHandle) -> Self {
         let mut mouse = config.mouse_bindings();
 

wezterm-gui/src/scripting/mod.rs

@@ -1,7 +1,13 @@
 use crate::frontend::try_front_end;
+use crate::inputmap::InputMap;
+use config::keyassignment::KeyTable;
 use config::lua::get_or_create_sub_module;
 use config::lua::mlua::{self, Lua};
+use config::{DeferredKeyCode, Key, KeyNoAction};
+use luahelper::dynamic_to_lua_value;
 use mux::window::WindowId as MuxWindowId;
+use std::collections::HashMap;
+use wezterm_dynamic::ToDynamic;
 
 pub mod guiwin;
 pub mod pane;
@@ -28,5 +34,41 @@ pub fn register(lua: &Lua) -> anyhow::Result<()> {
         })?,
     )?;
 
+    fn key_table_to_lua(table: &KeyTable) -> Vec<Key> {
+        let mut keys = vec![];
+        for ((key, mods), entry) in table {
+            keys.push(Key {
+                key: KeyNoAction {
+                    key: DeferredKeyCode::KeyCode(key.clone()),
+                    mods: *mods,
+                },
+                action: entry.action.clone(),
+            });
+        }
+        keys
+    }
+
+    window_mod.set(
+        "default_keys",
+        lua.create_function(|lua, _: ()| {
+            let map = InputMap::default_input_map();
+            let keys = key_table_to_lua(&map.keys.default);
+            dynamic_to_lua_value(lua, keys.to_dynamic())
+        })?,
+    )?;
+
+    window_mod.set(
+        "default_key_tables",
+        lua.create_function(|lua, _: ()| {
+            let inputmap = InputMap::default_input_map();
+            let mut tables: HashMap<String, Vec<Key>> = HashMap::new();
+            for (k, table) in &inputmap.keys.by_name {
+                let keys = key_table_to_lua(table);
+                tables.insert(k.to_string(), keys);
+            }
+            dynamic_to_lua_value(lua, tables.to_dynamic())
+        })?,
+    )?;
+
     Ok(())
 }