custom-keybinds: add run-statement script-message

This is an extremely powerful script-message that allows you to
basically embed small addons into custom-keybinds.

custom-keybinds.md

@@ -173,7 +173,8 @@ To avoid conflicts custom keybinds use the format: `file_browser/dynamic/custom/
 Expressions are used to evaluate Lua code into a string that can be used for commands.
 These behave similarly to those used for [`profile-cond`](https://mpv.io/manual/master/#conditional-auto-profiles)
 values. In an expression the `mp`, `mp.msg`, and `mp.utils` modules are available as `mp`, `msg`, and `utils` respectively.
-Additionally the file-browser [addon API](addons/addons.md#the-api) is available as `fb`.
+Additionally the file-browser [addon API](addons/addons.md#the-api) is available as `fb` and if [mpv-user-input](https://github.com/CogentRedTester/mpv-user-input)
+is installed then user-input API will be available in `input`.
 
 This example only runs the keybind if the browser is in the Windows C drive or if
 the selected item is a matroska file:
@@ -284,6 +285,41 @@ This example replaces all `/` characters in the path with `\`
 }
 ```
 
+### `run-statement <statement...>`
+
+Runs the following string a as a Lua statement. This is similar to an [expression](#expressions),
+but instead of the code evaluating to a value it must run a series of statements. Basically it allows
+for function bodies to be embedded into custom keybinds. All the same modules are available.
+If multiple strings are sent to the script-message then they will be concatenated together with newlines.
+
+The following keybind will use [mpv-user-input](https://github.com/CogentRedTester/mpv-user-input) to
+rename items in file-browser:
+
+```json
+{
+    "key": "KP1",
+    "command": ["script-message", "run-statement",
+                    "assert(input, 'install mpv-user-input!')",
+
+                    "local line, err = input.get_user_input_co({",
+                                            "id = 'rename-file',",
+                                            "source = 'custom-keybind',",
+                                            "request_text = 'rename file:',",
+                                            "queueable = true,",
+                                            "default_input = %N,",
+                                            "cursor_pos = #(%N) - #fb.get_extension(%N, '')",
+                                        "})",
+
+                    "if not line then return end",
+                    "os.rename(%F, utils.join_path(%P, line))",
+
+                    "fb.rescan()"
+                ],
+    "parser": "file",
+    "multiselect": true
+}
+```
+
 ## Examples
 
 See [here](file-browser-keybinds.json).

file-browser.lua

@@ -126,6 +126,10 @@ local o = {
 opt.read_options(o, 'file_browser')
 utils.shared_script_property_set("file_browser-open", "no")
 
+package.path = mp.command_native({"expand-path", o.module_directory}).."/?.lua;"..package.path
+local success, input = pcall(require, "user-input-module")
+if not success then input = nil end
+
 
 
 --------------------------------------------------------------------------------------------------------
@@ -161,8 +165,6 @@ local parse_state_API = {}
 local ass = mp.create_osd_overlay("ass-events")
 if not ass then return msg.error("Script requires minimum mpv version 0.31") end
 
-package.path = mp.command_native({"expand-path", o.module_directory}).."/?.lua;"..package.path
-
 local style = {
     global = o.alignment == 0 and "" or ([[{\an%d}]]):format(o.alignment),
 
@@ -579,6 +581,7 @@ function API.evaluate_string(str, name)
     env.msg = API.redirect_table(msg)
     env.utils = API.redirect_table(utils)
     env.fb = API.redirect_table(API)
+    env.input = input and API.redirect_table(input)
 
     local chunk, err
     if setfenv then
@@ -2167,12 +2170,11 @@ local function scan_directory_json(directory, response_str)
     mp.commandv("script-message", response_str, list or "", opts or "")
 end
 
-pcall(function()
-    local input = require "user-input-module"
+if input then
     mp.add_key_binding("Alt+o", "browse-directory/get-user-input", function()
         input.get_user_input(browse_directory, {request_text = "open directory:"})
     end)
-end)
+end
 
 
 
@@ -2228,6 +2230,14 @@ mp.register_script_message('evaluate-expressions', function(...)
     end)
 end)
 
+--a helper function for custom-keybinds
+--concatenates the command arguments with newlines and runs the
+--string as a statement of code
+mp.register_script_message('run-statement', function(...)
+    local statement = table.concat(table.pack(...), '\n')
+    API.coroutine.run(API.evaluate_string, statement)
+end)
+
 --allows keybinds/other scripts to auto-open specific directories
 mp.register_script_message('browse-directory', browse_directory)