lua: add wezterm.strftime

refs: https://github.com/wez/wezterm/issues/500

Cargo.lock

@@ -555,6 +555,7 @@ dependencies = [
  "libc",
  "num-integer",
  "num-traits 0.2.14",
+ "pure-rust-locales",
  "time",
  "winapi 0.3.9",
 ]
@@ -674,6 +675,7 @@ dependencies = [
  "anyhow",
  "bitflags",
  "bstr 0.2.15",
+ "chrono",
  "dirs-next",
  "filenamegen",
  "hostname",
@@ -2869,6 +2871,12 @@ dependencies = [
  "unicase",
 ]
 
+[[package]]
+name = "pure-rust-locales"
+version = "0.5.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4f72f6d09f6d70d4e704070c8d6d77e759f9b7f7820609ac0fe7776bbc7ce09d"
+
 [[package]]
 name = "quick-error"
 version = "1.2.3"

config/Cargo.toml

@@ -17,6 +17,7 @@ pretty_env_logger = "0.4"
 anyhow = "1.0"
 bitflags = "1.0"
 bstr = "0.2"
+chrono = {version="0.4", features=["unstable-locales"]}
 dirs-next = "2.0"
 filenamegen = "0.2"
 hostname = "0.3"

config/src/lua.rs

@@ -133,6 +133,7 @@ pub fn make_lua_context(config_dir: &Path) -> anyhow::Result<Lua> {
         wezterm_mod.set("emit", lua.create_async_function(emit_event)?)?;
         wezterm_mod.set("sleep_ms", lua.create_async_function(sleep_ms)?)?;
         wezterm_mod.set("format", lua.create_function(format)?)?;
+        wezterm_mod.set("strftime", lua.create_function(strftime)?)?;
 
         package.set("path", path_array.join(";"))?;
 
@@ -236,6 +237,12 @@ impl termwiz::render::RenderTty for FormatTarget {
     }
 }
 
+fn strftime<'lua>(_: &'lua Lua, format: String) -> mlua::Result<String> {
+    use chrono::prelude::*;
+    let local: DateTime<Local> = Local::now();
+    Ok(local.format(&format).to_string())
+}
+
 fn format<'lua>(_: &'lua Lua, items: Vec<FormatItem>) -> mlua::Result<String> {
     let mut changes: Vec<Change> = items.into_iter().map(Into::into).collect();
     changes.push(Change::AllAttributes(CellAttributes::default()).into());

docs/config/lua/wezterm/strftime.md

@@ -0,0 +1,14 @@
+# `wezterm.strftime(format)`
+
+*Since: nightly*
+
+Formats the current local date/time into a string using [the Rust chrono
+strftime syntax](https://docs.rs/chrono/0.4.19/chrono/format/strftime/index.html).
+
+```lua
+local wezterm = require 'wezterm';
+
+local date_and_time = wezterm.strftime("%Y-%m-%d %H:%M:%S");
+wezterm.log_info(date_and_time);
+```
+