feat: implement just_version() function

implement #2616

Author: nyurik

README.md

@@ -1628,12 +1628,13 @@ All functions ending in `_directory` can be abbreviated to `_dir`. So
   `"arm"`, `"asmjs"`, `"hexagon"`, `"mips"`, `"msp430"`, `"powerpc"`,
   `"powerpc64"`, `"s390x"`, `"sparc"`, `"wasm32"`, `"x86"`, `"x86_64"`, and
   `"xcore"`.
-- `num_cpus()`<sup>1.15.0</sup> - Number of logical CPUs.
+- `num_cpus()`<sup>1.15.0</sup> — Number of logical CPUs.
 - `os()` — Operating system. Possible values are: `"android"`, `"bitrig"`,
   `"dragonfly"`, `"emscripten"`, `"freebsd"`, `"haiku"`, `"ios"`, `"linux"`,
   `"macos"`, `"netbsd"`, `"openbsd"`, `"solaris"`, and `"windows"`.
 - `os_family()` — Operating system family; possible values are: `"unix"` and
   `"windows"`.
+- `just_version()`<sup>master</sup> — The version of `just` being run, e.g. `"1.42.5"`.
 
 For example:
 

examples/kitchen-sink.just

@@ -5,6 +5,12 @@ set positional-arguments
 set dotenv-load
 set export
 
+_required_just_ver := if semver_matches(just_version(), '>=1.43.0') == 'true' {
+  'yes'
+} else {
+  error('just version 1.43.0 or greater is required, found ' + just_version())
+}
+
 alias s := serve
 
 bt := '0'
@@ -16,7 +22,7 @@ log := "warn"
 export JUST_LOG := (log + "ing" + `grep loop /etc/networks | cut -f2`)
 
 tmpdir  := `mktemp`
-version := "0.2.7"
+version := just_version()
 tardir  := tmpdir / "awesomesauce-" + version
 foo1    := / "tmp"
 foo2_3  := "a/"

src/function.rs

@@ -73,6 +73,7 @@ pub(crate) fn get(name: &str) -> Option<Function> {
     "join" => BinaryPlus(join),
     "just_executable" => Nullary(just_executable),
     "just_pid" => Nullary(just_pid),
+    "just_version" => Nullary(just_version),
     "justfile" => Nullary(justfile),
     "justfile_directory" => Nullary(justfile_directory),
     "kebabcase" => Unary(kebabcase),
@@ -398,6 +399,10 @@ fn just_pid(_context: Context) -> FunctionResult {
   Ok(std::process::id().to_string())
 }
 
+fn just_version(_context: Context) -> FunctionResult {
+  Ok(env!("CARGO_PKG_VERSION").to_string())
+}
+
 fn justfile(context: Context) -> FunctionResult {
   context
     .evaluator

tests/functions.rs

@@ -6,26 +6,28 @@ fn test_os_arch_functions_in_interpolation() {
     .justfile(
       r"
 foo:
-  echo {{arch()}} {{os()}} {{os_family()}} {{num_cpus()}}
+  echo {{arch()}} {{os()}} {{os_family()}} {{num_cpus()}} {{just_version()}}
 ",
     )
     .stdout(
       format!(
-        "{} {} {} {}\n",
+        "{} {} {} {} {}\n",
         target::arch(),
         target::os(),
         target::family(),
-        num_cpus::get()
+        num_cpus::get(),
+        env!("CARGO_PKG_VERSION"),
       )
       .as_str(),
     )
     .stderr(
       format!(
-        "echo {} {} {} {}\n",
+        "echo {} {} {} {} {}\n",
         target::arch(),
         target::os(),
         target::family(),
-        num_cpus::get()
+        num_cpus::get(),
+        env!("CARGO_PKG_VERSION"),
       )
       .as_str(),
     )
@@ -41,28 +43,31 @@ a := arch()
 o := os()
 f := os_family()
 n := num_cpus()
+v := just_version()
 
 foo:
-  echo {{a}} {{o}} {{f}} {{n}}
+  echo {{a}} {{o}} {{f}} {{n}} {{v}}
 ",
     )
     .stdout(
       format!(
-        "{} {} {} {}\n",
+        "{} {} {} {} {}\n",
         target::arch(),
         target::os(),
         target::family(),
-        num_cpus::get()
+        num_cpus::get(),
+        env!("CARGO_PKG_VERSION"),
       )
       .as_str(),
     )
     .stderr(
       format!(
-        "echo {} {} {} {}\n",
+        "echo {} {} {} {} {}\n",
         target::arch(),
         target::os(),
         target::family(),
-        num_cpus::get()
+        num_cpus::get(),
+        env!("CARGO_PKG_VERSION"),
       )
       .as_str(),
     )
@@ -397,27 +402,29 @@ fn test_os_arch_functions_in_default() {
   Test::new()
     .justfile(
       r"
-foo a=arch() o=os() f=os_family() n=num_cpus():
-  echo {{a}} {{o}} {{f}} {{n}}
+foo a=arch() o=os() f=os_family() n=num_cpus() v=just_version():
+  echo {{a}} {{o}} {{f}} {{n}} {{v}}
 ",
     )
     .stdout(
       format!(
-        "{} {} {} {}\n",
+        "{} {} {} {} {}\n",
         target::arch(),
         target::os(),
         target::family(),
-        num_cpus::get()
+        num_cpus::get(),
+        env!("CARGO_PKG_VERSION"),
       )
       .as_str(),
     )
     .stderr(
       format!(
-        "echo {} {} {} {}\n",
+        "echo {} {} {} {} {}\n",
         target::arch(),
         target::os(),
         target::family(),
-        num_cpus::get()
+        num_cpus::get(),
+        env!("CARGO_PKG_VERSION"),
       )
       .as_str(),
     )