Add a gettext wrapper in Rust

This allows the wgettext! macro, which calls into C++.

fish-rust/src/ffi.rs

@@ -31,6 +31,7 @@ include_cpp! {
     generate!("parse_util_unescape_wildcards")
 
     generate!("wildcard_match")
+    generate!("wgettext_ptr")
 
 }
 

fish-rust/src/wutil/gettext.rs

@@ -0,0 +1,35 @@
+use crate::ffi;
+use crate::wchar::{wchar_t, wstr};
+use crate::wchar_ffi::wcslen;
+
+/// Support for wgettext.
+
+/// Implementation detail for wgettext!.
+pub fn wgettext_impl_do_not_use_directly(text: &[wchar_t]) -> &'static wstr {
+    assert!(
+        text.len() > 0 && text[text.len() - 1] == 0,
+        "should be nul-terminated"
+    );
+    let res: *const wchar_t = ffi::wgettext_ptr(text.as_ptr());
+    let slice = unsafe { std::slice::from_raw_parts(res as *const u32, wcslen(res)) };
+    wstr::from_slice(slice).expect("Invalid UTF-32")
+}
+
+/// Get a (possibly translated) string from a string literal.
+/// This returns a &'static wstr.
+#[allow(unused_macros)]
+macro_rules! wgettext {
+    ($string:literal) => {
+        crate::wutil::gettext::wgettext_impl_do_not_use_directly(
+            crate::wchar_ffi::u32cstr!($string).as_slice_with_nul(),
+        )
+    };
+}
+
+use crate::ffi_tests::add_test;
+add_test!("test_untranslated", || {
+    let s: &'static wstr = wgettext!("abc");
+    assert_eq!(s, "abc");
+    let s2: &'static wstr = wgettext!("static");
+    assert_eq!(s2, "static");
+});

fish-rust/src/wutil/mod.rs

@@ -1,3 +1,4 @@
+pub mod gettext;
 mod wcstoi;
 
 pub use wcstoi::*;

src/wutil.cpp

@@ -514,6 +514,8 @@ const wcstring &wgettext(const wchar_t *in) {
     return val;
 }
 
+const wchar_t *wgettext_ptr(const wchar_t *in) { return wgettext(in).c_str(); }
+
 int wmkdir(const wcstring &name, int mode) {
     cstring name_narrow = wcs2string(name);
     return mkdir(name_narrow.c_str(), mode);

src/wutil.h

@@ -90,6 +90,7 @@ std::wstring wbasename(std::wstring path);
 /// and bindtextdomain functions. This should probably be moved out of wgettext, so that wgettext
 /// will be nothing more than a wrapper around gettext, like all other functions in this file.
 const wcstring &wgettext(const wchar_t *in);
+const wchar_t *wgettext_ptr(const wchar_t *in);
 
 /// Wide character version of mkdir.
 int wmkdir(const wcstring &name, int mode);