yog_api/
lang.rs

1//! Translations — text in the player's language, from the lang files the
2//! game loaded (a mod's `.yres` texts become them at `yog build`).
3//!
4//! ```ignore
5//! let title = yog_api::tr("mymod.screen.title");
6//! let count = yog_api::tr!("mymod.screen.count", shown, total); // "%s of %s mods"
7//! ```
8
9use std::fmt::{Display, Write as _};
10
11use yog_abi::YogStr;
12
13/// The text of translation `key` in the current language, unformatted —
14/// `None` when no lang file defines it (or before the mod registered).
15pub fn translation(key: &str) -> Option<String> {
16    let api = crate::registry::global_api();
17    if api.is_null() {
18        return None;
19    }
20    let owned = unsafe { ((*api).translate)((*api).ctx, YogStr::from_str(key)) };
21    crate::registry::take_owned(unsafe { (*api).free_str }, owned)
22}
23
24/// The text of translation `key` in the current language, or `key` itself
25/// when it has none — what Minecraft shows for an unknown key, so a missing
26/// translation is easy to spot. Call it each time the text is shown (e.g.
27/// while building a UI tree): the player can switch language at any time.
28pub fn tr(key: &str) -> String {
29    match translation(key) {
30        Some(text) => format_translation(&text, &[]),
31        None => key.to_string(),
32    }
33}
34
35/// [`tr`] with arguments for the text's format specifiers — see
36/// [`format_translation`]. The [`tr!`](crate::tr!) macro is shorter.
37pub fn tr_args(key: &str, args: &[&dyn Display]) -> String {
38    format_translation(&translation(key).unwrap_or_else(|| key.to_string()), args)
39}
40
41/// Fills Minecraft-style format specifiers in `pattern` (what lang files
42/// use): `%s`/`%d` take the next argument, `%1$s`/`%2$d` a numbered one
43/// (from 1), `%%` is a literal `%`. A specifier without an argument stays
44/// as written.
45pub fn format_translation(pattern: &str, args: &[&dyn Display]) -> String {
46    let mut out = String::with_capacity(pattern.len());
47    let mut next = 0;
48    let mut rest = pattern;
49    while let Some(pos) = rest.find('%') {
50        out.push_str(&rest[..pos]);
51        let spec = &rest[pos + 1..];
52        if let Some(after) = spec.strip_prefix('%') {
53            out.push('%');
54            rest = after;
55            continue;
56        }
57        if let Some(after) = spec.strip_prefix(['s', 'd']) {
58            match args.get(next) {
59                Some(arg) => {
60                    let _ = write!(out, "{arg}");
61                }
62                None => out.push_str(&rest[pos..pos + 2]),
63            }
64            next += 1;
65            rest = after;
66            continue;
67        }
68        let digits = spec.bytes().take_while(u8::is_ascii_digit).count();
69        let numbered = (digits > 0)
70            .then(|| spec[digits..].strip_prefix('$'))
71            .flatten()
72            .and_then(|s| s.strip_prefix(['s', 'd']));
73        match (numbered, spec[..digits].parse::<usize>()) {
74            (Some(after), Ok(n)) if n >= 1 => {
75                match args.get(n - 1) {
76                    Some(arg) => {
77                        let _ = write!(out, "{arg}");
78                    }
79                    None => out.push_str(&rest[pos..rest.len() - after.len()]),
80                }
81                rest = after;
82            }
83            _ => {
84                out.push('%');
85                rest = spec;
86            }
87        }
88    }
89    out.push_str(rest);
90    out
91}
92
93/// `tr!("key")` = [`tr`]`("key")`; `tr!("key", a, b)` fills the text's
94/// `%s` specifiers with `a` and `b` (anything `Display`) — see
95/// [`format_translation`].
96#[macro_export]
97macro_rules! tr {
98    ($key:expr_2021 $(,)?) => {
99        $crate::tr($key)
100    };
101    ($key:expr_2021, $($arg:expr_2021),+ $(,)?) => {
102        $crate::tr_args($key, &[$(&$arg as &dyn ::std::fmt::Display),+])
103    };
104}
105
106#[cfg(test)]
107mod tests {
108    use super::*;
109
110    #[test]
111    fn formats_like_minecraft() {
112        assert_eq!(
113            format_translation("%s of %s mods", &[&3, &"58"]),
114            "3 of 58 mods"
115        );
116        assert_eq!(format_translation("%2$s, %1$s", &[&"a", &"b"]), "b, a");
117        assert_eq!(format_translation("100%% by %s", &[&"X"]), "100% by X");
118        assert_eq!(format_translation("%d items", &[&5]), "5 items");
119        assert_eq!(
120            format_translation("missing %s and %3$s", &[]),
121            "missing %s and %3$s"
122        );
123        assert_eq!(format_translation("50% off %x", &[&1]), "50% off %x");
124        assert_eq!(format_translation("trailing %", &[]), "trailing %");
125        assert_eq!(format_translation("Привет, %s!", &[&"мир"]), "Привет, мир!");
126    }
127
128    #[test]
129    fn unknown_key_without_runtime_is_the_key() {
130        assert_eq!(tr("mymod.nothing"), "mymod.nothing");
131        assert_eq!(crate::tr!("count %s", 4), "count 4");
132    }
133}
yog_api/lang.rs

yog_api/
lang.rs
