fluent_handlebars_runtime/
helper.rs

1use std::collections::HashMap;
2
3use fluent_templates::Loader;
4use fluent_templates::fluent_bundle::FluentValue;
5use handlebars::{Context, Handlebars, Helper, HelperDef, HelperResult, Output, RenderContext, RenderError};
6use serde_json::Value as Json;
7
8/// A lightweight newtype wrapper around [FluentLoader](https://docs.rs/fluent-templates/0.5.13/fluent_templates/struct.FluentLoader.html)
9/// that implements the [HelperDef](https://docs.rs/handlebars/3.3.0/handlebars/trait.HelperDef.html)
10/// trait in a different way. It resolves Fluent placeables by looking them up in the data hash
11/// provided to Handlebars.render_template() at runtime.
12pub struct FluentHandlebars<L: Loader + Send + Sync>{
13    loader: L
14}
15
16impl<L: Loader + Send + Sync> FluentHandlebars<L> {
17    pub fn new(ldr: L) -> FluentHandlebars<L> {
18        FluentHandlebars {
19            loader: ldr
20        }
21    }
22}
23
24impl<L: Loader + Send + Sync> HelperDef for FluentHandlebars<L> {
25    fn call<'reg: 'rc, 'rc>(
26        &self,
27        helper: &Helper<'reg, 'rc>,
28        _reg: &'reg Handlebars,
29        context: &'rc Context,
30        _rcx: &mut RenderContext<'reg, 'rc>,
31        out: &mut dyn Output,
32    ) -> HelperResult {
33        let id = if let Some(id) = helper.param(0) {
34            id
35        } else {
36            return Err(RenderError::new(
37                "{{t}} must have at least one parameter",
38            ));
39        };
40
41        if id.relative_path().is_some() {
42            return Err(RenderError::new(
43                "{{t}} takes a string literal, not a path",
44            ));
45        }
46
47        let id = if let Json::String(ref s) = *id.value() {
48            s
49        } else {
50            return Err(RenderError::new("{{t}} takes a string parameter"));
51        };
52
53        let args: Option<HashMap<String, FluentValue>> = if !context.data().is_object() {
54            None
55        } else {
56            let map = context
57                .data()
58                .as_object().unwrap()
59                .iter()
60                .filter_map(|(k, v)| {
61                    let val: FluentValue = match v {
62                        // `Number::as_f64` can't fail here because we haven't
63                        // enabled `arbitrary_precision` feature
64                        // in `serde_json`.
65                        Json::Number(n) => n.as_f64().unwrap().into(),
66                        Json::String(s) => s.to_owned().into(),
67                        _ => return None,
68                    };
69                    Some((k.to_string(), val))
70                })
71                .collect();
72            Some(map)
73        };
74
75        let lang = context
76            .data()
77            .get("lang")
78            .expect("Language not set in context")
79            .as_str()
80            .expect("Language must be string")
81            .parse()
82            .expect("Language not valid identifier");
83
84        let response = self.loader.lookup_complete(&lang, &id, args.as_ref());
85        out.write(&response).map_err(
86            |e| RenderError::from_error("fluent-handlebars-runtime helper", e)
87        )
88    }
89}
fluent_handlebars_runtime/helper.rs

fluent_handlebars_runtime/
helper.rs
