Rust embedded support

Cargo.toml

@@ -29,6 +29,7 @@ serde = "1.0.0"
 serde_json = "1.0.39"
 walkdir = { version = "2.2.3", optional = true }
 rhai = { version = "1", optional = true, features = ["sync", "serde"] }
+rust-embed = { version = "6.3.0", optional = true }
 
 [dev-dependencies]
 env_logger = "0.9"

src/lib.rs

@@ -166,6 +166,14 @@
 //! # }
 //! ```
 //!
+//! #### Additional features for loading template from
+//!
+//! * Feature `dir_source` enables template loading
+//! `register_templates_directory` from given directory.
+//! * Feature `rust-embed` enables template loading
+//! `register_embed_templates` from embedded resources in rust struct
+//! generated with `RustEmbed`.
+//!
 //! ### Rendering Something
 //!
 //! Since handlebars is originally based on JavaScript type system. It supports dynamic features like duck-typing, truthy/falsey values. But for a static language like Rust, this is a little difficult. As a solution, we are using the `serde_json::value::Value` internally for data rendering.

src/registry.rs

@@ -30,6 +30,9 @@ use rhai::Engine;
 #[cfg(feature = "script_helper")]
 use crate::helpers::scripting::ScriptHelper;
 
+#[cfg(feature = "rust-embed")]
+use rust_embed::RustEmbed;
+
 /// This type represents an *escape fn*, that is a function whose purpose it is
 /// to escape potentially problematic characters in a string.
 ///
@@ -322,6 +325,38 @@ impl<'reg> Registry<'reg> {
         Ok(())
     }
 
+    /// Register templates using a
+    /// [RustEmbed](https://github.com/pyros2097/rust-embed) type
+    ///
+    /// File names from embed struct are used as template name.
+    ///
+    /// ```skip
+    /// #[derive(RustEmbed)]
+    /// #[folder = "templates"]
+    /// struct Assets;
+    ///
+    /// let mut hbs = Handlebars::new();
+    /// hbs.register_embed_templates::<Assets>();
+    /// ```
+    ///
+    #[cfg(feature = "rust-embed")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rust-embed")))]
+    pub fn register_embed_templates<E>(&mut self) -> Result<(), TemplateError>
+    where
+        E: RustEmbed,
+    {
+        for item in E::iter() {
+            let file_name = item.as_ref();
+            if let Some(file) = E::get(file_name) {
+                let data = file.data;
+
+                let tpl_content = String::from_utf8_lossy(data.as_ref());
+                self.register_template_string(&file_name.to_owned(), tpl_content)?;
+            }
+        }
+        Ok(())
+    }
+
     /// Remove a template from the registry
     pub fn unregister_template(&mut self, name: &str) {
         self.templates.remove(name);

tests/embed.rs

@@ -0,0 +1,29 @@
+#[macro_use]
+extern crate serde_json;
+
+use handlebars::Handlebars;
+
+#[test]
+#[cfg(feature = "rust-embed")]
+fn test_embed() {
+    use rust_embed::RustEmbed;
+
+    #[derive(RustEmbed)]
+    #[folder = "tests/templates/"]
+    #[include = "*.hbs"]
+    struct Templates;
+
+    let mut hbs = Handlebars::new();
+    hbs.register_embed_templates::<Templates>().unwrap();
+
+    assert_eq!(1, hbs.get_templates().len());
+
+    let data = json!({
+        "name": "Andy"
+    });
+
+    assert_eq!(
+        hbs.render("hello.hbs", &data).unwrap().trim(),
+        "Hello, Andy"
+    );
+}

tests/templates/hello.hbs

@@ -0,0 +1 @@
+Hello, {{name}}