Macro handlebars_helper

macro_rules! handlebars_helper {
    ($struct_name:ident: |$($name:ident: $tpe:tt$(<$($gen:ty),+>)?),*
     $($(,)?{$($hash_name:ident: $hash_tpe:tt=$dft_val:literal),*})?
     $($(,)?*$args:ident)?
     $($(,)?**$kwargs:ident)?|
     $body:expr ) => { ... };
    (@as_json_value $x:ident, object) => { ... };
    (@as_json_value $x:ident, array) => { ... };
    (@as_json_value $x:ident, str) => { ... };
    (@as_json_value $x:ident, i64) => { ... };
    (@as_json_value $x:ident, u64) => { ... };
    (@as_json_value $x:ident, f64) => { ... };
    (@as_json_value $x:ident, bool) => { ... };
    (@as_json_value $x:ident, null) => { ... };
    (@as_json_value $x:ident, Json) => { ... };
    (@as_json_value $x:ident, $tpe:tt$(<$($gen:ty),+>)?) => { ... };
}

Macro that allows you to quickly define a handlebars helper by passing a name and a closure.

There are several types of arguments available to closure:

• Parameters are mapped to closure arguments one by one. Any declared parameters are required
• Hash are mapped as named arguments and declared in a bracket block. All named arguments are optional so default value is required.
• An optional *args provides a vector of all helper parameters.
• An optional **kwargs provides a map of all helper hash.

Examples

handlebars_helper!(is_above_10: |x: u64| x > 10);
handlebars_helper!(is_above: |x: u64, { compare: u64 = 10 }| x > compare);

let mut handlebars = Handlebars::new();
handlebars.register_helper("is-above-10", Box::new(is_above_10));
handlebars.register_helper("is-above", Box::new(is_above));

let result = handlebars
    .render_template("{{#if (is-above-10 12)}}great!{{else}}okay{{/if}}", &json!({}))?;
 assert_eq!(&result, "great!");

let result2 = handlebars
    .render_template("{{#if (is-above 12 compare=10)}}great!{{else}}okay{{/if}}", &json!({}))?;
 assert_eq!(&result2, "great!");