mdxbook/renderer/html_handlebars/helpers/
theme.rs

1use handlebars::{Context, Handlebars, Helper, Output, RenderContext, RenderError};
2use log::trace;
3
4pub fn theme_option(
5    h: &Helper<'_, '_>,
6    _r: &Handlebars<'_>,
7    ctx: &Context,
8    rc: &mut RenderContext<'_, '_>,
9    out: &mut dyn Output,
10) -> Result<(), RenderError> {
11    trace!("theme_option (handlebars helper)");
12
13    let param = h.param(0).and_then(|v| v.value().as_str()).ok_or_else(|| {
14        RenderError::new("Param 0 with String type is required for theme_option helper.")
15    })?;
16
17    let default_theme = rc.evaluate(ctx, "@root/default_theme")?;
18    let default_theme_name = default_theme
19        .as_json()
20        .as_str()
21        .ok_or_else(|| RenderError::new("Type error for `default_theme`, string expected"))?;
22
23    out.write(param)?;
24    if param.to_lowercase() == default_theme_name.to_lowercase() {
25        out.write(" (default)")?;
26    }
27
28    Ok(())
29}