vendor/handlebars/src/helpers/helper_lookup.rs

   1 use serde_json::value::Value as Json;
   2
   3 use crate::context::Context;
   4 use crate::error::RenderError;
   5 use crate::helpers::{HelperDef, HelperResult};
   6 use crate::output::Output;
   7 use crate::registry::Registry;
   8 use crate::render::{Helper, RenderContext};
   9 use crate::value::JsonRender;
  10
  11 #[derive(Clone, Copy)]
  12 pub struct LookupHelper;
  13
  14 impl HelperDef for LookupHelper {
  15     fn call<'reg: 'rc, 'rc>(
  16         &self,
  17         h: &Helper,
  18         _: &Registry,
  19         _: &Context,
  20         _: &mut RenderContext,
  21         out: &mut dyn Output,
  22     ) -> HelperResult {
  23         let collection_value = h
  24             .param(0)
  25             .ok_or_else(|| RenderError::new("Param not found for helper \"lookup\""))?;
  26         let index = h
  27             .param(1)
  28             .ok_or_else(|| RenderError::new("Insufficient params for helper \"lookup\""))?;
  29
  30         let null = Json::Null;
  31         let value = match *collection_value.value() {
  32             Json::Array(ref v) => index
  33                 .value()
  34                 .as_u64()
  35                 .and_then(|u| Some(u as usize))
  36                 .and_then(|u| v.get(u))
  37                 .unwrap_or(&null),
  38             Json::Object(ref m) => index
  39                 .value()
  40                 .as_str()
  41                 .and_then(|k| m.get(k))
  42                 .unwrap_or(&null),
  43             _ => &null,
  44         };
  45         let r = value.render();
  46         out.write(r.as_ref())?;
  47         Ok(())
  48     }
  49 }
  50
  51 pub static LOOKUP_HELPER: LookupHelper = LookupHelper;
  52
  53 #[cfg(test)]
  54 mod test {
  55     use crate::registry::Registry;
  56
  57     use std::collections::BTreeMap;
  58
  59     #[test]
  60     fn test_lookup() {
  61         let mut handlebars = Registry::new();
  62         assert!(handlebars
  63             .register_template_string("t0", "{{#each v1}}{{lookup ../../v2 @index}}{{/each}}")
  64             .is_ok());
  65         assert!(handlebars
  66             .register_template_string("t1", "{{#each v1}}{{lookup ../../v2 1}}{{/each}}")
  67             .is_ok());
  68         assert!(handlebars
  69             .register_template_string("t2", "{{lookup kk \"a\"}}")
  70             .is_ok());
  71
  72         let mut m: BTreeMap<String, Vec<u16>> = BTreeMap::new();
  73         m.insert("v1".to_string(), vec![1u16, 2u16, 3u16]);
  74         m.insert("v2".to_string(), vec![9u16, 8u16, 7u16]);
  75
  76         let m2 = btreemap! {
  77             "kk".to_string() => btreemap!{"a".to_string() => "world".to_string()}
  78         };
  79
  80         let r0 = handlebars.render("t0", &m);
  81         assert_eq!(r0.ok().unwrap(), "987".to_string());
  82
  83         let r1 = handlebars.render("t1", &m);
  84         assert_eq!(r1.ok().unwrap(), "888".to_string());
  85
  86         let r2 = handlebars.render("t2", &m2);
  87         assert_eq!(r2.ok().unwrap(), "world".to_string());
  88     }
  89 }