Add all the helpers

src/parser/parser.rs

@@ -19,6 +19,7 @@ use nom::multi::separated_nonempty_list;
 use nom::sequence::delimited;
 use nom::sequence::preceded;
 use nom::sequence::separated_pair;
+use nom::sequence::terminated;
 use nom::sequence::tuple;
 use nom::IResult;
 
@@ -33,6 +34,12 @@ enum DustTag<'a> {
     DTBlock(NamedBlock<'a>),
     DTInlinePartial(NamedBlock<'a>),
     DTPartial(Partial<'a>),
+    DTHelperEquals(ParameterizedBlock<'a>),
+    DTHelperNotEquals(ParameterizedBlock<'a>),
+    DTHelperGreaterThan(ParameterizedBlock<'a>),
+    DTHelperLessThan(ParameterizedBlock<'a>),
+    DTHelperGreaterThenOrEquals(ParameterizedBlock<'a>),
+    DTHelperLessThenOrEquals(ParameterizedBlock<'a>),
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -145,6 +152,12 @@ fn dust_tag(i: &str) -> IResult<&str, DustTag> {
         named_block("{+", DustTag::DTBlock),
         named_block("{<", DustTag::DTInlinePartial),
         partial("{>", DustTag::DTPartial),
+        parameterized_block("{@", "gte", DustTag::DTHelperGreaterThenOrEquals),
+        parameterized_block("{@", "lte", DustTag::DTHelperLessThenOrEquals),
+        parameterized_block("{@", "eq", DustTag::DTHelperEquals),
+        parameterized_block("{@", "ne", DustTag::DTHelperNotEquals),
+        parameterized_block("{@", "gt", DustTag::DTHelperGreaterThan),
+        parameterized_block("{@", "lt", DustTag::DTHelperLessThan),
     ))(i)
 }
 
@@ -338,6 +351,52 @@ where
     }
 }
 
+fn parameterized_block<'a, F>(
+    open_matcher: &'static str,
+    tag_name: &'static str,
+    constructor: F,
+) -> impl Fn(&'a str) -> IResult<&'a str, DustTag<'a>>
+where
+    F: Copy + Fn(ParameterizedBlock<'a>) -> DustTag<'a>,
+{
+    alt((
+        parameterized_block_with_body(open_matcher, tag_name, constructor),
+        parameterized_self_closing_block(open_matcher, tag_name, constructor),
+    ))
+}
+
+fn parameterized_block_with_body<'a, F>(
+    open_matcher: &'static str,
+    tag_name: &'static str,
+    constructor: F,
+) -> impl Fn(&'a str) -> IResult<&'a str, DustTag<'a>>
+where
+    F: Fn(ParameterizedBlock<'a>) -> DustTag<'a>,
+{
+    move |i: &'a str| {
+        let (i, (name, params, inner, maybe_else, _closing_name)) = tuple((
+            preceded(tag(open_matcher), tag(tag_name)),
+            terminated(
+                opt(preceded(space1, separated_list(space1, key_value_pair))),
+                tag("}"),
+            ),
+            opt(body),
+            opt(preceded(tag("{:else}"), opt(body))),
+            delimited(tag("{/"), tag(tag_name), tag("}")),
+        ))(i)?;
+
+        Ok((
+            i,
+            constructor(ParameterizedBlock {
+                name: name,
+                params: params.unwrap_or(Vec::new()),
+                contents: inner,
+                else_contents: maybe_else.flatten(),
+            }),
+        ))
+    }
+}
+
 fn parameterized_self_closing_block<'a, F>(
     open_matcher: &'static str,
     tag_name: &'static str,
@@ -771,4 +830,65 @@ mod tests {
             ))
         );
     }
+
+    #[test]
+    fn test_helper() {
+        assert_eq!(
+            dust_tag(r#"{@eq key=name value="cat"}Pet the {name}!{/eq}"#),
+            Ok((
+                "",
+                DustTag::DTHelperEquals(ParameterizedBlock {
+                    name: "eq",
+                    params: vec![
+                        KVPair {
+                            key: "key",
+                            value: RValue::RVPath(Path { keys: vec!["name"] })
+                        },
+                        KVPair {
+                            key: "value",
+                            value: RValue::RVString("cat".to_owned())
+                        }
+                    ],
+                    contents: Some(Body {
+                        elements: vec![
+                            TemplateElement::TESpan(Span {
+                                contents: "Pet the "
+                            }),
+                            TemplateElement::TETag(DustTag::DTReference(Reference {
+                                path: Path { keys: vec!["name"] },
+                                filters: Vec::new()
+                            })),
+                            TemplateElement::TESpan(Span { contents: "!" })
+                        ]
+                    }),
+                    else_contents: None
+                })
+            ))
+        );
+    }
+
+    #[test]
+    fn test_self_closing_helper() {
+        assert_eq!(
+            dust_tag(r#"{@eq key=name value="cat"/}"#),
+            Ok((
+                "",
+                DustTag::DTHelperEquals(ParameterizedBlock {
+                    name: "eq",
+                    params: vec![
+                        KVPair {
+                            key: "key",
+                            value: RValue::RVPath(Path { keys: vec!["name"] })
+                        },
+                        KVPair {
+                            key: "value",
+                            value: RValue::RVString("cat".to_owned())
+                        }
+                    ],
+                    contents: None,
+                    else_contents: None
+                })
+            ))
+        );
+    }
 }