Add a basic reference implementation missing filter support

src/duster/parser.rs

@@ -1,15 +1,20 @@
 use nom::branch::alt;
+use nom::bytes::complete::is_a;
 use nom::bytes::complete::tag;
 use nom::bytes::complete::take_until;
 use nom::combinator::map;
+use nom::combinator::recognize;
 use nom::combinator::value;
+use nom::multi::separated_list;
 use nom::sequence::delimited;
+use nom::sequence::tuple;
 use nom::IResult;
 
 #[derive(Clone, Debug)]
 enum DustTag<'a> {
     DTSpecial(Special),
     DTComment(Comment<'a>),
+    DTReference(Reference<'a>),
 }
 
 #[derive(Clone, Debug)]
@@ -26,10 +31,21 @@ struct Comment<'a> {
     value: &'a str,
 }
 
+#[derive(Clone, Debug)]
+struct Path<'a> {
+    keys: Vec<&'a str>,
+}
+
+#[derive(Clone, Debug)]
+struct Reference<'a> {
+    path: Path<'a>,
+}
+
 fn dust_tag(i: &str) -> IResult<&str, DustTag> {
     alt((
         map(special, DustTag::DTSpecial),
         map(comment, DustTag::DTComment),
+        map(reference, DustTag::DTReference),
     ))(i)
 }
 
@@ -52,3 +68,22 @@ fn comment(i: &str) -> IResult<&str, Comment> {
         Comment { value: body }
     })(i)
 }
+
+fn path(i: &str) -> IResult<&str, Path> {
+    map(
+        separated_list(
+            tag("."),
+            recognize(tuple((
+                is_a("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_$"),
+                is_a("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_$0123456789-"),
+            ))),
+        ),
+        |body| Path { keys: body },
+    )(i)
+}
+
+fn reference(i: &str) -> IResult<&str, Reference> {
+    // TODO: Add support for filters
+    let (remaining, p) = delimited(tag("{"), path, tag("}"))(i)?;
+    Ok((remaining, Reference { path: p }))
+}