Add parser support for select/any/none.

src/parser/parser.rs

@@ -44,6 +44,9 @@ pub enum DustTag<'a> {
     DTHelperSep(ParameterizedBlock<'a>),
     DTHelperFirst(ParameterizedBlock<'a>),
     DTHelperLast(ParameterizedBlock<'a>),
+    DTHelperSelect(ParameterizedBlock<'a>),
+    DTHelperAny(ParameterizedBlock<'a>),
+    DTHelperNone(ParameterizedBlock<'a>),
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -219,6 +222,15 @@ fn dust_tag(i: &str) -> IResult<&str, DustTag> {
             DustTag::DTInlinePartial,
         ),
         partial("{>", DustTag::DTPartial),
+        dust_tag_helper,
+    ))(i)
+}
+
+/// Nom's alt() is limited to 21 possibilities, so I pushed this out
+/// into its own parser. Otherwise there is no reason for this not to
+/// be part of the dust_tag parser.
+fn dust_tag_helper(i: &str) -> IResult<&str, DustTag> {
+    alt((
         map(
             parameterized_block("{@", &tag_to_path("gte")),
             DustTag::DTHelperGreaterThanOrEquals,
@@ -255,6 +267,18 @@ fn dust_tag(i: &str) -> IResult<&str, DustTag> {
             parameterized_block("{@", &tag_to_path("last")),
             DustTag::DTHelperLast,
         ),
+        map(
+            parameterized_block("{@", &tag_to_path("select")),
+            DustTag::DTHelperSelect,
+        ),
+        map(
+            parameterized_block("{@", &tag_to_path("any")),
+            DustTag::DTHelperAny,
+        ),
+        map(
+            parameterized_block("{@", &tag_to_path("none")),
+            DustTag::DTHelperNone,
+        ),
     ))(i)
 }