Finish adding explicit context to the parser for Container.

src/parser/parser.rs

@@ -95,6 +95,7 @@ pub struct Span<'a> {
 #[derive(Clone, Debug, PartialEq)]
 pub struct Container<'a> {
     pub path: Path<'a>,
+    pub explicit_context: Option<Path<'a>>,
     pub contents: Option<Body<'a>>,
     pub else_contents: Option<Body<'a>>,
 }
@@ -357,6 +358,7 @@ where
             i,
             constructor(Container {
                 path: opening_name,
+                explicit_context: maybe_explicit_context,
                 contents: inner,
                 else_contents: maybe_else.flatten(),
             }),
@@ -372,12 +374,16 @@ where
     F: Fn(Container<'a>) -> DustTag<'a>,
 {
     move |i: &'a str| {
-        let (i, path) = delimited(tag(open_matcher), path, tag("/}"))(i)?;
+        let (i, (opening_name, maybe_explicit_context)) = tuple((
+            preceded(tag(open_matcher), path),
+            terminated(opt(preceded(tag(":"), path)), tag("/}")),
+        ))(i)?;
 
         Ok((
             i,
             constructor(Container {
-                path: path,
+                path: opening_name,
+                explicit_context: maybe_explicit_context,
                 contents: None,
                 else_contents: None,
             }),
@@ -874,6 +880,7 @@ mod tests {
                     path: Path {
                         keys: vec!["foo", "bar"]
                     },
+                    explicit_context: None,
                     contents: None,
                     else_contents: None,
                 })
@@ -891,6 +898,7 @@ mod tests {
                     path: Path {
                         keys: vec!["foo", "bar"]
                     },
+                    explicit_context: None,
                     contents: None,
                     else_contents: None,
                 })
@@ -908,6 +916,7 @@ mod tests {
                     path: Path {
                         keys: vec!["foo", "bar"]
                     },
+                    explicit_context: None,
                     contents: Some(Body {
                         elements: vec![
                             TemplateElement::TESpan(Span { contents: "hello " }),
@@ -933,6 +942,7 @@ mod tests {
                     path: Path {
                         keys: vec!["greeting"]
                     },
+                    explicit_context: None,
                     contents: Some(Body {
                         elements: vec![
                             TemplateElement::TESpan(Span { contents: "hello " }),
@@ -958,6 +968,44 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_empty_section_with_explicit_context() {
+        assert_eq!(
+            super::dust_tag("{#foo.bar:baz.ipsum}{/foo.bar}"),
+            Ok((
+                "",
+                DustTag::DTSection(Container {
+                    path: Path {
+                        keys: vec!["foo", "bar"]
+                    },
+                    explicit_context: Some(Path {
+                        keys: vec!["baz", "ipsum"]
+                    }),
+                    contents: None,
+                    else_contents: None,
+                })
+            ))
+        );
+    }
+
+    #[test]
+    fn test_self_closing_section_with_explicit_context() {
+        assert_eq!(
+            super::dust_tag("{#foo.bar:$idx/}"),
+            Ok((
+                "",
+                DustTag::DTSection(Container {
+                    path: Path {
+                        keys: vec!["foo", "bar"]
+                    },
+                    explicit_context: Some(Path { keys: vec!["$idx"] }),
+                    contents: None,
+                    else_contents: None,
+                })
+            ))
+        );
+    }
+
     #[test]
     fn test_self_closing_block() {
         assert_eq!(
@@ -1236,6 +1284,7 @@ mod tests {
                                 path: Path {
                                     keys: vec!["names"]
                                 },
+                                explicit_context: None,
                                 contents: Some(Body {
                                     elements: vec![TemplateElement::TETag(DustTag::DTReference(
                                         Reference {
@@ -1261,6 +1310,7 @@ mod tests {
                                 path: Path {
                                     keys: vec!["names"]
                                 },
+                                explicit_context: None,
                                 contents: Some(Body {
                                     elements: vec![
                                         TemplateElement::TEIgnoredWhitespace(
@@ -1298,6 +1348,7 @@ mod tests {
                             path: Path {
                                 keys: vec!["level3", "level4"]
                             },
+                            explicit_context: None,
                             contents: Some(Body {
                                 elements: vec![TemplateElement::TETag(DustTag::DTPartial(
                                     Partial {