Add support for else blocks

src/duster/parser.rs

@@ -72,6 +72,7 @@ struct Span<'a> {
 struct Container<'a> {
     path: Path<'a>,
     contents: Option<Block<'a>>,
+    else_contents: Option<Block<'a>>,
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -168,13 +169,14 @@ where
     F: Fn(Container<'a>) -> DustTag<'a>,
 {
     move |i: &'a str| {
-        let (i, (opening_name, inner, _closing_name)) = verify(
+        let (i, (opening_name, inner, maybe_else, _closing_name)) = verify(
             tuple((
                 delimited(tag(open_matcher), path, tag("}")),
                 opt(block),
+                opt(preceded(tag("{:else}"), opt(block))),
                 delimited(tag("{/"), path, tag("}")),
             )),
-            |(open, _inn, close)| open == close,
+            |(open, _inn, _maybe_else, close)| open == close,
         )(i)?;
 
         Ok((
@@ -182,6 +184,7 @@ where
             constructor(Container {
                 path: opening_name,
                 contents: inner,
+                else_contents: maybe_else.flatten(),
             }),
         ))
     }
@@ -202,6 +205,7 @@ where
             constructor(Container {
                 path: path,
                 contents: None,
+                else_contents: None,
             }),
         ))
     }
@@ -366,7 +370,8 @@ mod tests {
                     path: Path {
                         keys: vec!["foo", "bar"]
                     },
-                    contents: None
+                    contents: None,
+                    else_contents: None,
                 })
             ))
         );
@@ -382,7 +387,8 @@ mod tests {
                     path: Path {
                         keys: vec!["foo", "bar"]
                     },
-                    contents: None
+                    contents: None,
+                    else_contents: None,
                 })
             ))
         );
@@ -406,7 +412,43 @@ mod tests {
                                 filters: Vec::new()
                             }))
                         ]
-                    })
+                    }),
+                    else_contents: None,
+                })
+            ))
+        );
+    }
+
+    #[test]
+    fn test_section_with_else_body() {
+        assert_eq!(
+            super::dust_tag("{#greeting}hello {name}{:else}goodbye {name}{/greeting}"),
+            Ok((
+                "",
+                DustTag::DTSection(Container {
+                    path: Path {
+                        keys: vec!["greeting"]
+                    },
+                    contents: Some(Block {
+                        elements: vec![
+                            TemplateElement::TESpan(Span { contents: "hello " }),
+                            TemplateElement::TETag(DustTag::DTReference(Reference {
+                                path: Path { keys: vec!["name"] },
+                                filters: Vec::new()
+                            }))
+                        ]
+                    }),
+                    else_contents: Some(Block {
+                        elements: vec![
+                            TemplateElement::TESpan(Span {
+                                contents: "goodbye "
+                            }),
+                            TemplateElement::TETag(DustTag::DTReference(Reference {
+                                path: Path { keys: vec!["name"] },
+                                filters: Vec::new()
+                            }))
+                        ]
+                    }),
                 })
             ))
         );