Refactor decoder

src/dav/decoder.rs

@@ -25,36 +25,32 @@ use super::xml::{Node, QRead, Reader, IRead, DAV_URN, CAL_URN};
 /// Propfind request
 impl<E: Extension> QRead<PropFind<E>> for PropFind<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
-        // Find propfind
         xml.open(DAV_URN, "propfind").await?;
-
-        // Find any tag
         let propfind: PropFind<E> = loop {
-            match xml.peek() {
-                Event::Start(_) if xml.is_tag(DAV_URN, "allprop") => {
-                    xml.open(DAV_URN, "allprop").await?;
+            // allprop
+            if let Some(_) = xml.maybe_open(DAV_URN, "allprop").await? {
                 let includ = xml.maybe_find::<Include<E>>().await?;
-                    let r = PropFind::AllProp(includ);
-                    xml.tag_stop(DAV_URN, "allprop").await?;
-                    break r
-                },
-                Event::Start(_) if xml.is_tag(DAV_URN, "prop") => {
-                    break PropFind::Prop(xml.find::<PropName<E>>().await?);
-                },
-                Event::Empty(_) if xml.is_tag(DAV_URN, "allprop") => {
-                    xml.next().await?;
-                    break PropFind::AllProp(None)
-                },
-                Event::Empty(_) if xml.is_tag(DAV_URN, "propname") => {
-                    xml.next().await?;
-                    break PropFind::PropName
-                },
-                _ => { xml.skip().await?; },
+                xml.close().await?;
+                break PropFind::AllProp(includ)
             }
-        };
 
-        // Close tag
-        xml.tag_stop(DAV_URN, "propfind").await?;
+            // propname
+            if let Some(_) = xml.maybe_open(DAV_URN, "propname").await? {
+                xml.close().await?;
+                break PropFind::PropName
+            }
+
+            // prop
+            let (mut maybe_prop, mut dirty) = (None, false);
+            xml.maybe_read::<PropName<E>>(&mut maybe_prop, &mut dirty).await?;
+            if let Some(prop) = maybe_prop {
+                break PropFind::Prop(prop)
+            }
+
+            // not found, skipping
+            xml.skip().await?;
+        };
+        xml.close().await?;
 
         Ok(propfind)
     }
@@ -65,7 +61,7 @@ impl<E: Extension> QRead<PropertyUpdate<E>> for PropertyUpdate<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "propertyupdate").await?;
         let collected_items = xml.collect::<PropertyUpdateItem<E>>().await?;
-        xml.tag_stop(DAV_URN, "propertyupdate").await?;
+        xml.close().await?;
         Ok(PropertyUpdate(collected_items))
     }
 }
@@ -89,7 +85,7 @@ impl<E: Extension, N: Node<N>> QRead<Multistatus<E,N>> for Multistatus<E,N> {
             }
         }
 
-        xml.tag_stop(DAV_URN, "multistatus").await?;
+        xml.close().await?;
         Ok(Multistatus { responses, responsedescription })
     }
 }
@@ -112,7 +108,7 @@ impl QRead<LockInfo> for LockInfo {
                 };
             }
         }
-        xml.tag_stop(DAV_URN, "lockinfo").await?;
+        xml.close().await?;
         match (m_scope, m_type) {
             (Some(lockscope), Some(locktype)) => Ok(LockInfo { lockscope, locktype, owner }),
             _ => Err(ParsingError::MissingChild),
@@ -125,7 +121,7 @@ impl<E: Extension> QRead<PropValue<E>> for PropValue<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "prop").await?;
         let mut acc = xml.collect::<Property<E>>().await?;
-        xml.tag_stop(DAV_URN, "prop").await?;
+        xml.close().await?;
         Ok(PropValue(acc))
     }
 }
@@ -136,7 +132,7 @@ impl<E: Extension> QRead<Error<E>> for Error<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "error").await?;
         let violations = xml.collect::<Violation<E>>().await?;
-        xml.tag_stop(DAV_URN, "error").await?;
+        xml.close().await?;
         Ok(Error(violations))
     }
 }
@@ -168,7 +164,7 @@ impl<E: Extension, N: Node<N>> QRead<Response<E,N>> for Response<E,N> {
             }
         }
 
-        xml.tag_stop(DAV_URN, "response").await?;
+        xml.close().await?;
         match (status, &propstat[..], &href[..]) {
             (Some(status), &[], &[_, ..]) => Ok(Response { 
                 status_or_propstat: StatusOrPropstat::Status(href, status), 
@@ -205,7 +201,7 @@ impl<E: Extension, N: Node<N>> QRead<PropStat<E,N>> for PropStat<E,N> {
             }
         }
 
-        xml.tag_stop(DAV_URN, "propstat").await?;
+        xml.close().await?;
         match (m_prop, m_status) {
             (Some(prop), Some(status)) => Ok(PropStat { prop, status, error, responsedescription }),
             _ => Err(ParsingError::MissingChild),
@@ -219,7 +215,7 @@ impl QRead<Status> for Status {
         let fullcode = xml.tag_string().await?;
         let txtcode = fullcode.splitn(3, ' ').nth(1).ok_or(ParsingError::InvalidValue)?;
         let code = http::status::StatusCode::from_bytes(txtcode.as_bytes()).or(Err(ParsingError::InvalidValue))?;
-        xml.tag_stop(DAV_URN, "status").await?;
+        xml.close().await?;
         Ok(Status(code))
     }
 }
@@ -228,7 +224,7 @@ impl QRead<ResponseDescription> for ResponseDescription {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "responsedescription").await?;
         let cnt = xml.tag_string().await?;
-        xml.tag_stop(DAV_URN, "responsedescription").await?;
+        xml.close().await?;
         Ok(ResponseDescription(cnt))
     }
 }
@@ -237,7 +233,7 @@ impl QRead<Location> for Location {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "location").await?;
         let href = xml.find::<Href>().await?;
-        xml.tag_stop(DAV_URN, "location").await?;
+        xml.close().await?;
         Ok(Location(href))
     }
 }
@@ -256,7 +252,7 @@ impl<E: Extension> QRead<Remove<E>> for Remove<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "remove").await?;
         let propname = xml.find::<PropName<E>>().await?;
-        xml.tag_stop(DAV_URN, "remove").await?;
+        xml.close().await?;
         Ok(Remove(propname))
     }
 }
@@ -265,69 +261,47 @@ impl<E: Extension> QRead<Set<E>> for Set<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "set").await?;
         let propvalue = xml.find::<PropValue<E>>().await?;
-        xml.tag_stop(DAV_URN, "set").await?;
+        xml.close().await?;
         Ok(Set(propvalue))
     }
 }
 
 impl<E: Extension> QRead<Violation<E>> for Violation<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
-        let bs = match xml.peek() {
-            Event::Start(b) | Event::Empty(b) => b,
-            _ => return Err(ParsingError::Recoverable),
-        };
-
-        // Option 1: a pure DAV property
-        let (ns, loc) = xml.rdr.resolve_element(bs.name());
-        if matches!(ns, Bound(Namespace(ns)) if ns == DAV_URN) {
-            match loc.into_inner() {
-                b"lock-token-matches-request-uri" => {
-                    xml.next().await?;
-                    return Ok(Violation::LockTokenMatchesRequestUri)
-                },
-                b"lock-token-submitted" => {
-                    xml.next().await?;
+        if xml.maybe_open(DAV_URN, "lock-token-matches-request-uri").await?.is_some() {
+            xml.close().await?;
+            Ok(Violation::LockTokenMatchesRequestUri)
+        } else if xml.maybe_open(DAV_URN, "lock-token-submitted").await?.is_some() {
             let links = xml.collect::<Href>().await?;
-                    xml.tag_stop(DAV_URN, "lock-token-submitted").await?;
-                    return Ok(Violation::LockTokenSubmitted(links))
-                },
-                b"no-conflicting-lock" => {
-                    // start tag
-                    xml.next().await?;
+            xml.close().await?;
+            Ok(Violation::LockTokenSubmitted(links))
+        } else if xml.maybe_open(DAV_URN, "no-conflicting-lock").await?.is_some() {
             let links = xml.collect::<Href>().await?;
-                    xml.tag_stop(DAV_URN, "no-conflicting-lock").await?;
-                    return Ok(Violation::NoConflictingLock(links))
-                },
-                b"no-external-entities" => {
-                    xml.next().await?;
-                    return Ok(Violation::NoExternalEntities)
-                },
-                b"preserved-live-properties" => {
-                    xml.next().await?;
-                    return Ok(Violation::PreservedLiveProperties)
-                },
-                b"propfind-finite-depth" => {
-                    xml.next().await?;
-                    return Ok(Violation::PropfindFiniteDepth)
-                },
-                b"cannot-modify-protected-property" => {
-                    xml.next().await?;
-                    return Ok(Violation::CannotModifyProtectedProperty)
-                },
-                _ => (),
-            };
-        }
-
-        // Option 2: an extension property, delegating
+            xml.close().await?;
+            Ok(Violation::NoConflictingLock(links))
+        } else if xml.maybe_open(DAV_URN, "no-external-entities").await?.is_some() {
+            xml.close().await?;
+            Ok(Violation::NoExternalEntities)
+        } else if xml.maybe_open(DAV_URN, "preserved-live-properties").await?.is_some() {
+            xml.close().await?;
+            Ok(Violation::PreservedLiveProperties)
+        } else if xml.maybe_open(DAV_URN, "propfind-finite-depth").await?.is_some() {
+            xml.close().await?;
+            Ok(Violation::PropfindFiniteDepth)
+        } else if xml.maybe_open(DAV_URN, "cannot-modify-protected-property").await?.is_some() {
+            xml.close().await?;
+            Ok(Violation::CannotModifyProtectedProperty)
+        } else {
             E::Error::qread(xml).await.map(Violation::Extension)
         }
+    }
 }
 
 impl<E: Extension> QRead<Include<E>> for Include<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "include").await?;
         let acc = xml.collect::<PropertyRequest<E>>().await?;
-        xml.tag_stop(DAV_URN, "include").await?;
+        xml.close().await?;
         Ok(Include(acc))
     }
 }
@@ -336,110 +310,92 @@ impl<E: Extension> QRead<PropName<E>> for PropName<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "prop").await?;
         let acc = xml.collect::<PropertyRequest<E>>().await?;
-        xml.tag_stop(DAV_URN, "prop").await?;
+        xml.close().await?;
         Ok(PropName(acc))
     }
 }
 
 impl<E: Extension> QRead<PropertyRequest<E>> for PropertyRequest<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
-        let bs = match xml.peek() {
-            Event::Start(b) | Event::Empty(b) => b,
-            _ => return Err(ParsingError::Recoverable),
+        let maybe = if xml.maybe_open(DAV_URN, "creationdate").await?.is_some() {
+            Some(PropertyRequest::CreationDate)
+        } else if xml.maybe_open(DAV_URN, "displayname").await?.is_some() {
+            Some(PropertyRequest::DisplayName)
+        } else if xml.maybe_open(DAV_URN, "getcontentlanguage").await?.is_some() {
+            Some(PropertyRequest::GetContentLanguage)
+        } else if xml.maybe_open(DAV_URN, "getcontentlength").await?.is_some() {
+            Some(PropertyRequest::GetContentLength)
+        } else if xml.maybe_open(DAV_URN, "getcontenttype").await?.is_some() {
+            Some(PropertyRequest::GetContentType)
+        } else if xml.maybe_open(DAV_URN, "getetag").await?.is_some() {
+            Some(PropertyRequest::GetEtag)
+        } else if xml.maybe_open(DAV_URN, "getlastmodified").await?.is_some() {
+            Some(PropertyRequest::GetLastModified)
+        } else if xml.maybe_open(DAV_URN, "lockdiscovery").await?.is_some() {
+            Some(PropertyRequest::LockDiscovery)
+        } else if xml.maybe_open(DAV_URN, "resourcetype").await?.is_some() {
+            Some(PropertyRequest::ResourceType)
+        } else if xml.maybe_open(DAV_URN, "supportedlock").await?.is_some() {
+            Some(PropertyRequest::SupportedLock)
+        } else {
+            None
         };
 
-        // Option 1: a pure core DAV property
-        let (ns, loc) = xml.rdr.resolve_element(bs.name());
-        if matches!(ns, Bound(Namespace(ns)) if ns == DAV_URN) {
-            let maybe_res = match loc.into_inner() {
-                b"creationdate" => Some(PropertyRequest::CreationDate),
-                b"displayname" => Some(PropertyRequest::DisplayName),
-                b"getcontentlanguage" => Some(PropertyRequest::GetContentLanguage),
-                b"getcontentlength" => Some(PropertyRequest::GetContentLength),
-                b"getcontenttype" => Some(PropertyRequest::GetContentType),
-                b"getetag" => Some(PropertyRequest::GetEtag),
-                b"getlastmodified" => Some(PropertyRequest::GetLastModified),
-                b"lockdiscovery" => Some(PropertyRequest::LockDiscovery),
-                b"resourcetype" => Some(PropertyRequest::ResourceType),
-                b"supportedlock" => Some(PropertyRequest::SupportedLock),
-                _ => None,
-            };
-            // Close the current tag if we read something
-            if let Some(res) = maybe_res {
-                xml.skip().await?; 
-                return Ok(res)
+        match maybe {
+            Some(pr) => {
+                xml.close().await?;
+                Ok(pr)
+            },
+            None => E::PropertyRequest::qread(xml).await.map(PropertyRequest::Extension),
         }
     }
-
-        // Option 2: an extension property, delegating
-        E::PropertyRequest::qread(xml).await.map(PropertyRequest::Extension)
-    }
 }
 
 impl<E: Extension> QRead<Property<E>> for Property<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         use chrono::{DateTime, FixedOffset, TimeZone};
 
-        let bs = match xml.peek() {
-            Event::Start(b) | Event::Empty(b) => b,
-            _ => return Err(ParsingError::Recoverable),
-        };
-
-        // Option 1: a pure core DAV property
-        let (ns, loc) = xml.rdr.resolve_element(bs.name());
-        if matches!(ns, Bound(Namespace(ns)) if ns == DAV_URN) {
-            match loc.into_inner() {
-                b"creationdate" => {
-                    xml.next().await?;
+        // Core WebDAV properties
+        if xml.maybe_open(DAV_URN, "creationdate").await?.is_some() {
             let datestr = xml.tag_string().await?;
+            xml.close().await?;
             return Ok(Property::CreationDate(DateTime::parse_from_rfc3339(datestr.as_str())?))
-                },
-                b"displayname" => {
-                    xml.next().await?;
-                    return Ok(Property::DisplayName(xml.tag_string().await?))
-                },
-                b"getcontentlanguage" => {
-                    xml.next().await?;
-                    return Ok(Property::GetContentLanguage(xml.tag_string().await?))
-                },
-                b"getcontentlength" => {
-                    xml.next().await?;
+        } else if xml.maybe_open(DAV_URN, "displayname").await?.is_some() {
+            let name = xml.tag_string().await?;
+            xml.close().await?;
+            return Ok(Property::DisplayName(name))
+        } else if xml.maybe_open(DAV_URN, "getcontentlanguage").await?.is_some() {
+            let lang = xml.tag_string().await?;
+            xml.close().await?;
+            return Ok(Property::GetContentLanguage(lang))
+        } else if xml.maybe_open(DAV_URN, "getcontentlength").await?.is_some() {
             let cl = xml.tag_string().await?.parse::<u64>()?;
+            xml.close().await?;
             return Ok(Property::GetContentLength(cl))
-                },
-                b"getcontenttype" => {
-                    xml.next().await?;
-                    return Ok(Property::GetContentType(xml.tag_string().await?))
-                },
-                b"getetag" => {
-                    xml.next().await?;
-                    return Ok(Property::GetEtag(xml.tag_string().await?))
-                },
-                b"getlastmodified" => {
-                    xml.next().await?;
+        } else if xml.maybe_open(DAV_URN, "getcontenttype").await?.is_some() {
+            let ct = xml.tag_string().await?;
+            xml.close().await?;
+            return Ok(Property::GetContentType(ct))
+        } else if xml.maybe_open(DAV_URN, "getetag").await?.is_some() {
+            let etag = xml.tag_string().await?;
+            xml.close().await?;
+            return Ok(Property::GetEtag(etag))
+        } else if xml.maybe_open(DAV_URN, "getlastmodified").await?.is_some() {
             let datestr = xml.tag_string().await?;
+            xml.close().await?;
             return Ok(Property::CreationDate(DateTime::parse_from_rfc2822(datestr.as_str())?))
-                },
-                b"lockdiscovery" => {
-                    xml.next().await?;
+        } else if xml.maybe_open(DAV_URN, "lockdiscovery").await?.is_some() {
             let acc = xml.collect::<ActiveLock>().await?;
-                    xml.tag_stop(DAV_URN, "lockdiscovery").await?;
+            xml.close().await?;
             return Ok(Property::LockDiscovery(acc))
-                },
-                b"resourcetype" => {
-                    xml.next().await?;
+        } else if xml.maybe_open(DAV_URN, "resourcetype").await?.is_some() {
             let acc = xml.collect::<ResourceType<E>>().await?;
-                    xml.tag_stop(DAV_URN, "resourcetype").await?;
+            xml.close().await?;
             return Ok(Property::ResourceType(acc))
-                },
-                b"supportedlock" => {
-                    xml.next().await?;
+        } else if xml.maybe_open(DAV_URN, "supportedlock").await?.is_some() {
             let acc = xml.collect::<LockEntry>().await?;
-                    xml.tag_stop(DAV_URN, "supportedlock").await?;
+            xml.close().await?;
             return Ok(Property::SupportedLock(acc))
-                },
-                _ => (),
-            };
         }
 
         // Option 2: an extension property, delegating
@@ -471,7 +427,7 @@ impl QRead<ActiveLock> for ActiveLock {
             }
         }
 
-        xml.tag_stop(DAV_URN, "activelock").await?;
+        xml.close().await?;
         match (m_scope, m_type, m_depth, m_root) {
             (Some(lockscope), Some(locktype), Some(depth), Some(lockroot)) =>
                 Ok(ActiveLock { lockscope, locktype, depth, owner, timeout, locktoken, lockroot }),
@@ -484,7 +440,7 @@ impl QRead<Depth> for Depth {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "depth").await?;
         let depth_str = xml.tag_string().await?;
-        xml.tag_stop(DAV_URN, "depth").await?;
+        xml.close().await?;
         match depth_str.as_str() {
             "0" => Ok(Depth::Zero),
             "1" => Ok(Depth::One),
@@ -518,7 +474,7 @@ impl QRead<Owner> for Owner {
                 _ => { xml.skip().await?; },
             }
         };
-        xml.tag_stop(DAV_URN, "owner").await?;
+        xml.close().await?;
         Ok(owner)
     }
 }
@@ -536,7 +492,7 @@ impl QRead<Timeout> for Timeout {
             },
         };
 
-        xml.tag_stop(DAV_URN, "timeout").await?;
+        xml.close().await?;
         Ok(timeout)
     }
 }
@@ -545,7 +501,7 @@ impl QRead<LockToken> for LockToken {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "locktoken").await?;
         let href = Href::qread(xml).await?;
-        xml.tag_stop(DAV_URN, "locktoken").await?;
+        xml.close().await?;
         Ok(LockToken(href))
     }
 }
@@ -554,20 +510,19 @@ impl QRead<LockRoot> for LockRoot {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "lockroot").await?;
         let href = Href::qread(xml).await?;
-        xml.tag_stop(DAV_URN, "lockroot").await?;
+        xml.close().await?;
         Ok(LockRoot(href))
     }
 }
 
 impl<E: Extension> QRead<ResourceType<E>> for ResourceType<E> {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
-        match xml.peek() {
-            Event::Empty(b) if xml.is_tag(DAV_URN, "collection") => {
-                xml.next().await?;
-                Ok(ResourceType::Collection)
-            },
-            _ => E::ResourceType::qread(xml).await.map(ResourceType::Extension),
+        if xml.maybe_open(DAV_URN, "collection").await?.is_some() {
+            xml.close().await?;
+            return Ok(ResourceType::Collection)
         }
+        
+        E::ResourceType::qread(xml).await.map(ResourceType::Extension)
     }
 }
 
@@ -588,7 +543,7 @@ impl QRead<LockEntry> for LockEntry {
             }
         }
 
-        xml.tag_stop(DAV_URN, "lockentry").await?;
+        xml.close().await?;
         match (maybe_scope, maybe_type) {
             (Some(lockscope), Some(locktype)) => Ok(LockEntry { lockscope, locktype }),
             _ => Err(ParsingError::MissingChild),
@@ -601,20 +556,18 @@ impl QRead<LockScope> for LockScope {
         xml.open(DAV_URN, "lockscope").await?;
 
         let lockscope = loop {
-            match xml.peek() {
-                Event::Empty(_) if xml.is_tag(DAV_URN, "exclusive") => {
-                    xml.next().await?;
+            if xml.maybe_open(DAV_URN, "exclusive").await?.is_some() {
+                xml.close().await?;
                 break LockScope::Exclusive
-                },
-                Event::Empty(_) if xml.is_tag(DAV_URN, "shared") => {
-                    xml.next().await?;
+            } else if xml.maybe_open(DAV_URN, "shared").await?.is_some() {
+                xml.close().await?;
                 break LockScope::Shared
             }
-                _ => xml.skip().await?,
-            };
+
+            xml.skip().await?;
         };
 
-        xml.tag_stop(DAV_URN, "lockscope").await?;
+        xml.close().await?;
         Ok(lockscope)
     }
 }
@@ -624,15 +577,15 @@ impl QRead<LockType> for LockType {
         xml.open(DAV_URN, "locktype").await?;
 
         let locktype = loop {
-            match xml.peek() {
-                Event::Empty(b) if xml.is_tag(DAV_URN, "write") => {
-                    xml.next().await?;
+            if xml.maybe_open(DAV_URN, "write").await?.is_some() {
+                xml.close().await?;
                 break LockType::Write
             }
-                _ => xml.skip().await?,
+
+            xml.skip().await?;
         };
-        };
-        xml.tag_stop(DAV_URN, "locktype").await?;
+
+        xml.close().await?;
         Ok(locktype)
     }
 }
@@ -641,7 +594,7 @@ impl QRead<Href> for Href {
     async fn qread(xml: &mut Reader<impl IRead>) -> Result<Self, ParsingError> {
         xml.open(DAV_URN, "href").await?;
         let mut url = xml.tag_string().await?;
-        xml.tag_stop(DAV_URN, "href").await?;
+        xml.close().await?;
         Ok(Href(url))
     }
 }
@@ -859,4 +812,68 @@ mod tests {
             responsedescription: None,
         });
     }
+
+
+    #[tokio::test]
+    async fn rfc_multistatus_value() {
+        let src = r#"
+     <?xml version="1.0" encoding="utf-8" ?>
+     <D:multistatus xmlns:D="DAV:">
+       <D:response>
+         <D:href>/container/</D:href>
+         <D:propstat>
+           <D:prop xmlns:R="http://ns.example.com/boxschema/">
+             <R:bigbox><R:BoxType>Box type A</R:BoxType></R:bigbox>
+             <R:author><R:Name>Hadrian</R:Name></R:author>
+             <D:creationdate>1997-12-01T17:42:21-08:00</D:creationdate>
+             <D:displayname>Example collection</D:displayname>
+             <D:resourcetype><D:collection/></D:resourcetype>
+             <D:supportedlock>
+               <D:lockentry>
+                 <D:lockscope><D:exclusive/></D:lockscope>
+                 <D:locktype><D:write/></D:locktype>
+               </D:lockentry>
+               <D:lockentry>
+                 <D:lockscope><D:shared/></D:lockscope>
+                 <D:locktype><D:write/></D:locktype>
+               </D:lockentry>
+             </D:supportedlock>
+           </D:prop>
+           <D:status>HTTP/1.1 200 OK</D:status>
+         </D:propstat>
+       </D:response>
+       <D:response>
+         <D:href>/container/front.html</D:href>
+         <D:propstat>
+           <D:prop xmlns:R="http://ns.example.com/boxschema/">
+             <R:bigbox><R:BoxType>Box type B</R:BoxType>
+             </R:bigbox>
+             <D:creationdate>1997-12-01T18:27:21-08:00</D:creationdate>
+             <D:displayname>Example HTML resource</D:displayname>
+             <D:getcontentlength>4525</D:getcontentlength>
+             <D:getcontenttype>text/html</D:getcontenttype>
+             <D:getetag>"zzyzx"</D:getetag>
+             <D:getlastmodified
+               >Mon, 12 Jan 1998 09:25:56 GMT</D:getlastmodified>
+             <D:resourcetype/>
+             <D:supportedlock>
+               <D:lockentry>
+                 <D:lockscope><D:exclusive/></D:lockscope>
+                 <D:locktype><D:write/></D:locktype>
+               </D:lockentry>
+               <D:lockentry>
+                 <D:lockscope><D:shared/></D:lockscope>
+                 <D:locktype><D:write/></D:locktype>
+               </D:lockentry>
+             </D:supportedlock>
+           </D:prop>
+           <D:status>HTTP/1.1 200 OK</D:status>
+         </D:propstat>
+       </D:response>
+     </D:multistatus>"#;
+
+        let mut rdr = Reader::new(NsReader::from_reader(src.as_bytes())).await.unwrap();
+        let got = rdr.find::<Multistatus::<Core, PropValue<Core>>>().await.unwrap();
+    }
+
 }

src/dav/xml.rs

@@ -53,25 +53,33 @@ impl<T: IWrite> Writer<T> {
 /// Transform an XML stream of characters into a Rust object
 pub struct Reader<T: IRead> {
     pub rdr: NsReader<T>,
-    evt: Event<'static>,
+    cur: Event<'static>,
+    parents: Vec<Event<'static>>,
     buf: Vec<u8>,
 }
 impl<T: IRead> Reader<T> {
     pub async fn new(mut rdr: NsReader<T>) -> Result<Self, ParsingError> {
         let mut buf: Vec<u8> = vec![];
-        let evt = rdr.read_event_into_async(&mut buf).await?.into_owned();
+        let cur = rdr.read_event_into_async(&mut buf).await?.into_owned();
+        let parents = vec![];
         buf.clear();
-        Ok(Self { evt, rdr, buf })
+        Ok(Self { cur, parents, rdr, buf })
     }
 
-    pub fn peek(&self) -> &Event<'static> {
-        &self.evt
+    /// read one more tag
+    /// do not expose it publicly
+    async fn next(&mut self) -> Result<Event<'static>, ParsingError> {
+       let evt = self.rdr.read_event_into_async(&mut self.buf).await?.into_owned(); 
+       self.buf.clear();
+       let old_evt = std::mem::replace(&mut self.cur, evt);
+       Ok(old_evt)
     }
 
-    /// skip tag. Can't skip end, can't skip eof.
+    /// skip a node at current level
+    /// I would like to make this one private but not ready
     pub async fn skip(&mut self) -> Result<Event<'static>, ParsingError> {
-        println!("skip on {:?}", &self.evt);
-        match &self.evt {
+        println!("skipping inside node {:?}", self.parents.last());
+        match &self.cur {
             Event::Start(b) => {
                 let _span = self.rdr.read_to_end_into_async(b.to_end().name(), &mut self.buf).await?;
                 self.next().await
@@ -82,17 +90,8 @@ impl<T: IRead> Reader<T> {
         }
     }
 
-    /// read one more tag
-    pub async fn next(&mut self) -> Result<Event<'static>, ParsingError> {
-       let evt = self.rdr.read_event_into_async(&mut self.buf).await?.into_owned(); 
-       self.buf.clear();
-       let old_evt = std::mem::replace(&mut self.evt, evt);
-       Ok(old_evt)
-    }
-
-
     /// check if this is the desired tag
-    pub fn is_tag(&self, ns: &[u8], key: &str) -> bool {
+    fn is_tag(&self, ns: &[u8], key: &str) -> bool {
         let qname = match self.peek() {
             Event::Start(bs) | Event::Empty(bs) => bs.name(),
             Event::End(be) => be.name(),
@@ -111,43 +110,25 @@ impl<T: IRead> Reader<T> {
         }
     }
 
-    /*
-     * Disabled
-    /// maybe find start tag
-    pub async fn maybe_tag_start(&mut self, ns: &[u8], key: &str) -> Result<Option<Event<'static>>, ParsingError> {
-        println!("maybe start tag {}", key);
-        let peek = self.peek();
-        match peek {
-            Event::Start(_) | Event::Empty(_) if self.is_tag(ns, key) => Ok(Some(self.next().await?)),
-            _ => Ok(None),
+    fn parent_has_child(&self) -> bool {
+        matches!(self.parents.last(), Some(Event::Start(_)) | None)
+    }
+
+    fn ensure_parent_has_child(&self) -> Result<(), ParsingError> {
+        match self.parent_has_child() {
+            true => Ok(()),
+            false => Err(ParsingError::Recoverable),
         }
     }
 
-    /// find start tag
-    pub async fn tag_start(&mut self, ns: &[u8], key: &str) -> Result<Event<'static>, ParsingError> {
-        loop {
-            match self.peek() {
-                Event::Start(b) if self.is_tag(ns, key) => break,
-                _ => { self.skip().await?; },
-            }
-        }
-        self.next().await
-    }
-    */
-
-    // find stop tag
-    pub async fn tag_stop(&mut self, ns: &[u8], key: &str) -> Result<Event<'static>, ParsingError> {
-        println!("search stop tag {}", key);
-        loop {
-            match self.peek() {
-                Event::End(b) if self.is_tag(ns, key) => break,
-                _ => { self.skip().await?; },
-            }
-        }
-        self.next().await
+    pub fn peek(&self) -> &Event<'static> {
+        &self.cur
     }
 
+    // NEW API
     pub async fn tag_string(&mut self) -> Result<String, ParsingError> {
+        self.ensure_parent_has_child()?;
+
         let mut acc = String::new();
         loop {
             match self.peek() {
@@ -165,8 +146,11 @@ impl<T: IRead> Reader<T> {
         }
     }
 
-    // NEW API
     pub async fn maybe_read<N: Node<N>>(&mut self, t: &mut Option<N>, dirty: &mut bool) -> Result<(), ParsingError> {
+        if !self.parent_has_child() {
+            return Ok(())
+        }
+
         match N::qread(self).await {
             Ok(v) => { 
                 *t = Some(v); 
@@ -179,6 +163,10 @@ impl<T: IRead> Reader<T> {
     }
 
     pub async fn maybe_push<N: Node<N>>(&mut self, t: &mut Vec<N>, dirty: &mut bool) -> Result<(), ParsingError> {
+        if !self.parent_has_child() {
+            return Ok(())
+        }
+
         match N::qread(self).await {
             Ok(v) => { 
                 t.push(v); 
@@ -191,6 +179,8 @@ impl<T: IRead> Reader<T> {
     }
 
     pub async fn find<N: Node<N>>(&mut self) -> Result<N, ParsingError> {
+        self.ensure_parent_has_child()?;
+
         loop {
             // Try parse
             match N::qread(self).await {
@@ -204,6 +194,8 @@ impl<T: IRead> Reader<T> {
     }
 
     pub async fn maybe_find<N: Node<N>>(&mut self) -> Result<Option<N>, ParsingError> {
+        self.ensure_parent_has_child()?;
+
         loop {
             // Try parse
             match N::qread(self).await {
@@ -219,7 +211,9 @@ impl<T: IRead> Reader<T> {
     }
 
     pub async fn collect<N: Node<N>>(&mut self) -> Result<Vec<N>, ParsingError> {
+        self.ensure_parent_has_child()?;
         let mut acc = Vec::new();
+
         loop {
             match N::qread(self).await {
                 Err(ParsingError::Recoverable) => match self.peek() {
@@ -235,10 +229,45 @@ impl<T: IRead> Reader<T> {
     }
 
     pub async fn open(&mut self, ns: &[u8], key: &str) -> Result<Event<'static>, ParsingError> {
-        if self.is_tag(ns, key) {
+        let evt = match self.peek() {
+            Event::Empty(_) if self.is_tag(ns, key) => self.cur.clone(),
+            Event::Start(_) if self.is_tag(ns, key) => self.next().await?,
+            _ => return Err(ParsingError::Recoverable),
+        };
+
+        println!("open tag {:?}", evt);
+        self.parents.push(evt.clone());
+        Ok(evt)
+    }
+
+    pub async fn maybe_open(&mut self, ns: &[u8], key: &str) -> Result<Option<Event<'static>>, ParsingError> {
+        match self.open(ns, key).await {
+            Ok(v) => Ok(Some(v)),
+            Err(ParsingError::Recoverable) => Ok(None),
+            Err(e) => Err(e),
+        }
+    }
+
+    // find stop tag
+    pub async fn close(&mut self) -> Result<Event<'static>, ParsingError> {
+        println!("close tag {:?}", self.parents.last());
+
+        // Handle the empty case
+        if !self.parent_has_child() {
+            self.parents.pop();
             return self.next().await 
         }
-        return Err(ParsingError::Recoverable);
+
+        // Handle the start/end case
+        loop {
+            match self.peek() {
+                Event::End(_) => {
+                    self.parents.pop();
+                    return self.next().await
+                },
+                _ => self.skip().await?,
+            };
+        }
     }
 }