clean up header map

actix-http/Cargo.toml

@@ -53,7 +53,6 @@ bytes = "1"
 bytestring = "1"
 cookie = { version = "0.14.1", features = ["percent-encode"] }
 derive_more = "0.99.5"
-either = "1.5.3"
 encoding_rs = "0.8"
 futures-channel = { version = "0.3.7", default-features = false, features = ["alloc"] }
 futures-core = { version = "0.3.7", default-features = false, features = ["alloc"] }

actix-http/src/header/map.rs

@@ -1,16 +1,12 @@
-use std::{
+use std::{borrow::Cow, collections::hash_map, str::FromStr};
-    collections::hash_map::{self, Entry},
-    convert::TryFrom,
-};
 
 use ahash::AHashMap;
-use either::Either;
+use http::header::{HeaderName, HeaderValue, InvalidHeaderName};
-use http::header::{HeaderName, HeaderValue};
 use smallvec::{smallvec, SmallVec};
 
 /// A multi-map of HTTP headers.
 ///
-/// `HeaderMap` is a "multi-map" of [`HeaderName`] to one or more values.
+/// `HeaderMap` is a "multi-map" of [`HeaderName`] to one or more [`HeaderValue`]s.
 #[derive(Debug, Clone, Default)]
 pub struct HeaderMap {
     pub(crate) inner: AHashMap<HeaderName, Value>,
@@ -54,33 +50,29 @@ impl Value {
 impl HeaderMap {
     /// Create an empty `HeaderMap`.
     ///
-    /// The map will be created without any capacity. This function will not
+    /// The map will be created without any capacity. This function will not allocate.
-    /// allocate.
     pub fn new() -> Self {
-        HeaderMap {
+        HeaderMap::default()
-            inner: AHashMap::default(),
-        }
     }
 
     /// Create an empty `HeaderMap` with the specified capacity.
     ///
-    /// The returned map will allocate internal storage in order to hold about
+    /// The returned map will allocate internal storage in order to hold about `capacity` elements
-    /// `capacity` elements without reallocating. However, this is a "best
+    /// without reallocating. However, this is a "best effort" as there are usage patterns that
-    /// effort" as there are usage patterns that could cause additional
+    /// could cause additional allocations before `capacity` headers are stored in the map.
-    /// allocations before `capacity` headers are stored in the map.
     ///
     /// More capacity than requested may be allocated.
     pub fn with_capacity(capacity: usize) -> HeaderMap {
         HeaderMap {
-            inner: AHashMap::with_capacity_and_hasher(capacity, Default::default()),
+            inner: AHashMap::with_capacity(capacity),
         }
     }
 
     /// Returns the number of keys stored in the map.
     ///
-    /// This number could be be less than or equal to actual headers stored in
+    /// This number could be be less than or equal to actual headers stored in the map.
-    /// the map.
     pub fn len(&self) -> usize {
+        // TODO: wat!? that's messed up
         self.inner.len()
     }
 
@@ -89,206 +81,210 @@ impl HeaderMap {
         self.inner.len() == 0
     }
 
-    /// Clears the map, removing all key-value pairs. Keeps the allocated memory
+    /// Clears the map, removing all name-value pairs. Keeps the allocated memory for reuse.
-    /// for reuse.
     pub fn clear(&mut self) {
         self.inner.clear();
     }
 
     /// Returns the number of headers the map can hold without reallocating.
     ///
-    /// This number is an approximation as certain usage patterns could cause
+    /// This number is an approximation as certain usage patterns could cause additional allocations
-    /// additional allocations before the returned capacity is filled.
+    /// before the returned capacity is filled.
     pub fn capacity(&self) -> usize {
         self.inner.capacity()
     }
 
-    /// Reserves capacity for at least `additional` more headers to be inserted
+    /// Reserves capacity for at least `additional` more headers to be inserted in the map.
-    /// into the `HeaderMap`.
     ///
-    /// The header map may reserve more space to avoid frequent reallocations.
+    /// The header map may reserve more space to avoid frequent reallocations. Like with
-    /// Like with `with_capacity`, this will be a "best effort" to avoid
+    /// `with_capacity`, this will be a "best effort" to avoid allocations until `additional` more
-    /// allocations until `additional` more headers are inserted. Certain usage
+    /// headers are inserted. Certain usage patterns could cause additional allocations before the
-    /// patterns could cause additional allocations before the number is
+    /// number is reached.
-    /// reached.
     pub fn reserve(&mut self, additional: usize) {
         self.inner.reserve(additional)
     }
 
-    /// Returns a reference to the value associated with the key.
+    fn get_value(&self, key: impl AsHeaderName) -> Option<&Value> {
+        match key.try_as_name().ok()? {
+            Cow::Borrowed(name) => self.inner.get(name),
+            Cow::Owned(name) => self.inner.get(&name),
+        }
+    }
+
+    /// Returns a reference to the first value associated with a header name.
     ///
-    /// If there are multiple values associated with the key, then the first one
+    /// If there are multiple values associated with the key, then the first one is returned.
-    /// is returned. Use `get_all` to get all values associated with a given
+    /// Use `get_all` to get all values associated with a given key. Returns `None` if there are no
-    /// key. Returns `None` if there are no values associated with the key.
+    /// values associated with the key.
-    pub fn get<N: AsName>(&self, name: N) -> Option<&HeaderValue> {
+    pub fn get(&self, key: impl AsHeaderName) -> Option<&HeaderValue> {
-        self.get2(name).map(|v| v.first())
+        self.get_value(key).map(|val| val.first())
     }
 
-    fn get2<N: AsName>(&self, name: N) -> Option<&Value> {
+    /// Returns a mutable reference to the first value associated a header name.
-        match name.as_name() {
+    ///
-            Either::Left(name) => self.inner.get(name),
+    /// If there are multiple values associated with the key, then the first one is returned.
-            Either::Right(s) => {
+    /// Use `get_all` to get all values associated with a given key. Returns `None` if there are no
-                if let Ok(name) = HeaderName::try_from(s) {
+    /// values associated with the key.
-                    self.inner.get(&name)
+    pub fn get_mut(&mut self, key: impl AsHeaderName) -> Option<&mut HeaderValue> {
-                } else {
+        match key.try_as_name().ok()? {
-                    None
+            Cow::Borrowed(name) => self.inner.get_mut(name).map(|v| v.first_mut()),
-                }
+            Cow::Owned(name) => self.inner.get_mut(&name).map(|v| v.first_mut()),
-            }
         }
     }
 
-    /// Returns an iterator of all values associated with a key.
+    /// Returns an iterator of all values associated with a header name.
     ///
     /// The returned view does not incur any allocations and allows iterating the values associated
-    /// with the key. Returns `None` if there are no values associated with the key. Iteration order
+    /// with the key. Iterator will yield no items if there are no values associated with the key.
-    /// is not guaranteed to be the same as insertion order.
+    /// Iteration order is not guaranteed to be the same as insertion order.
-    pub fn get_all<N: AsName>(&self, name: N) -> GetAll<'_> {
+    pub fn get_all(&self, key: impl AsHeaderName) -> GetAll<'_> {
-        GetAll {
+        GetAll::new(self.get_value(key))
-            idx: 0,
-            item: self.get2(name),
-        }
-    }
-
-    /// Returns a mutable reference to the value associated with the key.
-    ///
-    /// If there are multiple values associated with the key, then the first one
-    /// is returned. Use `entry` to get all values associated with a given
-    /// key. Returns `None` if there are no values associated with the key.
-    pub fn get_mut<N: AsName>(&mut self, name: N) -> Option<&mut HeaderValue> {
-        match name.as_name() {
-            Either::Left(name) => self.inner.get_mut(name).map(|v| v.first_mut()),
-            Either::Right(s) => {
-                if let Ok(name) = HeaderName::try_from(s) {
-                    self.inner.get_mut(&name).map(|v| v.first_mut())
-                } else {
-                    None
-                }
-            }
-        }
     }
 
     /// Returns true if the map contains a value for the specified key.
-    pub fn contains_key<N: AsName>(&self, key: N) -> bool {
+    ///
-        match key.as_name() {
+    /// Invalid header names will simply return false.
-            Either::Left(name) => self.inner.contains_key(name),
+    pub fn contains_key(&self, key: impl AsHeaderName) -> bool {
-            Either::Right(s) => {
+        match key.try_as_name() {
-                if let Ok(name) = HeaderName::try_from(s) {
+            Ok(Cow::Borrowed(name)) => self.inner.contains_key(name),
-                    self.inner.contains_key(&name)
+            Ok(Cow::Owned(name)) => self.inner.contains_key(&name),
-                } else {
+            Err(_) => false,
-                    false
-                }
-            }
         }
     }
 
-    /// An iterator visiting all key-value pairs.
+    /// An iterator visiting all name-value pairs.
     ///
-    /// The iteration order is arbitrary, but consistent across platforms for
+    /// The iteration order is arbitrary but consistent across platforms for the same crate version.
-    /// the same crate version. Each key will be yielded once per associated
+    /// Each key will be yielded once per associated value. So, if a key has 3 associated values, it
-    /// value. So, if a key has 3 associated values, it will be yielded 3 times.
+    /// will be yielded 3 times.
     pub fn iter(&self) -> Iter<'_> {
         Iter::new(self.inner.iter())
     }
 
     /// An iterator visiting all keys.
     ///
-    /// The iteration order is arbitrary, but consistent across platforms for
+    /// The iteration order is arbitrary but consistent across platforms for the same crate version.
-    /// the same crate version. Each key will be yielded only once even if it
+    /// Each key will be yielded only once even if it has multiple associated values.
-    /// has multiple associated values.
     pub fn keys(&self) -> Keys<'_> {
         Keys(self.inner.keys())
     }
 
-    /// Inserts a key-value pair into the map.
+    /// Inserts a name-value pair into the map.
     ///
-    /// If the map did not previously have this key present, then `None` is
+    /// If the map did have this key present, the new value is associated with the key and all
-    /// returned.
+    /// previous values are removed. **Note** that only a single one of the previous values
-    ///
+    /// is returned. If there are multiple values that have been previously associated with the key,
-    /// If the map did have this key present, the new value is associated with
+    /// then the first one is returned. See `insert_mult` on `OccupiedEntry` for an API that returns
-    /// the key and all previous values are removed. **Note** that only a single
-    /// one of the previous values is returned. If there are multiple values
-    /// that have been previously associated with the key, then the first one is
-    /// returned. See `insert_mult` on `OccupiedEntry` for an API that returns
     /// all values.
     ///
     /// The key is not updated, though; this matters for types that can be `==`
     /// without being identical.
     pub fn insert(&mut self, key: HeaderName, val: HeaderValue) {
-        let _ = self.inner.insert(key, Value::One(val));
+        self.inner.insert(key, Value::One(val));
     }
 
-    /// Inserts a key-value pair into the map.
+    /// Inserts a name-value pair into the map.
     ///
-    /// If the map did not previously have this key present, then `false` is
+    /// If the map did have this key present, the new value is pushed to the end of the list of
-    /// returned.
+    /// values currently associated with the key. The key is not updated, though; this matters for
-    ///
+    /// types that can be `==` without being identical.
-    /// If the map did have this key present, the new value is pushed to the end
-    /// of the list of values currently associated with the key. The key is not
-    /// updated, though; this matters for types that can be `==` without being
-    /// identical.
     pub fn append(&mut self, key: HeaderName, value: HeaderValue) {
         match self.inner.entry(key) {
-            Entry::Occupied(mut entry) => entry.get_mut().append(value),
+            hash_map::Entry::Occupied(mut entry) => {
-            Entry::Vacant(entry) => {
+                entry.get_mut().append(value);
+            }
+            hash_map::Entry::Vacant(entry) => {
                 entry.insert(Value::One(value));
             }
-        }
+        };
     }
 
     /// Removes all headers for a particular header name from the map.
-    pub fn remove<N: AsName>(&mut self, key: N) {
+    // TODO: return value somehow
-        match key.as_name() {
+    pub fn remove(&mut self, key: impl AsHeaderName) {
-            Either::Left(name) => {
+        match key.try_as_name() {
-                let _ = self.inner.remove(name);
+            Ok(Cow::Borrowed(name)) => self.inner.remove(name),
-            }
+            Ok(Cow::Owned(name)) => self.inner.remove(&name),
-            Either::Right(s) => {
+            Err(_) => None,
-                if let Ok(name) = HeaderName::try_from(s) {
+        };
-                    let _ = self.inner.remove(&name);
-                }
-            }
-        }
     }
 }
 
-#[doc(hidden)]
+impl IntoIterator for HeaderMap {
-pub trait AsName {
+    type Item = (HeaderName, HeaderValue);
-    fn as_name(&self) -> Either<&HeaderName, &str>;
+    type IntoIter = IntoIter;
-}
 
-impl AsName for HeaderName {
+    #[inline]
-    fn as_name(&self) -> Either<&HeaderName, &str> {
+    fn into_iter(self) -> Self::IntoIter {
-        Either::Left(self)
+        IntoIter::new(self.inner.into_iter())
     }
 }
 
-impl<'a> AsName for &'a HeaderName {
+impl<'a> IntoIterator for &'a HeaderMap {
-    fn as_name(&self) -> Either<&HeaderName, &str> {
+    type Item = (&'a HeaderName, &'a HeaderValue);
-        Either::Left(self)
+    type IntoIter = Iter<'a>;
+
+    #[inline]
+    fn into_iter(self) -> Self::IntoIter {
+        Iter::new(self.inner.iter())
     }
 }
 
-impl<'a> AsName for &'a str {
+pub trait AsHeaderName: sealed::Sealed {}
-    fn as_name(&self) -> Either<&HeaderName, &str> {
-        Either::Right(self)
-    }
-}
 
-impl AsName for String {
+mod sealed {
-    fn as_name(&self) -> Either<&HeaderName, &str> {
+    use super::*;
-        Either::Right(self.as_str())
-    }
-}
 
-impl<'a> AsName for &'a String {
+    pub trait Sealed {
-    fn as_name(&self) -> Either<&HeaderName, &str> {
+        fn try_as_name(&self) -> Result<Cow<'_, HeaderName>, InvalidHeaderName>;
-        Either::Right(self.as_str())
     }
+
+    impl Sealed for HeaderName {
+        fn try_as_name(&self) -> Result<Cow<'_, HeaderName>, InvalidHeaderName> {
+            Ok(Cow::Borrowed(self))
+        }
+    }
+    impl AsHeaderName for HeaderName {}
+
+    impl Sealed for &HeaderName {
+        fn try_as_name(&self) -> Result<Cow<'_, HeaderName>, InvalidHeaderName> {
+            Ok(Cow::Borrowed(*self))
+        }
+    }
+    impl AsHeaderName for &HeaderName {}
+
+    impl Sealed for &str {
+        fn try_as_name(&self) -> Result<Cow<'_, HeaderName>, InvalidHeaderName> {
+            HeaderName::from_str(self).map(Cow::Owned)
+        }
+    }
+    impl AsHeaderName for &str {}
+
+    impl Sealed for String {
+        fn try_as_name(&self) -> Result<Cow<'_, HeaderName>, InvalidHeaderName> {
+            HeaderName::from_str(self).map(Cow::Owned)
+        }
+    }
+    impl AsHeaderName for String {}
+
+    impl Sealed for &String {
+        fn try_as_name(&self) -> Result<Cow<'_, HeaderName>, InvalidHeaderName> {
+            HeaderName::from_str(self).map(Cow::Owned)
+        }
+    }
+    impl AsHeaderName for &String {}
 }
 
 /// Iterator for all values in a `HeaderMap` with the same name.
 pub struct GetAll<'a> {
     idx: usize,
-    item: Option<&'a Value>,
+    value: Option<&'a Value>,
+}
+
+impl<'a> GetAll<'a> {
+    fn new(value: Option<&'a Value>) -> Self {
+        Self { idx: 0, value }
+    }
 }
 
 impl<'a> Iterator for GetAll<'a> {
@@ -296,25 +292,25 @@ impl<'a> Iterator for GetAll<'a> {
 
     #[inline]
     fn next(&mut self) -> Option<&'a HeaderValue> {
-        if let Some(ref val) = self.item {
+        let val = self.value?;
+
         match val {
             Value::One(ref val) => {
-                    self.item.take();
+                // remove value to fast-path future next calls
+                self.value = None;
                 Some(val)
             }
-                Value::Multi(ref vec) => {
+            Value::Multi(ref vec) => match vec.get(self.idx) {
-                    if self.idx < vec.len() {
+                Some(val) => {
-                        let item = Some(&vec[self.idx]);
                     self.idx += 1;
-                        item
+                    Some(val)
-                    } else {
+                }
-                        self.item.take();
+                None => {
+                    // current index is none; remove value to fast-path future next calls
+                    self.value = None;
                     None
                 }
-                }
+            },
-            }
-        } else {
-            None
         }
     }
 }
@@ -330,27 +326,18 @@ impl<'a> Iterator for Keys<'a> {
     }
 }
 
-impl<'a> IntoIterator for &'a HeaderMap {
-    type Item = (&'a HeaderName, &'a HeaderValue);
-    type IntoIter = Iter<'a>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        self.iter()
-    }
-}
-
 pub struct Iter<'a> {
-    idx: usize,
-    current: Option<(&'a HeaderName, &'a SmallVec<[HeaderValue; 4]>)>,
     iter: hash_map::Iter<'a, HeaderName, Value>,
+    multi_inner: Option<(&'a HeaderName, &'a SmallVec<[HeaderValue; 4]>)>,
+    multi_idx: usize,
 }
 
 impl<'a> Iter<'a> {
     fn new(iter: hash_map::Iter<'a, HeaderName, Value>) -> Self {
         Self {
             iter,
-            idx: 0,
+            multi_idx: 0,
-            current: None,
+            multi_inner: None,
         }
     }
 }
@@ -360,26 +347,171 @@ impl<'a> Iterator for Iter<'a> {
 
     #[inline]
     fn next(&mut self) -> Option<(&'a HeaderName, &'a HeaderValue)> {
-        if let Some(ref mut item) = self.current {
+        // handle in-progress multi value lists first
-            if self.idx < item.1.len() {
+        if let Some((ref name, ref mut vals)) = self.multi_inner {
-                let item = (item.0, &item.1[self.idx]);
+            match vals.get(self.multi_idx) {
-                self.idx += 1;
+                Some(val) => {
-                return Some(item);
+                    self.multi_idx += 1;
-            } else {
+                    return Some((name, val));
-                self.idx = 0;
+                }
-                self.current.take();
+                None => {
+                    // no more items in value list; reset state
+                    self.multi_idx = 0;
+                    self.multi_inner = None;
                 }
             }
-        if let Some(item) = self.iter.next() {
+        }
-            match item.1 {
+
-                Value::One(ref value) => Some((item.0, value)),
+        let (name, value) = self.iter.next()?;
-                Value::Multi(ref vec) => {
+
-                    self.current = Some((item.0, vec));
+        match value {
+            Value::One(ref value) => Some((name, value)),
+            Value::Multi(ref vals) => {
+                // set up new multi value inner iter and recurse into it
+                self.multi_inner = Some((name, vals));
                 self.next()
             }
         }
-        } else {
+    }
-            None
+}
+
+pub struct IntoIter {
+    iter: hash_map::IntoIter<HeaderName, Value>,
+    multi_inner: Option<(HeaderName, smallvec::IntoIter<[HeaderValue; 4]>)>,
+}
+
+impl IntoIter {
+    fn new(iter: hash_map::IntoIter<HeaderName, Value>) -> Self {
+        Self {
+            iter,
+            multi_inner: None,
         }
     }
 }
+
+impl Iterator for IntoIter {
+    type Item = (HeaderName, HeaderValue);
+
+    #[inline]
+    fn next(&mut self) -> Option<(HeaderName, HeaderValue)> {
+        // handle in-progress multi value iterators first
+        if let Some((ref name, ref mut vals)) = self.multi_inner {
+            match vals.next() {
+                Some(val) => {
+                    return Some((name.clone(), val));
+                }
+                None => {
+                    // no more items in value iterator; reset state
+                    self.multi_inner = None;
+                }
+            }
+        }
+
+        let (name, value) = self.iter.next()?;
+
+        match value {
+            Value::One(value) => Some((name, value)),
+            Value::Multi(vals) => {
+                // set up new multi value inner iter and recurse into it
+                self.multi_inner = Some((name, vals.into_iter()));
+                self.next()
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use http::header;
+
+    use super::*;
+
+    #[test]
+    fn test_new() {
+        let map = HeaderMap::new();
+        assert_eq!(map.len(), 0);
+        assert_eq!(map.capacity(), 0);
+
+        let map = HeaderMap::with_capacity(16);
+        assert_eq!(map.len(), 0);
+        assert!(map.capacity() >= 16);
+    }
+
+    #[test]
+    fn test_insert() {
+        let mut map = HeaderMap::new();
+
+        map.insert(header::LOCATION, HeaderValue::from_static("/test"));
+        assert_eq!(map.len(), 1);
+    }
+
+    #[test]
+    fn test_contains() {
+        let mut map = HeaderMap::new();
+        assert!(!map.contains_key(header::LOCATION));
+
+        map.insert(header::LOCATION, HeaderValue::from_static("/test"));
+        assert!(map.contains_key(header::LOCATION));
+        assert!(map.contains_key("Location"));
+        assert!(map.contains_key("Location".to_owned()));
+        assert!(map.contains_key("location"));
+    }
+
+    #[test]
+    fn test_entries_iter() {
+        let mut map = HeaderMap::new();
+
+        map.append(header::HOST, HeaderValue::from_static("duck.com"));
+        map.append(header::COOKIE, HeaderValue::from_static("one=1"));
+        map.append(header::COOKIE, HeaderValue::from_static("two=2"));
+
+        let mut iter = map.iter();
+        assert!(iter.next().is_some());
+        assert!(iter.next().is_some());
+        assert!(iter.next().is_some());
+        assert!(iter.next().is_none());
+
+        let pairs = map.iter().collect::<Vec<_>>();
+        assert!(pairs.contains(&(&header::HOST, &HeaderValue::from_static("duck.com"))));
+        assert!(pairs.contains(&(&header::COOKIE, &HeaderValue::from_static("one=1"))));
+        assert!(pairs.contains(&(&header::COOKIE, &HeaderValue::from_static("two=2"))));
+    }
+
+    #[test]
+    fn test_entries_into_iter() {
+        let mut map = HeaderMap::new();
+
+        map.append(header::HOST, HeaderValue::from_static("duck.com"));
+        map.append(header::COOKIE, HeaderValue::from_static("one=1"));
+        map.append(header::COOKIE, HeaderValue::from_static("two=2"));
+
+        let mut iter = map.into_iter();
+        assert!(iter.next().is_some());
+        assert!(iter.next().is_some());
+        assert!(iter.next().is_some());
+        assert!(iter.next().is_none());
+    }
+
+    #[test]
+    fn test_entries_iter_and_into_iter_same_order() {
+        let mut map = HeaderMap::new();
+
+        map.append(header::HOST, HeaderValue::from_static("duck.com"));
+        map.append(header::COOKIE, HeaderValue::from_static("one=1"));
+        map.append(header::COOKIE, HeaderValue::from_static("two=2"));
+
+        let mut iter = map.iter();
+        let mut into_iter = map.clone().into_iter();
+
+        assert_eq!(iter.next().map(owned_pair), into_iter.next());
+        assert_eq!(iter.next().map(owned_pair), into_iter.next());
+        assert_eq!(iter.next().map(owned_pair), into_iter.next());
+        assert_eq!(iter.next().map(owned_pair), into_iter.next());
+    }
+
+    fn owned_pair<'a>(
+        (name, val): (&'a HeaderName, &'a HeaderValue),
+    ) -> (HeaderName, HeaderValue) {
+        (name.clone(), val.clone())
+    }
+}

actix-http/src/request.rs

@@ -177,13 +177,17 @@ impl<P> fmt::Debug for Request<P> {
             self.method(),
             self.path()
         )?;
+
         if let Some(q) = self.uri().query().as_ref() {
             writeln!(f, "  query: ?{:?}", q)?;
         }
+
         writeln!(f, "  headers:")?;
-        for (key, val) in self.headers() {
+
+        for (key, val) in self.headers().iter() {
             writeln!(f, "    {:?}: {:?}", key, val)?;
         }
+
         Ok(())
     }
 }

actix-http/src/response.rs

@@ -752,9 +752,11 @@ impl<'a> From<&'a ResponseHead> for ResponseBuilder {
         let mut msg = BoxedResponseHead::new(head.status);
         msg.version = head.version;
         msg.reason = head.reason;
-        for (k, v) in &head.headers {
+
+        for (k, v) in head.headers.iter() {
             msg.headers.append(k.clone(), v.clone());
         }
+
         msg.no_chunking(!head.chunked());
 
         ResponseBuilder {