proper serde deserializer implementation for path

src/de.rs

@@ -1,3 +1,5 @@
+use std::slice::Iter;
+use std::borrow::Cow;
 use std::ops::{Deref, DerefMut};
 
 use serde_urlencoded;
@@ -25,6 +27,32 @@ use httprequest::HttpRequest;
 /// /// Application state
 /// struct State {}
 ///
+/// /// extract path info using serde
+/// fn index(info: Path<(String, u32), State>) -> Result<String> {
+///     Ok(format!("Welcome {}! {}", info.0, info.1))
+/// }
+///
+/// fn main() {
+///     let app = Application::with_state(State{}).resource(
+///        "/{username}/{count}/?index.html",       // <- define path parameters
+///        |r| r.method(Method::GET).with(index));  // <- use `with` extractor
+/// }
+/// ```
+///
+/// It is possible to extract path information to a specific type that implements
+/// `Deserialize` trait from *serde*.
+///
+/// ```rust
+/// # extern crate bytes;
+/// # extern crate actix_web;
+/// # extern crate futures;
+/// #[macro_use] extern crate serde_derive;
+/// # use actix_web::*;
+/// use actix_web::Path;
+///
+/// /// Application state
+/// struct State {}
+///
 /// #[derive(Deserialize)]
 /// struct Info {
 ///     username: String,
@@ -203,8 +231,10 @@ impl<'de, S: 'de> Deserializer<'de> for PathDeserializer<'de, S>
     fn deserialize_map<V>(self, visitor: V) -> Result<V::Value, Self::Error>
         where V: Visitor<'de>,
     {
-        visitor.visit_map(de::value::MapDeserializer::new(
+        visitor.visit_map(ParamsDeserializer{
-            self.req.match_info().iter().map(|&(ref k, ref v)| (k.as_ref(), v.as_ref()))))
+            params: self.req.match_info().iter(),
+            current: None,
+        })
     }
 
     fn deserialize_struct<V>(self, _: &'static str, _: &'static [&'static str], visitor: V)
@@ -243,8 +273,7 @@ impl<'de, S: 'de> Deserializer<'de> for PathDeserializer<'de, S>
                 format!("wrong number of parameters: {} expected {}",
                         self.req.match_info().len(), len).as_str()))
         } else {
-            visitor.visit_seq(de::value::SeqDeserializer::new(
+            visitor.visit_seq(ParamsSeq{params: self.req.match_info().iter()})
-                self.req.match_info().iter().map(|&(_, ref v)| v.as_ref())))
         }
     }
 
@@ -252,8 +281,7 @@ impl<'de, S: 'de> Deserializer<'de> for PathDeserializer<'de, S>
                                    -> Result<V::Value, Self::Error>
         where V: Visitor<'de>
     {
-        visitor.visit_seq(de::value::SeqDeserializer::new(
+        visitor.visit_seq(ParamsSeq{params: self.req.match_info().iter()})
-            self.req.match_info().iter().map(|&(_, ref v)| v.as_ref())))
     }
 
     fn deserialize_enum<V>(self, _: &'static str, _: &'static [&'static str], _: V)
@@ -286,6 +314,237 @@ impl<'de, S: 'de> Deserializer<'de> for PathDeserializer<'de, S>
     unsupported_type!(deserialize_ignored_any, "ignored_any");
 }
 
+struct ParamsDeserializer<'de> {
+    params: Iter<'de, (Cow<'de, str>, Cow<'de, str>)>,
+    current: Option<(&'de str, &'de str)>,
+}
+
+impl<'de> de::MapAccess<'de> for ParamsDeserializer<'de>
+{
+    type Error = de::value::Error;
+
+    fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Self::Error>
+        where K: de::DeserializeSeed<'de>,
+    {
+        self.current = self.params.next().map(|&(ref k, ref v)| (k.as_ref(), v.as_ref()));
+        match self.current {
+            Some((key, _)) => Ok(Some(seed.deserialize(Key{key})?)),
+            None => Ok(None),
+        }
+    }
+
+    fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Self::Error>
+        where V: de::DeserializeSeed<'de>,
+    {
+        if let Some((_, value)) = self.current.take() {
+            seed.deserialize(Value { value })
+        } else {
+            Err(de::value::Error::custom("unexpected item"))
+        }
+    }
+}
+
+struct Key<'de> {
+    key: &'de str,
+}
+
+impl<'de> Deserializer<'de> for Key<'de> {
+    type Error = de::value::Error;
+
+    fn deserialize_identifier<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        visitor.visit_str(self.key)
+    }
+
+    fn deserialize_any<V>(self, _visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        Err(de::value::Error::custom("Unexpected"))
+    }
+
+    forward_to_deserialize_any! {
+        bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string bytes
+            byte_buf option unit unit_struct newtype_struct seq tuple
+            tuple_struct map struct enum ignored_any
+    }
+}
+
+macro_rules! parse_value {
+    ($trait_fn:ident, $visitor_fn:ident, $tp:tt) => {
+        fn $trait_fn<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+            where V: Visitor<'de>
+        {
+            let v = self.value.parse().map_err(
+                |_| de::value::Error::custom(
+                    format!("can not parse {:?} to a {}", self.value, $tp)))?;
+            visitor.$visitor_fn(v)
+        }
+    }
+}
+
+struct Value<'de> {
+    value: &'de str,
+}
+
+impl<'de> Deserializer<'de> for Value<'de>
+{
+    type Error = de::value::Error;
+
+    parse_value!(deserialize_bool, visit_bool, "bool");
+    parse_value!(deserialize_i8, visit_i8, "i8");
+    parse_value!(deserialize_i16, visit_i16, "i16");
+    parse_value!(deserialize_i32, visit_i32, "i16");
+    parse_value!(deserialize_i64, visit_i64, "i64");
+    parse_value!(deserialize_u8, visit_u8, "u8");
+    parse_value!(deserialize_u16, visit_u16, "u16");
+    parse_value!(deserialize_u32, visit_u32, "u32");
+    parse_value!(deserialize_u64, visit_u64, "u64");
+    parse_value!(deserialize_f32, visit_f32, "f32");
+    parse_value!(deserialize_f64, visit_f64, "f64");
+    parse_value!(deserialize_string, visit_string, "String");
+    parse_value!(deserialize_byte_buf, visit_string, "String");
+    parse_value!(deserialize_char, visit_char, "char");
+
+    fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        visitor.visit_unit()
+    }
+
+    fn deserialize_unit<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        visitor.visit_unit()
+    }
+
+    fn deserialize_unit_struct<V>(
+        self, _: &'static str, visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>
+    {
+        visitor.visit_unit()
+    }
+
+    fn deserialize_bytes<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        visitor.visit_borrowed_bytes(self.value.as_bytes())
+    }
+
+    fn deserialize_str<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        visitor.visit_borrowed_str(self.value)
+    }
+
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        visitor.visit_some(self)
+    }
+
+    fn deserialize_enum<V>(self, _: &'static str, _: &'static [&'static str], visitor: V)
+                           -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        visitor.visit_enum(ValueEnum {value: self.value})
+    }
+
+    fn deserialize_newtype_struct<V>(self, _: &'static str, visitor: V)
+                                     -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        visitor.visit_newtype_struct(self)
+    }
+
+    fn deserialize_tuple<V>(self, _: usize, _: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>
+    {
+        Err(de::value::Error::custom("unsupported type: tuple"))
+    }
+
+    fn deserialize_struct<V>(self, _: &'static str, _: &'static [&'static str], _: V)
+                             -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>
+    {
+        Err(de::value::Error::custom("unsupported type: struct"))
+    }
+
+    fn deserialize_tuple_struct<V>(self, _: &'static str, _: usize, _: V)
+                                   -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>
+    {
+        Err(de::value::Error::custom("unsupported type: tuple struct"))
+    }
+
+    unsupported_type!(deserialize_any, "");
+    unsupported_type!(deserialize_seq, "seq");
+    unsupported_type!(deserialize_map, "map");
+    unsupported_type!(deserialize_identifier, "identifier");
+}
+
+struct ParamsSeq<'de> {
+    params: Iter<'de, (Cow<'de, str>, Cow<'de, str>)>,
+}
+
+impl<'de> de::SeqAccess<'de> for ParamsSeq<'de>
+{
+    type Error = de::value::Error;
+
+    fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+        where T: de::DeserializeSeed<'de>,
+    {
+        match self.params.next() {
+            Some(item) => Ok(Some(seed.deserialize(Value { value: item.1.as_ref() })?)),
+            None => Ok(None),
+        }
+    }
+}
+
+struct ValueEnum<'de> {
+    value: &'de str,
+}
+
+impl<'de> de::EnumAccess<'de> for ValueEnum<'de> {
+    type Error = de::value::Error;
+    type Variant = UnitVariant;
+
+    fn variant_seed<V>(self, seed: V) -> Result<(V::Value, Self::Variant), Self::Error>
+        where V: de::DeserializeSeed<'de>,
+    {
+        Ok((seed.deserialize(Key { key: self.value })?, UnitVariant))
+    }
+}
+
+struct UnitVariant;
+
+impl<'de> de::VariantAccess<'de> for UnitVariant {
+    type Error = de::value::Error;
+
+    fn unit_variant(self) -> Result<(), Self::Error> {
+        Ok(())
+    }
+
+    fn newtype_variant_seed<T>(self, _seed: T) -> Result<T::Value, Self::Error>
+        where T: de::DeserializeSeed<'de>,
+    {
+        Err(de::value::Error::custom("not supported"))
+    }
+
+    fn tuple_variant<V>(self, _len: usize, _visitor: V) -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        Err(de::value::Error::custom("not supported"))
+    }
+
+    fn struct_variant<V>(self, _: &'static [&'static str], _: V)
+                         -> Result<V::Value, Self::Error>
+        where V: Visitor<'de>,
+    {
+        Err(de::value::Error::custom("not supported"))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use futures::{Async, Future};
@@ -306,6 +565,12 @@ mod tests {
         id: String,
     }
 
+    #[derive(Deserialize)]
+    struct Test2 {
+        key: String,
+        value: u32,
+    }
+
     #[test]
     fn test_request_extract() {
         let mut req = TestRequest::with_uri("/name/user1/?id=test").finish();
@@ -339,5 +604,24 @@ mod tests {
             },
             _ => unreachable!(),
         }
+
+        let mut req = TestRequest::with_uri("/name/32/").finish();
+        assert!(router.recognize(&mut req).is_some());
+
+        match Path::<Test2, _>::from_request(&req).poll().unwrap() {
+            Async::Ready(s) => {
+                assert_eq!(s.key, "name");
+                assert_eq!(s.value, 32);
+            },
+            _ => unreachable!(),
+        }
+
+        match Path::<(String, u8), _>::from_request(&req).poll().unwrap() {
+            Async::Ready(s) => {
+                assert_eq!(s.0, "name");
+                assert_eq!(s.1, 32);
+            },
+            _ => unreachable!(),
+        }
     }
 }

src/lib.rs

@@ -76,7 +76,7 @@ extern crate language_tags;
 extern crate rand;
 extern crate url;
 extern crate libc;
-extern crate serde;
+#[macro_use] extern crate serde;
 extern crate serde_json;
 extern crate serde_urlencoded;
 extern crate flate2;