1 files changed, 445 insertions, 0 deletions
diff --git a/src/ser/mod.rs b/src/ser/mod.rs
new file mode 100644
index 0000000..387766d
--- /dev/null
+++ b/src/ser/mod.rs
@@ -0,0 +1,445 @@
+//! Serialization support for the `application/x-www-form-urlencoded` format.
+
+mod key;
+mod pair;
+mod value;
+
+use serde::ser;
+use std::borrow::Cow;
+use std::error;
+use std::fmt;
+use std::str;
+use url::form_urlencoded;
+
+/// A serializer for the `application/x-www-form-urlencoded` format.
+///
+/// * Supported top-level inputs are structs, maps and sequences of pairs,
+///   with or without a given length.
+///
+/// * Supported keys and values are integers, bytes (if convertible to strings),
+///   unit structs and unit variants.
+///
+/// * Newtype structs defer to their inner values.
+pub struct Serializer<T>(form_urlencoded::Serializer<T>)
+    where T: form_urlencoded::Target;
+
+/// Errors returned during serializing to `application/x-www-form-urlencoded`.
+#[derive(Clone, Debug)]
+pub enum Error {
+    Custom(Cow<'static, str>),
+    InvalidValue(Cow<'static, str>),
+    Utf8(str::Utf8Error),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        match *self {
+            Error::Custom(ref msg) => msg.fmt(f),
+            Error::InvalidValue(ref msg) => write!(f, "invalid value: {}", msg),
+            Error::Utf8(ref err) => write!(f, "invalid UTF-8: {}", err),
+        }
+    }
+}
+
+impl error::Error for Error {
+    fn description(&self) -> &str {
+        match *self {
+            Error::Custom(ref msg) => msg,
+            Error::InvalidValue(ref msg) => msg,
+            Error::Utf8(ref err) => error::Error::description(err),
+        }
+    }
+
+    /// The lower-level cause of this error, in the case of a `Utf8` error.
+    fn cause(&self) -> Option<&error::Error> {
+        match *self {
+            Error::Custom(_) | Error::InvalidValue(_) => None,
+            Error::Utf8(ref err) => Some(err),
+        }
+    }
+}
+
+impl ser::Error for Error {
+    fn custom<T: Into<String>>(msg: T) -> Self {
+        Error::Custom(msg.into().into())
+    }
+
+    fn invalid_value(msg: &str) -> Self {
+        Error::InvalidValue(String::from(msg).into())
+    }
+}
+
+/// State used when serializing sequences.
+pub struct SeqState(());
+
+/// State used when serializing tuples.
+pub struct TupleState(());
+
+/// State used when serializing tuple structs.
+pub struct TupleStructState(());
+
+/// State used when serializing tuple variants.
+pub struct TupleVariantState(());
+
+/// State used when serializing maps.
+pub struct MapState(Option<Cow<'static, str>>);
+
+/// State used when serializing structs.
+pub struct StructState(());
+
+/// State used when serializing struct variants.
+pub struct StructVariantState(());
+
+impl<Target: form_urlencoded::Target> ser::Serializer for Serializer<Target> {
+    type Error = Error;
+
+    /// State used when serializing sequences.
+    type SeqState = SeqState;
+
+    /// State used when serializing tuples.
+    type TupleState = TupleState;
+
+    /// State used when serializing tuple structs.
+    type TupleStructState = TupleStructState;
+
+    /// State used when serializing tuple variants.
+    type TupleVariantState = TupleVariantState;
+
+    /// State used when serializing maps.
+    type MapState = MapState;
+
+    /// State used when serializing structs.
+    type StructState = StructState;
+
+    /// State used when serializing struct variants.
+    type StructVariantState = StructVariantState;
+
+    /// Returns an error.
+    fn serialize_bool(&mut self, _v: bool) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_isize(&mut self, _v: isize) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_i8(&mut self, _v: i8) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_i16(&mut self, _v: i16) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_i32(&mut self, _v: i32) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_i64(&mut self, _v: i64) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_usize(&mut self, _v: usize) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_u8(&mut self, _v: u8) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_u16(&mut self, _v: u16) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_u32(&mut self, _v: u32) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_u64(&mut self, _v: u64) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_f32(&mut self, _v: f32) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_f64(&mut self, _v: f64) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_char(&mut self, _v: char) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_str(&mut self, _value: &str) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_bytes(&mut self, _value: &[u8]) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_unit(&mut self) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_unit_struct(
+            &mut self, _name: &'static str)
+            -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_unit_variant(
+            &mut self,
+            _name: &'static str,
+            _variant_index: usize,
+            _variant: &'static str)
+            -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Serializes the inner value, ignoring the newtype name.
+    fn serialize_newtype_struct<T>(
+            &mut self, _name: &'static str, value: T)
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        value.serialize(self)
+    }
+
+    /// Returns an error.
+    fn serialize_newtype_variant<T>(
+            &mut self,                                    
+            _name: &'static str,                                    
+            _variant_index: usize,                                    
+            _variant: &'static str,                                    
+            _value: T)                                    
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_none(&mut self) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_some<T>(&mut self, _value: T) -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        Err(Error::top_level())
+    }
+
+    /// Begins to serialize a sequence, given length (if any) is ignored.
+    fn serialize_seq(
+            &mut self, _len: Option<usize>)
+            -> Result<SeqState, Error> {
+        Ok(SeqState(()))
+    }
+
+    /// Serializes a sequence element.
+    fn serialize_seq_elt<T>(
+            &mut self, _state: &mut SeqState, value: T)
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        value.serialize(&mut pair::PairSerializer::new(&mut self.0))
+    }
+
+    /// Finishes serializing a sequence.
+    fn serialize_seq_end(&mut self, _state: SeqState) -> Result<(), Error> {
+        Ok(())
+    }
+
+    /// Begins to serialize a sequence, given length is ignored.
+    fn serialize_seq_fixed_size(
+            &mut self, _length: usize)
+            -> Result<SeqState, Error> {
+        Ok(SeqState(()))
+    }
+
+    /// Returns an error.
+    fn serialize_tuple(&mut self, _len: usize) -> Result<TupleState, Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_tuple_elt<T>(
+            &mut self, _state: &mut TupleState, _value: T)
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_tuple_end(&mut self, _state: TupleState) -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_tuple_struct(
+            &mut self, _name: &'static str, _len: usize)
+            -> Result<TupleStructState, Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_tuple_struct_elt<T>(
+            &mut self, _state: &mut TupleStructState, _value: T)
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_tuple_struct_end(
+            &mut self, _state: TupleStructState)
+            -> Result<(), Error>
+    {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_tuple_variant(
+            &mut self,
+            _name: &'static str,
+            _variant_index: usize,
+            _variant: &'static str,
+            _len: usize)
+            -> Result<TupleVariantState, Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_tuple_variant_elt<T>(
+            &mut self, _state: &mut TupleVariantState, _value: T)
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_tuple_variant_end(
+            &mut self, _state: TupleVariantState)
+            -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Begins to serialize a map, given length (if any) is ignored.
+    fn serialize_map(
+            &mut self, _len: Option<usize>)
+            -> Result<MapState, Error> {
+        Ok(MapState(None))
+    }
+
+    /// Serializes a map key.
+    fn serialize_map_key<T>(
+            &mut self, state: &mut MapState, key: T)
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        key.serialize(&mut key::MapKeySerializer::new(&mut state.0))
+    }
+
+    /// Serializes a map value.
+    fn serialize_map_value<T>(
+            &mut self, state: &mut MapState, value: T)
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        let mut value_serializer =
+            try!(value::ValueSerializer::new(&mut state.0, &mut self.0));
+        value.serialize(&mut value_serializer)
+    }
+
+    /// Finishes serializing a map.
+    fn serialize_map_end(&mut self, _state: MapState) -> Result<(), Error> {
+        Ok(())
+    }
+
+    /// Begins to serialize a struct, given length is ignored.
+    fn serialize_struct(
+            &mut self, _name: &'static str, _len: usize)
+            -> Result<StructState, Error> {
+        Ok(StructState(()))
+    }
+
+    /// Serializes a struct element.
+    fn serialize_struct_elt<T>(
+            &mut self,
+            _state: &mut StructState,
+            key: &'static str,
+            value: T)
+            -> Result<(), Error>
+        where T: ser::Serialize
+    {
+        let mut key = Some(key.into());
+        let mut value_serializer =
+            value::ValueSerializer::new(&mut key, &mut self.0).unwrap();
+        value.serialize(&mut value_serializer)
+    }
+
+    /// Finishes serializing a struct.
+    fn serialize_struct_end(&mut self, _state: StructState)
+                            -> Result<(), Error> {
+        Ok(())
+    }
+
+    /// Returns an error.
+    fn serialize_struct_variant(
+            &mut self,
+            _name: &'static str,
+            _variant_index: usize,
+            _variant: &'static str,
+            _len: usize)
+            -> Result<StructVariantState, Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_struct_variant_elt<T>(
+            &mut self,
+            _state: &mut StructVariantState,
+            _key: &'static str,
+            _value: T)
+            -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+
+    /// Returns an error.
+    fn serialize_struct_variant_end(
+            &mut self, _state: StructVariantState)
+            -> Result<(), Error> {
+        Err(Error::top_level())
+    }
+}
+
+impl Error {
+    fn top_level() -> Self {
+        Error::Custom(
+            "top-level serializer supports only maps and structs".into())
+    }
+}