serde/bench_struct.rs

use collections::HashMap;
use test::Bencher;

use serialize::{Decoder, Decodable};

use de::{Deserializer, Deserializable};

//////////////////////////////////////////////////////////////////////////////

#[deriving(Clone, Eq, Show, Decodable)]
struct Inner {
    a: (),
    b: uint,
    c: HashMap<StrBuf, Option<char>>,
}

impl<E, D: Deserializer<E>> Deserializable<E, D> for Inner {
    #[inline]
    fn deserialize(d: &mut D) -> Result<Inner, E> {
        try!(d.expect_struct_start("Inner"));
        let a = try!(d.expect_struct_field("a"));
        let b = try!(d.expect_struct_field("b"));
        let c = try!(d.expect_struct_field("c"));
        try!(d.expect_end());
        Ok(Inner { a: a, b: b, c: c })
    }
}

//////////////////////////////////////////////////////////////////////////////

#[deriving(Clone, Eq, Show, Decodable)]
struct Outer {
    inner: Vec<Inner>,
}

impl<E, D: Deserializer<E>> Deserializable<E, D> for Outer {
    #[inline]
    fn deserialize(d: &mut D) -> Result<Outer, E> {
        try!(d.expect_struct_start("Outer"));
        let inner = try!(d.expect_struct_field("inner"));
        try!(d.expect_end());
        Ok(Outer { inner: inner })
    }
}

//////////////////////////////////////////////////////////////////////////////

#[deriving(Show)]
enum Error {
    EndOfStream,
    SyntaxError,
}

mod decoder {
    use collections::HashMap;
    use serialize::Decoder;

    use super::{Outer, Inner, Error, SyntaxError};

    #[deriving(Show)]
    enum State {
        OuterState(Outer),
        InnerState(Inner),
        NullState,
        UintState(uint),
        CharState(char),
        StrState(StrBuf),
        FieldState(&'static str),
        VecState(Vec<Inner>),
        MapState(HashMap<StrBuf, Option<char>>),
        OptionState(bool),
    }

    pub struct OuterDecoder {
        stack: Vec<State>,

    }

    impl OuterDecoder {
        #[inline]
        pub fn new(animal: Outer) -> OuterDecoder {
            OuterDecoder {
                stack: vec!(OuterState(animal)),
            }
        }
    }

    impl Decoder<Error> for OuterDecoder {
        // Primitive types:
        #[inline]
        fn read_nil(&mut self) -> Result<(), Error> {
            match self.stack.pop() {
                Some(NullState) => Ok(()),
                _ => Err(SyntaxError),
            }
        }
        #[inline]
        fn read_uint(&mut self) -> Result<uint, Error> {
            match self.stack.pop() {
                Some(UintState(value)) => Ok(value),
                _ => Err(SyntaxError),
            }
        }
        fn read_u64(&mut self) -> Result<u64, Error> { Err(SyntaxError) }
        fn read_u32(&mut self) -> Result<u32, Error> { Err(SyntaxError) }
        fn read_u16(&mut self) -> Result<u16, Error> { Err(SyntaxError) }
        fn read_u8(&mut self) -> Result<u8, Error> { Err(SyntaxError) }
        fn read_int(&mut self) -> Result<int, Error> { Err(SyntaxError) }
        fn read_i64(&mut self) -> Result<i64, Error> { Err(SyntaxError) }
        fn read_i32(&mut self) -> Result<i32, Error> { Err(SyntaxError) }
        fn read_i16(&mut self) -> Result<i16, Error> { Err(SyntaxError) }
        fn read_i8(&mut self) -> Result<i8, Error> { Err(SyntaxError) }
        fn read_bool(&mut self) -> Result<bool, Error> { Err(SyntaxError) }
        fn read_f64(&mut self) -> Result<f64, Error> { Err(SyntaxError) }
        fn read_f32(&mut self) -> Result<f32, Error> { Err(SyntaxError) }
        #[inline]
        fn read_char(&mut self) -> Result<char, Error> {
            match self.stack.pop() {
                Some(CharState(c)) => Ok(c),
                _ => Err(SyntaxError),
            }
        }
        #[inline]
        fn read_str(&mut self) -> Result<StrBuf, Error> {
            match self.stack.pop() {
                Some(StrState(value)) => Ok(value),
                _ => Err(SyntaxError),
            }
        }

        // Compound types:
        fn read_enum<T>(&mut self, _name: &str, _f: |&mut OuterDecoder| -> Result<T, Error>) -> Result<T, Error> { Err(SyntaxError) }

        fn read_enum_variant<T>(&mut self,
                                _names: &[&str],
                                _f: |&mut OuterDecoder, uint| -> Result<T, Error>)
                                -> Result<T, Error> { Err(SyntaxError) }
        fn read_enum_variant_arg<T>(&mut self,
                                    _a_idx: uint,
                                    _f: |&mut OuterDecoder| -> Result<T, Error>)
                                    -> Result<T, Error> { Err(SyntaxError) }

        fn read_enum_struct_variant<T>(&mut self,
                                       _names: &[&str],
                                       _f: |&mut OuterDecoder, uint| -> Result<T, Error>)
                                       -> Result<T, Error> { Err(SyntaxError) }
        fn read_enum_struct_variant_field<T>(&mut self,
                                             _f_name: &str,
                                             _f_idx: uint,
                                             _f: |&mut OuterDecoder| -> Result<T, Error>)
                                             -> Result<T, Error> { Err(SyntaxError) }

        #[inline]
        fn read_struct<T>(&mut self, s_name: &str, _len: uint, f: |&mut OuterDecoder| -> Result<T, Error>) -> Result<T, Error> {
            match self.stack.pop() {
                Some(OuterState(Outer { inner: inner })) => {
                    if s_name == "Outer" {
                        self.stack.push(VecState(inner));
                        self.stack.push(FieldState("inner"));
                        f(self)
                    } else {
                        Err(SyntaxError)
                    }
                }
                Some(InnerState(Inner { a: (), b: b, c: c })) => {
                    if s_name == "Inner" {
                        self.stack.push(MapState(c));
                        self.stack.push(FieldState("c"));

                        self.stack.push(UintState(b));
                        self.stack.push(FieldState("b"));

                        self.stack.push(NullState);
                        self.stack.push(FieldState("a"));
                        f(self)
                    } else {
                        Err(SyntaxError)
                    }
                }
                _ => Err(SyntaxError),
            }
        }
        #[inline]
        fn read_struct_field<T>(&mut self, f_name: &str, _f_idx: uint, f: |&mut OuterDecoder| -> Result<T, Error>) -> Result<T, Error> {
            match self.stack.pop() {
                Some(FieldState(name)) => {
                    if f_name == name {
                        f(self)
                    } else {
                        Err(SyntaxError)
                    }
                }
                _ => Err(SyntaxError)
            }
        }

        fn read_tuple<T>(&mut self, _f: |&mut OuterDecoder, uint| -> Result<T, Error>) -> Result<T, Error> { Err(SyntaxError) }
        fn read_tuple_arg<T>(&mut self, _a_idx: uint, _f: |&mut OuterDecoder| -> Result<T, Error>) -> Result<T, Error> { Err(SyntaxError) }

        fn read_tuple_struct<T>(&mut self,
                                _s_name: &str,
                                _f: |&mut OuterDecoder, uint| -> Result<T, Error>)
                                -> Result<T, Error> { Err(SyntaxError) }
        fn read_tuple_struct_arg<T>(&mut self,
                                    _a_idx: uint,
                                    _f: |&mut OuterDecoder| -> Result<T, Error>)
                                    -> Result<T, Error> { Err(SyntaxError) }

        // Specialized types:
        #[inline]
        fn read_option<T>(&mut self, f: |&mut OuterDecoder, bool| -> Result<T, Error>) -> Result<T, Error> {
            match self.stack.pop() {
                Some(OptionState(b)) => f(self, b),
                _ => Err(SyntaxError),
            }
        }

        #[inline]
        fn read_seq<T>(&mut self, f: |&mut OuterDecoder, uint| -> Result<T, Error>) -> Result<T, Error> {
            match self.stack.pop() {
                Some(VecState(value)) => {
                    let len = value.len();
                    for inner in value.move_iter().rev() {
                        self.stack.push(InnerState(inner));
                    }
                    f(self, len)
                }
                _ => Err(SyntaxError)
            }
        }
        #[inline]
        fn read_seq_elt<T>(&mut self, _idx: uint, f: |&mut OuterDecoder| -> Result<T, Error>) -> Result<T, Error> {
            f(self)
        }

        #[inline]
        fn read_map<T>(&mut self, f: |&mut OuterDecoder, uint| -> Result<T, Error>) -> Result<T, Error> {
            match self.stack.pop() {
                Some(MapState(map)) => {
                    let len = map.len();
                    for (key, value) in map.move_iter() {
                        match value {
                            Some(c) => {
                                self.stack.push(CharState(c));
                                self.stack.push(OptionState(true));
                            }
                            None => {
                                self.stack.push(OptionState(false));
                            }
                        }
                        self.stack.push(StrState(key));
                    }
                    f(self, len)
                }
                _ => Err(SyntaxError),
            }
        }
        #[inline]
        fn read_map_elt_key<T>(&mut self, _idx: uint, f: |&mut OuterDecoder| -> Result<T, Error>) -> Result<T, Error> {
            f(self)
        }
        #[inline]
        fn read_map_elt_val<T>(&mut self, _idx: uint, f: |&mut OuterDecoder| -> Result<T, Error>) -> Result<T, Error> {
            f(self)
        }
    }
}

//////////////////////////////////////////////////////////////////////////////

mod deserializer {
    use super::{Outer, Inner, Error, EndOfStream, SyntaxError};
    use de::Deserializer;
    use de::{Token, Uint, Char, StrBuf, Null, TupleStart, StructStart, StructField, SeqStart, MapStart, Sep, End, Option};

    enum State {
        OuterState(Outer),
        InnerState(Inner),
        FieldState(&'static str),
        NullState,
        UintState(uint),
        CharState(char),
        StrState(StrBuf),
        OptionState(bool),
        TupleState(uint),
        VecState(uint),
        MapState(uint),
        SepState,
        EndState,

    }

    pub struct OuterDeserializer {
        stack: Vec<State>,
    }

    impl OuterDeserializer {
        #[inline]
        pub fn new(outer: Outer) -> OuterDeserializer {
            OuterDeserializer {
                stack: vec!(OuterState(outer)),
            }
        }
    }

    impl Iterator<Result<Token, Error>> for OuterDeserializer {
        #[inline]
        fn next(&mut self) -> Option<Result<Token, Error>> {
            match self.stack.last() {
                Some(&OuterState(_)) => {
                    outer_state(self)
                }
                Some(&InnerState(_)) => {
                    inner_state(self)
                }
                Some(&FieldState(_)) => {
                    field_state(self)
                }
                Some(&VecState(_)) => {
                    vec_state(self)
                }
                Some(&MapState(_)) => {
                    map_state(self)
                }
                Some(&TupleState(_)) => {
                    tuple_state(self)
                }
                Some(&SepState) => {
                    sep_state(self)
                }
                Some(&NullState) => {
                    null_state(self)
                }
                Some(&UintState(_)) => {
                    uint_state(self)
                }
                Some(&CharState(_)) => {
                    char_state(self)
                }
                Some(&StrState(_)) => {
                    strbuf_state(self)
                }
                Some(&OptionState(_)) => {
                    option_state(self)
                }
                Some(&EndState) => {
                    end_state(self)
                }
                None => None,
            }
        }
    }

    impl Deserializer<Error> for OuterDeserializer {
        #[inline]
        fn end_of_stream_error(&self) -> Error {
            EndOfStream
        }

        #[inline]
        fn syntax_error(&self) -> Error {
            SyntaxError
        }
    }

    fn outer_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        let inner = match d.stack.pop() {
            Some(OuterState(Outer { inner })) => inner,
            _ => { return Some(Err(d.syntax_error())); }
        };

        d.stack.push(EndState);

        d.stack.push(EndState);
        let len = inner.len();
        for v in inner.move_iter().rev() {
            d.stack.push(InnerState(v));
            d.stack.push(SepState);
        }
        d.stack.push(VecState(len));

        d.stack.push(FieldState("inner"));
        Some(Ok(StructStart("Outer")))
    }

    fn inner_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        let ((), b, c) = match d.stack.pop() {
            Some(InnerState(Inner { a, b, c })) => (a, b, c),
            _ => { return Some(Err(d.syntax_error())); }
        };

        d.stack.push(EndState);

        d.stack.push(EndState);
        let len = c.len();
        for (k, v) in c.move_iter() {
            d.stack.push(EndState);
            match v {
                Some(c) => {
                    d.stack.push(CharState(c));
                    d.stack.push(OptionState(true));
                }
                None => {
                    d.stack.push(OptionState(false));
                }
            }
            d.stack.push(SepState);

            d.stack.push(StrState(k));
            d.stack.push(SepState);
            d.stack.push(TupleState(2));

            d.stack.push(SepState);
        }
        d.stack.push(MapState(len));

        d.stack.push(FieldState("c"));

        d.stack.push(UintState(b));
        d.stack.push(FieldState("b"));

        d.stack.push(NullState);
        d.stack.push(FieldState("a"));
        Some(Ok(StructStart("Inner")))
    }

    fn field_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(FieldState(name)) => Some(Ok(StructField(name))),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn vec_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(VecState(len)) => Some(Ok(SeqStart(len))),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn map_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(MapState(len)) => Some(Ok(MapStart(len))),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn tuple_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(TupleState(len)) => Some(Ok(TupleStart(len))),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn sep_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(SepState) => Some(Ok(Sep)),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn null_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(NullState) => Some(Ok(Null)),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn uint_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(UintState(x)) => Some(Ok(Uint(x))),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn char_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(CharState(x)) => Some(Ok(Char(x))),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn strbuf_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(StrState(x)) => Some(Ok(StrBuf(x))),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn option_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(OptionState(x)) => Some(Ok(Option(x))),
            _ => Some(Err(d.syntax_error())),
        }
    }

    fn end_state(d: &mut OuterDeserializer) -> Option<Result<Token, Error>> {
        match d.stack.pop() {
            Some(EndState) => Some(Ok(End)),
            _ => Some(Err(d.syntax_error())),
        }
    }
}

#[bench]
fn bench_struct_decoder(b: &mut Bencher) {
    b.iter(|| {
        let mut map = HashMap::new();
        map.insert("abc".to_strbuf(), Some('c'));

        let outer = Outer {
            inner: vec!(
                Inner {
                    a: (),
                    b: 5,
                    c: map,
                },
            )
        };

        let mut d = decoder::OuterDecoder::new(outer.clone());
        let value: Outer = Decodable::decode(&mut d).unwrap();

        assert_eq!(value, outer);
    })
}

#[bench]
fn bench_struct_deserializer(b: &mut Bencher) {
    b.iter(|| {
        let mut map = HashMap::new();
        map.insert("abc".to_strbuf(), Some('c'));

        let outer = Outer {
            inner: vec!(
                Inner {
                    a: (),
                    b: 5,
                    c: map,
                },
            )
        };

        let mut d = deserializer::OuterDeserializer::new(outer.clone());
        let value: Outer = Deserializable::deserialize(&mut d).unwrap();

        assert_eq!(value, outer);
    })
}