extern crate nom;
extern crate exec_helpers;
use std::collections::HashMap;
use std::io::{Write, Read};
use std::fmt::{Display, Debug};
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum T {
// Unit
Unit,
// Boolean
N1(bool),
// Naturals
N3(u8),
N6(u64),
N7(u128),
// Integers
I3(i8),
I6(i64),
I7(i128),
// Text
// TODO: make into &str
Text(String),
// TODO: rename to Bytes
Binary(Vec<u8>),
// Tags
// TODO: make into &str
// TODO: rename to Tag
Sum(Tag<String, T>),
// TODO: make into &str
Record(HashMap<String, T>),
List(Vec<T>),
}
impl T {
pub fn to_u<'a>(&'a self) -> U<'a> {
match self {
T::Unit => U::Unit,
T::N1(b) => U::N1(*b),
T::N3(u) => U::N3(*u),
T::N6(u) => U::N6(*u),
T::N7(u) => U::N7(*u),
T::I3(i) => U::I3(*i),
T::I6(i) => U::I6(*i),
T::I7(i) => U::I7(*i),
T::Text(t) => U::Text(t.as_str()),
T::Binary(v) => U::Binary(v),
T::Sum(Tag { tag, val }) => U::Sum(
Tag { tag: tag.as_str(), val: Box::new(val.to_u()) }
),
T::Record(map) => U::Record(
map.iter().map(|(k, v)| (k.as_str(), v.to_u())).collect()
),
T::List(l) => U::List(
l.iter().map(|v| v.to_u()).collect::<Vec<U<'a>>>()
),
}
}
pub fn encode<'a>(&'a self) -> Vec<u8> {
match self {
// TODO: don’t go via U, inefficient
o => o.to_u().encode()
}
}
}
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum U<'a> {
Unit,
// Boolean
N1(bool),
// Naturals
N3(u8),
N6(u64),
N7(u128),
// Integers
I3(i8),
I6(i64),
I7(i128),
// Text
Text(&'a str),
Binary(&'a [u8]),
// TODO: the U-recursion we do here means we can’t be breadth-lazy anymore
// like we originally planned; maybe we want to go `U<'a>` → `&'a [u8]` again?
// Tags
// TODO: rename to Tag
Sum(Tag<&'a str, U<'a>>),
Record(HashMap<&'a str, U<'a>>),
List(Vec<U<'a>>),
}
impl<'a> U<'a> {
pub fn encode(&self) -> Vec<u8> {
let mut c = std::io::Cursor::new(vec![]);
encode(&mut c, self);
c.into_inner()
}
pub fn to_t(&self) -> T {
match self {
U::Unit => T::Unit,
U::N1(b) => T::N1(*b),
U::N3(u) => T::N3(*u),
U::N6(u) => T::N6(*u),
U::N7(u) => T::N7(*u),
U::I3(i) => T::I3(*i),
U::I6(i) => T::I6(*i),
U::I7(i) => T::I7(*i),
U::Text(t) => T::Text((*t).to_owned()),
U::Binary(v) => T::Binary((*v).to_owned()),
U::Sum(Tag { tag, val }) => T::Sum(
Tag { tag: (*tag).to_owned(), val: Box::new(val.to_t()) }
),
U::Record(map) => T::Record(
map.iter().map(|(k, v)| ((*k).to_owned(), v.to_t())).collect::<HashMap<String, T>>()
),
U::List(l) => T::List(
l.iter().map(|v| v.to_t()).collect::<Vec<T>>()
),
}
}
}
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Tag<S, A> {
// TODO: make into &str
pub tag: S,
pub val: Box<A>
}
impl<S, A> Tag<S, A> {
fn map<F, B>(self, f: F) -> Tag<S, B>
where F: Fn(A) -> B {
Tag {
tag: self.tag,
val: Box::new(f(*self.val))
}
}
}
fn encode_tag<W: Write>(w: &mut W, tag: &str, val: &U) -> std::io::Result<()> {
write!(w, "<{}:{}|", tag.len(), tag)?;
encode(w, val)?;
Ok(())
}
pub fn encode<W: Write>(w: &mut W, u: &U) -> std::io::Result<()> {
match u {
U::Unit => write!(w, "u,"),
U::N1(b) => if *b { write!(w, "n1:1,") } else { write!(w, "n1:0,") },
U::N3(n) => write!(w, "n3:{},", n),
U::N6(n) => write!(w, "n6:{},", n),
U::N7(n) => write!(w, "n7:{},", n),
U::I3(i) => write!(w, "i3:{},", i),
U::I6(i) => write!(w, "i6:{},", i),
U::I7(i) => write!(w, "i7:{},", i),
U::Text(s) => {
write!(w, "t{}:", s.len());
w.write_all(s.as_bytes());
write!(w, ",")
}
U::Binary(s) => {
write!(w, "b{}:", s.len());
w.write_all(&s);
write!(w, ",")
},
U::Sum(Tag{tag, val}) => encode_tag(w, tag, val),
U::Record(m) => {
let mut c = std::io::Cursor::new(vec![]);
for (k, v) in m {
encode_tag(&mut c, k, v)?;
}
write!(w, "{{{}:", c.get_ref().len())?;
w.write_all(c.get_ref())?;
write!(w, "}}")
},
U::List(l) => {
let mut c = std::io::Cursor::new(vec![]);
for u in l {
encode(&mut c, u)?;
}
write!(w, "[{}:", c.get_ref().len())?;
w.write_all(c.get_ref())?;
write!(w, "]")
}
}
}
pub fn text(s: String) -> T {
T::Text(s)
}
pub fn u_from_stdin_or_die_user_error<'a>(prog_name: &'_ str, stdin_buf: &'a mut Vec<u8>) -> U<'a> {
std::io::stdin().lock().read_to_end(stdin_buf);
let u = match parse::u_u(stdin_buf) {
Ok((rest, u)) => match rest {
b"" => u,
_ => exec_helpers::die_user_error(prog_name, format!("stdin contained some soup after netencode value: {:?}", String::from_utf8_lossy(rest)))
},
Err(err) => exec_helpers::die_user_error(prog_name, format!("unable to parse netencode from stdin: {:?}", err))
};
u
}
pub mod parse {
use super::{T, Tag, U};
use std::str::FromStr;
use std::ops::Neg;
use std::collections::HashMap;
use nom::{IResult};
use nom::branch::{alt};
use nom::bytes::streaming::{tag, take};
use nom::character::streaming::{digit1, char};
use nom::sequence::{tuple};
use nom::combinator::{map, map_res, flat_map, map_parser, opt};
use nom::error::{context, ErrorKind, ParseError};
fn unit_t(s: &[u8]) -> IResult<&[u8], ()> {
let (s, _) = context("unit", tag("u,"))(s)?;
Ok((s, ()))
}
fn usize_t(s: &[u8]) -> IResult<&[u8], usize> {
context(
"usize",
map_res(
map_res(digit1, |n| std::str::from_utf8(n)),
|s| s.parse::<usize>())
)(s)
}
fn sized(begin: char, end: char) -> impl Fn(&[u8]) -> IResult<&[u8], &[u8]> {
move |s: &[u8]| {
// This is the point where we check the descriminator;
// if the beginning char does not match, we can immediately return.
let (s, _) = char(begin)(s)?;
let (s, (len, _)) = tuple((
usize_t,
char(':')
))(s)?;
let (s, (res, _)) = tuple((
take(len),
char(end)
))(s)?;
Ok((s, res))
}
}
fn uint_t<'a, I: FromStr + 'a>(t: &'static str) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], I> {
move |s: &'a [u8]| {
let (s, (_, _, int, _)) = tuple((
tag(t.as_bytes()),
char(':'),
map_res(
map_res(digit1, |n: &[u8]| std::str::from_utf8(n)),
|s| s.parse::<I>()
),
char(',')
))(s)?;
Ok((s, int))
}
}
fn bool_t<'a>() -> impl Fn(&'a [u8]) -> IResult<&'a [u8], bool> {
context("bool", alt((
map(tag("n1:0,"), |_| false),
map(tag("n1:1,"), |_| true),
)))
}
fn int_t<'a, I: FromStr + Neg<Output=I>>(t: &'static str) -> impl Fn(&'a [u8]) -> IResult<&[u8], I> {
context(
t,
move |s: &'a [u8]| {
let (s, (_, _, neg, int, _)) = tuple((
tag(t.as_bytes()),
char(':'),
opt(char('-')),
map_res(
map_res(digit1, |n: &[u8]| std::str::from_utf8(n)),
|s| s.parse::<I>()
),
char(',')
))(s)?;
let res = match neg {
Some(_) => -int,
None => int,
};
Ok((s, res))
}
)
}
fn tag_t(s: &[u8]) -> IResult<&[u8], Tag<String, T>> {
// recurses into the main parser
map(tag_g(t_t),
|Tag {tag, val}|
Tag {
tag: tag.to_string(),
val
})(s)
}
fn tag_g<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], Tag<&'a str, O>>
where
P: Fn(&'a [u8]) -> IResult<&'a [u8], O>
{
move |s: &[u8]| {
let (s, tag) = sized('<', '|')(s)?;
let (s, val) = inner(s)?;
Ok((s, Tag {
tag: std::str::from_utf8(tag)
.map_err(|_| nom::Err::Failure((s, ErrorKind::Char)))?,
val: Box::new(val)
}))
}
}
/// parse text scalar (`t5:hello,`)
fn text(s: &[u8]) -> IResult<&[u8], T> {
let (s, res) = text_g(s)?;
Ok((s, T::Text(res.to_string())))
}
fn text_g(s: &[u8]) -> IResult<&[u8], &str> {
let (s, res) = sized('t', ',')(s)?;
Ok((s,
std::str::from_utf8(res)
.map_err(|_| nom::Err::Failure((s, ErrorKind::Char)))?,
))
}
fn binary<'a>() -> impl Fn(&'a [u8]) -> IResult<&'a [u8], T> {
map(binary_g(), |b| T::Binary(b.to_owned()))
}
fn binary_g() -> impl Fn(&[u8]) -> IResult<&[u8], &[u8]> {
sized('b', ',')
}
fn list_t(s: &[u8]) -> IResult<&[u8], Vec<T>> {
list_g(t_t)(s)
}
/// Wrap the inner parser of an `many0`/`fold_many0`, so that the parser
/// is not called when the `s` is empty already, preventing it from
/// returning `Incomplete` on streaming parsing.
fn inner_no_empty_string<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], O>
where
O: Clone,
P: Fn(&'a [u8]) -> IResult<&'a [u8], O>,
{
move |s: &'a [u8]| {
if s.is_empty() {
// This is a bit hacky, `many0` considers the inside done
// when a parser returns `Err::Error`, ignoring the actual error content
Err(nom::Err::Error((s, nom::error::ErrorKind::Many0)))
} else {
inner(s)
}
}
}
fn list_g<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], Vec<O>>
where
O: Clone,
P: Fn(&'a [u8]) -> IResult<&'a [u8], O>,
{
map_parser(
sized('[', ']'),
nom::multi::many0(inner_no_empty_string(inner))
)
}
fn record_t<'a>(s: &'a [u8]) -> IResult<&'a [u8], HashMap<String, T>> {
let (s, r) = record_g(t_t)(s)?;
Ok((s,
r.into_iter()
.map(|(k, v)| (k.to_string(), v))
.collect::<HashMap<_,_>>()))
}
fn record_g<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], HashMap<&'a str, O>>
where
O: Clone,
P: Fn(&'a [u8]) -> IResult<&'a [u8], O>
{
move |s: &'a [u8]| {
let (s, map) = map_parser(
sized('{', '}'),
nom::multi::fold_many0(
inner_no_empty_string(tag_g(&inner)),
HashMap::new(),
|mut acc: HashMap<_,_>, Tag { tag, mut val }| {
// ignore duplicated tag names that appear later
// according to netencode spec
if ! acc.contains_key(tag) {
acc.insert(tag, *val);
}
acc
}
)
)(s)?;
if map.is_empty() {
// records must not be empty, according to the spec
Err(nom::Err::Failure((s,nom::error::ErrorKind::Many1)))
} else {
Ok((s, map))
}
}
}
pub fn u_u(s: &[u8]) -> IResult<&[u8], U> {
alt((
map(text_g, U::Text),
map(binary_g(), U::Binary),
map(unit_t, |()| U::Unit),
map(tag_g(u_u), |t| U::Sum(t)),
map(list_g(u_u), U::List),
map(record_g(u_u), U::Record),
map(bool_t(), |u| U::N1(u)),
map(uint_t("n3"), |u| U::N3(u)),
map(uint_t("n6"), |u| U::N6(u)),
map(uint_t("n7"), |u| U::N7(u)),
map(int_t("i3"), |u| U::I3(u)),
map(int_t("i6"), |u| U::I6(u)),
map(int_t("i7"), |u| U::I7(u)),
// less common
map(uint_t("n2"), |u| U::N3(u)),
map(uint_t("n4"), |u| U::N6(u)),
map(uint_t("n5"), |u| U::N6(u)),
map(int_t("i1"), |u| U::I3(u)),
map(int_t("i2"), |u| U::I3(u)),
map(int_t("i4"), |u| U::I6(u)),
map(int_t("i5"), |u| U::I6(u)),
// TODO: 8, 9 not supported
))(s)
}
pub fn t_t(s: &[u8]) -> IResult<&[u8], T> {
alt((
text,
binary(),
map(unit_t, |_| T::Unit),
map(tag_t, |t| T::Sum(t)),
map(list_t, |l| T::List(l)),
map(record_t, |p| T::Record(p)),
map(bool_t(), |u| T::N1(u)),
// 8, 64 and 128 bit
map(uint_t("n3"), |u| T::N3(u)),
map(uint_t("n6"), |u| T::N6(u)),
map(uint_t("n7"), |u| T::N7(u)),
map(int_t("i3"), |u| T::I3(u)),
map(int_t("i6"), |u| T::I6(u)),
map(int_t("i7"), |u| T::I7(u)),
// less common
map(uint_t("n2"), |u| T::N3(u)),
map(uint_t("n4"), |u| T::N6(u)),
map(uint_t("n5"), |u| T::N6(u)),
map(int_t("i1"), |u| T::I3(u)),
map(int_t("i2"), |u| T::I3(u)),
map(int_t("i4"), |u| T::I6(u)),
map(int_t("i5"), |u| T::I6(u)),
// TODO: 8, 9 not supported
))(s)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_parse_unit_t() {
assert_eq!(
unit_t("u,".as_bytes()),
Ok(("".as_bytes(), ()))
);
}
#[test]
fn test_parse_bool_t() {
assert_eq!(
bool_t()("n1:0,".as_bytes()),
Ok(("".as_bytes(), false))
);
assert_eq!(
bool_t()("n1:1,".as_bytes()),
Ok(("".as_bytes(), true))
);
}
#[test]
fn test_parse_usize_t() {
assert_eq!(
usize_t("32foo".as_bytes()),
Ok(("foo".as_bytes(), 32))
);
}
#[test]
fn test_parse_int_t() {
assert_eq!(
uint_t::<u8>("n3")("n3:42,abc".as_bytes()),
Ok(("abc".as_bytes(), 42))
);
assert_eq!(
uint_t::<u8>("n3")("n3:1024,abc".as_bytes()),
Err(nom::Err::Error(("1024,abc".as_bytes(), nom::error::ErrorKind::MapRes)))
);
assert_eq!(
int_t::<i64>("i6")("i6:-23,abc".as_bytes()),
Ok(("abc".as_bytes(), -23))
);
assert_eq!(
int_t::<i128>("i3")("i3:0,:abc".as_bytes()),
Ok((":abc".as_bytes(), 0))
);
assert_eq!(
uint_t::<u8>("n7")("n7:09,".as_bytes()),
Ok(("".as_bytes(), 9))
);
// assert_eq!(
// length("c"),
// Err(nom::Err::Error(("c", nom::error::ErrorKind::Digit)))
// );
// assert_eq!(
// length(":"),
// Err(nom::Err::Error((":", nom::error::ErrorKind::Digit)))
// );
}
#[test]
fn test_parse_text() {
assert_eq!(
text("t5:hello,".as_bytes()),
Ok(("".as_bytes(), T::Text("hello".to_owned()))),
"{}", r"t5:hello,"
);
assert_eq!(
text("t4:fo".as_bytes()),
// The content of the text should be 4 long
Err(nom::Err::Incomplete(nom::Needed::Size(4))),
"{}", r"t4:fo,"
);
assert_eq!(
text("t9:今日は,".as_bytes()),
Ok(("".as_bytes(), T::Text("今日は".to_owned()))),
"{}", r"t9:今日は,"
);
}
#[test]
fn test_parse_binary() {
assert_eq!(
binary()("b5:hello,".as_bytes()),
Ok(("".as_bytes(), T::Binary(Vec::from("hello".to_owned())))),
"{}", r"b5:hello,"
);
assert_eq!(
binary()("b4:fo".as_bytes()),
// The content of the byte should be 4 long
Err(nom::Err::Incomplete(nom::Needed::Size(4))),
"{}", r"b4:fo,"
);
assert_eq!(
binary()("b4:foob".as_bytes()),
// The content is 4 bytes now, but the finishing , is missing
Err(nom::Err::Incomplete(nom::Needed::Size(1))),
"{}", r"b4:fo,"
);
assert_eq!(
binary()("b9:今日は,".as_bytes()),
Ok(("".as_bytes(), T::Binary(Vec::from("今日は".as_bytes())))),
"{}", r"b9:今日は,"
);
}
#[test]
fn test_list() {
assert_eq!(
list_t("[0:]".as_bytes()),
Ok(("".as_bytes(), vec![])),
"{}", r"[0:]"
);
assert_eq!(
list_t("[6:u,u,u,]".as_bytes()),
Ok(("".as_bytes(), vec![
T::Unit,
T::Unit,
T::Unit,
])),
"{}", r"[6:u,u,u,]"
);
assert_eq!(
list_t("[15:u,[7:t3:foo,]u,]".as_bytes()),
Ok(("".as_bytes(), vec![
T::Unit,
T::List(vec![T::Text("foo".to_owned())]),
T::Unit,
])),
"{}", r"[15:u,[7:t3:foo,]u,]"
);
}
#[test]
fn test_record() {
assert_eq!(
record_t("{21:<1:a|u,<1:b|u,<1:c|u,}".as_bytes()),
Ok(("".as_bytes(), vec![
("a".to_owned(), T::Unit),
("b".to_owned(), T::Unit),
("c".to_owned(), T::Unit),
].into_iter().collect::<HashMap<String, T>>())),
"{}", r"{21:<1:a|u,<1:b|u,<1:c|u,}"
);
// duplicated keys are ignored (first is taken)
assert_eq!(
record_t("{25:<1:a|u,<1:b|u,<1:a|i1:-1,}".as_bytes()),
Ok(("".as_bytes(), vec![
("a".to_owned(), T::Unit),
("b".to_owned(), T::Unit),
].into_iter().collect::<HashMap<_,_>>())),
"{}", r"{25:<1:a|u,<1:b|u,<1:a|i1:-1,}"
);
// empty records are not allowed
assert_eq!(
record_t("{0:}".as_bytes()),
Err(nom::Err::Failure(("".as_bytes(), nom::error::ErrorKind::Many1))),
"{}", r"{0:}"
);
}
#[test]
fn test_parse() {
assert_eq!(
t_t("n3:255,".as_bytes()),
Ok(("".as_bytes(), T::N3(255))),
"{}", r"n3:255,"
);
assert_eq!(
t_t("t6:halloo,".as_bytes()),
Ok(("".as_bytes(), T::Text("halloo".to_owned()))),
"{}", r"t6:halloo,"
);
assert_eq!(
t_t("<3:foo|t6:halloo,".as_bytes()),
Ok(("".as_bytes(), T::Sum (Tag {
tag: "foo".to_owned(),
val: Box::new(T::Text("halloo".to_owned()))
}))),
"{}", r"<3:foo|t6:halloo,"
);
// { a: Unit
// , foo: List <A: Unit | B: List i3> }
assert_eq!(
t_t("{52:<1:a|u,<3:foo|[33:<1:A|u,<1:A|n1:1,<1:B|[7:i3:127,]]}".as_bytes()),
Ok(("".as_bytes(), T::Record(vec![
("a".to_owned(), T::Unit),
("foo".to_owned(), T::List(vec![
T::Sum(Tag { tag: "A".to_owned(), val: Box::new(T::Unit) }),
T::Sum(Tag { tag: "A".to_owned(), val: Box::new(T::N1(true)) }),
T::Sum(Tag { tag: "B".to_owned(), val: Box::new(T::List(vec![T::I3(127)])) }),
]))
].into_iter().collect::<HashMap<String, T>>()))),
"{}", r"{52:<1:a|u,<3:foo|[33:<1:A|u,<1:A|n1:1,<1:B|[7:i3:127,]]}"
);
}
}
}
pub mod dec {
use super::*;
use std::collections::HashMap;
pub struct DecodeError(pub String);
pub trait Decoder<'a> {
type A;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError>;
}
/// Any netencode, as `T`.
#[derive(Clone, Copy)]
pub struct AnyT;
/// Any netencode, as `U`.
#[derive(Clone, Copy)]
pub struct AnyU;
impl<'a> Decoder<'a> for AnyT {
type A = T;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
Ok(u.to_t())
}
}
impl<'a> Decoder<'a> for AnyU {
type A = U<'a>;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
Ok(u)
}
}
/// A text
#[derive(Clone, Copy)]
pub struct Text;
/// A bytestring
// TODO: rename to Bytes
#[derive(Clone, Copy)]
pub struct Binary;
impl<'a> Decoder<'a> for Text {
type A = &'a str;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match u {
U::Text(t) => Ok(t),
other => Err(DecodeError(format!("Cannot decode {:?} into Text", other))),
}
}
}
impl<'a> Decoder<'a> for Binary {
type A = &'a [u8];
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match u {
U::Binary(b) => Ok(b),
other => Err(DecodeError(format!("Cannot decode {:?} into Binary", other))),
}
}
}
/// Any scalar, converted to bytes.
#[derive(Clone, Copy)]
pub struct ScalarAsBytes;
impl<'a> Decoder<'a> for ScalarAsBytes {
type A = Vec<u8>;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match u {
U::N3(u) => Ok(format!("{}", u).into_bytes()),
U::N6(u) => Ok(format!("{}", u).into_bytes()),
U::N7(u) => Ok(format!("{}", u).into_bytes()),
U::I3(i) => Ok(format!("{}", i).into_bytes()),
U::I6(i) => Ok(format!("{}", i).into_bytes()),
U::I7(i) => Ok(format!("{}", i).into_bytes()),
U::Text(t) => Ok(t.as_bytes().to_owned()),
U::Binary(b) => Ok(b.to_owned()),
o => Err(DecodeError(format!("Cannot decode {:?} into scalar", o))),
}
}
}
/// A map of Ts (TODO: rename to map)
#[derive(Clone, Copy)]
pub struct Record<T>(pub T);
impl<'a, Inner> Decoder<'a> for Record<Inner>
where Inner: Decoder<'a>
{
type A = HashMap<&'a str, Inner::A>;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match u {
U::Record(map) =>
map.into_iter()
.map(|(k, v)| self.0.dec(v).map(|v2| (k, v2)))
.collect::<Result<Self::A, _>>(),
o => Err(DecodeError(format!("Cannot decode {:?} into record", o)))
}
}
}
/// Assume a record and project out the field with the given name and type.
#[derive(Clone, Copy)]
pub struct RecordDot<'a, T> {
pub field: &'a str,
pub inner: T
}
impl <'a, Inner> Decoder<'a> for RecordDot<'_, Inner>
where Inner: Decoder<'a> + Clone
{
type A = Inner::A;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match Record(self.inner.clone()).dec(u) {
Ok(mut map) => match map.remove(self.field) {
Some(inner) => Ok(inner),
None => Err(DecodeError(format!("Cannot find `{}` in record map", self.field))),
},
Err(err) => Err(err),
}
}
}
/// Equals one of the listed `A`s exactly, after decoding.
#[derive(Clone)]
pub struct OneOf<T, A>{
pub inner: T,
pub list: Vec<A>,
}
impl <'a, Inner> Decoder<'a> for OneOf<Inner, Inner::A>
where Inner: Decoder<'a>,
Inner::A: Display + Debug + PartialEq
{
type A = Inner::A;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match self.inner.dec(u) {
Ok(inner) => match self.list.iter().any(|x| x.eq(&inner)) {
true => Ok(inner),
false => Err(DecodeError(format!("{} is not one of {:?}", inner, self.list)))
},
Err(err) => Err(err)
}
}
}
/// Try decoding as `T`.
#[derive(Clone)]
pub struct Try<T>(pub T);
impl <'a, Inner> Decoder<'a> for Try<Inner>
where Inner: Decoder<'a>
{
type A = Option<Inner::A>;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match self.0.dec(u) {
Ok(inner) => Ok(Some(inner)),
Err(err) => Ok(None)
}
}
}
}
