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|
use dhall_core::*;
use itertools::*;
use serde_cbor::value::value as cbor;
use std::path::PathBuf;
use std::rc::Rc;
type ParsedExpr = Rc<Expr<X, Import>>;
#[derive(Debug)]
pub enum DecodeError {
CBORError(serde_cbor::error::Error),
WrongFormatError(String),
}
pub fn decode(data: &[u8]) -> Result<ParsedExpr, DecodeError> {
match serde_cbor::de::from_slice(data) {
Ok(v) => cbor_value_to_dhall(&v),
Err(e) => Err(DecodeError::CBORError(e)),
}
}
fn cbor_value_to_dhall(data: &cbor::Value) -> Result<ParsedExpr, DecodeError> {
use cbor::Value::*;
use dhall_core::{BinOp, Builtin, Const};
use Expr::*;
Ok(rc(match data {
String(s) => match Builtin::parse(s) {
Some(b) => Expr::Builtin(b),
None => match s.as_str() {
"True" => BoolLit(true),
"False" => BoolLit(false),
"Type" => Const(Const::Type),
"Kind" => Const(Const::Kind),
s => Var(V(Label::from(s), 0)),
},
},
U64(n) => Var(V(Label::from("_"), *n as usize)),
F64(x) => DoubleLit((*x).into()),
Bool(b) => BoolLit(*b),
Array(vec) => match vec.as_slice() {
[String(l), U64(n)] => {
let l = Label::from(l.as_str());
Var(V(l, *n as usize))
}
[U64(0), f, args..] => {
let f = cbor_value_to_dhall(&f)?;
let args = args
.iter()
.map(cbor_value_to_dhall)
.collect::<Result<Vec<_>, _>>()?;
App(f, args)
}
[U64(1), x, y] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
Lam(Label::from("_"), x, y)
}
[U64(1), String(l), x, y] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
let l = Label::from(l.as_str());
Lam(l, x, y)
}
[U64(2), x, y] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
Pi(Label::from("_"), x, y)
}
[U64(2), String(l), x, y] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
let l = Label::from(l.as_str());
Pi(l, x, y)
}
[U64(3), U64(n), x, y] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
use BinOp::*;
let op = match n {
0 => BoolOr,
1 => BoolAnd,
2 => BoolEQ,
3 => BoolNE,
4 => NaturalPlus,
5 => NaturalTimes,
6 => TextAppend,
7 => ListAppend,
8 => Combine,
9 => Prefer,
10 => CombineTypes,
11 => ImportAlt,
_ => {
Err(DecodeError::WrongFormatError("binop".to_owned()))?
}
};
BinOp(op, x, y)
}
[U64(4), t] => {
let t = cbor_value_to_dhall(&t)?;
EmptyListLit(t)
}
[U64(4), Null, rest..] => {
let rest = rest
.iter()
.map(cbor_value_to_dhall)
.collect::<Result<Vec<_>, _>>()?;
NEListLit(rest)
}
[U64(5), t] => {
let t = cbor_value_to_dhall(&t)?;
EmptyOptionalLit(t)
}
[U64(5), Null, x] => {
let x = cbor_value_to_dhall(&x)?;
NEOptionalLit(x)
}
[U64(5), t, x] => {
let x = cbor_value_to_dhall(&x)?;
let t = cbor_value_to_dhall(&t)?;
Annot(rc(NEOptionalLit(x)), t)
}
[U64(6), x, y] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
Merge(x, y, None)
}
[U64(6), x, y, z] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
let z = cbor_value_to_dhall(&z)?;
Merge(x, y, Some(z))
}
[U64(7), Object(map)] => {
let map = cbor_map_to_dhall_map(map)?;
RecordType(map)
}
[U64(8), Object(map)] => {
let map = cbor_map_to_dhall_map(map)?;
RecordLit(map)
}
[U64(9), x, String(l)] => {
let x = cbor_value_to_dhall(&x)?;
let l = Label::from(l.as_str());
Field(x, l)
}
[U64(11), Object(map)] => {
let map = cbor_map_to_dhall_map(map)?;
UnionType(map)
}
[U64(12), String(l), x, Object(map)] => {
let map = cbor_map_to_dhall_map(map)?;
let x = cbor_value_to_dhall(&x)?;
let l = Label::from(l.as_str());
UnionLit(l, x, map)
}
[U64(14), x, y, z] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
let z = cbor_value_to_dhall(&z)?;
BoolIf(x, y, z)
}
[U64(15), U64(x)] => NaturalLit(*x as Natural),
[U64(16), U64(x)] => IntegerLit(*x as Integer),
[U64(16), I64(x)] => IntegerLit(*x as Integer),
[U64(18), String(first), rest..] => {
TextLit(InterpolatedText::from((
first.clone(),
rest.iter()
.tuples()
.map(|(x, y)| {
let x = cbor_value_to_dhall(&x)?;
let y = match y {
String(s) => s.clone(),
_ => Err(DecodeError::WrongFormatError(
"text".to_owned(),
))?,
};
Ok((x, y))
})
.collect::<Result<_, _>>()?,
)))
}
[U64(24), Null, U64(0), U64(3), rest..] => {
let mut path = PathBuf::new();
for s in rest {
match s {
String(s) => path.push(s),
_ => Err(DecodeError::WrongFormatError)?,
}
}
Embed(Import {
mode: ImportMode::Code,
hash: None,
location: ImportLocation::Local(FilePrefix::Here, path),
})
}
[U64(25), bindings..] => {
let mut tuples = bindings.iter().tuples();
let bindings = (&mut tuples)
.map(|(x, t, v)| {
let x = x.as_string().ok_or(
DecodeError::WrongFormatError(
"let/label".to_owned(),
),
)?;
let x = Label::from(x.as_str());
let t = match t {
Null => None,
t => Some(cbor_value_to_dhall(&t)?),
};
let v = cbor_value_to_dhall(&v)?;
Ok((x, t, v))
})
.collect::<Result<Vec<_>, _>>()?;
let expr = tuples.into_buffer().next().ok_or(
DecodeError::WrongFormatError("let/expr".to_owned()),
)?;
let expr = cbor_value_to_dhall(expr)?;
return Ok(bindings
.into_iter()
.fold(expr, |acc, (x, t, v)| rc(Let(x, t, v, acc))));
}
[U64(26), x, y] => {
let x = cbor_value_to_dhall(&x)?;
let y = cbor_value_to_dhall(&y)?;
Annot(x, y)
}
[U64(t), ..] => Err(DecodeError::WrongFormatError(format!(
"unknown tag: {}",
t
)))?,
_ => Err(DecodeError::WrongFormatError("array".to_owned()))?,
},
_ => Err(DecodeError::WrongFormatError("unknown type".to_owned()))?,
}))
}
fn cbor_map_to_dhall_map(
map: &std::collections::BTreeMap<cbor::ObjectKey, cbor::Value>,
) -> Result<std::collections::BTreeMap<Label, ParsedExpr>, DecodeError> {
map.iter()
.map(|(k, v)| -> Result<(_, _), _> {
let k = k
.as_string()
.ok_or(DecodeError::WrongFormatError("map/key".to_owned()))?;
let v = cbor_value_to_dhall(v)?;
Ok((Label::from(k.as_ref()), v))
})
.collect::<Result<_, _>>()
}
|
