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use std::collections::{BTreeMap, HashMap};
use dhall::semantics::{Hir, HirKind, Nir, NirKind};
use dhall::syntax::{Builtin, ExprKind, NumKind, Span};
use crate::{Deserialize, Error, Result, Sealed, Value};
/// A simple value of the kind that can be decoded with serde
#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) enum SimpleValue {
Num(NumKind),
Text(String),
Optional(Option<Box<SimpleValue>>),
List(Vec<SimpleValue>),
Record(BTreeMap<String, SimpleValue>),
Union(String, Option<Box<SimpleValue>>),
}
/// The type of a value that can be decoded by Serde, like `{ x: Bool, y: List Natural }`.
///
/// A `SimpleType` is used when deserializing values to ensure they are of the expected type.
/// Rather than letting `serde` handle potential type mismatches, this uses the type-checking
/// capabilities of Dhall to catch errors early and cleanly indicate in the user's code where the
/// mismatch happened.
///
/// You would typically not manipulate `SimpleType`s by hand but rather let Rust infer it for your
/// datatype using the [`StaticType`][TODO] trait, and methods that require it like
/// [`from_file_static_type`][TODO] and [`Options::static_type_annotation`][TODO]. If you need to supply a
/// `SimpleType` manually however, you can deserialize it like any other Dhall value using the
/// functions provided by this crate.
///
/// # Examples
///
/// ```rust
/// # fn main() -> serde_dhall::Result<()> {
/// use std::collections::HashMap;
/// use serde_dhall::SimpleType;
///
/// let ty: SimpleType =
/// serde_dhall::from_str("{ x: Natural, y: Natural }")?;
///
/// let mut map = HashMap::new();
/// map.insert("x".to_string(), SimpleType::Natural);
/// map.insert("y".to_string(), SimpleType::Natural);
/// assert_eq!(ty, SimpleType::Record(map));
/// # Ok(())
/// # }
/// ```
///
/// ```rust
/// # fn main() -> serde_dhall::Result<()> {
/// use serde_dhall::{SimpleType, StaticType};
///
/// #[derive(StaticType)]
/// struct Foo {
/// x: bool,
/// y: Vec<u64>,
/// }
///
/// let ty: SimpleType =
/// serde_dhall::from_str("{ x: Bool, y: List Natural }")?;
///
/// assert_eq!(ty, Foo::static_type());
/// # Ok(())
/// # }
/// ```
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum SimpleType {
/// Corresponds to the Dhall type `Bool`
Bool,
/// Corresponds to the Dhall type `Natural`
Natural,
/// Corresponds to the Dhall type `Integer`
Integer,
/// Corresponds to the Dhall type `Double`
Double,
/// Corresponds to the Dhall type `Text`
Text,
/// Corresponds to the Dhall type `Optional T`
Optional(Box<SimpleType>),
/// Corresponds to the Dhall type `List T`
List(Box<SimpleType>),
/// Corresponds to the Dhall type `{ x : T, y : U }`
Record(HashMap<String, SimpleType>),
/// Corresponds to the Dhall type `< x : T | y : U >`
Union(HashMap<String, Option<SimpleType>>),
}
impl SimpleValue {
pub(crate) fn from_nir(nir: &Nir) -> Option<Self> {
Some(match nir.kind() {
NirKind::Num(lit) => SimpleValue::Num(lit.clone()),
NirKind::TextLit(x) => SimpleValue::Text(
x.as_text()
.expect("Normal form should ensure the text is a string"),
),
NirKind::EmptyOptionalLit(_) => SimpleValue::Optional(None),
NirKind::NEOptionalLit(x) => {
SimpleValue::Optional(Some(Box::new(Self::from_nir(x)?)))
}
NirKind::EmptyListLit(_) => SimpleValue::List(vec![]),
NirKind::NEListLit(xs) => SimpleValue::List(
xs.iter().map(Self::from_nir).collect::<Option<_>>()?,
),
NirKind::RecordLit(kvs) => SimpleValue::Record(
kvs.iter()
.map(|(k, v)| Some((k.into(), Self::from_nir(v)?)))
.collect::<Option<_>>()?,
),
NirKind::UnionLit(field, x, _) => SimpleValue::Union(
field.into(),
Some(Box::new(Self::from_nir(x)?)),
),
NirKind::UnionConstructor(field, ty)
if ty.get(field).map(|f| f.is_some()) == Some(false) =>
{
SimpleValue::Union(field.into(), None)
}
_ => return None,
})
}
}
impl SimpleType {
pub(crate) fn from_nir(nir: &Nir) -> Option<Self> {
Some(match nir.kind() {
NirKind::BuiltinType(b) => match b {
Builtin::Bool => SimpleType::Bool,
Builtin::Natural => SimpleType::Natural,
Builtin::Integer => SimpleType::Integer,
Builtin::Double => SimpleType::Double,
Builtin::Text => SimpleType::Text,
_ => unreachable!(),
},
NirKind::OptionalType(t) => {
SimpleType::Optional(Box::new(Self::from_nir(t)?))
}
NirKind::ListType(t) => {
SimpleType::List(Box::new(Self::from_nir(t)?))
}
NirKind::RecordType(kts) => SimpleType::Record(
kts.iter()
.map(|(k, v)| Some((k.into(), Self::from_nir(v)?)))
.collect::<Option<_>>()?,
),
NirKind::UnionType(kts) => SimpleType::Union(
kts.iter()
.map(|(k, v)| {
Some((
k.into(),
v.as_ref()
.map(|v| Ok(Self::from_nir(v)?))
.transpose()?,
))
})
.collect::<Option<_>>()?,
),
_ => return None,
})
}
pub(crate) fn to_value(&self) -> Value {
Value {
hir: self.to_hir(),
as_simple_val: None,
as_simple_ty: Some(self.clone()),
}
}
pub(crate) fn to_hir(&self) -> Hir {
let hir = |k| Hir::new(HirKind::Expr(k), Span::Artificial);
hir(match self {
SimpleType::Bool => ExprKind::Builtin(Builtin::Bool),
SimpleType::Natural => ExprKind::Builtin(Builtin::Natural),
SimpleType::Integer => ExprKind::Builtin(Builtin::Integer),
SimpleType::Double => ExprKind::Builtin(Builtin::Double),
SimpleType::Text => ExprKind::Builtin(Builtin::Text),
SimpleType::Optional(t) => ExprKind::App(
hir(ExprKind::Builtin(Builtin::Optional)),
t.to_hir(),
),
SimpleType::List(t) => {
ExprKind::App(hir(ExprKind::Builtin(Builtin::List)), t.to_hir())
}
SimpleType::Record(kts) => ExprKind::RecordType(
kts.into_iter()
.map(|(k, t)| (k.as_str().into(), t.to_hir()))
.collect(),
),
SimpleType::Union(kts) => ExprKind::UnionType(
kts.into_iter()
.map(|(k, t)| {
(k.as_str().into(), t.as_ref().map(|t| t.to_hir()))
})
.collect(),
),
})
}
}
impl Sealed for SimpleValue {}
impl Deserialize for SimpleValue {
fn from_dhall(v: &Value) -> Result<Self> {
v.to_simple_value().ok_or_else(|| {
Error::Deserialize(format!(
"this cannot be deserialized into a simple type: {}",
v
))
})
}
}
impl Sealed for SimpleType {}
impl Deserialize for SimpleType {
fn from_dhall(v: &Value) -> Result<Self> {
v.to_simple_type().ok_or_else(|| {
Error::Deserialize(format!(
"this cannot be deserialized into a simple type: {}",
v
))
})
}
}
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