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authorNadrieril Feneanar2019-08-13 16:47:10 +0200
committerGitHub2019-08-13 16:47:10 +0200
commitfc6c42f9a80902f7183c297cd8f9dcdbe5376ec5 (patch)
tree48d04a37f15612fba2efb88c15149ed39731d96e /serde_dhall/src
parent7d17d39005531cb77d8eaf32ed7de8938c66f874 (diff)
parentbf5d33f3ba991afe398d58fb4fed38ec72d6f4c7 (diff)
Merge pull request #100 from Nadrieril/api
Rework API
Diffstat (limited to '')
-rw-r--r--serde_dhall/src/lib.rs301
-rw-r--r--serde_dhall/src/serde.rs (renamed from dhall/src/api/serde.rs)13
-rw-r--r--serde_dhall/src/static_type.rs (renamed from dhall/src/api/static_type.rs)26
3 files changed, 316 insertions, 24 deletions
diff --git a/serde_dhall/src/lib.rs b/serde_dhall/src/lib.rs
new file mode 100644
index 0000000..19aabec
--- /dev/null
+++ b/serde_dhall/src/lib.rs
@@ -0,0 +1,301 @@
+#![feature(non_exhaustive)]
+
+//! [Dhall][dhall] is a programmable configuration language that provides a non-repetitive
+//! alternative to JSON and YAML.
+//!
+//! You can think of Dhall as: JSON + types + imports + functions
+//!
+//! For a description of the Dhall language, examples, tutorials, and more, see the [language
+//! website][dhall].
+//!
+//! This crate provides support for consuming Dhall files the same way you would consume JSON or
+//! YAML. It uses the [Serde][serde] serialization library to provide drop-in support for Dhall
+//! for any datatype that supports serde (and that's a lot of them !).
+//!
+//! This library is limited to deserializing (reading) Dhall values; serializing (writing)
+//! values to Dhall is not supported for now.
+//!
+//! # Examples
+//!
+//! ### Custom datatype
+//!
+//! If you have a custom datatype for which you derived [serde::Deserialize], chances are
+//! you will be able to derive [StaticType] for it as well.
+//! This allows easy type-safe deserializing.
+//!
+//! ```edition2018
+//! use serde::Deserialize;
+//! use serde_dhall::{de::Error, StaticType};
+//!
+//! #[derive(Debug, Deserialize, StaticType)]
+//! struct Point {
+//! x: u64,
+//! y: u64,
+//! }
+//!
+//! fn main() -> Result<(), Error> {
+//! // Some Dhall data
+//! let data = "{ x = 1, y = 1 + 1 }";
+//!
+//! // Convert the Dhall string to a Point.
+//! let point: Point = serde_dhall::from_str_auto_type(data)?;
+//! assert_eq!(point.x, 1);
+//! assert_eq!(point.y, 2);
+//!
+//! // Invalid data fails the type validation
+//! let invalid_data = "{ x = 1, z = 0.3 }";
+//! assert!(serde_dhall::from_str_auto_type::<Point>(invalid_data).is_err());
+//!
+//! Ok(())
+//! }
+//! ```
+//!
+//! ### Loosely typed
+//!
+//! If you used to consume JSON or YAML in a loosely typed way, you can continue to do so
+//! with Dhall. You only need to replace [serde_json::from_str] or [serde_yaml::from_str]
+//! with [serde_dhall::from_str][from_str].
+//! More generally, if the [StaticType] derive doesn't suit your
+//! needs, you can still deserialize any valid Dhall file that serde can handle.
+//!
+//! [serde_json::from_str]: https://docs.serde.rs/serde_json/de/fn.from_str.html
+//! [serde_yaml::from_str]: https://docs.serde.rs/serde_yaml/fn.from_str.html
+//!
+//! ```edition2018
+//! # fn main() -> serde_dhall::de::Result<()> {
+//! use std::collections::BTreeMap;
+//!
+//! // Some Dhall data
+//! let data = "{ x = 1, y = 1 + 1 } : { x: Natural, y: Natural }";
+//!
+//! // Deserialize it to a Rust type.
+//! let deserialized_map: BTreeMap<String, usize> = serde_dhall::from_str(data)?;
+//!
+//! let mut expected_map = BTreeMap::new();
+//! expected_map.insert("x".to_string(), 1);
+//! expected_map.insert("y".to_string(), 2);
+//!
+//! assert_eq!(deserialized_map, expected_map);
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! You can alternatively specify a Dhall type that the input should match.
+//!
+//! ```edition2018
+//! # fn main() -> serde_dhall::de::Result<()> {
+//! use std::collections::BTreeMap;
+//!
+//! // Parse a Dhall type
+//! let point_type_str = "{ x: Natural, y: Natural }";
+//! let point_type = serde_dhall::from_str(point_type_str)?;
+//!
+//! // Some Dhall data
+//! let point_data = "{ x = 1, y = 1 + 1 }";
+//!
+//! // Deserialize the data to a Rust type. This ensures that
+//! // the data matches the point type.
+//! let deserialized_map: BTreeMap<String, usize> =
+//! serde_dhall::from_str_check_type(point_data, &point_type)?;
+//!
+//! let mut expected_map = BTreeMap::new();
+//! expected_map.insert("x".to_string(), 1);
+//! expected_map.insert("y".to_string(), 2);
+//!
+//! assert_eq!(deserialized_map, expected_map);
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! [dhall]: https://dhall-lang.org/
+//! [serde]: https://docs.serde.rs/serde/
+//! [serde::Deserialize]: https://docs.serde.rs/serde/trait.Deserialize.html
+
+mod serde;
+mod static_type;
+
+#[doc(inline)]
+pub use de::{from_str, from_str_auto_type, from_str_check_type};
+#[doc(hidden)]
+pub use dhall_proc_macros::StaticType;
+pub use static_type::StaticType;
+#[doc(inline)]
+pub use value::Value;
+
+// A Dhall value.
+pub mod value {
+ use dhall::core::thunk::{Thunk, TypeThunk};
+ use dhall::core::value::Value as DhallValue;
+ use dhall::phase::{NormalizedSubExpr, Parsed, Type, Typed};
+ use dhall_syntax::Builtin;
+
+ use super::de::{Error, Result};
+
+ /// A Dhall value
+ #[derive(Debug, Clone, PartialEq, Eq)]
+ pub struct Value(Typed);
+
+ impl Value {
+ pub fn from_str(s: &str, ty: Option<&Value>) -> Result<Self> {
+ Value::from_str_using_dhall_error_type(s, ty).map_err(Error::Dhall)
+ }
+ fn from_str_using_dhall_error_type(
+ s: &str,
+ ty: Option<&Value>,
+ ) -> dhall::error::Result<Self> {
+ let resolved = Parsed::parse_str(s)?.resolve()?;
+ let typed = match ty {
+ None => resolved.typecheck()?,
+ Some(t) => resolved.typecheck_with(&t.to_type())?,
+ };
+ Ok(Value(typed))
+ }
+ pub(crate) fn to_expr(&self) -> NormalizedSubExpr {
+ self.0.to_expr()
+ }
+ pub(crate) fn to_thunk(&self) -> Thunk {
+ self.0.to_thunk()
+ }
+ pub(crate) fn to_type(&self) -> Type {
+ self.0.to_type()
+ }
+
+ pub(crate) fn from_dhall_value(v: DhallValue) -> Self {
+ Value(Typed::from_value_untyped(v))
+ }
+ pub(crate) fn make_builtin_type(b: Builtin) -> Self {
+ Self::from_dhall_value(DhallValue::from_builtin(b))
+ }
+ pub(crate) fn make_optional_type(t: Value) -> Self {
+ Self::from_dhall_value(DhallValue::AppliedBuiltin(
+ Builtin::Optional,
+ vec![t.to_thunk()],
+ ))
+ }
+ pub(crate) fn make_list_type(t: Value) -> Self {
+ Self::from_dhall_value(DhallValue::AppliedBuiltin(
+ Builtin::List,
+ vec![t.to_thunk()],
+ ))
+ }
+ // Made public for the StaticType derive macro
+ #[doc(hidden)]
+ pub fn make_record_type(
+ kts: impl Iterator<Item = (String, Value)>,
+ ) -> Self {
+ Self::from_dhall_value(DhallValue::RecordType(
+ kts.map(|(k, t)| {
+ (k.into(), TypeThunk::from_thunk(t.to_thunk()))
+ })
+ .collect(),
+ ))
+ }
+ #[doc(hidden)]
+ pub fn make_union_type(
+ kts: impl Iterator<Item = (String, Option<Value>)>,
+ ) -> Self {
+ Self::from_dhall_value(DhallValue::UnionType(
+ kts.map(|(k, t)| {
+ (k.into(), t.map(|t| TypeThunk::from_thunk(t.to_thunk())))
+ })
+ .collect(),
+ ))
+ }
+ }
+
+ impl super::de::Deserialize for Value {
+ fn from_dhall(v: &Value) -> Result<Self> {
+ Ok(v.clone())
+ }
+ }
+}
+
+/// Deserialize Dhall data to a Rust data structure.
+pub mod de {
+ use super::StaticType;
+ use super::Value;
+ pub use error::{Error, Result};
+
+ mod error {
+ use dhall::error::Error as DhallError;
+
+ pub type Result<T> = std::result::Result<T, Error>;
+
+ #[derive(Debug)]
+ #[non_exhaustive]
+ pub enum Error {
+ Dhall(DhallError),
+ Deserialize(String),
+ }
+
+ impl std::fmt::Display for Error {
+ fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+ match self {
+ Error::Dhall(err) => write!(f, "{}", err),
+ Error::Deserialize(err) => write!(f, "{}", err),
+ }
+ }
+ }
+
+ impl std::error::Error for Error {}
+
+ impl serde::de::Error for Error {
+ fn custom<T>(msg: T) -> Self
+ where
+ T: std::fmt::Display,
+ {
+ Error::Deserialize(msg.to_string())
+ }
+ }
+ }
+
+ /// A data structure that can be deserialized from a Dhall expression
+ ///
+ /// This is automatically implemented for any type that [serde][serde]
+ /// can deserialize.
+ ///
+ /// This trait cannot be implemented manually.
+ // TODO: seal trait
+ pub trait Deserialize: Sized {
+ /// See [serde_dhall::from_str][crate::from_str]
+ fn from_dhall(v: &Value) -> Result<Self>;
+ }
+
+ /// Deserialize an instance of type `T` from a string of Dhall text.
+ ///
+ /// This will recursively resolve all imports in the expression, and
+ /// typecheck it before deserialization. Relative imports will be resolved relative to the
+ /// provided file. More control over this process is not yet available
+ /// but will be in a coming version of this crate.
+ pub fn from_str<T>(s: &str) -> Result<T>
+ where
+ T: Deserialize,
+ {
+ T::from_dhall(&Value::from_str(s, None)?)
+ }
+
+ /// Deserialize an instance of type `T` from a string of Dhall text,
+ /// additionally checking that it matches the supplied type.
+ ///
+ /// Like [from_str], but this additionally checks that
+ /// the type of the provided expression matches the supplied type.
+ pub fn from_str_check_type<T>(s: &str, ty: &Value) -> Result<T>
+ where
+ T: Deserialize,
+ {
+ T::from_dhall(&Value::from_str(s, Some(ty))?)
+ }
+
+ /// Deserialize an instance of type `T` from a string of Dhall text,
+ /// additionally checking that it matches the type of `T`.
+ ///
+ /// Like [from_str], but this additionally checks that
+ /// the type of the provided expression matches the output type `T`. The [StaticType] trait
+ /// captures Rust types that are valid Dhall types.
+ pub fn from_str_auto_type<T>(s: &str) -> Result<T>
+ where
+ T: Deserialize + StaticType,
+ {
+ from_str_check_type(s, &<T as StaticType>::static_type())
+ }
+}
diff --git a/dhall/src/api/serde.rs b/serde_dhall/src/serde.rs
index e1c8eef..10d5a17 100644
--- a/dhall/src/api/serde.rs
+++ b/serde_dhall/src/serde.rs
@@ -1,5 +1,5 @@
-use crate::api::de::{Deserialize, Value};
-use crate::error::{Error, Result};
+use crate::de::{Deserialize, Error, Result};
+use crate::Value;
use dhall_syntax::{ExprF, SubExpr, X};
use std::borrow::Cow;
@@ -14,15 +14,6 @@ where
struct Deserializer<'a>(Cow<'a, SubExpr<X, X>>);
-impl serde::de::Error for Error {
- fn custom<T>(msg: T) -> Self
- where
- T: std::fmt::Display,
- {
- Error::Deserialize(msg.to_string())
- }
-}
-
impl<'de: 'a, 'a> serde::de::IntoDeserializer<'de, Error> for Deserializer<'a> {
type Deserializer = Deserializer<'a>;
fn into_deserializer(self) -> Self::Deserializer {
diff --git a/dhall/src/api/static_type.rs b/serde_dhall/src/static_type.rs
index 906bcef..67a7bc4 100644
--- a/dhall/src/api/static_type.rs
+++ b/serde_dhall/src/static_type.rs
@@ -1,6 +1,6 @@
use dhall_syntax::{Builtin, Integer, Natural};
-use crate::api::Type;
+use crate::Value;
/// A Rust type that can be represented as a Dhall type.
///
@@ -14,14 +14,14 @@ use crate::api::Type;
/// [StaticType] because each different value would
/// have a different Dhall record type.
pub trait StaticType {
- fn static_type() -> Type;
+ fn static_type() -> Value;
}
macro_rules! derive_builtin {
($ty:ty, $builtin:ident) => {
impl StaticType for $ty {
- fn static_type() -> Type {
- Type::make_builtin_type(Builtin::$builtin)
+ fn static_type() -> Value {
+ Value::make_builtin_type(Builtin::$builtin)
}
}
};
@@ -38,8 +38,8 @@ where
A: StaticType,
B: StaticType,
{
- fn static_type() -> Type {
- Type::make_record_type(
+ fn static_type() -> Value {
+ Value::make_record_type(
vec![
("_1".to_owned(), A::static_type()),
("_2".to_owned(), B::static_type()),
@@ -54,8 +54,8 @@ where
T: StaticType,
E: StaticType,
{
- fn static_type() -> Type {
- Type::make_union_type(
+ fn static_type() -> Value {
+ Value::make_union_type(
vec![
("Ok".to_owned(), Some(T::static_type())),
("Err".to_owned(), Some(E::static_type())),
@@ -69,8 +69,8 @@ impl<T> StaticType for Option<T>
where
T: StaticType,
{
- fn static_type() -> Type {
- Type::make_optional_type(T::static_type())
+ fn static_type() -> Value {
+ Value::make_optional_type(T::static_type())
}
}
@@ -78,8 +78,8 @@ impl<T> StaticType for Vec<T>
where
T: StaticType,
{
- fn static_type() -> Type {
- Type::make_list_type(T::static_type())
+ fn static_type() -> Value {
+ Value::make_list_type(T::static_type())
}
}
@@ -87,7 +87,7 @@ impl<'a, T> StaticType for &'a T
where
T: StaticType,
{
- fn static_type() -> Type {
+ fn static_type() -> Value {
T::static_type()
}
}