Add typed Decodal derive support

crates/decodal-core/src/constraints.rs

@@ -70,7 +70,10 @@ pub fn normalize_constraints(
 
     if matches!(
         primitive,
-        Some((PrimitiveType::String | PrimitiveType::Bool, _))
+        Some((
+            PrimitiveType::String | PrimitiveType::Bool | PrimitiveType::Array,
+            _
+        ))
     ) && (lower.is_some() || upper.is_some())
     {
         let mut diagnostic = Diagnostic::new(

crates/decodal-core/src/embedding.rs

@@ -63,6 +63,18 @@ impl HostValue {
         )
     }
 
+    pub fn object_from_paths<I, N>(fields: I) -> Self
+    where
+        I: IntoIterator<Item = (N, HostValue)>,
+        N: Into<String>,
+    {
+        let mut root = Vec::new();
+        for (path, value) in fields {
+            insert_path(&mut root, &path.into(), value);
+        }
+        Self::Object(root)
+    }
+
     pub fn string_type() -> Self {
         Self::abstract_with_constraint(Constraint::Type(PrimitiveType::String))
     }
@@ -79,6 +91,10 @@ impl HostValue {
         Self::abstract_with_constraint(Constraint::Type(PrimitiveType::Bool))
     }
 
+    pub fn array_type() -> Self {
+        Self::abstract_with_constraint(Constraint::Type(PrimitiveType::Array))
+    }
+
     pub fn builtin_predicate(name: impl Into<String>) -> Self {
         Self::abstract_with_constraint(Constraint::BuiltinPredicate(name.into()))
     }
@@ -162,3 +178,38 @@ impl HostValue {
         self.default(Self::bool(value))
     }
 }
+
+impl HostField {
+    pub fn new(name: impl Into<String>, value: HostValue) -> Self {
+        Self {
+            name: name.into(),
+            value,
+        }
+    }
+}
+
+fn insert_path(fields: &mut Vec<HostField>, path: &str, value: HostValue) {
+    let mut parts = path.splitn(2, '.');
+    let Some(head) = parts.next().filter(|part| !part.is_empty()) else {
+        return;
+    };
+    if let Some(tail) = parts.next() {
+        if let Some(field) = fields.iter_mut().find(|field| field.name == head) {
+            if let HostValue::Object(children) = &mut field.value {
+                insert_path(children, tail, value);
+            } else {
+                let mut children = Vec::new();
+                insert_path(&mut children, tail, value);
+                field.value = HostValue::Object(children);
+            }
+        } else {
+            let mut children = Vec::new();
+            insert_path(&mut children, tail, value);
+            fields.push(HostField::new(head, HostValue::Object(children)));
+        }
+    } else if let Some(field) = fields.iter_mut().find(|field| field.name == head) {
+        field.value = value;
+    } else {
+        fields.push(HostField::new(head, value));
+    }
+}

crates/decodal-core/src/eval.rs

@@ -1170,6 +1170,7 @@ fn primitive_type(name: &str) -> Option<PrimitiveType> {
         "Int" => Some(PrimitiveType::Int),
         "Float" => Some(PrimitiveType::Float),
         "Bool" => Some(PrimitiveType::Bool),
+        "Array" => Some(PrimitiveType::Array),
         _ => None,
     }
 }
@@ -1250,6 +1251,9 @@ fn value_matches_primitive(value: &RuntimeValue, primitive: PrimitiveType) -> bo
         ) | (
             RuntimeValue::Concrete(ConcreteValue::Bool(_)),
             PrimitiveType::Bool
+        ) | (
+            RuntimeValue::Concrete(ConcreteValue::Array(_)),
+            PrimitiveType::Array
         )
     )
 }

crates/decodal-core/src/lib.rs

@@ -12,6 +12,7 @@ pub mod module;
 pub mod parser;
 pub mod runtime;
 pub mod span;
+pub mod typed;
 
 pub use ast::{Ast, BinaryOp, CompareOp, Expr, ExprId, Field, Literal, Param};
 pub use constraints::normalize_constraints;
@@ -23,6 +24,10 @@ pub use module::{EmptyLoader, LoadedSource, Module, SourceLoader};
 pub use parser::{ParseOutput, Parser, SourceForm, parse_source, parse_source_with_source_id};
 pub use runtime::{Constraint, Data, ExprRef, LiteralValue, ModuleId, PrimitiveType, RuntimeValue};
 pub use span::{SourceId, Span};
+pub use typed::{
+    DecodalDecode, DecodalSchema, DecodeError, DecodeResult, IntoHostValue, data_at_path,
+    decode_path, prefix_decode_error,
+};
 
 pub fn version() -> &'static str {
     env!("CARGO_PKG_VERSION")

crates/decodal-core/src/runtime.rs

@@ -79,6 +79,7 @@ pub enum PrimitiveType {
     Int,
     Float,
     Bool,
+    Array,
 }
 
 #[derive(Debug, Clone, PartialEq)]

crates/decodal-core/src/typed.rs

@@ -0,0 +1,227 @@
+use alloc::{format, string::String, vec::Vec};
+
+use crate::{Data, HostValue};
+
+pub trait DecodalSchema {
+    fn decodal_schema() -> HostValue;
+}
+
+pub trait DecodalDecode: Sized {
+    fn decodal_decode(data: &Data) -> DecodeResult<Self>;
+}
+
+pub trait IntoHostValue {
+    fn into_host_value(self) -> HostValue;
+}
+
+pub type DecodeResult<T> = core::result::Result<T, DecodeError>;
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct DecodeError {
+    pub path: String,
+    pub message: String,
+}
+
+impl DecodeError {
+    pub fn new(path: impl Into<String>, message: impl Into<String>) -> Self {
+        Self {
+            path: path.into(),
+            message: message.into(),
+        }
+    }
+
+    pub fn at_type(path: &str, expected: &'static str) -> Self {
+        Self::new(path, format!("expected {expected}"))
+    }
+}
+
+impl core::fmt::Display for DecodeError {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        if self.path.is_empty() {
+            write!(f, "{}", self.message)
+        } else {
+            write!(f, "{}: {}", self.path, self.message)
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for DecodeError {}
+
+pub fn decode_path<T: DecodalDecode>(data: &Data, path: &str) -> DecodeResult<T> {
+    let value = data_at_path(data, path).ok_or_else(|| DecodeError::new(path, "missing field"))?;
+    T::decodal_decode(value).map_err(|error| prefix_error(path, error))
+}
+
+pub fn data_at_path<'a>(data: &'a Data, path: &str) -> Option<&'a Data> {
+    let mut current = data;
+    for part in path.split('.') {
+        if part.is_empty() {
+            return None;
+        }
+        let Data::Object(fields) = current else {
+            return None;
+        };
+        current = &fields.iter().find(|field| field.name == part)?.value;
+    }
+    Some(current)
+}
+
+pub fn prefix_decode_error(path: &str, error: DecodeError) -> DecodeError {
+    prefix_error(path, error)
+}
+
+fn prefix_error(path: &str, mut error: DecodeError) -> DecodeError {
+    if error.path.is_empty() {
+        error.path = String::from(path);
+    } else if !path.is_empty() {
+        error.path = format!("{path}.{}", error.path);
+    }
+    error
+}
+
+impl DecodalSchema for String {
+    fn decodal_schema() -> HostValue {
+        HostValue::string_type()
+    }
+}
+
+impl DecodalDecode for String {
+    fn decodal_decode(data: &Data) -> DecodeResult<Self> {
+        match data {
+            Data::String(value) => Ok(value.clone()),
+            _ => Err(DecodeError::at_type("", "String")),
+        }
+    }
+}
+
+impl IntoHostValue for String {
+    fn into_host_value(self) -> HostValue {
+        HostValue::string(self)
+    }
+}
+
+impl IntoHostValue for &str {
+    fn into_host_value(self) -> HostValue {
+        HostValue::string(self)
+    }
+}
+
+macro_rules! impl_int_decode {
+    ($($ty:ty),* $(,)?) => {
+        $(
+            impl DecodalSchema for $ty {
+                fn decodal_schema() -> HostValue {
+                    HostValue::int_type()
+                }
+            }
+
+            impl DecodalDecode for $ty {
+                fn decodal_decode(data: &Data) -> DecodeResult<Self> {
+                    match data {
+                        Data::Int(value) => <$ty>::try_from(*value)
+                            .map_err(|_| DecodeError::new("", "integer value is out of range")),
+                        _ => Err(DecodeError::at_type("", "Int")),
+                    }
+                }
+            }
+
+            impl IntoHostValue for $ty {
+                fn into_host_value(self) -> HostValue {
+                    HostValue::int(self as i64)
+                }
+            }
+        )*
+    };
+}
+
+impl_int_decode!(i8, i16, i32, i64, u8, u16, u32);
+
+impl DecodalSchema for f64 {
+    fn decodal_schema() -> HostValue {
+        HostValue::float_type()
+    }
+}
+
+impl DecodalDecode for f64 {
+    fn decodal_decode(data: &Data) -> DecodeResult<Self> {
+        match data {
+            Data::Float(value) => Ok(*value),
+            Data::Int(value) => Ok(*value as f64),
+            _ => Err(DecodeError::at_type("", "Float")),
+        }
+    }
+}
+
+impl IntoHostValue for f64 {
+    fn into_host_value(self) -> HostValue {
+        HostValue::float(self)
+    }
+}
+
+impl DecodalSchema for f32 {
+    fn decodal_schema() -> HostValue {
+        HostValue::float_type()
+    }
+}
+
+impl DecodalDecode for f32 {
+    fn decodal_decode(data: &Data) -> DecodeResult<Self> {
+        f64::decodal_decode(data).map(|value| value as f32)
+    }
+}
+
+impl IntoHostValue for f32 {
+    fn into_host_value(self) -> HostValue {
+        HostValue::float(f64::from(self))
+    }
+}
+
+impl DecodalSchema for bool {
+    fn decodal_schema() -> HostValue {
+        HostValue::bool_type()
+    }
+}
+
+impl DecodalDecode for bool {
+    fn decodal_decode(data: &Data) -> DecodeResult<Self> {
+        match data {
+            Data::Bool(value) => Ok(*value),
+            _ => Err(DecodeError::at_type("", "Bool")),
+        }
+    }
+}
+
+impl IntoHostValue for bool {
+    fn into_host_value(self) -> HostValue {
+        HostValue::bool(self)
+    }
+}
+
+impl<T> DecodalSchema for Vec<T> {
+    fn decodal_schema() -> HostValue {
+        HostValue::array_type()
+    }
+}
+
+impl<T: DecodalDecode> DecodalDecode for Vec<T> {
+    fn decodal_decode(data: &Data) -> DecodeResult<Self> {
+        match data {
+            Data::Array(items) => items
+                .iter()
+                .enumerate()
+                .map(|(index, item)| {
+                    T::decodal_decode(item)
+                        .map_err(|error| prefix_error(&format!("[{index}]"), error))
+                })
+                .collect(),
+            _ => Err(DecodeError::at_type("", "Array")),
+        }
+    }
+}
+
+impl<T: IntoHostValue> IntoHostValue for Vec<T> {
+    fn into_host_value(self) -> HostValue {
+        HostValue::array(self.into_iter().map(IntoHostValue::into_host_value))
+    }
+}