v0.0.2

Cargo.lock

@@ -16,7 +16,7 @@ checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
 name = "datapath"
-version = "0.0.1"
+version = "0.0.2"
 dependencies = [
  "datapath-macro",
  "uuid",
@@ -24,7 +24,7 @@ dependencies = [
 
 [[package]]
 name = "datapath-macro"
-version = "0.0.1"
+version = "0.0.2"
 dependencies = [
  "proc-macro2",
  "quote",

Cargo.toml

@@ -11,7 +11,7 @@ readme = "README.md"
 authors = ["rm-dr"]
 
 # Don't forget to bump datapath-macro below!
-version = "0.0.1"
+version = "0.0.2"
 
 [workspace.lints.rust]
 unused_import_braces = "deny"
@@ -70,7 +70,7 @@ cargo_common_metadata = "deny"
 #
 
 [workspace.dependencies]
-datapath-macro = { path = "crates/datapath-macro", version = "0.0.1" }
+datapath-macro = { path = "crates/datapath-macro", version = "0.0.2" }
 datapath = { path = "crates/datapath" }
 
 chrono = "0.4.42"

crates/datapath-macro/src/lib.rs

@@ -343,13 +343,14 @@ fn generate_simple_datapath(
 	segments: &[Segment],
 	attrs: &[syn::Attribute],
 ) -> proc_macro2::TokenStream {
-	let (struct_def, display_impl, datapath_impl) =
+	let (struct_def, display_impl, datapath_impl, from_trait_impls) =
 		generate_common_impls(struct_name, segments, attrs);
 
 	quote! {
 		#struct_def
 		#display_impl
 		#datapath_impl
+		#from_trait_impls
 	}
 }
 
@@ -360,7 +361,7 @@ fn generate_schema_datapath(
 	schema_type: &Type,
 	attrs: &[syn::Attribute],
 ) -> proc_macro2::TokenStream {
-	let (struct_def, display_impl, datapath_impl) =
+	let (struct_def, display_impl, datapath_impl, from_trait_impls) =
 		generate_common_impls(struct_name, segments, attrs);
 
 	// Generate SchemaDatapath implementation
@@ -374,6 +375,7 @@ fn generate_schema_datapath(
 		#struct_def
 		#display_impl
 		#datapath_impl
+		#from_trait_impls
 		#schema_datapath_impl
 	}
 }
@@ -387,6 +389,7 @@ fn generate_common_impls(
 	proc_macro2::TokenStream,
 	proc_macro2::TokenStream,
 	proc_macro2::TokenStream,
+	proc_macro2::TokenStream,
 ) {
 	// Extract typed fields
 	let typed_fields: Vec<_> = segments
@@ -404,21 +407,25 @@ fn generate_common_impls(
 		}
 	});
 
-	let mut doc_str = String::new();
-	for s in segments {
-		if !doc_str.is_empty() {
-			doc_str.push('/');
-		}
+	// Build pattern string
+	let pattern_str = {
+		let mut s = String::new();
+		for seg in segments {
+			if !s.is_empty() {
+				s.push('/');
+			}
 
-		match s {
-			Segment::Constant(x) => doc_str.push_str(x),
-			Segment::Typed { name, ty } => {
-				doc_str.push_str(&format!("{name}={}", ty.to_token_stream()))
+			match seg {
+				Segment::Constant(x) => s.push_str(x),
+				Segment::Typed { name, ty } => {
+					s.push_str(&format!("{name}={}", ty.to_token_stream()))
+				}
 			}
 		}
-	}
+		s
+	};
 
-	let doc_str = format!("\n\nDatapath pattern: `{doc_str}`");
+	let doc_str = format!("\n\nDatapath pattern: `{pattern_str}`");
 
 	let struct_def = quote! {
 		#(#attrs)*
@@ -444,6 +451,72 @@ fn generate_common_impls(
 		}
 	};
 
+	// Generate tuple types
+	let tuple_type = if typed_fields.is_empty() {
+		quote! { () }
+	} else {
+		let field_types = typed_fields.iter().map(|(_, ty)| ty);
+		quote! { (#(#field_types,)*) }
+	};
+
+	let wildcardable_tuple_type = if typed_fields.is_empty() {
+		quote! { () }
+	} else {
+		let wildcardable_types = typed_fields.iter().map(|(_, ty)| {
+			quote! { ::datapath::Wildcardable<#ty> }
+		});
+		quote! { (#(#wildcardable_types,)*) }
+	};
+
+	// Generate from_tuple implementation
+	let from_tuple_body = if typed_fields.is_empty() {
+		quote! { Self {} }
+	} else {
+		let field_assignments = typed_fields.iter().enumerate().map(|(idx, (name, _))| {
+			let index = syn::Index::from(idx);
+			quote! { #name: tuple.#index }
+		});
+
+		quote! {
+			Self {
+				#(#field_assignments),*
+			}
+		}
+	};
+
+	// Generate to_tuple implementation
+	let to_tuple_body = if typed_fields.is_empty() {
+		quote! { () }
+	} else {
+		let field_names = typed_fields.iter().map(|(name, _)| name);
+		quote! { (#(self.#field_names,)*) }
+	};
+
+	// Generate from_wildcardable implementation
+	let from_wildcardable_body = {
+		let mut parts = Vec::new();
+		let mut field_idx = 0;
+
+		for seg in segments {
+			match seg {
+				Segment::Constant(s) => {
+					parts.push(quote! { #s.to_string() });
+				}
+				Segment::Typed { name, .. } => {
+					let idx = syn::Index::from(field_idx);
+					field_idx += 1;
+					parts.push(quote! {
+						format!("{}={}", stringify!(#name), tuple.#idx)
+					});
+				}
+			}
+		}
+
+		quote! {
+			vec![#(#parts),*].join("/")
+		}
+	};
+
 	// Generate parse implementation
 	let mut parse_body = Vec::new();
 
@@ -480,6 +553,23 @@ fn generate_common_impls(
 
 	let datapath_impl = quote! {
 		impl ::datapath::Datapath for #struct_name {
+			const PATTERN: &'static str = #pattern_str;
+
+			type Tuple = #tuple_type;
+			type WildcardableTuple = #wildcardable_tuple_type;
+
+			fn from_tuple(tuple: Self::Tuple) -> Self {
+				#from_tuple_body
+			}
+
+			fn to_tuple(self) -> Self::Tuple {
+				#to_tuple_body
+			}
+
+			fn from_wildcardable(tuple: Self::WildcardableTuple) -> ::std::string::String {
+				#from_wildcardable_body
+			}
+
 			fn with_file(&self, file: impl ::core::convert::Into<::std::string::String>) -> ::datapath::DatapathFile<Self> {
 				::datapath::DatapathFile {
 					path: self.clone(),
@@ -513,7 +603,31 @@ fn generate_common_impls(
 		}
 	};
 
-	(struct_def, display_impl, datapath_impl)
+	// Generate From<Tuple> for Struct
+	let from_tuple_impl = quote! {
+		impl ::core::convert::From<#tuple_type> for #struct_name {
+			fn from(value: #tuple_type) -> Self {
+				<Self as ::datapath::Datapath>::from_tuple(value)
+			}
+		}
+	};
+
+	// Generate From<Struct> for Tuple
+	let from_struct_impl = quote! {
+		impl ::core::convert::From<#struct_name> for #tuple_type {
+			fn from(value: #struct_name) -> Self {
+				<#struct_name as ::datapath::Datapath>::to_tuple(value)
+			}
+		}
+	};
+
+	// Combine both implementations
+	let from_trait_impls = quote! {
+		#from_tuple_impl
+		#from_struct_impl
+	};
+
+	(struct_def, display_impl, datapath_impl, from_trait_impls)
 }
 
 /// The `datapath!` macro generates datapath struct definitions with parsing and formatting logic.

crates/datapath/README.md

@@ -42,7 +42,7 @@ match parsed {
 Associate datapaths with schema types for type-safe data handling:
 
 ```rust
-use datapath::datapath;
+use datapath::{datapath, Datapath};
 
 pub struct UserEvent {
     pub action: String,
@@ -60,10 +60,46 @@ datapath! {
 // EventPath::Schema == UserEvent
 ```
 
+## Pattern Introspection and Wildcards
+
+Access the pattern string and work with wildcarded paths:
+
+```rust
+use datapath::{datapath, Datapath, Wildcardable};
+use uuid::Uuid;
+
+datapath! {
+    struct Metrics(metrics/service=String/timestamp=i64/v1);
+}
+
+// Access the pattern string
+// (use for logging/debug)
+assert_eq!(Metrics::PATTERN, "metrics/service=String/timestamp=i64/v1");
+
+// Convert to/from tuples
+let metrics = Metrics {
+    service: "api".to_string(),
+    timestamp: 1234567890,
+};
+let tuple = metrics.clone().to_tuple();
+assert_eq!(tuple, ("api".to_string(), 1234567890i64));
+
+let recreated = Metrics::from_tuple(tuple);
+assert_eq!(recreated.service, "api");
+assert_eq!(recreated.timestamp, 1234567890);
+
+// Create wildcarded paths for querying
+let all_services = Metrics::from_wildcardable((
+    Wildcardable::Star,
+    Wildcardable::Value(1234567890i64),
+));
+assert_eq!(all_services, "metrics/service=*/timestamp=1234567890/v1");
+```
+
 ## Examples
 
 ```rust
-use datapath::datapath;
+use datapath::{datapath, Datapath};
 
 pub struct MetricsSchema;
 
@@ -86,4 +122,30 @@ datapath! {
         schema: MetricsSchema
     };
 }
+```
+
+### Constant-Only Paths
+
+Paths with no typed fields work correctly with empty tuples:
+
+```rust
+use datapath::{datapath, Datapath};
+
+datapath! {
+    struct ConstantPath(assets/data/"v1.0");
+}
+
+// PATTERN works for constant-only paths
+assert_eq!(ConstantPath::PATTERN, "assets/data/v1.0");
+
+// Tuple type is unit ()
+let empty_tuple = ConstantPath {}.to_tuple();
+assert_eq!(empty_tuple, ());
+
+let path = ConstantPath::from_tuple(());
+assert_eq!(format!("{}", path), "assets/data/v1.0");
+
+// from_wildcardable also works (no wildcards possible)
+let path_str = ConstantPath::from_wildcardable(());
+assert_eq!(path_str, "assets/data/v1.0");
 ```

crates/datapath/src/datapath.rs

@@ -12,7 +12,20 @@ where
 	Self: Eq + PartialEq + Hash,
 	Self: Debug + Display,
 {
-	// Default
+	/// The exact pattern string passed to the macro that generated this struct
+	const PATTERN: &'static str;
+
+	/// A tuple of this path's parameter types, in the order they appear in the pattern
+	type Tuple;
+
+	/// [Datapath::Tuple], but each type is wrapped in a [crate::Wildcardable].
+	type WildcardableTuple;
+
+	fn from_tuple(tuple: Self::Tuple) -> Self;
+	fn to_tuple(self) -> Self::Tuple;
+
+	/// Return a string where wildcarded partitions are `*`.
+	fn from_wildcardable(tuple: Self::WildcardableTuple) -> String;
 
 	/// Returns a [DatapathFile] with the given file at this datapath
 	fn with_file(&self, file: impl Into<String>) -> DatapathFile<Self>;

crates/datapath/src/lib.rs

@@ -16,4 +16,7 @@ pub use datapathfile::*;
 mod schema;
 pub use schema::*;
 
+mod wildcardable;
+pub use wildcardable::*;
+
 pub use datapath_macro::datapath;

crates/datapath/src/wildcardable.rs

@@ -0,0 +1,77 @@
+use std::{
+	fmt::{Debug, Display},
+	hash::Hash,
+	str::FromStr,
+};
+
+/// A wrapper for wildcardable partition values.
+/// Allows us to specify, for example, `ts=1337` and `ts=*`.
+#[derive(Debug, PartialEq, Eq, Hash, Default)]
+pub enum Wildcardable<T: FromStr + Display + Debug + Eq + PartialEq + Hash> {
+	/// This value is wildcarded with a star,
+	/// as in `ts=*`
+	#[default]
+	Star,
+
+	/// This value is explicitly given,
+	/// as in `ts=1337`
+	Value(T),
+}
+
+impl<T: FromStr + Display + Debug + Eq + PartialEq + Hash> Wildcardable<T> {
+	pub fn inner(&self) -> Option<&T> {
+		match self {
+			Self::Star => None,
+			Self::Value(x) => Some(x),
+		}
+	}
+
+	pub fn into_inner(self) -> Option<T> {
+		match self {
+			Self::Star => None,
+			Self::Value(x) => Some(x),
+		}
+	}
+}
+
+impl<T: FromStr + Display + Debug + Eq + PartialEq + Hash + Copy> Copy for Wildcardable<T> {}
+
+impl<T: FromStr + Display + Debug + Eq + PartialEq + Hash + Clone> Clone for Wildcardable<T> {
+	fn clone(&self) -> Self {
+		match self {
+			Self::Star => Self::Star,
+			Self::Value(x) => Self::Value(x.clone()),
+		}
+	}
+}
+
+impl<T: FromStr + Display + Debug + Eq + PartialEq + Hash> Display for Wildcardable<T> {
+	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+		match self {
+			Self::Star => write!(f, "*"),
+			Self::Value(x) => write!(f, "{x}"),
+		}
+	}
+}
+
+impl<T: FromStr + Display + Debug + Eq + PartialEq + Hash> FromStr for Wildcardable<T> {
+	type Err = ();
+	fn from_str(s: &str) -> Result<Self, Self::Err> {
+		return Ok(match s {
+			"*" => Self::Star,
+			value => Self::Value(value.parse().map_err(|_err| ())?),
+		});
+	}
+}
+
+impl<T: FromStr + Display + Debug + Eq + PartialEq + Hash> From<T> for Wildcardable<T> {
+	fn from(value: T) -> Self {
+		Self::Value(value)
+	}
+}
+
+impl<T: FromStr + Display + Debug + Eq + PartialEq + Hash> From<Wildcardable<T>> for Option<T> {
+	fn from(value: Wildcardable<T>) -> Self {
+		value.into_inner()
+	}
+}