Add variants json definitions

Cargo.lock

@@ -6013,8 +6013,10 @@ dependencies = [
  "itertools 0.14.0",
  "rkyv",
  "serde",
+ "serde_json",
  "sha3",
  "thiserror 2.0.12",
+ "uv-pep508",
 ]
 
 [[package]]

crates/uv-variants/Cargo.toml

@@ -10,6 +10,8 @@ authors.workspace = true
 license.workspace = true
 
 [dependencies]
+uv-pep508 = { workspace = true }
+
 hex = { workspace = true }
 itertools = { workspace = true }
 rkyv = { workspace = true }
@@ -17,5 +19,8 @@ serde = { workspace = true }
 sha3 = { workspace = true }
 thiserror = { workspace = true }
 
+[dev-dependencies]
+serde_json = { workspace = true }
+
 [lints]
 workspace = true

crates/uv-variants/src/lib.rs

@@ -1,3 +1,5 @@
+pub mod variants_json;
+
 use std::cmp;
 use std::collections::HashMap;
 use std::num::NonZeroU32;

crates/uv-variants/src/variants_json.rs

@@ -0,0 +1,56 @@
+use std::collections::HashMap;
+
+use serde::Deserialize;
+
+use uv_pep508::{MarkerTree, Requirement};
+
+/// Mapping of namespaces in a variant
+pub type Variant = HashMap<String, VariantNamespace>;
+
+/// Mapping of features to their possible values in a namespace
+pub type VariantNamespace = HashMap<String, Vec<String>>;
+
+// TODO(konsti): Validate the string contents
+pub type Namespace = String;
+pub type Feature = String;
+pub type Property = String;
+
+/// Combined index metadata for wheel variants.
+///
+/// See <https://wheelnext.dev/variants.json>
+#[derive(Debug, PartialEq, Eq, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub struct VariantsJsonContent {
+    /// Default provider priorities
+    pub default_priorities: DefaultPriorities,
+    /// Mapping of namespaces to provider information
+    pub providers: HashMap<String, Provider>,
+    /// Mapping of variant labels to properties
+    pub variants: HashMap<String, Variant>,
+}
+
+/// Default provider priorities
+#[derive(Debug, PartialEq, Eq, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub struct DefaultPriorities {
+    /// Default namespace priorities
+    pub namespace: Vec<String>,
+    /// Default feature priorities
+    #[serde(default)]
+    pub feature: HashMap<Namespace, Vec<Feature>>,
+    /// Default property priorities
+    #[serde(default)]
+    pub property: HashMap<Namespace, HashMap<Feature, Vec<Property>>>,
+}
+
+/// Provider information
+#[derive(Debug, PartialEq, Eq, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub struct Provider {
+    /// Object reference to plugin class
+    pub plugin_api: Option<String>,
+    /// Environment marker specifying when to enable the plugin
+    pub enable_if: Option<MarkerTree>,
+    /// Dependency specifiers for how to install the plugin
+    pub requires: Vec<Requirement>,
+}