config: add canonical Decodal source core

crates/config-source-wasm/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "config-source-wasm"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+publish = false
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+config-source.workspace = true
+serde.workspace = true
+serde-wasm-bindgen = "0.6.5"
+wasm-bindgen = "0.2.105"

crates/config-source-wasm/src/lib.rs

@@ -0,0 +1,51 @@
+use config_source::{
+    ConfigTreeSnapshot, EvaluationResult, SnapshotEnvironment, ToolchainContract, VirtualPath,
+};
+use serde_wasm_bindgen::{from_value, to_value};
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen]
+pub fn evaluate_snapshot(snapshot: JsValue, contract: JsValue) -> Result<JsValue, JsValue> {
+    let snapshot: ConfigTreeSnapshot = decode(snapshot)?;
+    let contract: ToolchainContract = decode(contract)?;
+    encode(
+        SnapshotEnvironment::new(snapshot)
+            .evaluate_contract(&contract)
+            .map_err(|diagnostics| {
+                to_value(&diagnostics).unwrap_or_else(|_| JsValue::from_str("evaluation failed"))
+            })?,
+    )
+}
+
+#[wasm_bindgen]
+pub fn analyze_snapshot(
+    snapshot: JsValue,
+    entrypoint: String,
+    source_override: Option<String>,
+) -> Result<JsValue, JsValue> {
+    let snapshot: ConfigTreeSnapshot = decode(snapshot)?;
+    let entrypoint = VirtualPath::parse(entrypoint).map_err(js_error)?;
+    encode(SnapshotEnvironment::new(snapshot).analyze(&entrypoint, source_override.as_deref()))
+}
+
+#[wasm_bindgen]
+pub fn format_source(source: String) -> Result<String, JsValue> {
+    SnapshotEnvironment::new(ConfigTreeSnapshot::empty())
+        .format(&source)
+        .map_err(|error| JsValue::from_str(&error))
+}
+
+fn decode<T: serde::de::DeserializeOwned>(value: JsValue) -> Result<T, JsValue> {
+    from_value(value).map_err(|error| JsValue::from_str(&error.to_string()))
+}
+
+fn encode<T: serde::Serialize>(value: T) -> Result<JsValue, JsValue> {
+    to_value(&value).map_err(|error| JsValue::from_str(&error.to_string()))
+}
+
+fn js_error(error: impl std::fmt::Display) -> JsValue {
+    JsValue::from_str(&error.to_string())
+}
+
+#[allow(dead_code)]
+fn _assert_serializable(_: EvaluationResult) {}