Expression validation

actions-languageservice/src/expression-validation/error-dictionary.ts

@@ -0,0 +1,38 @@
+import {data} from "@github/actions-expressions";
+import {isDictionary} from "@github/actions-expressions/data/dictionary";
+import {ExpressionData, Pair} from "@github/actions-expressions/data/expressiondata";
+
+export class AccessError extends Error {
+  constructor(message: string, public readonly keyName: string) {
+    super(message);
+  }
+}
+
+export class ErrorDictionary extends data.Dictionary {
+  constructor(...pairs: Pair[]) {
+    super(...pairs);
+  }
+
+  get(key: string): ExpressionData | undefined {
+    const value = super.get(key);
+    if (value) {
+      return value;
+    }
+
+    throw new AccessError(`Invalid context access: ${key}`, key);
+  }
+}
+
+export function wrapDictionary(d: data.Dictionary): ErrorDictionary {
+  const e = new ErrorDictionary();
+
+  for (const {key, value} of d.pairs()) {
+    if (isDictionary(value)) {
+      e.add(key, wrapDictionary(value));
+    } else {
+      e.add(key, value);
+    }
+  }
+
+  return e;
+}