Simplify AST validators (#18103)

packages/babel-types/scripts/generators/validators.ts

@@ -61,24 +61,25 @@ function addIsHelper(
     // Signature overload to avoid issues like https://github.com/babel/babel/pull/17503#discussion_r2325598609
     `export function is${type}(node: t.Node | null | undefined): ${result};`,
     `export function is${type}<Opts extends Options<t.${type}>>(node: t.Node | null | undefined, opts?: Opts | null): ${resultWithOpts};`,
-    `export function is${type}<Opts extends Options<t.${type}>>(node: t.Node | null | undefined, opts?: Opts | null): boolean {
-    ${deprecatedWarning || ""}
-    if (!node) return false;
+    `export function is${type}<Opts extends Options<t.${type}>>(node: t.Node | null | undefined, opts?: Opts | null): boolean {`,
+    deprecatedWarning || "",
+    cases
+      ? `
+  if (!node) return false;
 
-    ${
-      cases
-        ? `
-          switch(node.type){
-            ${cases}
-            default:
-              return false;
-          }`
-        : `if (node.type !== ${targetType}) return false;`
-    }
-
-    return opts == null || shallowEqual(node, opts);
+  switch(node.type){
+    ${cases}
+    default:
+      return false;
   }
+
+  return opts == null || shallowEqual(node, opts);
+    `
+      : `
+  return isType<t.${type}>(${targetType}, node, opts);
   `,
+    "}",
+    "",
   ].join("\n");
 }
 
@@ -91,17 +92,9 @@ export default function generateValidators() {
   /* eslint-disable no-fallthrough */
 
 import shallowEqual from "../../utils/shallowEqual.ts";
+import isType, {type Options} from "../../utils/isType.ts";
 import type * as t from "../../index.ts";
 import deprecationWarning from "../../utils/deprecationWarning.ts";
-
-type Options<Obj> = Partial<{
-  [Prop in Exclude<keyof Obj, "type">]: Obj[Prop] extends t.Node
-    ? t.Node
-    : Obj[Prop] extends t.Node[]
-    ? t.Node[]
-    : Obj[Prop];
-}>;
-
 `;
 
   Object.keys(VISITOR_KEYS).forEach(type => {

packages/babel-types/src/utils/isType.ts

@@ -0,0 +1,18 @@
+import shallowEqual from "./shallowEqual.ts";
+import type * as t from "../index.ts";
+
+export type Options<Obj> = Partial<{
+  [Prop in Exclude<keyof Obj, "type">]: Obj[Prop] extends t.Node
+    ? t.Node
+    : Obj[Prop] extends t.Node[]
+      ? t.Node[]
+      : Obj[Prop];
+}>;
+
+export default function isType<T extends t.Node>(
+  type: T["type"],
+  node: t.Node | null | undefined,
+  opts: Options<T> | null | undefined,
+): boolean {
+  return node?.type === type && (opts == null || shallowEqual(node, opts));
+}