Reuse arrays in visitor keys (#18386)

scripts/build/config.js

@@ -598,7 +598,10 @@ const pluginFiles = [
             "const LOCAL_DEBUG = false &&",
           );
 
-          text = text.replace(/(?<=\n)export .*?;/u, "export { preprocess };");
+          text = text.replace(
+            /(?<=\n)export .*?;/u,
+            "export { preprocess, getVoidTags, visitorKeys };",
+          );
 
           return text;
         },

scripts/build/esbuild-plugins/evaluate.js

@@ -1,33 +1,89 @@
+import assert from "node:assert";
+import path from "node:path";
 import url from "node:url";
 import { isValidIdentifier } from "@babel/types";
+import { outdent } from "outdent";
 import serialize from "serialize-javascript";
 
+function serializeModule(module) {
+  return Object.entries(module)
+    .map(([specifier, value]) => {
+      const code =
+        value instanceof RegExp
+          ? `/${value.source}/${value.flags}`
+          : serialize(value, { space: 2, unsafe: true });
+      if (specifier === "default") {
+        return `export default ${code};`;
+      }
+
+      if (!isValidIdentifier(specifier)) {
+        throw new Error(`${specifier} is not a valid specifier`);
+      }
+
+      return `export const ${specifier} = ${code};`;
+    })
+    .join("\n");
+}
+
+function serializeVisitorKeys(module) {
+  const specifiers = Object.keys(module);
+  assert.deepEqual(specifiers, ["default"]);
+
+  const references = new Map();
+  const properties = Object.entries(module.default);
+  for (const [, keys] of properties) {
+    if (!references.has(keys)) {
+      references.set(keys, 1);
+    } else {
+      references.set(keys, references.get(keys) + 1);
+    }
+  }
+
+  const variables = [];
+  const propertiesText = [];
+  for (const [type, keys] of properties) {
+    const isSingleReference = references.get(keys) === 1;
+    const key = isValidIdentifier(type) ? type : JSON.stringify(type);
+    if (isSingleReference) {
+      propertiesText.push(`  ${key}: ${JSON.stringify(keys)},`);
+    } else {
+      if (!variables.includes(keys)) {
+        variables.push(keys);
+      }
+      const index = variables.indexOf(keys);
+      propertiesText.push(`  ${key}: vk[${index}],`);
+    }
+  }
+
+  const code = outdent`
+    const vk = [
+    ${variables.map((keys) => `  ${JSON.stringify(keys)},`).join("\n")}
+    ];
+
+    export default {
+    ${propertiesText.join("\n")}
+    };
+  `;
+
+  return code;
+}
+
 export default function esbuildPluginEvaluate() {
   return {
     name: "evaluate",
     setup(build) {
       build.onLoad(
         { filter: /\.evaluate\.[cm]?js$/, namespace: "file" },
-        async ({ path }) => {
-          const module = await import(url.pathToFileURL(path));
-          const text = Object.entries(module)
-            .map(([specifier, value]) => {
-              const code =
-                value instanceof RegExp
-                  ? `/${value.source}/${value.flags}`
-                  : serialize(value, { space: 2 });
+        async ({ path: filePath }) => {
+          const module = await import(url.pathToFileURL(filePath));
+          const isVisitorKeys =
+            path.basename(filePath, path.extname(filePath)) ===
+            "visitor-keys.evaluate";
 
-              if (specifier === "default") {
-                return `export default ${code};`;
-              }
+          const text = isVisitorKeys
+            ? serializeVisitorKeys(module)
+            : serializeModule(module);
 
-              if (!isValidIdentifier(specifier)) {
-                throw new Error(`${specifier} is not a valid specifier`);
-              }
-
-              return `export const ${specifier} = ${code};`;
-            })
-            .join("\n");
           return { contents: text };
         },
       );

src/language-css/get-visitor-keys.js

@@ -1,5 +1,5 @@
 import createGetVisitorKeys from "../utilities/create-get-visitor-keys.js";
-import visitorKeys from "./visitor-keys.js";
+import visitorKeys from "./visitor-keys.evaluate.js";
 
 const getVisitorKeys = createGetVisitorKeys(visitorKeys);
 

src/language-css/visitor-keys.evaluate.js

@@ -1,4 +1,6 @@
-const visitorKeys = {
+import { generateReferenceSharedVisitorKeys } from "../utilities/visitor-keys.js";
+
+const visitorKeys = generateReferenceSharedVisitorKeys({
   "css-root": ["frontMatter", "nodes"],
   "css-comment": [],
   "css-rule": ["selector", "nodes"],
@@ -43,6 +45,6 @@ const visitorKeys = {
   "value-atword": [],
   "value-unicode-range": [],
   "value-unknown": [],
-};
+});
 
 export default visitorKeys;

src/language-handlebars/get-visitor-keys.js

@@ -1,5 +1,5 @@
 import createGetVisitorKeys from "../utilities/create-get-visitor-keys.js";
-import visitorKeys from "./visitor-keys.evaluate.js";
+import visitorKeys from "./visitor-keys.js";
 
 const getVisitorKeys = createGetVisitorKeys(visitorKeys);
 

src/language-handlebars/html-void-elements.evaluate.js

@@ -1,5 +0,0 @@
-import { getVoidTags } from "@glimmer/syntax";
-
-const htmlVoidElements = new Set(getVoidTags());
-
-export default htmlVoidElements;

src/language-handlebars/utilities.js

@@ -1,4 +1,7 @@
-import htmlVoidElements from "./html-void-elements.evaluate.js";
+// Do not use void tags from other package, won't match
+import { getVoidTags } from "@glimmer/syntax";
+
+const htmlVoidElements = new Set(getVoidTags());
 
 function isUppercase(string) {
   return string.toUpperCase() === string;

src/language-html/get-visitor-keys.js

@@ -1,5 +1,5 @@
 import createGetVisitorKeys from "../utilities/create-get-visitor-keys.js";
-import visitorKeys from "./visitor-keys.js";
+import visitorKeys from "./visitor-keys.evaluate.js";
 
 const getVisitorKeys = createGetVisitorKeys(visitorKeys, "kind");
 

src/language-html/visitor-keys.evaluate.js

@@ -1,4 +1,6 @@
-const visitorKeys = {
+import { generateReferenceSharedVisitorKeys } from "../utilities/visitor-keys.js";
+
+const visitorKeys = generateReferenceSharedVisitorKeys({
   root: ["children"],
   element: ["attrs", "children"],
   ieConditionalComment: ["children"],
@@ -17,6 +19,6 @@ const visitorKeys = {
   angularLetDeclarationInitializer: [],
   angularIcuExpression: ["cases"],
   angularIcuCase: ["expression"],
-};
+});
 
 export default visitorKeys;

src/language-js/traverse/visitor-keys.evaluate.js

@@ -3,10 +3,11 @@ import { visitorKeys as tsVisitorKeys } from "@typescript-eslint/visitor-keys";
 import { visitorKeys as angularVisitorKeys } from "angular-estree-parser";
 import flowVisitorKeys from "hermes-parser/dist/generated/ESTreeVisitorKeys.js";
 import {
+  generateReferenceSharedVisitorKeys,
   removeNodeTypes,
   removeVisitorKeys,
   unionVisitorKeys,
-} from "./utilities.js";
+} from "../../utilities/visitor-keys.js";
 
 const additionalVisitorKeys = {
   // Prettier
@@ -70,4 +71,7 @@ let visitorKeys = unionVisitorKeys(
 visitorKeys = removeNodeTypes(visitorKeys, excludeNodeTypes);
 visitorKeys = removeVisitorKeys(visitorKeys, excludeVisitorKeys);
 
+// This should be the last step
+visitorKeys = generateReferenceSharedVisitorKeys(visitorKeys);
+
 export default visitorKeys;

src/language-json/get-visitor-keys.js

@@ -1,5 +1,5 @@
 import createGetVisitorKeys from "../utilities/create-get-visitor-keys.js";
-import visitorKeys from "./visitor-keys.js";
+import visitorKeys from "./visitor-keys.evaluate.js";
 
 const getVisitorKeys = createGetVisitorKeys(visitorKeys);
 

src/language-json/visitor-keys.evaluate.js

@@ -1,4 +1,6 @@
-const visitorKeys = {
+import { generateReferenceSharedVisitorKeys } from "../utilities/visitor-keys.js";
+
+const visitorKeys = generateReferenceSharedVisitorKeys({
   JsonRoot: ["node"],
   ArrayExpression: ["elements"],
   ObjectExpression: ["properties"],
@@ -11,6 +13,6 @@ const visitorKeys = {
   Identifier: [],
   TemplateLiteral: ["quasis"],
   TemplateElement: [],
-};
+});
 
 export default visitorKeys;

src/language-markdown/get-visitor-keys.js

@@ -1,5 +1,5 @@
 import createGetVisitorKeys from "../utilities/create-get-visitor-keys.js";
-import visitorKeys from "./visitor-keys.js";
+import visitorKeys from "./visitor-keys.evaluate.js";
 
 const getVisitorKeys = createGetVisitorKeys(visitorKeys);
 

src/language-markdown/visitor-keys.evaluate.js

@@ -1,4 +1,6 @@
-const visitorKeys = {
+import { generateReferenceSharedVisitorKeys } from "../utilities/visitor-keys.js";
+
+const visitorKeys = generateReferenceSharedVisitorKeys({
   root: ["children"],
   paragraph: ["children"],
   sentence: ["children"],
@@ -36,6 +38,6 @@ const visitorKeys = {
   tableRow: ["children"],
   listItem: ["children"],
   text: [],
-};
+});
 
 export default visitorKeys;

src/language-yaml/get-visitor-keys.js

@@ -1,5 +1,5 @@
 import createGetVisitorKeys from "../utilities/create-get-visitor-keys.js";
-import visitorKeys from "./visitor-keys.js";
+import visitorKeys from "./visitor-keys.evaluate.js";
 
 const getVisitorKeys = createGetVisitorKeys(visitorKeys);
 

src/language-yaml/visitor-keys.evaluate.js

@@ -1,4 +1,21 @@
-const visitorKeys = Object.fromEntries(
+import { generateReferenceSharedVisitorKeys } from "../utilities/visitor-keys.js";
+
+/**
+@import {VisitorKeys} from "../utilities/visitor-keys.js";
+*/
+
+const commentsKeys = [
+  "indicatorComment",
+  "leadingComments",
+  "middleComments",
+  "trailingComment",
+  "endComments",
+];
+
+const tagAndAnchor = ["anchor", "tag"];
+
+/** @type {VisitorKeys} */
+let visitorKeys = Object.fromEntries(
   Object.entries({
     root: ["children"],
     document: ["head", "body", "children"],
@@ -28,15 +45,12 @@ const visitorKeys = Object.fromEntries(
     type,
     [
       ...keys,
-      "anchor",
-      "tag",
-      "indicatorComment",
-      "leadingComments",
-      "middleComments",
-      "trailingComment",
-      "endComments",
+      ...(type !== "tag" && type !== "anchor" ? tagAndAnchor : []),
+      ...commentsKeys,
     ],
   ]),
 );
 
+visitorKeys = generateReferenceSharedVisitorKeys(visitorKeys);
+
 export default visitorKeys;

src/utilities/visitor-keys.js

@@ -1,4 +1,6 @@
-/** @typedef {Record<string, readonly string[]>} VisitorKeys */
+/**
+@typedef {readonly string[]} Keys
+@typedef {Record<string, Keys>} VisitorKeys */
 
 const unique = (values) => [...new Set(values)];
 
@@ -64,4 +66,30 @@ function removeNodeTypes(visitorKeys, nodeTypesToRemove) {
   return result;
 }
 
-export { removeNodeTypes, removeVisitorKeys, unionVisitorKeys };
+/**
+@param {VisitorKeys} visitorKeys
+@returns {VisitorKeys}
+*/
+function generateReferenceSharedVisitorKeys(visitorKeys) {
+  /** @type {Map<string, Keys>} */
+  const cache = new Map();
+  /** @type {VisitorKeys} */
+  const result = {};
+
+  for (const [type, keys] of Object.entries(visitorKeys)) {
+    const cacheKey = keys.toSorted().join("\0");
+    if (!cache.has(cacheKey)) {
+      cache.set(cacheKey, keys);
+    }
+    result[type] = cache.get(cacheKey);
+  }
+
+  return result;
+}
+
+export {
+  generateReferenceSharedVisitorKeys,
+  removeNodeTypes,
+  removeVisitorKeys,
+  unionVisitorKeys,
+};

tests/integration/__tests__/bundle.js

@@ -1,5 +1,6 @@
 import fs from "node:fs/promises";
 import path from "node:path";
+import { inspect } from "node:util";
 import createEsmUtils from "esm-utils";
 import fastGlob from "fast-glob";
 import coreOptions from "../../../src/main/core-options.evaluate.js";
@@ -70,6 +71,111 @@ describe("standalone", () => {
       expect(esmOutput).toBe(umdOutput);
     });
   }
+
+  const printerVisitorKeysSettings = new Map([
+    [
+      "estree",
+      {
+        sharedVisitorKeys: true,
+        nodes: [
+          { type: "FunctionDeclaration" },
+          { type: "FunctionExpression" },
+        ],
+      },
+    ],
+    [
+      "estree-json",
+      {
+        sharedVisitorKeys: true,
+        nodes: [{ type: "StringLiteral" }, { type: "Identifier" }],
+      },
+    ],
+    [
+      "glimmer",
+      {
+        sharedVisitorKeys: false,
+        nodes: [{ type: "Template" }, { type: "Block" }],
+      },
+    ],
+    [
+      "graphql",
+      {
+        sharedVisitorKeys: false,
+        nodes: [{ kind: "StringValue" }, { kind: "BooleanValue" }],
+      },
+    ],
+    [
+      "html",
+      {
+        sharedVisitorKeys: true,
+        nodes: [{ kind: "comment" }, { kind: "cdata" }],
+      },
+    ],
+    [
+      "mdast",
+      {
+        sharedVisitorKeys: true,
+        nodes: [{ type: "code" }, { type: "image" }],
+      },
+    ],
+    [
+      "postcss",
+      {
+        sharedVisitorKeys: true,
+        nodes: [{ type: "media-query-list" }, { type: "selector-pseudo" }],
+      },
+    ],
+    [
+      "yaml",
+      {
+        sharedVisitorKeys: true,
+        nodes: [{ type: "blockLiteral" }, { type: "quoteSingle" }],
+      },
+    ],
+  ]);
+
+  test("visitor keys with shared reference", () => {
+    for (const [name, printer] of esmPlugins.flatMap((plugin) =>
+      Object.entries(plugin.printers ?? {}),
+    )) {
+      try {
+        expect(printerVisitorKeysSettings.has(name)).toBe(true);
+      } catch {
+        throw new Error(`Missing settings for printer '${name}'.`);
+      }
+      const { getVisitorKeys } = printer;
+      expect(typeof getVisitorKeys).toBe("function");
+      const { sharedVisitorKeys, nodes } = printerVisitorKeysSettings.get(name);
+      expect(
+        typeof sharedVisitorKeys === "boolean" &&
+          Array.isArray(nodes) &&
+          nodes.length > 1,
+      ).toBe(true);
+      const keys = nodes.map((node) => getVisitorKeys(node));
+
+      try {
+        expect(keys.every((keys) => Array.isArray(keys))).toBe(true);
+      } catch {
+        throw new Error(
+          `Missing visitor keys for '${name}' nodes: ${inspect(nodes)}.`,
+        );
+      }
+      const [firstNodeKeys, ...restNodeKeys] = keys;
+      if (sharedVisitorKeys) {
+        // Should be same reference
+        expect(restNodeKeys.every((keys) => keys === firstNodeKeys)).toBe(true);
+      } else {
+        // Should be same, but not same reference
+        expect(
+          restNodeKeys.every(
+            (keys) =>
+              keys !== firstNodeKeys &&
+              JSON.stringify(keys) === JSON.stringify(firstNodeKeys),
+          ),
+        ).toBe(true);
+      }
+    }
+  });
 });
 
 test("global objects", async () => {

tests/unit/__snapshots__/visitor-keys.js.snap

@@ -1668,12 +1668,10 @@ exports[`visitor keys yaml 1`] = `
     "trailingComment",
   ],
   "anchor": [
-    "anchor",
     "endComments",
     "indicatorComment",
     "leadingComments",
     "middleComments",
-    "tag",
     "trailingComment",
   ],
   "blockFolded": [
@@ -1892,12 +1890,10 @@ exports[`visitor keys yaml 1`] = `
     "trailingComment",
   ],
   "tag": [
-    "anchor",
     "endComments",
     "indicatorComment",
     "leadingComments",
     "middleComments",
-    "tag",
     "trailingComment",
   ],
 }

tests/unit/visitor-keys.js

@@ -1,11 +1,11 @@
-import postcssVisitorKeys from "../../src/language-css/visitor-keys.js";
+import postcssVisitorKeys from "../../src/language-css/visitor-keys.evaluate.js";
 import graphqlVisitorKeys from "../../src/language-graphql/visitor-keys.js";
-import glimmerVisitorKeys from "../../src/language-handlebars/visitor-keys.evaluate.js";
-import htmlVisitorKeys from "../../src/language-html/visitor-keys.js";
+import glimmerVisitorKeys from "../../src/language-handlebars/visitor-keys.js";
+import htmlVisitorKeys from "../../src/language-html/visitor-keys.evaluate.js";
 import estreeVisitorKeys from "../../src/language-js/traverse/visitor-keys.evaluate.js";
-import jsonVisitorKeys from "../../src/language-json/visitor-keys.js";
-import remarkVisitorKeys from "../../src/language-markdown/visitor-keys.js";
-import yamlVisitorKeys from "../../src/language-yaml/visitor-keys.js";
+import jsonVisitorKeys from "../../src/language-json/visitor-keys.evaluate.js";
+import remarkVisitorKeys from "../../src/language-markdown/visitor-keys.evaluate.js";
+import yamlVisitorKeys from "../../src/language-yaml/visitor-keys.evaluate.js";
 
 // Keep eye on package change
 describe("visitor keys", () => {