Add transform support for JSON modules imports (babel#16172)

packages/babel-helper-import-to-platform-api/.npmignore

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+src
+test
+*.log

packages/babel-helper-import-to-platform-api/README.md

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+# @babel/helper-import-to-platform-api
+
+> Helper function to transform import statements to platform-specific APIs
+
+See our website [@babel/helper-import-to-platform-api](https://babeljs.io/docs/babel-helper-import-to-platform-api) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save @babel/helper-import-to-platform-api
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/helper-import-to-platform-api
+```

packages/babel-helper-import-to-platform-api/package.json

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+{
+  "name": "@babel/helper-import-to-platform-api",
+  "version": "7.22.5",
+  "description": "Helper function to transform import statements to platform-specific APIs",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/babel/babel.git",
+    "directory": "packages/babel-helper-import-to-platform-api"
+  },
+  "homepage": "https://babel.dev/docs/en/next/babel-helper-import-to-platform-api",
+  "license": "MIT",
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "./lib/index.js",
+  "dependencies": {
+    "@babel/helper-compilation-targets": "workspace:^",
+    "@babel/helper-module-imports": "workspace:^"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.0.0-0"
+  },
+  "TODO": "The @babel/traverse dependency is only needed for the NodePath TS type. We can consider exporting it from @babel/core.",
+  "devDependencies": {
+    "@babel/core": "workspace:^",
+    "@babel/traverse": "workspace:^"
+  },
+  "engines": {
+    "node": ">=6.9.0"
+  },
+  "author": "The Babel Team (https://babel.dev/team)",
+  "conditions": {
+    "BABEL_8_BREAKING": [
+      {
+        "engines": {
+          "node": "^16.20.0 || ^18.16.0 || >=20.0.0"
+        }
+      },
+      {
+        "exports": null
+      }
+    ],
+    "USE_ESM": [
+      {
+        "type": "module"
+      },
+      null
+    ]
+  },
+  "exports": {
+    ".": "./lib/index.js",
+    "./package.json": "./package.json"
+  },
+  "type": "commonjs"
+}

packages/babel-helper-import-to-platform-api/src/index.ts

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+import { types as t, template } from "@babel/core";
+import type { NodePath } from "@babel/traverse";
+import type { Targets } from "@babel/helper-compilation-targets";
+import { addNamed } from "@babel/helper-module-imports";
+
+import getSupport from "./platforms-support.ts";
+
+function imp(path: NodePath, name: string, module: string) {
+  return addNamed(path, name, module, { importedType: "es6" });
+}
+
+export interface Pieces {
+  webFetch: (fetch: t.Expression) => t.Expression;
+  nodeFsSync: (read: t.Expression) => t.Expression;
+  nodeFsAsync: () => t.Expression;
+}
+
+export interface Builders {
+  buildFetch: (specifier: t.Expression, path: NodePath) => t.Expression;
+  buildFetchAsync: (specifier: t.Expression, path: NodePath) => t.Expression;
+  needsAwait: boolean;
+}
+
+const imr = (s: t.Expression) => template.expression.ast`
+  import.meta.resolve(${s})
+`;
+const imrWithFallback = (s: t.Expression) => template.expression.ast`
+  import.meta.resolve?.(${s}) ?? new URL(${t.cloneNode(s)}, import.meta.url)
+`;
+
+export function importToPlatformApi(
+  targets: Targets,
+  transformers: Pieces,
+  toCommonJS: boolean,
+) {
+  const {
+    needsNodeSupport,
+    needsWebSupport,
+    nodeSupportsIMR,
+    webSupportsIMR,
+    nodeSupportsFsPromises,
+  } = getSupport(targets);
+
+  let buildFetchAsync: (
+    specifier: t.Expression,
+    path: NodePath,
+  ) => t.Expression;
+  let buildFetchSync: typeof buildFetchAsync;
+
+  // "p" stands for pattern matching :)
+  const p = ({
+    web: w,
+    node: n,
+    nodeFSP: nF = nodeSupportsFsPromises,
+    webIMR: wI = webSupportsIMR,
+    nodeIMR: nI = nodeSupportsIMR,
+    toCJS: c = toCommonJS,
+  }: {
+    web: boolean;
+    node: boolean;
+    nodeFSP?: boolean;
+    webIMR?: boolean;
+    nodeIMR?: boolean;
+    toCJS?: boolean;
+    preferSync?: boolean;
+  }) => +w + (+n << 1) + (+wI << 2) + (+nI << 3) + (+c << 4) + (+nF << 5);
+
+  const readFileP = (fs: t.Expression, arg: t.Expression) => {
+    if (nodeSupportsFsPromises) {
+      return template.expression.ast`${fs}.promises.readFile(${arg})`;
+    }
+    return template.expression.ast`
+      new Promise(
+        (a =>
+          (r, j) => ${fs}.readFile(a, (e, d) => e ? j(e) : r(d))
+        )(${arg})
+      )`;
+  };
+
+  switch (
+    p({
+      web: needsWebSupport,
+      node: needsNodeSupport,
+      webIMR: webSupportsIMR,
+      nodeIMR: nodeSupportsIMR,
+      toCJS: toCommonJS,
+    })
+  ) {
+    case p({ web: true, node: true }):
+      buildFetchAsync = specifier => {
+        const web = transformers.webFetch(
+          t.callExpression(t.identifier("fetch"), [
+            (webSupportsIMR ? imr : imrWithFallback)(t.cloneNode(specifier)),
+          ]),
+        );
+        const node = nodeSupportsIMR
+          ? template.expression.ast`
+                import("fs").then(
+                  fs => ${readFileP(
+                    t.identifier("fs"),
+                    template.expression.ast`new URL(${imr(specifier)})`,
+                  )}
+                ).then(${transformers.nodeFsAsync()})
+              `
+          : template.expression.ast`
+                Promise.all([import("fs"), import("module")])
+                  .then(([fs, module]) =>
+                    ${readFileP(
+                      t.identifier("fs"),
+                      template.expression.ast`
+                        module.createRequire(import.meta.url).resolve(${specifier})
+                      `,
+                    )}
+                  )
+                  .then(${transformers.nodeFsAsync()})
+              `;
+
+        return template.expression.ast`
+            typeof process === "object" && process.versions?.node
+              ? ${node}
+              : ${web}
+          `;
+      };
+      break;
+    case p({ web: true, node: false, webIMR: true }):
+      buildFetchAsync = specifier =>
+        transformers.webFetch(
+          t.callExpression(t.identifier("fetch"), [imr(specifier)]),
+        );
+      break;
+    case p({ web: true, node: false, webIMR: false }):
+      buildFetchAsync = specifier =>
+        transformers.webFetch(
+          t.callExpression(t.identifier("fetch"), [imrWithFallback(specifier)]),
+        );
+      break;
+    case p({ web: false, node: true, toCJS: true }):
+      buildFetchSync = specifier =>
+        transformers.nodeFsSync(template.expression.ast`
+            require("fs").readFileSync(require.resolve(${specifier}))
+          `);
+      buildFetchAsync = specifier => template.expression.ast`
+            require("fs").promises.readFile(require.resolve(${specifier}))
+              .then(${transformers.nodeFsAsync()})
+          `;
+      break;
+    case p({ web: false, node: true, toCJS: false, nodeIMR: true }):
+      buildFetchSync = (specifier, path) =>
+        transformers.nodeFsSync(template.expression.ast`
+            ${imp(path, "readFileSync", "fs")}(
+              new URL(${imr(specifier)})
+            )
+          `);
+      buildFetchAsync = (specifier, path) =>
+        template.expression.ast`
+          ${imp(path, "promises", "fs")}
+            .readFile(new URL(${imr(specifier)}))
+            .then(${transformers.nodeFsAsync()})
+        `;
+      break;
+    case p({ web: false, node: true, toCJS: false, nodeIMR: false }):
+      buildFetchSync = (specifier, path) =>
+        transformers.nodeFsSync(template.expression.ast`
+            ${imp(path, "readFileSync", "fs")}(
+              ${imp(path, "createRequire", "module")}(import.meta.url)
+                .resolve(${specifier})
+            )
+          `);
+      buildFetchAsync = (specifier, path) =>
+        transformers.webFetch(template.expression.ast`
+            ${imp(path, "promises", "fs")}
+              .readFile(
+                ${imp(path, "createRequire", "module")}(import.meta.url)
+                  .resolve(${specifier})
+              )
+          `);
+      break;
+    default:
+      throw new Error("Internal Babel error: unreachable code.");
+  }
+
+  buildFetchAsync ??= buildFetchSync;
+  const buildFetchAsyncWrapped: typeof buildFetchAsync = (expression, path) => {
+    if (t.isStringLiteral(expression)) {
+      return template.expression.ast`
+        Promise.resolve().then(() => ${buildFetchAsync(expression, path)})
+      `;
+    } else {
+      return template.expression.ast`
+        Promise.resolve(\`\${${expression}}\`).then((s) => ${buildFetchAsync(
+          t.identifier("s"),
+          path,
+        )})
+      `;
+    }
+  };
+
+  return {
+    buildFetch: buildFetchSync || buildFetchAsync,
+    buildFetchAsync: buildFetchAsyncWrapped,
+    needsAwait: !buildFetchSync,
+  };
+}
+
+export function buildParallelStaticImports(
+  data: Array<{ id: t.Identifier; fetch: t.Expression }>,
+  needsAwait: boolean,
+): t.VariableDeclaration | null {
+  if (data.length === 0) return null;
+
+  const declarators: t.VariableDeclarator[] = [];
+
+  if (data.length === 1) {
+    let rhs = data[0].fetch;
+    if (needsAwait) rhs = t.awaitExpression(rhs);
+    declarators.push(t.variableDeclarator(data[0].id, rhs));
+  } else if (needsAwait) {
+    const ids = data.map(({ id }) => id);
+    const fetches = data.map(({ fetch }) => fetch);
+    declarators.push(
+      t.variableDeclarator(
+        t.arrayPattern(ids),
+        t.awaitExpression(
+          template.expression.ast`
+            Promise.all(${t.arrayExpression(fetches)})
+          `,
+        ),
+      ),
+    );
+  } else {
+    for (const { id, fetch } of data) {
+      declarators.push(t.variableDeclarator(id, fetch));
+    }
+  }
+
+  return t.variableDeclaration("const", declarators);
+}

packages/babel-helper-import-to-platform-api/src/platforms-support.ts

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+import { isRequired, type Targets } from "@babel/helper-compilation-targets";
+
+function isEmpty(obj: object) {
+  return Object.keys(obj).length === 0;
+}
+
+const isRequiredOptions = {
+  compatData: {
+    // `import.meta.resolve` compat data.
+    // Source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import.meta/resolve#browser_compatibility
+    // Once Node.js implements `fetch` of local files, we can re-use the web implementation for it
+    // similarly to how we do for Deno.
+    webIMR: {
+      chrome: "105.0.0",
+      edge: "105.0.0",
+      firefox: "106.0.0",
+      opera: "91.0.0",
+      safari: "16.4.0",
+      opera_mobile: "72.0.0",
+      ios: "16.4.0",
+      samsung: "20.0",
+      deno: "1.24.0",
+    },
+    nodeIMR: {
+      node: "20.6.0",
+    },
+    // Node.js require("fs").promises compat data.
+    nodeFSP: {
+      node: "10.0.0",
+    },
+  },
+};
+
+interface Support {
+  needsNodeSupport: boolean;
+  needsWebSupport: boolean;
+  nodeSupportsIMR: boolean;
+  webSupportsIMR: boolean;
+  nodeSupportsFsPromises: boolean;
+}
+
+const SUPPORT_CACHE = new WeakMap<Targets, Support>();
+export default function getSupport(targets: Targets): Support {
+  if (SUPPORT_CACHE.has(targets)) return SUPPORT_CACHE.get(targets)!;
+
+  const { node: nodeTarget, ...webTargets } = targets;
+  const emptyNodeTarget = nodeTarget == null;
+  const emptyWebTargets = isEmpty(webTargets);
+  const needsNodeSupport = !emptyNodeTarget || emptyWebTargets;
+  const needsWebSupport = !emptyWebTargets || emptyNodeTarget;
+
+  const webSupportsIMR =
+    !emptyWebTargets && !isRequired("webIMR", webTargets, isRequiredOptions);
+  const nodeSupportsIMR =
+    !emptyNodeTarget &&
+    !isRequired("nodeIMR", { node: nodeTarget }, isRequiredOptions);
+  const nodeSupportsFsPromises =
+    !emptyNodeTarget &&
+    !isRequired("nodeFSP", { node: nodeTarget }, isRequiredOptions);
+
+  const result = {
+    needsNodeSupport,
+    needsWebSupport,
+    nodeSupportsIMR,
+    webSupportsIMR,
+    nodeSupportsFsPromises,
+  };
+  SUPPORT_CACHE.set(targets, result);
+  return result;
+}

packages/babel-plugin-proposal-import-wasm-source/package.json

@@ -29,8 +29,7 @@
     "stage-3"
   ],
   "dependencies": {
-    "@babel/helper-compilation-targets": "workspace:^",
-    "@babel/helper-module-imports": "workspace:^",
+    "@babel/helper-import-to-platform-api": "workspace:^",
     "@babel/helper-plugin-utils": "workspace:^",
     "@babel/plugin-syntax-import-source": "workspace:^"
   },