annotate local paths

package.json

@@ -26,8 +26,9 @@
     "test": "concurrently npm:test:mocha npm:test:tsc npm:test:lint npm:test:prettier",
     "test:coverage": "c8 --check-coverage --lines 80 --per-file yarn test:mocha",
     "test:build": "rimraf test/build && cross-env npm_package_version=1.0.0-test node build.js --sourcemap --outdir=test/build \"{src,test}/**/*.{ts,js,css}\" --ignore \"test/input/**\" --ignore \"test/output/**\" --ignore \"test/preview/dashboard/**\" --ignore \"**/*.d.ts\" && cp -r templates test/build",
-    "test:mocha": "yarn test:build && rimraf --glob test/.observablehq/cache test/input/build/*/.observablehq/cache && cross-env OBSERVABLE_TELEMETRY_DISABLE=1 TZ=America/Los_Angeles mocha --timeout 30000 -p \"test/build/test/**/*-test.js\"",
-    "test:mocha:serial": "yarn test:build && rimraf --glob test/.observablehq/cache test/input/build/*/.observablehq/cache && cross-env OBSERVABLE_TELEMETRY_DISABLE=1 TZ=America/Los_Angeles mocha --timeout 30000 \"test/build/test/**/*-test.js\"",
+    "test:mocha": "yarn test:build && rimraf --glob test/.observablehq/cache test/input/build/*/.observablehq/cache && cross-env OBSERVABLE_TELEMETRY_DISABLE=1 TZ=America/Los_Angeles mocha --timeout 30000 -p \"test/build/test/**/*-test.js\" && yarn test:annotate",
+    "test:mocha:serial": "yarn test:build && rimraf --glob test/.observablehq/cache test/input/build/*/.observablehq/cache && cross-env OBSERVABLE_TELEMETRY_DISABLE=1 TZ=America/Los_Angeles mocha --timeout 30000 \"test/build/test/**/*-test.js\" && yarn test:annotate",
+    "test:annotate": "yarn test:build && cross-env OBSERVABLE_ANNOTATE_FILES=true TZ=America/Los_Angeles mocha --timeout 30000 \"test/build/test/**/annotate.js\"",
     "test:lint": "eslint src test --max-warnings=0",
     "test:prettier": "prettier --check src test",
     "test:tsc": "tsc --noEmit",

src/javascript/annotate.ts

@@ -0,0 +1,14 @@
+import {isPathImport} from "../path.js";
+
+/**
+ * Annotate a path to a local import or file so it can be reworked server-side.
+ */
+
+const annotate = process.env["OBSERVABLE_ANNOTATE_FILES"];
+if (typeof annotate === "string" && annotate !== "true")
+  throw new Error(`unsupported OBSERVABLE_ANNOTATE_FILES value: ${annotate}`);
+export default annotate
+  ? function (uri: string): string {
+      return `${JSON.stringify(uri)}${isPathImport(uri) ? "/* observablehq-file */" : ""}`;
+    }
+  : JSON.stringify;

src/javascript/transpile.ts

@@ -7,6 +7,7 @@ import {isPathImport, relativePath, resolvePath, resolveRelativePath} from "../p
 import {getModuleResolver} from "../resolvers.js";
 import type {Params} from "../route.js";
 import {Sourcemap} from "../sourcemap.js";
+import annotate from "./annotate.js";
 import type {FileExpression} from "./files.js";
 import {findFiles} from "./files.js";
 import type {ExportNode, ImportNode} from "./imports.js";
@@ -101,7 +102,7 @@ export async function transpileModule(
 
   async function rewriteImportSource(source: StringLiteral) {
     const specifier = getStringLiteralValue(source);
-    output.replaceLeft(source.start, source.end, JSON.stringify(await resolveImport(specifier)));
+    output.replaceLeft(source.start, source.end, annotate(await resolveImport(specifier)));
   }
 
   for (const {name, node} of findFiles(body, path, input)) {
@@ -111,17 +112,15 @@ export async function transpileModule(
     output.replaceLeft(
       source.start,
       source.end,
-      `${JSON.stringify(
+      `${
         info
-          ? {
-              name: p,
-              mimeType: mime.getType(name) ?? undefined,
-              path: relativePath(servePath, resolveFile(name)),
-              lastModified: info.mtimeMs,
-              size: info.size
-            }
-          : p
-      )}, import.meta.url`
+          ? `{"name":${JSON.stringify(p)},"mimeType":${JSON.stringify(
+              mime.getType(name) ?? undefined
+            )},"path":${annotate(relativePath(servePath, resolveFile(name)))},"lastModified":${JSON.stringify(
+              info.mtimeMs
+            )},"size":${JSON.stringify(info.size)}}`
+          : JSON.stringify(p)
+      }, import.meta.url`
     );
   }
 
@@ -137,7 +136,7 @@ export async function transpileModule(
     if (isImportMetaResolve(node) && isStringLiteral(source)) {
       const value = getStringLiteralValue(source);
       const resolution = isPathImport(value) && !isJavaScript(value) ? resolveFile(value) : await resolveImport(value);
-      output.replaceLeft(source.start, source.end, JSON.stringify(resolution));
+      output.replaceLeft(source.start, source.end, annotate(resolution));
     }
   }
 
@@ -205,7 +204,7 @@ function rewriteImportDeclarations(
   for (const node of declarations) {
     output.delete(node.start, node.end + +(output.input[node.end] === "\n"));
     specifiers.push(rewriteImportSpecifiers(node));
-    imports.push(`import(${JSON.stringify(resolve(getStringLiteralValue(node.source as StringLiteral)))})`);
+    imports.push(`import(${annotate(resolve(getStringLiteralValue(node.source as StringLiteral)))})`);
   }
   if (declarations.length > 1) {
     output.insertLeft(0, `const [${specifiers.join(", ")}] = await Promise.all([${imports.join(", ")}]);\n`);

src/node.ts

@@ -13,6 +13,7 @@ import type {AstNode, OutputChunk, Plugin, ResolveIdResult} from "rollup";
 import {rollup} from "rollup";
 import esbuild from "rollup-plugin-esbuild";
 import {prepareOutput, toOsPath} from "./files.js";
+import annotate from "./javascript/annotate.js";
 import type {ImportReference} from "./javascript/imports.js";
 import {isJavaScript, parseImports} from "./javascript/imports.js";
 import {parseNpmSpecifier, rewriteNpmImports} from "./npm.js";
@@ -86,7 +87,7 @@ function isBadCommonJs(specifier: string): boolean {
 }
 
 function shimCommonJs(specifier: string, require: NodeRequire): string {
-  return `export {${Object.keys(require(specifier))}} from ${JSON.stringify(specifier)};\n`;
+  return `export {${Object.keys(require(specifier))}} from ${annotate(specifier)};\n`;
 }
 
 async function bundle(

src/npm.ts

@@ -5,6 +5,7 @@ import type {CallExpression} from "acorn";
 import {simple} from "acorn-walk";
 import {maxSatisfying, rsort, satisfies, validRange} from "semver";
 import {isEnoent} from "./error.js";
+import annotate from "./javascript/annotate.js";
 import type {ExportNode, ImportNode, ImportReference} from "./javascript/imports.js";
 import {isImportMetaResolve, parseImports} from "./javascript/imports.js";
 import {parseProgram} from "./javascript/parse.js";
@@ -64,7 +65,7 @@ export function rewriteNpmImports(input: string, resolve: (s: string) => string
     const value = getStringLiteralValue(source);
     const resolved = resolve(value);
     if (resolved === undefined || value === resolved) return;
-    output.replaceLeft(source.start, source.end, JSON.stringify(resolved));
+    output.replaceLeft(source.start, source.end, annotate(resolved));
   }
 
   // TODO Preserve the source map, but download it too.

src/rollup.ts

@@ -6,6 +6,7 @@ import type {AstNode, OutputChunk, Plugin, ResolveIdResult} from "rollup";
 import {rollup} from "rollup";
 import esbuild from "rollup-plugin-esbuild";
 import {getClientPath, getStylePath} from "./files.js";
+import annotate from "./javascript/annotate.js";
 import type {StringLiteral} from "./javascript/source.js";
 import {getStringLiteralValue, isStringLiteral} from "./javascript/source.js";
 import {resolveNpmImport} from "./npm.js";
@@ -177,7 +178,7 @@ function importMetaResolve(path: string, resolveImport: ImportResolver): Plugin
       for (const source of resolves) {
         const specifier = getStringLiteralValue(source);
         const resolution = await resolveImport(specifier);
-        if (resolution) output.replaceLeft(source.start, source.end, JSON.stringify(relativePath(path, resolution)));
+        if (resolution) output.replaceLeft(source.start, source.end, annotate(relativePath(path, resolution)));
       }
 
       return {code: String(output)};

test/javascript/annotate.ts

@@ -0,0 +1,63 @@
+/**
+ * This file is not suffixed with '-test'; it expects to run with an extra
+ * OBSERVABLE_ANNOTATE_FILES=true environment variable.
+ */
+import assert from "node:assert";
+import type {TranspileModuleOptions} from "../../src/javascript/transpile.js";
+import {transpileModule} from "../../src/javascript/transpile.js";
+import {fromJsDelivrPath, rewriteNpmImports} from "../../src/npm.js";
+import {relativePath} from "../../src/path.js";
+
+// prettier-ignore
+describe("annotates", () => {
+  const options: TranspileModuleOptions = {root: "src", path: "test.js"};
+  it("npm imports", async () => {
+    const input = 'import "npm:d3-array";';
+    const output = (await transpileModule(input, options)).split("\n").pop()!;
+    assert.strictEqual(output, 'import "../_npm/[email protected]/_esm.js"/* observablehq-file */;');
+  });
+  it("node imports", async () => {
+    const input = 'import "d3-array";';
+    const output = (await transpileModule(input, options)).split("\n").pop()!;
+    assert.strictEqual(output, 'import "../_node/[email protected]/index.js"/* observablehq-file */;');
+  });
+  it("dynamic imports", async () => {
+    const input = 'import("d3-array");';
+    const output = (await transpileModule(input, options)).split("\n").pop()!;
+    assert.strictEqual(output, 'import("../_node/[email protected]/index.js"/* observablehq-file */);');
+  });
+   it("/npm/ exports", () => {
+    assert.strictEqual(rewriteNpmImports('export * from "/npm/[email protected]/dist/d3-array.js";\n', (v) => resolve("/_npm/[email protected]/dist/d3.js", v)), 'export * from "../../[email protected]/dist/d3-array.js"/* observablehq-file */;\n');
+   });
+   it("/npm/ imports", () => {
+    assert.strictEqual(rewriteNpmImports('import "/npm/[email protected]/dist/d3-array.js";\n', (v) => resolve("/_npm/[email protected]/dist/d3.js", v)), 'import "../../[email protected]/dist/d3-array.js"/* observablehq-file */;\n');
+    assert.strictEqual(rewriteNpmImports('import "/npm/[email protected]/dist/d3-array.js";\n', (v) => resolve("/_npm/[email protected]/d3.js", v)), 'import "../[email protected]/dist/d3-array.js"/* observablehq-file */;\n');
+   });
+   it("named imports", () => {
+     assert.strictEqual(rewriteNpmImports('import {sort} from "/npm/[email protected]/+esm";\n', (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'import {sort} from "../[email protected]/_esm.js"/* observablehq-file */;\n');
+   });
+   it("empty imports", () => {
+     assert.strictEqual(rewriteNpmImports('import "/npm/[email protected]/+esm";\n', (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'import "../[email protected]/_esm.js"/* observablehq-file */;\n');
+   });
+   it("default imports", () => {
+     assert.strictEqual(rewriteNpmImports('import d3 from "/npm/[email protected]/+esm";\n', (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'import d3 from "../[email protected]/_esm.js"/* observablehq-file */;\n');
+   });
+   it("namespace imports", () => {
+     assert.strictEqual(rewriteNpmImports('import * as d3 from "/npm/[email protected]/+esm";\n', (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'import * as d3 from "../[email protected]/_esm.js"/* observablehq-file */;\n');
+   });
+   it("named exports", () => {
+     assert.strictEqual(rewriteNpmImports('export {sort} from "/npm/[email protected]/+esm";\n', (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'export {sort} from "../[email protected]/_esm.js"/* observablehq-file */;\n');
+   });
+   it("namespace exports", () => {
+     assert.strictEqual(rewriteNpmImports('export * from "/npm/[email protected]/+esm";\n', (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'export * from "../[email protected]/_esm.js"/* observablehq-file */;\n');
+   });
+   it("dynamic imports with static module specifiers", () => {
+     assert.strictEqual(rewriteNpmImports('import("/npm/[email protected]/+esm");\n', (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'import("../[email protected]/_esm.js"/* observablehq-file */);\n');
+     assert.strictEqual(rewriteNpmImports("import(`/npm/[email protected]/+esm`);\n", (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'import("../[email protected]/_esm.js"/* observablehq-file */);\n');
+     assert.strictEqual(rewriteNpmImports("import('/npm/[email protected]/+esm');\n", (v) => resolve("/_npm/[email protected]/_esm.js", v)), 'import("../[email protected]/_esm.js"/* observablehq-file */);\n');
+   });
+});
+
+function resolve(path: string, specifier: string): string {
+  return specifier.startsWith("/npm/") ? relativePath(path, fromJsDelivrPath(specifier)) : specifier;
+}