Add ability to load JSON as modules (#1065)

js/compiler.ts

@@ -79,7 +79,7 @@ export interface Ts {
  */
 export class ModuleMetaData implements ts.IScriptSnapshot {
   public deps?: ModuleFileName[];
-  public readonly exports = {};
+  public exports = {};
   public factory?: AmdFactory;
   public gatheringDeps = false;
   public hasRun = false;
@@ -129,6 +129,15 @@ function getExtension(
   }
 }
 
+/** Generate output code for a provided JSON string along with its source. */
+export function jsonAmdTemplate(
+  jsonString: string,
+  sourceFileName: string
+): OutputCode {
+  // tslint:disable-next-line:max-line-length
+  return `define([], function() { return JSON.parse(\`${jsonString}\`); });\n//# sourceURL=${sourceFileName}`;
+}
+
 /** A singleton class that combines the TypeScript Language Service host API
  * with Deno specific APIs to provide an interface for compiling and running
  * TypeScript and JavaScript modules.
@@ -153,11 +162,12 @@ export class DenoCompiler
   >();
   // TODO ideally this are not static and can be influenced by command line
   // arguments
-  private readonly _options: Readonly<ts.CompilerOptions> = {
+  private readonly _options: ts.CompilerOptions = {
     allowJs: true,
     checkJs: true,
     module: ts.ModuleKind.AMD,
     outDir: "$deno$",
+    resolveJsonModule: true,
     sourceMap: true,
     stripComments: true,
     target: ts.ScriptTarget.ESNext
@@ -198,7 +208,15 @@ export class DenoCompiler
       );
       assert(moduleMetaData.hasRun === false, "Module has already been run.");
       // asserts not tracked by TypeScripts, so using not null operator
-      moduleMetaData.factory!(...this._getFactoryArguments(moduleMetaData));
+      const exports = moduleMetaData.factory!(
+        ...this._getFactoryArguments(moduleMetaData)
+      );
+      // For JSON module support and potential future features.
+      // TypeScript always imports `exports` and mutates it directly, but the
+      // AMD specification allows values to be returned from the factory.
+      if (exports != null) {
+        moduleMetaData.exports = exports;
+      }
       moduleMetaData.hasRun = true;
     }
   }
@@ -421,50 +439,74 @@ export class DenoCompiler
     if (!recompile && moduleMetaData.outputCode) {
       return moduleMetaData.outputCode;
     }
-    const { fileName, sourceCode, moduleId } = moduleMetaData;
+    const { fileName, sourceCode, mediaType, moduleId } = moduleMetaData;
     console.warn("Compiling", moduleId);
     const service = this._service;
-    const output = service.getEmitOutput(fileName);
-
-    // Get the relevant diagnostics - this is 3x faster than
-    // `getPreEmitDiagnostics`.
-    const diagnostics = [
-      ...service.getCompilerOptionsDiagnostics(),
-      ...service.getSyntacticDiagnostics(fileName),
-      ...service.getSemanticDiagnostics(fileName)
-    ];
-    if (diagnostics.length > 0) {
-      const errMsg = this._ts.formatDiagnosticsWithColorAndContext(
-        diagnostics,
-        this
+    // Instead of using TypeScript to transpile JSON modules, we will just do
+    // it directly.
+    if (mediaType === MediaType.Json) {
+      moduleMetaData.outputCode = jsonAmdTemplate(sourceCode, fileName);
+    } else {
+      assert(
+        mediaType === MediaType.TypeScript || mediaType === MediaType.JavaScript
       );
-      console.log(errMsg);
-      // All TypeScript errors are terminal for deno
-      this._os.exit(1);
-    }
+      // TypeScript is overly opinionated that only CommonJS modules kinds can
+      // support JSON imports.  Allegedly this was fixed in
+      // Microsoft/TypeScript#26825 but that doesn't seem to be working here,
+      // so we will trick the TypeScript compiler.
+      this._options.module = ts.ModuleKind.AMD;
+      const output = service.getEmitOutput(fileName);
+      this._options.module = ts.ModuleKind.CommonJS;
+
+      // Get the relevant diagnostics - this is 3x faster than
+      // `getPreEmitDiagnostics`.
+      const diagnostics = [
+        ...service.getCompilerOptionsDiagnostics(),
+        ...service.getSyntacticDiagnostics(fileName),
+        ...service.getSemanticDiagnostics(fileName)
+      ];
+      if (diagnostics.length > 0) {
+        const errMsg = this._ts.formatDiagnosticsWithColorAndContext(
+          diagnostics,
+          this
+        );
+        console.log(errMsg);
+        // All TypeScript errors are terminal for deno
+        this._os.exit(1);
+      }
 
-    assert(!output.emitSkipped, "The emit was skipped for an unknown reason.");
+      assert(
+        !output.emitSkipped,
+        "The emit was skipped for an unknown reason."
+      );
 
-    assert(
-      output.outputFiles.length === 2,
-      `Expected 2 files to be emitted, got ${output.outputFiles.length}.`
-    );
+      assert(
+        output.outputFiles.length === 2,
+        `Expected 2 files to be emitted, got ${output.outputFiles.length}.`
+      );
+
+      const [sourceMapFile, outputFile] = output.outputFiles;
+      assert(
+        sourceMapFile.name.endsWith(".map"),
+        "Expected first emitted file to be a source map"
+      );
+      assert(
+        outputFile.name.endsWith(".js"),
+        "Expected second emitted file to be JavaScript"
+      );
+      moduleMetaData.outputCode = `${
+        outputFile.text
+      }\n//# sourceURL=${fileName}`;
+      moduleMetaData.sourceMap = sourceMapFile.text;
+    }
 
-    const [sourceMapFile, outputFile] = output.outputFiles;
-    assert(
-      sourceMapFile.name.endsWith(".map"),
-      "Expected first emitted file to be a source map"
-    );
-    assert(
-      outputFile.name.endsWith(".js"),
-      "Expected second emitted file to be JavaScript"
-    );
-    const outputCode = (moduleMetaData.outputCode = `${
-      outputFile.text
-    }\n//# sourceURL=${fileName}`);
-    const sourceMap = (moduleMetaData.sourceMap = sourceMapFile.text);
     moduleMetaData.scriptVersion = "1";
-    this._os.codeCache(fileName, sourceCode, outputCode, sourceMap);
+    this._os.codeCache(
+      fileName,
+      sourceCode,
+      moduleMetaData.outputCode,
+      moduleMetaData.sourceMap
+    );
     return moduleMetaData.outputCode;
   }
 

js/compiler_test.ts

@@ -6,7 +6,7 @@ import * as ts from "typescript";
 // We use a silly amount of `any` in these tests...
 // tslint:disable:no-any
 
-const { DenoCompiler } = (deno as any)._compiler;
+const { DenoCompiler, jsonAmdTemplate } = (deno as any)._compiler;
 
 interface ModuleInfo {
   moduleName: string | undefined;
@@ -118,6 +118,11 @@ const fooBazTsOutput = `define(["require", "exports", "./bar.ts"], function (req
 
 // This is not a valid map, just mock data
 const fooBazTsSourcemap = `{"version":3,"file":"baz.js","sourceRoot":"","sources":["file:///root/project/foo/baz.ts"],"names":[],"mappings":""}`;
+
+const loadConfigSource = `import * as config from "./config.json";
+console.log(config.foo.baz);
+`;
+const configJsonSource = `{"foo":{"bar": true,"baz": ["qat", 1]}}`;
 // tslint:enable:max-line-length
 
 const moduleMap: {
@@ -148,6 +153,14 @@ const moduleMap: {
       "console.log();",
       null,
       null
+    ),
+    "loadConfig.ts": mockModuleInfo(
+      "/root/project/loadConfig.ts",
+      "/root/project/loadConfig.ts",
+      MediaType.TypeScript,
+      loadConfigSource,
+      null,
+      null
     )
   },
   "/root/project/foo/baz.ts": {
@@ -166,6 +179,16 @@ const moduleMap: {
   "/root/project/modB.ts": {
     "./modA.ts": modAModuleInfo
   },
+  "/root/project/loadConfig.ts": {
+    "./config.json": mockModuleInfo(
+      "/root/project/config.json",
+      "/root/project/config.json",
+      MediaType.Json,
+      configJsonSource,
+      null,
+      null
+    )
+  },
   "/moduleKinds": {
     "foo.ts": mockModuleInfo(
       "foo",
@@ -280,7 +303,7 @@ const osMock = {
     return mockModuleInfo(null, null, null, null, null, null);
   },
   exit(code: number): never {
-    throw new Error(`os.exit(${code})`);
+    throw new Error(`Unexpected call to os.exit(${code})`);
   }
 };
 const tsMock = {
@@ -289,9 +312,9 @@ const tsMock = {
   },
   formatDiagnosticsWithColorAndContext(
     diagnostics: ReadonlyArray<ts.Diagnostic>,
-    host: ts.FormatDiagnosticsHost
+    _host: ts.FormatDiagnosticsHost
   ): string {
-    return "";
+    return JSON.stringify(diagnostics.map(({ messageText }) => messageText));
   }
 };
 
@@ -374,6 +397,23 @@ function teardown() {
   Object.assign(compilerInstance, originals);
 }
 
+test(function testJsonAmdTemplate() {
+  let deps: string[];
+  let factory: Function;
+  function define(d: string[], f: Function) {
+    deps = d;
+    factory = f;
+  }
+
+  const code = jsonAmdTemplate(`{ "hello": "world", "foo": "bar" }`);
+  const result = eval(code);
+  assert(result == null);
+  assertEqual(deps && deps.length, 0);
+  assert(factory != null);
+  const factoryResult = factory();
+  assertEqual(factoryResult, { hello: "world", foo: "bar" });
+});
+
 test(function compilerInstance() {
   assert(DenoCompiler != null);
   assert(DenoCompiler.instance() != null);
@@ -479,6 +519,29 @@ test(function compilerRunCircularDependency() {
   teardown();
 });
 
+test(function compilerLoadJsonModule() {
+  setup();
+  const factoryStack: string[] = [];
+  const configJsonDeps: string[] = [];
+  const configJsonFactory = () => {
+    factoryStack.push("configJson");
+    return JSON.parse(configJsonSource);
+  };
+  const loadConfigDeps = ["require", "exports", "./config.json"];
+  const loadConfigFactory = (_require, _exports, _config) => {
+    factoryStack.push("loadConfig");
+    assertEqual(_config, JSON.parse(configJsonSource));
+  };
+
+  mockDepsStack.push(configJsonDeps);
+  mockFactoryStack.push(configJsonFactory);
+  mockDepsStack.push(loadConfigDeps);
+  mockFactoryStack.push(loadConfigFactory);
+  compilerInstance.run("loadConfig.ts", "/root/project");
+  assertEqual(factoryStack, ["configJson", "loadConfig"]);
+  teardown();
+});
+
 test(function compilerResolveModule() {
   setup();
   const moduleMetaData = compilerInstance.resolveModule(
@@ -544,6 +607,7 @@ test(function compilerGetCompilationSettings() {
     "checkJs",
     "module",
     "outDir",
+    "resolveJsonModule",
     "sourceMap",
     "stripComments",
     "target"

tests/020_json_modules.ts

+import * as config from "./subdir/config.json";
+
+console.log(JSON.stringify(config));

tests/020_json_modules.ts.out

+{"foo":{"bar":true,"baz":["qat",1]}}

tests/subdir/config.json

+{
+  "foo": {
+    "bar": true,
+    "baz": ["qat", 1]
+  }
+}

tsconfig.json

@@ -16,6 +16,7 @@
     "preserveConstEnums": true,
     "pretty": true,
     "removeComments": true,
+    "resolveJsonModule": true,
     "sourceMap": true,
     "strict": true,
     "target": "esnext",