chore(typescript): refactor compiler host (#214)

packages/typescript/src/diagnostics/emit.ts

@@ -0,0 +1,34 @@
+import { PluginContext } from 'rollup';
+
+import { DiagnosticsHost } from './host';
+import diagnosticToWarning from './toWarning';
+
+// `Cannot compile modules into 'es6' when targeting 'ES5' or lower.`
+const CANNOT_COMPILE_ESM = 1204;
+
+/**
+ * For each type error reported by Typescript, emit a Rollup warning or error.
+ */
+export default function emitDiagnostics(
+  ts: typeof import('typescript'),
+  context: PluginContext,
+  host: DiagnosticsHost,
+  diagnostics: readonly import('typescript').Diagnostic[] | undefined
+) {
+  if (!diagnostics) return;
+  const { noEmitOnError } = host.getCompilationSettings();
+
+  diagnostics
+    .filter((diagnostic) => diagnostic.code !== CANNOT_COMPILE_ESM)
+    .forEach((diagnostic) => {
+      // Build a Rollup warning object from the diagnostics object.
+      const warning = diagnosticToWarning(ts, host, diagnostic);
+
+      // Errors are fatal. Otherwise emit warnings.
+      if (noEmitOnError && diagnostic.category === ts.DiagnosticCategory.Error) {
+        context.error(warning);
+      } else {
+        context.warn(warning);
+      }
+    });
+}

packages/typescript/src/diagnostics/host.ts

@@ -0,0 +1,38 @@
+type FormatDiagnosticsHost = import('typescript').FormatDiagnosticsHost;
+
+export interface DiagnosticsHost extends FormatDiagnosticsHost {
+  getCompilationSettings(): import('typescript').CompilerOptions;
+}
+
+/**
+ * Create a format diagnostics host to use with the Typescript type checking APIs.
+ * Typescript hosts are used to represent the user's system,
+ * with an API for checking case sensitivity etc.
+ * @param compilerOptions Typescript compiler options. Affects functions such as `getNewLine`.
+ * @see https://github.com/Microsoft/TypeScript/wiki/Using-the-Compiler-API
+ */
+export default function createFormattingHost(
+  ts: typeof import('typescript'),
+  compilerOptions: import('typescript').CompilerOptions
+): DiagnosticsHost {
+  return {
+    /** Returns the compiler options for the project. */
+    getCompilationSettings: () => compilerOptions,
+    /** Returns the current working directory. */
+    getCurrentDirectory: () => process.cwd(),
+    /** Returns the string that corresponds with the selected `NewLineKind`. */
+    getNewLine() {
+      switch (compilerOptions.newLine) {
+        case ts.NewLineKind.CarriageReturnLineFeed:
+          return '\r\n';
+        case ts.NewLineKind.LineFeed:
+          return '\n';
+        default:
+          return ts.sys.newLine;
+      }
+    },
+    /** Returns a lower case name on case insensitive systems, otherwise the original name. */
+    getCanonicalFileName: (fileName) =>
+      ts.sys.useCaseSensitiveFileNames ? fileName : fileName.toLowerCase()
+  };
+}

packages/typescript/src/diagnostics.ts → packages/typescript/src/diagnostics/toWarning.ts

@@ -1,40 +1,9 @@
-import { PluginContext, RollupLogProps } from 'rollup';
-
-// `Cannot compile modules into 'es6' when targeting 'ES5' or lower.`
-const CANNOT_COMPILE_ESM = 1204;
-
-/**
- * For each type error reported by Typescript, emit a Rollup warning or error.
- */
-export function emitDiagnostics(
-  ts: typeof import('typescript'),
-  context: PluginContext,
-  host: import('typescript').FormatDiagnosticsHost &
-    Pick<import('typescript').LanguageServiceHost, 'getCompilationSettings'>,
-  diagnostics: readonly import('typescript').Diagnostic[] | undefined
-) {
-  if (!diagnostics) return;
-  const { noEmitOnError } = host.getCompilationSettings();
-
-  diagnostics
-    .filter((diagnostic) => diagnostic.code !== CANNOT_COMPILE_ESM)
-    .forEach((diagnostic) => {
-      // Build a Rollup warning object from the diagnostics object.
-      const warning = diagnosticToWarning(ts, host, diagnostic);
-
-      // Errors are fatal. Otherwise emit warnings.
-      if (noEmitOnError && diagnostic.category === ts.DiagnosticCategory.Error) {
-        context.error(warning);
-      } else {
-        context.warn(warning);
-      }
-    });
-}
+import { RollupLogProps } from 'rollup';
 
 /**
  * Converts a Typescript type error into an equivalent Rollup warning object.
  */
-export function diagnosticToWarning(
+export default function diagnosticToWarning(
   ts: typeof import('typescript'),
   host: import('typescript').FormatDiagnosticsHost | null,
   diagnostic: import('typescript').Diagnostic

packages/typescript/src/host.ts

@@ -1,8 +1,8 @@
-import createModuleResolver, { Resolver } from './resolver';
+import createFormattingHost, { DiagnosticsHost } from './diagnostics/host';
+import createModuleResolutionHost, { ModuleResolutionHost } from './moduleResolution/host';
+import createModuleResolver, { Resolver } from './moduleResolution/resolver';
 
-type BaseHost = import('typescript').LanguageServiceHost &
-  import('typescript').ModuleResolutionHost &
-  import('typescript').FormatDiagnosticsHost;
+type BaseHost = import('typescript').LanguageServiceHost & ModuleResolutionHost & DiagnosticsHost;
 
 export interface TypescriptHost extends BaseHost {
   /**
@@ -35,6 +35,10 @@ interface File {
 
 /**
  * Create a language service host to use with the Typescript compiler & type checking APIs.
+ * Typescript hosts are used to represent the user's system,
+ * with an API for reading files, checking directories and case sensitivity etc.
+ * This host creates a local file cache which can be updated with `addFile`.
+ *
  * @param parsedOptions Parsed options for Typescript.
  * @param parsedOptions.options Typescript compiler options. Affects functions such as `getNewLine`.
  * @param parsedOptions.fileNames Declaration files to include for typechecking.
@@ -79,16 +83,10 @@ export default function createHost(
 
   let resolver: Resolver;
   const host: TypescriptHost = {
-    getCompilationSettings: () => parsedOptions.options,
-    getCurrentDirectory: () => process.cwd(),
-    getNewLine: () => getNewLine(ts, parsedOptions.options.newLine),
-    getCanonicalFileName: (fileName) =>
-      ts.sys.useCaseSensitiveFileNames ? fileName : fileName.toLowerCase(),
+    ...createModuleResolutionHost(ts),
+    ...createFormattingHost(ts, parsedOptions.options),
     useCaseSensitiveFileNames: () => ts.sys.useCaseSensitiveFileNames,
     getDefaultLibFileName: ts.getDefaultLibFilePath,
-    getDirectories: ts.sys.getDirectories,
-    directoryExists: ts.sys.directoryExists,
-    realpath: ts.sys.realpath,
     readDirectory: ts.sys.readDirectory,
     readFile(fileName, encoding) {
       const file = files.get(fileName);
@@ -109,20 +107,3 @@ export default function createHost(
 
   return host;
 }
-
-/**
- * Returns the string that corresponds with the selected `NewLineKind`.
- */
-function getNewLine(
-  ts: typeof import('typescript'),
-  kind: import('typescript').NewLineKind | undefined
-) {
-  switch (kind) {
-    case ts.NewLineKind.CarriageReturnLineFeed:
-      return '\r\n';
-    case ts.NewLineKind.LineFeed:
-      return '\n';
-    default:
-      return ts.sys.newLine;
-  }
-}

packages/typescript/src/index.ts

@@ -4,29 +4,27 @@ import { Plugin } from 'rollup';
 
 import { RollupTypescriptOptions } from '../types';
 
-import { diagnosticToWarning, emitDiagnostics } from './diagnostics';
+import emitDiagnostics from './diagnostics/emit';
+import createFormattingHost from './diagnostics/host';
 import getDocumentRegistry from './documentRegistry';
 import createHost from './host';
-import { getPluginOptions, parseTypescriptConfig } from './options';
+import { emitParsedOptionsErrors, getPluginOptions, parseTypescriptConfig } from './options';
 import typescriptOutputToRollupTransformation from './outputToRollupTransformation';
 import { TSLIB_ID } from './tslib';
 
 export default function typescript(options: RollupTypescriptOptions = {}): Plugin {
   const { filter, tsconfig, compilerOptions, tslib, typescript: ts } = getPluginOptions(options);
 
   const parsedOptions = parseTypescriptConfig(ts, tsconfig, compilerOptions);
+  const formatHost = createFormattingHost(ts, parsedOptions.options);
   const host = createHost(ts, parsedOptions);
   const services = ts.createLanguageService(host, getDocumentRegistry(ts, process.cwd()));
 
   return {
     name: 'typescript',
 
     buildStart() {
-      if (parsedOptions.errors.length > 0) {
-        parsedOptions.errors.forEach((error) => this.warn(diagnosticToWarning(ts, host, error)));
-
-        this.error(`@rollup/plugin-typescript: Couldn't process compiler options`);
-      }
+      emitParsedOptionsErrors(ts, this, parsedOptions);
     },
 
     resolveId(importee, importer) {
@@ -68,7 +66,7 @@ export default function typescript(options: RollupTypescriptOptions = {}): Plugi
         const allDiagnostics = ([] as import('typescript').Diagnostic[])
           .concat(services.getSyntacticDiagnostics(id))
           .concat(services.getSemanticDiagnostics(id));
-        emitDiagnostics(ts, this, host, allDiagnostics);
+        emitDiagnostics(ts, this, formatHost, allDiagnostics);
 
         throw new Error(`Couldn't compile ${id}`);
       }
@@ -79,7 +77,7 @@ export default function typescript(options: RollupTypescriptOptions = {}): Plugi
     generateBundle() {
       const program = services.getProgram();
       if (program == null) return;
-      emitDiagnostics(ts, this, host, ts.getPreEmitDiagnostics(program));
+      emitDiagnostics(ts, this, formatHost, ts.getPreEmitDiagnostics(program));
     }
   };
 }

packages/typescript/src/moduleResolution/host.ts

@@ -0,0 +1,19 @@
+export type ModuleResolutionHost = import('typescript').ModuleResolutionHost;
+
+/**
+ * Creates a module resolution host to use with the Typescript compiler API.
+ * Typescript hosts are used to represent the user's system,
+ * with an API for reading files, checking directories and case sensitivity etc.
+ * @see https://github.com/Microsoft/TypeScript/wiki/Using-the-Compiler-API
+ */
+export default function createModuleResolutionHost(
+  ts: typeof import('typescript')
+): ModuleResolutionHost {
+  return {
+    fileExists: ts.sys.fileExists,
+    readFile: ts.sys.readFile,
+    directoryExists: ts.sys.directoryExists,
+    realpath: ts.sys.realpath,
+    getDirectories: ts.sys.getDirectories
+  };
+}

packages/typescript/src/resolver.ts → packages/typescript/src/moduleResolution/resolver.ts

@@ -1,6 +1,7 @@
-type ModuleResolverHost = import('typescript').ModuleResolutionHost &
-  Pick<import('typescript').FormatDiagnosticsHost, 'getCanonicalFileName'> &
-  Pick<import('typescript').LanguageServiceHost, 'getCompilationSettings'>;
+import { DiagnosticsHost } from '../diagnostics/host';
+
+type ModuleResolutionHost = import('typescript').ModuleResolutionHost;
+type ModuleResolverHost = ModuleResolutionHost & DiagnosticsHost;
 
 export type Resolver = (
   moduleName: string,
@@ -9,6 +10,8 @@ export type Resolver = (
 
 /**
  * Create a helper for resolving modules using Typescript.
+ * @param host Typescript host that extends `ModuleResolutionHost`
+ * with methods for sanitizing filenames and getting compiler options.
  */
 export default function createModuleResolver(
   ts: typeof import('typescript'),

packages/typescript/src/options.ts

@@ -2,11 +2,12 @@ import { readFileSync } from 'fs';
 import { resolve } from 'path';
 
 import { createFilter } from '@rollup/pluginutils';
+import { PluginContext } from 'rollup';
 import * as defaultTs from 'typescript';
 
 import { RollupTypescriptOptions } from '../types';
 
-import { diagnosticToWarning } from './diagnostics';
+import diagnosticToWarning from './diagnostics/toWarning';
 import { getTsLibCode } from './tslib';
 
 /** Properties of `CompilerOptions` that are normally enums */
@@ -240,3 +241,19 @@ export function parseTypescriptConfig(
 
   return parsedConfig;
 }
+
+/**
+ * If errors are detected in the parsed options,
+ * display all of them as warnings then emit an error.
+ */
+export function emitParsedOptionsErrors(
+  ts: typeof import('typescript'),
+  context: PluginContext,
+  parsedOptions: import('typescript').ParsedCommandLine
+) {
+  if (parsedOptions.errors.length > 0) {
+    parsedOptions.errors.forEach((error) => context.warn(diagnosticToWarning(ts, null, error)));
+
+    context.error(`@rollup/plugin-typescript: Couldn't process compiler options`);
+  }
+}

packages/typescript/test/test.js

@@ -352,9 +352,7 @@ test.serial('should support extends property with node resolution', async (t) =>
 
   const bundle = await rollup({
     input: 'main.tsx',
-    plugins: [
-      typescript()
-    ],
+    plugins: [typescript()],
     onwarn
   });
   const code = await getCode(bundle, outputOptions);