Method wrap

packages/compiler-cli/src/ngtsc/core/src/host.ts:199–274

* Create an `NgCompilerHost` from a delegate host, an array of input filenames, and the full set * of TypeScript and Angular compiler options.

(
    delegate: ts.CompilerHost,
    inputFiles: ReadonlyArray<string>,
    options: NgCompilerOptions,
    oldProgram: ts.Program | null,
  )

   * of TypeScript and Angular compiler options.
   */
  static wrap(
    delegate: ts.CompilerHost,
    inputFiles: ReadonlyArray<string>,
    options: NgCompilerOptions,
    oldProgram: ts.Program | null,
  ): NgCompilerHost {
    const topLevelShimGenerators: TopLevelShimGenerator[] = [];
    const perFileShimGenerators: PerFileShimGenerator[] = [];

    const rootDirs = getRootDirs(delegate, options as ts.CompilerOptions);

    perFileShimGenerators.push(new TypeCheckShimGenerator());

    let diagnostics: ts.Diagnostic[] = [];

    const normalizedTsInputFiles: AbsoluteFsPath[] = [];
    for (const inputFile of inputFiles) {
      if (!isNonDeclarationTsPath(inputFile)) {
        continue;
      }
      normalizedTsInputFiles.push(resolve(inputFile));
    }

    let entryPoint: AbsoluteFsPath | null = null;
    if (options.flatModuleOutFile != null && options.flatModuleOutFile !== '') {
      entryPoint = findFlatIndexEntryPoint(normalizedTsInputFiles);
      if (entryPoint === null) {
        // This error message talks specifically about having a single .ts file in "files". However
        // the actual logic is a bit more permissive. If a single file exists, that will be taken,
        // otherwise the highest level (shortest path) "index.ts" file will be used as the flat
        // module entry point instead. If neither of these conditions apply, the error below is
        // given.
        //
        // The user is not informed about the "index.ts" option as this behavior is deprecated -
        // an explicit entrypoint should always be specified.
        diagnostics.push({
          category: ts.DiagnosticCategory.Error,
          code: ngErrorCode(ErrorCode.CONFIG_FLAT_MODULE_NO_INDEX),
          file: undefined,
          start: undefined,
          length: undefined,
          messageText:
            'Angular compiler option "flatModuleOutFile" requires one and only one .ts file in the "files" field.',
        });
      } else {
        const flatModuleId = options.flatModuleId || null;
        const flatModuleOutFile = normalizeSeparators(options.flatModuleOutFile);
        const flatIndexGenerator = new FlatIndexGenerator(
          entryPoint,
          flatModuleOutFile,
          flatModuleId,
        );
        topLevelShimGenerators.push(flatIndexGenerator);
      }
    }

    const shimAdapter = new ShimAdapter(
      delegate,