Function createProgram

packages/ttypescript/src/patchCreateProgram.ts:43–110

(
        rootNamesOrOptions: ReadonlyArray<string> | ts.CreateProgramOptions,
        options?: ts.CompilerOptions,
        host?: ts.CompilerHost,
        oldProgram?: ts.Program,
        configFileParsingDiagnostics?: ReadonlyArray<ts.Diagnostic>
    )

        configFileParsingDiagnostics?: ReadonlyArray<ts.Diagnostic>
    ): ts.Program;
    function createProgram(
        rootNamesOrOptions: ReadonlyArray<string> | ts.CreateProgramOptions,
        options?: ts.CompilerOptions,
        host?: ts.CompilerHost,
        oldProgram?: ts.Program,
        configFileParsingDiagnostics?: ReadonlyArray<ts.Diagnostic>
    ): ts.Program {
        let rootNames;
        let createOpts: ts.CreateProgramOptions | undefined;
        if (!Array.isArray(rootNamesOrOptions)) {
            createOpts = rootNamesOrOptions as ts.CreateProgramOptions;
        }
        if (createOpts) {
            rootNames = createOpts.rootNames;
            options = createOpts.options;
            host = createOpts.host;
            oldProgram = createOpts.oldProgram;
            configFileParsingDiagnostics = createOpts.configFileParsingDiagnostics;
        } else {
            options = options!;
            rootNames = rootNamesOrOptions as ReadonlyArray<string>;
        }

        if (forceReadConfig) {
            const info = getConfig(tsm, options, rootNames, projectDir);
            options = info.compilerOptions;
            if (createOpts) {
                createOpts.options = options;
            }
            projectDir = info.projectDir;
        }
        const program: ts.Program = createOpts
            ? originCreateProgram(createOpts)
            : originCreateProgram(rootNames, options, host, oldProgram, configFileParsingDiagnostics);

        const plugins = preparePluginsFromCompilerOptions(options.plugins);
        const pluginCreator = new PluginCreator(tsm, plugins, projectDir);

        const originEmit = program.emit;

        /**
         * The emit method has the following declaration:
         * https://github.com/microsoft/TypeScript/blob/bfc55b5762443c37ecdef08a3b5a4e057b4d1e85/src/compiler/builderPublic.ts#L101
         * The declaration specifies 5 arguments, but it's not true. Sometimes the emit method takes 6 arguments.
         */
        program.emit = function newEmit(
            targetSourceFile?: ts.SourceFile,
            writeFile?: ts.WriteFileCallback,
            cancellationToken?: ts.CancellationToken,
            emitOnlyDtsFiles?: boolean,
            customTransformers?: ts.CustomTransformers,
            arg?: boolean
        ): ts.EmitResult {
            const mergedTransformers = pluginCreator.createTransformers({ program }, customTransformers);
            const result: ts.EmitResult = (originEmit as any)(
                targetSourceFile,
                writeFile,
                cancellationToken,