async transform()

in packages/shared-config/src/unPlugins/compilation.ts [76:177]
78 lines of code
19 McCabe index (conditional complexity)

    async transform(source: string, fileId: string) {
      const id = formatId(fileId);
      const suffix = (['jsx', 'tsx'] as JSXSuffix[]).find(suffix => new RegExp(`\\.${suffix}?$`).test(id));

      const programmaticOptions: SwcConfig = {
        swcrc: false,
        filename: id,
        sourceMaps: !!sourceMap,
      };
      const compileOptions = { rootDir, mode, suffix, fastRefresh, polyfill, enableEnv };
      const commonOptions = getJsxTransformOptions(compileOptions);

      // auto detect development mode
      if (
        mode &&
        commonOptions?.jsc?.transform?.react &&
        !Object.prototype.hasOwnProperty.call(commonOptions.jsc.transform.react, 'development')
      ) {
        commonOptions.jsc.transform.react.development = mode === 'development';
      }

      merge(programmaticOptions, commonOptions);

      if (typeof compilationConfig === 'function') {
        merge(programmaticOptions, compilationConfig(source, fileId, compileOptions));
      } else if (compilationConfig) {
        merge(programmaticOptions, compilationConfig);
      }

      const swcPlugins = [];

      // handle app.tsx and page entries only
      if (removeExportExprs) {
        if (isRouteEntry(id) || isAppEntry(id)) {
          swcPlugins.push([
            swcPluginRemoveExport,
            removeExportExprs,
          ]);
        }
      }
      if (keepExports) {
        // Make a copy of keepExports, otherwise it will be modified by side effects operation such as push.
        const keepList = [...(Array.isArray(keepExports) ? keepExports : keepExports.value)];
        const customInlcude = !Array.isArray(keepExports) && keepExports?.include;
        let matchRule = false;
        if (customInlcude) {
          matchRule = customInlcude(id);
        } else {
          const matchRoute = isRouteEntry(id);
          const matchEntry = isAppEntry(id);
          if (matchEntry && keepList.indexOf('pageConfig') > -1) {
            // when build for pageConfig, should keep default, it equals to getAppConfig
            keepList.push('default');
          }
          matchRule = matchRoute || matchEntry;
        }
        if (matchRule) {
          swcPlugins.push([
            swcPluginKeepExport,
            keepList,
          ]);
        }
      }

      if (nodeTransform) {
        swcPlugins.push([swcPluginNodeTransform, {}]);
      }
      if (swcPlugins.length > 0) {
        merge(programmaticOptions, {
          jsc: {
            experimental: {
              cacheRoot: cacheDir,
              plugins: swcPlugins,
            },
          },
        });
      }

      try {
        const output = await swc.transform(source, programmaticOptions);

        const { code } = output;
        let { map } = output;
        return {
          code: await transformImport(
            code,
            coreJsPath,
          ),
          map,
        };
      } catch (error) {
        // Catch error for unhandled promise rejection.
        if (this) {
          // Handled by unplugin.
          this.error(error);
          return { code: null, map: null };
        } else {
          // Handled by webpack.
          throw error;
        }
      }
    },