Function reloadPreview

scripts/experimental/swiftui-preview.mjs:233–371

(context, sourceFile, args, xcode)

}

async function reloadPreview(context, sourceFile, args, xcode) {
  const started = Date.now();
  const timings = [];
  const timed = (label, action) => {
    const stageStarted = Date.now();
    const result = action();
    timings.push([label, Date.now() - stageStarted]);
    return result;
  };
  const timedAsync = async (label, action) => {
    const stageStarted = Date.now();
    const result = await action();
    timings.push([label, Date.now() - stageStarted]);
    return result;
  };
  const source = timed("read source", () =>
    fs.readFileSync(sourceFile, "utf8"),
  );
  const previews = timed("extract previews", () => extractPreviews(source));
  if (previews.length === 0) {
    throw new Error(`No #Preview blocks found in ${sourceFile}.`);
  }
  const preview = timed("select preview", () =>
    selectPreview(previews, args.preview),
  );
  const stamp = `${Date.now()}-${process.pid}`;
  const payloadDir = path.join(context.buildRoot, "payloads", stamp);
  timed("prepare payload dir", () =>
    fs.mkdirSync(payloadDir, { recursive: true }),
  );

  const sanitizedPath = path.join(payloadDir, "PreviewSource.swift");
  const wrapperPath = path.join(payloadDir, "SimDeckPreviewPayload.swift");
  const dylibPath = path.join(
    payloadDir,
    `SimDeckPreviewPayload-${stamp}.dylib`,
  );
  const sanitizedSource = timed("sanitize source", () =>
    sanitizePreviewSource(
      removeRanges(
        source,
        previews.map((item) => item.range),
      ),
      xcode?.moduleName,
    ),
  );
  const sourceModule = args.splitCompile
    ? timed("resolve source cache", () =>
        previewSourceModule(context, sanitizedSource, args, xcode),
      )
    : null;
  timed("write generated swift", () => {
    fs.writeFileSync(sanitizedPath, sanitizedSource);
    fs.writeFileSync(
      wrapperPath,
      payloadWrapperSource(
        preview.body,
        xcode?.moduleName,