fluorine-loader/src/index.ts

A webpack loader to compile fluorine specializations and catalyst handlers.

import { getOptions } from "loader-utils";
import { performance } from "perf_hooks";
import { RawSourceMap } from "source-map";
import sorcery = require("source-map");
import { loader } from "webpack";

import { transform } from "./transformer";

let now = performance.now;

export interface Options {
  benchmark?: boolean;
  sourceMap?: boolean;
  _filename?: string;
}

function fluorine_loader(
  this: loader.LoaderContext,
  source: string | Buffer,
  last_sourcemap: RawSourceMap | undefined
) {
  let opts: Options = getOptions(this) || {};
  if (opts.sourceMap === undefined) opts.sourceMap = this.sourceMap;
  opts._filename = this.resource;

  let callback = this.async()!;
  _async_loader(source, last_sourcemap, opts)
    .then(([code, sourcemap]) => {
      callback(null, code, sourcemap as any);
    })
    .catch(err => {
      callback(err);
    });

  return undefined;
}

export default fluorine_loader;

async function _async_loader(
  source: string | Buffer,
  last_sourcemap: RawSourceMap | undefined,
  opts: Options = {}
): Promise<[string, RawSourceMap?]> {
  let { code, sourcemap: next_sourcemap, performance: time } = await transform(
    source instanceof Buffer ? source.toString() : source,
    { sourcemap: opts.sourceMap, now }
  );

  if (next_sourcemap) {
    let merged_sourcemap = next_sourcemap;

    if (last_sourcemap) {
      next_sourcemap.file = last_sourcemap.file;
      next_sourcemap.sourceRoot = last_sourcemap.sourceRoot;

      let source_gen = sorcery.SourceMapGenerator.fromSourceMap(
        await new sorcery.SourceMapConsumer(next_sourcemap)
      );
      source_gen.applySourceMap(
        await new sorcery.SourceMapConsumer(last_sourcemap)
      );
      merged_sourcemap = source_gen.toJSON();
    }

    time.sourcemap = now();
    if (opts.benchmark) show_performance(time, opts);
    return [code, merged_sourcemap];
  } else {
    if (opts.benchmark) show_performance(time, opts);
    return [code];
  }
}

function show_performance(time: { [key: string]: number }, opts: Options = {}) {
  console.log(
    "  Fluorine Loader transformed",
    opts._filename,
    "in",
    i(
      (time.sourcemap !== undefined ? time.sourcemap : time.walk) - time.start
    ) + "ms"
  );
  console.log(
    `
    - parse ..................${h(time.parse - time.start)}ms
    - walk ...................${h(time.walk - time.parse)}ms
      - visit ................${h(time.visit)}ms
        - transform_element ..${h(time.transform_element)}ms
        - transform_catalyst .${h(time.transform_catalyst)}ms
      - md5 ..................${h(time.md5)}ms
    ${
      time.sourcemap !== undefined
        ? `- sourcemap ..............${h(time.sourcemap - time.walk)}ms`
        : ""
    }
  `.slice(1, -1)
  );
}

function h(num: number) {
  let prefix = "";
  for (let ix = 0; ix < 3 - ("" + Math.floor(num)).length; ix += 1)
    prefix += ".";
  return prefix + " " + i(num);
}

function i(num: number) {
  if (Math.floor(num) == num) return "" + num;
  else return num.toFixed(3);
}