serialize.ts

// From https://github.com/nodeca/js-yaml/issues/586#issuecomment-814310104
// This file ensures that simple objects and arrays (ie without array or object
// children) will be serialized inline, and also ensures that "fullTargets" will be inlined as well

import * as yaml from "js-yaml";

class CustomDump {
  constructor(
    private readonly data: unknown,
    private readonly opts: yaml.DumpOptions,
  ) {}

  represent(): string {
    let result = yaml.dump(
      this.data,
      Object.assign({ replacer, schema }, this.opts),
    );
    result = result.trim();
    if (result.includes("\n")) {
      result = "\n" + result;
    }
    return result;
  }
}

const customDumpType = new yaml.Type("!format", {
  kind: "scalar",
  resolve: () => false,
  instanceOf: CustomDump,
  represent: (d: unknown) => (d as CustomDump).represent(),
});

const schema = yaml.DEFAULT_SCHEMA.extend({ implicit: [customDumpType] });

const isObject = (value: unknown): value is object =>
  typeof value === "object" && value != null;

function hasSimpleChildren(value: unknown): boolean {
  if (isObject(value)) {
    return Object.values(value).every(
      (value) => !isObject(value) && !Array.isArray(value),
    );
  }
  if (Array.isArray(value)) {
    return value.every((value) => !isObject(value) && !Array.isArray(value));
  }
  return false;
}

function replacer(key: string, value: unknown): unknown {
  if (key === "") {
    return value;
  } // top-level, don't change this

  if (hasSimpleChildren(value)) {
    return new CustomDump(value, { flowLevel: 0 });
  }

  return value; // default
}

export function serialize(obj: unknown): string {
  return (
    new CustomDump(obj, { noRefs: true, quotingType: '"' }).represent().trim() +
    "\n"
  );
}