Class GitProgressParser

app/src/lib/progress/git.ts:170–247

 * for Git.
 */
export class GitProgressParser implements IGitProgressParser {
  private readonly steps: ReadonlyArray<IProgressStep>

  /* The provided steps should always occur in order but some
   * might not happen at all (like remote compression of objects) so
   * we keep track of the "highest" seen step so that we can fill in
   * progress with the assumption that we've already seen the previous
   * steps.
   */
  private stepIndex = 0

  private lastPercent = 0

  /**
   * Initialize a new instance of a Git progress parser.
   *
   * @param steps - A series of steps that could be present in the git
   *                output with relative weight between these steps. Note
   *                that order is significant here as once the parser sees
   *                a progress line that matches a step all previous steps
   *                are considered completed and overall progress is adjusted
   *                accordingly.
   */
  public constructor(steps: ReadonlyArray<IProgressStep>) {
    if (!steps.length) {
      throw new Error('must specify at least one step')
    }

    // Scale the step weight so that they're all a percentage
    // adjusted to the total weight of all steps.
    const totalStepWeight = steps.reduce((sum, step) => sum + step.weight, 0)

    this.steps = steps.map(step => ({
      title: step.title,
      weight: step.weight / totalStepWeight,
    }))
  }

  /**
   * Parse the given line of output from Git, returns either an `IGitProgress`
   * instance if the line could successfully be parsed as a Git progress
   * event whose title was registered with this parser or an `IGitOutput`
   * instance if the line couldn't be parsed or if the title wasn't
   * registered with the parser.
   */
  public parse(line: string): IGitProgress | IGitOutput {
    // In case we're parsing hook output or similar we want to
    // strip out any control characters that may be present. IGitProgress
    // is supposed to be readable text that can be used in tooltips and such.
    const text = stripVTControlCharacters(line)
    const progress = parse(text)

    if (!progress) {
      return { kind: 'context', text, percent: this.lastPercent }
    }

    let percent = 0