Function getTaskDescription

build-system/task-runner/amp-task-runner.js:173–199

* Uses esprima to extract the description from a task file without require-ing * it, by tokenizing the JS file and finding the sequence that matches the text * "fooTask.description = ' '". * @param {string} taskSourceFileName * @param {string} taskFuncName * @return {string}

(taskSourceFileName, taskFuncName)

 * @return {string}
 */
function getTaskDescription(taskSourceFileName, taskFuncName) {
  const taskSourceFilePath = getTaskSourceFilePath(taskSourceFileName);
  const taskSourceFile = fs.existsSync(`${taskSourceFilePath}.js`)
    ? `${taskSourceFilePath}.js`
    : path.join(taskSourceFilePath, 'index.js');
  const contents = fs.readFileSync(taskSourceFile, 'utf-8').trim();
  const tokens = Array.from(esprima.tokenize(contents));
  let description = '';
  for (let i = 0; i < tokens.length; ++i) {
    if (
      tokens[i]?.type == 'Identifier' &&
      tokens[i]?.value == taskFuncName &&
      tokens[i + 1]?.type == 'Punctuator' &&
      tokens[i + 1]?.value == '.' &&
      tokens[i + 2]?.type == 'Identifier' &&
      tokens[i + 2]?.value == 'description' &&
      tokens[i + 3]?.type == 'Punctuator' &&
      tokens[i + 3]?.value == '=' &&
      tokens[i + 4]?.type == 'String'
    ) {
      description = tokens[i + 4]?.value
        ?.replace(/^['"]/, '')
        ?.replace(/['"]$/, '');
    }
  }
  return description;
}

/**
 * Helper that creates the tasks in AMP's toolchain based on the invocation: