recipe_modules/jsonutil/api.py

# Copyright 2019 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import re

from recipe_engine import recipe_api


class JsonUtilApi(recipe_api.RecipeApi):
  """JsonUtilApi contains JSON-related utilities."""

  def extract_from_text(self, name, text, key, default_contents):
    """Extracts JSON from supplied text.

    It is expected that the JSON substring appears in the text as
    <key>:`<JSON>`.

    Args:
      name (str): The name of the step.
      text (str): Text containing a JSON substring.
      key (str): A key in the text to match against.
      default_contents (obj): A JSON-serializable Python object to return
          in the event that no JSON substring is found.

    Returns:
      A JSON object representing the extracted JSON string from the text.
    """
    with self.m.step.nest(name):
      regex = r'^\s*%s:[\s\n]*`((.|\n)*?)`' % key
      match = re.search(regex, text, re.MULTILINE)
      result = str(default_contents)
      if match:
        result = match.group(1)
      self.m.step.active_result.presentation.logs['value'] = result.splitlines()
      try:
        return self.m.json.loads(result)
      except ValueError as e:
        raise self.m.step.StepFailure('failed to load JSON: %s' % str(e))