recipe_modules/utils/api.py

# Copyright 2020 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.
"""Helper functions for common boilerplate tasks.

Top-level functions can be imported and used directly (without needing a
`RecipeApi` object) using `RECIPE_MODULES` imports. E.g.:

  ```
  from RECIPE_MODULES.fuchsia.utils.api import memoize

  @memoize
  def expensive_computation(inputs):
    return do_work(inputs)

  def RunSteps(api, ...):
    expensive_computation(...)
  ```
"""

import functools

from recipe_engine import recipe_api


def memoize(func):
  """A decorator to cache the return values of a function by args/kwargs."""
  cache = {}

  @functools.wraps(func)
  def wrapper(*args, **kwargs):
    key = (args, frozenset(kwargs.iteritems()))
    if key not in cache:
      cache[key] = func(*args, **kwargs)
    return cache[key]

  return wrapper


class CodeUtilsApi(recipe_api.RecipeApi):
  memoize = staticmethod(memoize)