sapling/eden/fs/cli/configinterpolator.py
John Reese 737849c9dd apply black 20.8b1 formatting update
Summary:
allow-large-files

black_any_style

Reviewed By: zertosh

Differential Revision: D24325133

fbshipit-source-id: b4afe80d1e8b2bc993f4b8e3822c02964df47462
2020-10-14 20:21:52 -07:00

42 lines
1.5 KiB
Python

#!/usr/bin/env python3
# Copyright (c) Facebook, Inc. and its affiliates.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2.
import configparser
from typing import Dict
class EdenConfigInterpolator(configparser.Interpolation):
"""Python provides a couple of interpolation options but neither
of them quite match the simplicity that we want. This class
will interpolate the keys of the provided map and replace
those tokens with the values from the map. There is no
recursion or referencing of values from other sections of
the config.
Limiting the scope interpolation makes it easier to replicate
this approach in the C++ implementation of the parser.
"""
def __init__(self, defaults) -> None:
self._defaults: Dict[str, str] = {}
""" pre-construct the token name that we're going to substitute.
eg: {"foo": "bar"} is stored as {"${foo}": "bar"} internally
"""
for k, v in defaults.items():
self._defaults["${" + k + "}"] = v
def _interpolate(self, value: str) -> str:
"""simple brute force replacement using the defaults that were
provided to us during construction"""
for k, v in self._defaults.items():
value = value.replace(k, v)
return value
def before_get(self, parser, section, option, value, defaults) -> str:
return self._interpolate(value)
def before_read(self, parser, section, option, value) -> str:
return self._interpolate(value)