Added utils.evaluate_vars function

netjsonconfig/utils.py

@@ -1,6 +1,9 @@
import re
from collections import OrderedDict
from copy import deepcopy

import six


def merge_config(template, config):
    """
@@ -34,6 +37,32 @@ def sorted_dict(dictionary):
    return OrderedDict(sorted(dictionary.items()))


var_pattern = re.compile(r'\{\{\s(\w*)\s\}\}')


def evaluate_vars(data, context={}):
    """
    Evaluates variables in ``data``

    :param data: data structure containing variables, may be
                 ``str``, ``dict`` or ``list``
    :param context: ``dict`` containing variables
    :returns: modified data structure
    """
    if isinstance(data, (dict, list)):
        if isinstance(data, dict):
            loop_items = data.items()
        elif isinstance(data, list):
            loop_items = enumerate(data)
        for key, value in loop_items:
            data[key] = evaluate_vars(value, context)
    elif isinstance(data, six.string_types):
        for var in var_pattern.findall(data):
            if var in context:
                data = data.replace('{{ %s }}' % var, context[var])
    return data


class _TabsMixin(object):  # pragma: nocover
    """
    mixin that adds _tabs method to test classes

tests/test_utils.py

@@ -1,6 +1,6 @@
import unittest

from netjsonconfig.utils import merge_config
from netjsonconfig.utils import evaluate_vars, merge_config


class TestUtils(unittest.TestCase):
@@ -109,3 +109,27 @@ def test_merge_list_of_dicts_unchanged(self):
                {"c": "original"}
            ]
        })

    def test_evaluate_vars(self):
        self.assertEqual(evaluate_vars('{{ tz }}', {'tz': 'UTC'}), 'UTC')
        self.assertEqual(evaluate_vars('tz: {{ tz }}', {'tz': 'UTC'}), 'tz: UTC')

    def test_evaluate_vars_missing(self):
        self.assertEqual(evaluate_vars('{{ tz }}'), '{{ tz }}')
        self.assertEqual(evaluate_vars('tz: {{ tz }}'), 'tz: {{ tz }}')

    def test_evaluate_vars_dict(self):
        val = evaluate_vars({'timezone': '{{ tz }}'}, {'tz': 'UTC'})
        self.assertEqual(val, {'timezone': 'UTC'})

    def test_evaluate_vars_nested_dict(self):
        val = evaluate_vars({'general': {'timezone': '{{ tz }}'}}, {'tz': 'UTC'})
        self.assertEqual(val, {'general': {'timezone': 'UTC'}})

    def test_evaluate_vars_list(self):
        val = evaluate_vars(['{{ a }}', '{{ b }}'], {'a': '1', 'b': '2'})
        self.assertEqual(val, ['1', '2'])

    def test_evaluate_vars_list_in_dict(self):
        val = evaluate_vars({'l': ['{{ a }}', '{{ b }}']}, {'a': '1', 'b': '2'})
        self.assertEqual(val, {'l': ['1', '2']})