An example module for parsing json with JS style comments.

json_with_comments.py

"""An example module for parsing json with JS style comments.

Primarily intended for parsing config files in json format,
where the use of comments may be desirable.

As Douglas Crockford suggests:

   "Suppose you are using JSON to keep configuration files,
    which you would like to annotate. Go ahead and insert all
    the comments you like. Then pipe it through JSMin before
    handing it to your JSON parser."

(https://plus.google.com/+DouglasCrockfordEsq/posts/RK8qyGVaGSr)

Inspired by Damien Riquet's example:
http://www.lifl.fr/~riquetd/parse-a-json-file-with-comments.html

"""

import re
import json


def loads(text, parse_comments=True):
    """Parse a json text, with the option to parse out comments (JS style)."""
    if parse_comments:
        regex = re.compile(r'(^)?[^\S\n]*/(?:\*(.*?)\*/[^\S\n]*|/[^\n]*)($)?',
            re.DOTALL | re.MULTILINE
        )
        match = regex.search(text)
        while match:
            text = text[:match.start()] + text[match.end():]
            match = regex.search(text)
    return json.loads(text)

test_json_with_comments.py

# pylint: disable=missing-docstring
# pylint: disable=too-many-public-methods
# pylint: disable=line-too-long
 
import unittest
 
import json_with_comments as jsontools
 
 
class TestConfigManage(unittest.TestCase):
 
    def test_a_loads(self):
        text1 = '{\n    "key": "value"\n}'
        text2 = '{\r\n    "key": "value"\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_b_loads(self):
        text1 = '{\n    "key": "value" // JavaScript single line comment.\n}'
        text2 = '{\r\n    "key": "value" // JavaScript single line comment.\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_c_loads(self):
        text1 = '{\n    // JavaScript single line comment.\n    "key": "value"\n}'
        text2 = '{\r\n    // JavaScript single line comment.\r\n    "key": "value"\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_d_loads(self):
        text1 = '{\n    "key": "value"\n    // JavaScript single line comment.\n}'
        text2 = '{\r\n    "key": "value"\r\n    // JavaScript single line comment.\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_e_loads(self):
        text1 = '// JavaScript single line comment.\n{\n    "key": "value"\n}'
        text2 = '// JavaScript single line comment.\r\n{\r\n    "key": "value"\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_f_loads(self):
        text1 = '{\n    "key": "value" /* JavaScript multiline comment. */\n}'
        text2 = '{\r\n    "key": "value" /* JavaScript multiline comment. */\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_g_loads(self):
        text1 = '{\n    "key": "value" /*\n        JavaScript\n        multiline\n        comment. */\n}'
        text2 = '{\r\n    "key": "value" /*\r\n        JavaScript\r\n        multiline\r\n        comment. */\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_h_loads(self):
        text1 = '{\n    /*\n    JavaScript\n    multiline\n    comment.\n    */\n    "key": "value"\n}'
        text2 = '{\r\n    /*\r\n    JavaScript\r\n    multiline\r\n    comment.\r\n    */\r\n    "key": "value"\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_i_loads(self):
        text1 = '/*\n    JavaScript\n    multiline\n    comment.\n    */\n    {\n    "key": "value"\n}'
        text2 = '/*\r\n    JavaScript\r\n    multiline\r\n    comment.\r\n    */\r\n    {\r\n    "key": "value"\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})
 
    def test_j_loads(self):
        text1 = '/*\n    JavaScript\n    multiline\n    comment.\n    */\n    {\n    "key": "value" // JavaScript single line comment.\n}'
        text2 = '/*\r\n    JavaScript\r\n    multiline\r\n    comment.\r\n    */\r\n    {\r\n    "key": "value" // JavaScript single line comment.\r\n}'
        parsed1 = jsontools.loads(text1)
        parsed2 = jsontools.loads(text2)
        self.assertEqual(parsed1, {"key": "value"})
        self.assertEqual(parsed2, {"key": "value"})

    def test_loads_exception(self):
        text1 = '/*\n    JavaScript\n    multiline\n    comment.\n    */\n    {\n    "key": "value" // JavaScript single line comment.\n}'
        self.assertRaises(ValueError, jsontools.loads, text1, False)

 
if __name__ == '__main__':
    unittest.main()