1 #!/usr/bin/env python 2 # Copyright (c) 2012 The Chromium Authors. All rights reserved. 3 # Use of this source code is governed by a BSD-style license that can be 4 # found in the LICENSE file. 5 6 '''Utility to remove comments from JSON files so that they can be parsed by 7 json.loads. 8 ''' 9 10 import sys 11 12 13 def _Rcount(string, chars): 14 '''Returns the number of consecutive characters from |chars| that occur at the 15 end of |string|. 16 ''' 17 return len(string) - len(string.rstrip(chars)) 18 19 20 def _FindNextToken(string, tokens, start): 21 '''Finds the next token in |tokens| that occurs in |string| from |start|. 22 Returns a tuple (index, token key). 23 ''' 24 min_index, min_key = (-1, None) 25 for k in tokens: 26 index = string.find(k, start) 27 if index != -1 and (min_index == -1 or index < min_index): 28 min_index, min_key = (index, k) 29 return (min_index, min_key) 30 31 32 def _ReadString(input, start, output): 33 output.append('"') 34 start_range, end_range = (start, input.find('"', start)) 35 # \" escapes the ", \\" doesn't, \\\" does, etc. 36 while (end_range != -1 and 37 _Rcount(input[start_range:end_range], '\\') % 2 == 1): 38 start_range, end_range = (end_range, input.find('"', end_range + 1)) 39 if end_range == -1: 40 return start_range + 1 41 output.append(input[start:end_range + 1]) 42 return end_range + 1 43 44 45 def _ReadComment(input, start, output): 46 eol_tokens = ('\n', '\r') 47 eol_token_index, eol_token = _FindNextToken(input, eol_tokens, start) 48 if eol_token is None: 49 return len(input) 50 output.append(eol_token) 51 return eol_token_index + len(eol_token) 52 53 54 def Nom(input): 55 token_actions = { 56 '"': _ReadString, 57 '//': _ReadComment, 58 } 59 output = [] 60 pos = 0 61 while pos < len(input): 62 token_index, token = _FindNextToken(input, token_actions.keys(), pos) 63 if token is None: 64 output.append(input[pos:]) 65 break 66 output.append(input[pos:token_index]) 67 pos = token_actions[token](input, token_index + len(token), output) 68 return ''.join(output) 69 70 71 if __name__ == '__main__': 72 sys.stdout.write(Nom(sys.stdin.read())) 73
