code.kerkeslager.com Git - fur/blob - parsing.py

   1 import collections
   2
   3 StringLiteral = collections.namedtuple(
   4     'StringLiteral',
   5     [
   6         'value',
   7     ],
   8 )
   9
  10 def _string_literal_parser(index, tokens):
  11     failure = (False, index, None)
  12
  13     if tokens[index].type != 'single_quoted_string_literal':
  14         return failure
  15     value = tokens[index].match[1:-1]
  16     index += 1
  17
  18     return True, index, StringLiteral(value=value)
  19
  20
  21 FunctionCall = collections.namedtuple(
  22     'FunctionCall',
  23     [
  24         'name',
  25         'arguments',
  26     ],
  27 )
  28
  29 def _function_call_parser(index, tokens):
  30     failure = (False, index, None)
  31
  32     if tokens[index].type != 'symbol':
  33         return failure
  34     name = tokens[index].match
  35     index += 1
  36
  37     if tokens[index].type != 'open_parenthese':
  38         return failure
  39     index += 1
  40
  41     success, index, argument = _string_literal_parser(index, tokens)
  42
  43     if not success:
  44         return failure
  45
  46     if tokens[index].type != 'close_parenthese':
  47         return failure
  48     index += 1
  49
  50     return True, index, FunctionCall(name=name, arguments=(argument,))
  51
  52 def _parse(parser, tokens):
  53     success, index, result = parser(0, tokens)
  54
  55     if success:
  56         return result
  57
  58     raise Exception('Unable to parse')
  59
  60
  61 def parse(tokens):
  62     return _parse(_function_call_parser, tokens)
  63
  64 if __name__ == '__main__':
  65     import unittest
  66
  67     import tokenization
  68
  69     class StringLiteralParserTests(unittest.TestCase):
  70         def test_parses_single_quoted_string_literal(self):
  71             self.assertEqual(
  72                 _string_literal_parser(0, tokenization.tokenize("'Hello, world'")),
  73                 (
  74                     True,
  75                     1,
  76                     StringLiteral(value='Hello, world'),
  77                 ),
  78             )
  79
  80     class FunctionCallParserTests(unittest.TestCase):
  81         def test_parses_function_with_string_literal_argument(self):
  82             self.assertEqual(
  83                 _function_call_parser(0, tokenization.tokenize("print('Hello, world')")),
  84                 (
  85                     True,
  86                     4,
  87                     FunctionCall(
  88                         name='print',
  89                         arguments=(StringLiteral(value='Hello, world'),),
  90                     ),
  91                 ),
  92             )
  93
  94     unittest.main()