Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/pygments/scanner.py: 80%

1""" 

2 pygments.scanner 

3 ~~~~~~~~~~~~~~~~ 

4 

5 This library implements a regex based scanner. Some languages 

6 like Pascal are easy to parse but have some keywords that 

7 depend on the context. Because of this it's impossible to lex 

8 that just by using a regular expression lexer like the 

9 `RegexLexer`. 

10 

11 Have a look at the `DelphiLexer` to get an idea of how to use 

12 this scanner. 

13 

14 :copyright: Copyright 2006-2023 by the Pygments team, see AUTHORS. 

15 :license: BSD, see LICENSE for details. 

16""" 

17import re 

18 

19 

20class EndOfText(RuntimeError): 

21 """ 

22 Raise if end of text is reached and the user 

23 tried to call a match function. 

24 """ 

25 

26 

27class Scanner: 

28 """ 

29 Simple scanner 

30 

31 All method patterns are regular expression strings (not 

32 compiled expressions!) 

33 """ 

34 

35 def __init__(self, text, flags=0): 

36 """ 

37 :param text: The text which should be scanned 

38 :param flags: default regular expression flags 

39 """ 

40 self.data = text 

41 self.data_length = len(text) 

42 self.start_pos = 0 

43 self.pos = 0 

44 self.flags = flags 

45 self.last = None 

46 self.match = None 

47 self._re_cache = {} 

48 

49 def eos(self): 

50 """`True` if the scanner reached the end of text.""" 

51 return self.pos >= self.data_length 

52 eos = property(eos, eos.__doc__) 

53 

54 def check(self, pattern): 

55 """ 

56 Apply `pattern` on the current position and return 

57 the match object. (Doesn't touch pos). Use this for 

58 lookahead. 

59 """ 

60 if self.eos: 

61 raise EndOfText() 

62 if pattern not in self._re_cache: 

63 self._re_cache[pattern] = re.compile(pattern, self.flags) 

64 return self._re_cache[pattern].match(self.data, self.pos) 

65 

66 def test(self, pattern): 

67 """Apply a pattern on the current position and check 

68 if it patches. Doesn't touch pos. 

69 """ 

70 return self.check(pattern) is not None 

71 

72 def scan(self, pattern): 

73 """ 

74 Scan the text for the given pattern and update pos/match 

75 and related fields. The return value is a boolean that 

76 indicates if the pattern matched. The matched value is 

77 stored on the instance as ``match``, the last value is 

78 stored as ``last``. ``start_pos`` is the position of the 

79 pointer before the pattern was matched, ``pos`` is the 

80 end position. 

81 """ 

82 if self.eos: 

83 raise EndOfText() 

84 if pattern not in self._re_cache: 

85 self._re_cache[pattern] = re.compile(pattern, self.flags) 

86 self.last = self.match 

87 m = self._re_cache[pattern].match(self.data, self.pos) 

88 if m is None: 

89 return False 

90 self.start_pos = m.start() 

91 self.pos = m.end() 

92 self.match = m.group() 

93 return True 

94 

95 def get_char(self): 

96 """Scan exactly one char.""" 

97 self.scan('.') 

98 

99 def __repr__(self): 

100 return '<%s %d/%d>' % ( 

101 self.__class__.__name__, 

102 self.pos, 

103 self.data_length 

104 )