Coverage for /pythoncovmergedfiles/medio/medio/usr/lib/python3.9/codeop.py: 94%

1r"""Utilities to compile possibly incomplete Python source code. 

2 

3This module provides two interfaces, broadly similar to the builtin 

4function compile(), which take program text, a filename and a 'mode' 

5and: 

6 

7- Return code object if the command is complete and valid 

8- Return None if the command is incomplete 

9- Raise SyntaxError, ValueError or OverflowError if the command is a 

10 syntax error (OverflowError and ValueError can be produced by 

11 malformed literals). 

12 

13Approach: 

14 

15First, check if the source consists entirely of blank lines and 

16comments; if so, replace it with 'pass', because the built-in 

17parser doesn't always do the right thing for these. 

18 

19Compile three times: as is, with \n, and with \n\n appended. If it 

20compiles as is, it's complete. If it compiles with one \n appended, 

21we expect more. If it doesn't compile either way, we compare the 

22error we get when compiling with \n or \n\n appended. If the errors 

23are the same, the code is broken. But if the errors are different, we 

24expect more. Not intuitive; not even guaranteed to hold in future 

25releases; but this matches the compiler's behavior from Python 1.4 

26through 2.2, at least. 

27 

28Caveat: 

29 

30It is possible (but not likely) that the parser stops parsing with a 

31successful outcome before reaching the end of the source; in this 

32case, trailing symbols may be ignored instead of causing an error. 

33For example, a backslash followed by two newlines may be followed by 

34arbitrary garbage. This will be fixed once the API for the parser is 

35better. 

36 

37The two interfaces are: 

38 

39compile_command(source, filename, symbol): 

40 

41 Compiles a single command in the manner described above. 

42 

43CommandCompiler(): 

44 

45 Instances of this class have __call__ methods identical in 

46 signature to compile_command; the difference is that if the 

47 instance compiles program text containing a __future__ statement, 

48 the instance 'remembers' and compiles all subsequent program texts 

49 with the statement in force. 

50 

51The module also provides another class: 

52 

53Compile(): 

54 

55 Instances of this class act like the built-in function compile, 

56 but with 'memory' in the sense described above. 

57""" 

58 

59import __future__ 

60import warnings 

61 

62_features = [getattr(__future__, fname) 

63 for fname in __future__.all_feature_names] 

64 

65__all__ = ["compile_command", "Compile", "CommandCompiler"] 

66 

67PyCF_DONT_IMPLY_DEDENT = 0x200 # Matches pythonrun.h 

68 

69def _maybe_compile(compiler, source, filename, symbol): 

70 # Check for source consisting of only blank lines and comments 

71 for line in source.split("\n"): 

72 line = line.strip() 

73 if line and line[0] != '#': 

74 break # Leave it alone 

75 else: 

76 if symbol != "eval": 

77 source = "pass" # Replace it with a 'pass' statement 

78 

79 err = err1 = err2 = None 

80 code = code1 = code2 = None 

81 

82 try: 

83 code = compiler(source, filename, symbol) 

84 except SyntaxError: 

85 pass 

86 

87 # Catch syntax warnings after the first compile 

88 # to emit warnings (SyntaxWarning, DeprecationWarning) at most once. 

89 with warnings.catch_warnings(): 

90 warnings.simplefilter("error") 

91 

92 try: 

93 code1 = compiler(source + "\n", filename, symbol) 

94 except SyntaxError as e: 

95 err1 = e 

96 

97 try: 

98 code2 = compiler(source + "\n\n", filename, symbol) 

99 except SyntaxError as e: 

100 err2 = e 

101 

102 try: 

103 if code: 

104 return code 

105 if not code1 and repr(err1) == repr(err2): 

106 raise err1 

107 finally: 

108 err1 = err2 = None 

109 

110def _compile(source, filename, symbol): 

111 return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT) 

112 

113def compile_command(source, filename="<input>", symbol="single"): 

114 r"""Compile a command and determine whether it is incomplete. 

115 

116 Arguments: 

117 

118 source -- the source string; may contain \n characters 

119 filename -- optional filename from which source was read; default 

120 "<input>" 

121 symbol -- optional grammar start symbol; "single" (default), "exec" 

122 or "eval" 

123 

124 Return value / exceptions raised: 

125 

126 - Return a code object if the command is complete and valid 

127 - Return None if the command is incomplete 

128 - Raise SyntaxError, ValueError or OverflowError if the command is a 

129 syntax error (OverflowError and ValueError can be produced by 

130 malformed literals). 

131 """ 

132 return _maybe_compile(_compile, source, filename, symbol) 

133 

134class Compile: 

135 """Instances of this class behave much like the built-in compile 

136 function, but if one is used to compile text containing a future 

137 statement, it "remembers" and compiles all subsequent program texts 

138 with the statement in force.""" 

139 def __init__(self): 

140 self.flags = PyCF_DONT_IMPLY_DEDENT 

141 

142 def __call__(self, source, filename, symbol): 

143 codeob = compile(source, filename, symbol, self.flags, True) 

144 for feature in _features: 

145 if codeob.co_flags & feature.compiler_flag: 

146 self.flags |= feature.compiler_flag 

147 return codeob 

148 

149class CommandCompiler: 

150 """Instances of this class have __call__ methods identical in 

151 signature to compile_command; the difference is that if the 

152 instance compiles program text containing a __future__ statement, 

153 the instance 'remembers' and compiles all subsequent program texts 

154 with the statement in force.""" 

155 

156 def __init__(self,): 

157 self.compiler = Compile() 

158 

159 def __call__(self, source, filename="<input>", symbol="single"): 

160 r"""Compile a command and determine whether it is incomplete. 

161 

162 Arguments: 

163 

164 source -- the source string; may contain \n characters 

165 filename -- optional filename from which source was read; 

166 default "<input>" 

167 symbol -- optional grammar start symbol; "single" (default) or 

168 "eval" 

169 

170 Return value / exceptions raised: 

171 

172 - Return a code object if the command is complete and valid 

173 - Return None if the command is incomplete 

174 - Raise SyntaxError, ValueError or OverflowError if the command is a 

175 syntax error (OverflowError and ValueError can be produced by 

176 malformed literals). 

177 """ 

178 return _maybe_compile(self.compiler, source, filename, symbol)