Showing the changes to sys/lib/python/codeop.py (1 of 3706 files). Show all
Unified · Split
| @@ -0,0 +1,168 @@ | ||
| 1 | +r"""Utilities to compile possibly incomplete Python source code. | |
| 2 | + | |
| 3 | +This module provides two interfaces, broadly similar to the builtin | |
| 4 | +function compile(), which take program text, a filename and a 'mode' | |
| 5 | +and: | |
| 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 | + | |
| 13 | +Approach: | |
| 14 | + | |
| 15 | +First, check if the source consists entirely of blank lines and | |
| 16 | +comments; if so, replace it with 'pass', because the built-in | |
| 17 | +parser doesn't always do the right thing for these. | |
| 18 | + | |
| 19 | +Compile three times: as is, with \n, and with \n\n appended. If it | |
| 20 | +compiles as is, it's complete. If it compiles with one \n appended, | |
| 21 | +we expect more. If it doesn't compile either way, we compare the | |
| 22 | +error we get when compiling with \n or \n\n appended. If the errors | |
| 23 | +are the same, the code is broken. But if the errors are different, we | |
| 24 | +expect more. Not intuitive; not even guaranteed to hold in future | |
| 25 | +releases; but this matches the compiler's behavior from Python 1.4 | |
| 26 | +through 2.2, at least. | |
| 27 | + | |
| 28 | +Caveat: | |
| 29 | + | |
| 30 | +It is possible (but not likely) that the parser stops parsing with a | |
| 31 | +successful outcome before reaching the end of the source; in this | |
| 32 | +case, trailing symbols may be ignored instead of causing an error. | |
| 33 | +For example, a backslash followed by two newlines may be followed by | |
| 34 | +arbitrary garbage. This will be fixed once the API for the parser is | |
| 35 | +better. | |
| 36 | + | |
| 37 | +The two interfaces are: | |
| 38 | + | |
| 39 | +compile_command(source, filename, symbol): | |
| 40 | + | |
| 41 | + Compiles a single command in the manner described above. | |
| 42 | + | |
| 43 | +CommandCompiler(): | |
| 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 | + | |
| 51 | +The module also provides another class: | |
| 52 | + | |
| 53 | +Compile(): | |
| 54 | + | |
| 55 | + Instances of this class act like the built-in function compile, | |
| 56 | + but with 'memory' in the sense described above. | |
| 57 | +""" | |
| 58 | + | |
| 59 | +import __future__ | |
| 60 | + | |
| 61 | +_features = [getattr(__future__, fname) | |
| 62 | + for fname in __future__.all_feature_names] | |
| 63 | + | |
| 64 | +__all__ = ["compile_command", "Compile", "CommandCompiler"] | |
| 65 | + | |
| 66 | +PyCF_DONT_IMPLY_DEDENT = 0x200 # Matches pythonrun.h | |
| 67 | + | |
| 68 | +def _maybe_compile(compiler, source, filename, symbol): | |
| 69 | + # Check for source consisting of only blank lines and comments | |
| 70 | + for line in source.split("\n"): | |
| 71 | + line = line.strip() | |
| 72 | + if line and line[0] != '#': | |
| 73 | + break # Leave it alone | |
| 74 | + else: | |
| 75 | + if symbol != "eval": | |
| 76 | + source = "pass" # Replace it with a 'pass' statement | |
| 77 | + | |
| 78 | + err = err1 = err2 = None | |
| 79 | + code = code1 = code2 = None | |
| 80 | + | |
| 81 | + try: | |
| 82 | + code = compiler(source, filename, symbol) | |
| 83 | + except SyntaxError, err: | |
| 84 | + pass | |
| 85 | + | |
| 86 | + try: | |
| 87 | + code1 = compiler(source + "\n", filename, symbol) | |
| 88 | + except SyntaxError, err1: | |
| 89 | + pass | |
| 90 | + | |
| 91 | + try: | |
| 92 | + code2 = compiler(source + "\n\n", filename, symbol) | |
| 93 | + except SyntaxError, err2: | |
| 94 | + pass | |
| 95 | + | |
| 96 | + if code: | |
| 97 | + return code | |
| 98 | + if not code1 and repr(err1) == repr(err2): | |
| 99 | + raise SyntaxError, err1 | |
| 100 | + | |
| 101 | +def _compile(source, filename, symbol): | |
| 102 | + return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT) | |
| 103 | + | |
| 104 | +def compile_command(source, filename="<input>", symbol="single"): | |
| 105 | + r"""Compile a command and determine whether it is incomplete. | |
| 106 | + | |
| 107 | + Arguments: | |
| 108 | + | |
| 109 | + source -- the source string; may contain \n characters | |
| 110 | + filename -- optional filename from which source was read; default | |
| 111 | + "<input>" | |
| 112 | + symbol -- optional grammar start symbol; "single" (default) or "eval" | |
| 113 | + | |
| 114 | + Return value / exceptions raised: | |
| 115 | + | |
| 116 | + - Return a code object if the command is complete and valid | |
| 117 | + - Return None if the command is incomplete | |
| 118 | + - Raise SyntaxError, ValueError or OverflowError if the command is a | |
| 119 | + syntax error (OverflowError and ValueError can be produced by | |
| 120 | + malformed literals). | |
| 121 | + """ | |
| 122 | + return _maybe_compile(_compile, source, filename, symbol) | |
| 123 | + | |
| 124 | +class Compile: | |
| 125 | + """Instances of this class behave much like the built-in compile | |
| 126 | + function, but if one is used to compile text containing a future | |
| 127 | + statement, it "remembers" and compiles all subsequent program texts | |
| 128 | + with the statement in force.""" | |
| 129 | + def __init__(self): | |
| 130 | + self.flags = PyCF_DONT_IMPLY_DEDENT | |
| 131 | + | |
| 132 | + def __call__(self, source, filename, symbol): | |
| 133 | + codeob = compile(source, filename, symbol, self.flags, 1) | |
| 134 | + for feature in _features: | |
| 135 | + if codeob.co_flags & feature.compiler_flag: | |
| 136 | + self.flags |= feature.compiler_flag | |
| 137 | + return codeob | |
| 138 | + | |
| 139 | +class CommandCompiler: | |
| 140 | + """Instances of this class have __call__ methods identical in | |
| 141 | + signature to compile_command; the difference is that if the | |
| 142 | + instance compiles program text containing a __future__ statement, | |
| 143 | + the instance 'remembers' and compiles all subsequent program texts | |
| 144 | + with the statement in force.""" | |
| 145 | + | |
| 146 | + def __init__(self,): | |
| 147 | + self.compiler = Compile() | |
| 148 | + | |
| 149 | + def __call__(self, source, filename="<input>", symbol="single"): | |
| 150 | + r"""Compile a command and determine whether it is incomplete. | |
| 151 | + | |
| 152 | + Arguments: | |
| 153 | + | |
| 154 | + source -- the source string; may contain \n characters | |
| 155 | + filename -- optional filename from which source was read; | |
| 156 | + default "<input>" | |
| 157 | + symbol -- optional grammar start symbol; "single" (default) or | |
| 158 | + "eval" | |
| 159 | + | |
| 160 | + Return value / exceptions raised: | |
| 161 | + | |
| 162 | + - Return a code object if the command is complete and valid | |
| 163 | + - Return None if the command is incomplete | |
| 164 | + - Raise SyntaxError, ValueError or OverflowError if the command is a | |
| 165 | + syntax error (OverflowError and ValueError can be produced by | |
| 166 | + malformed literals). | |
| 167 | + """ | |
| 168 | + return _maybe_compile(self.compiler, source, filename, symbol) | |