|
| 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 | +The two interfaces are: |
| 14 | +
|
| 15 | +compile_command(source, filename, symbol): |
| 16 | +
|
| 17 | + Compiles a single command in the manner described above. |
| 18 | +
|
| 19 | +CommandCompiler(): |
| 20 | +
|
| 21 | + Instances of this class have __call__ methods identical in |
| 22 | + signature to compile_command; the difference is that if the |
| 23 | + instance compiles program text containing a __future__ statement, |
| 24 | + the instance 'remembers' and compiles all subsequent program texts |
| 25 | + with the statement in force. |
| 26 | +
|
| 27 | +The module also provides another class: |
| 28 | +
|
| 29 | +Compile(): |
| 30 | +
|
| 31 | + Instances of this class act like the built-in function compile, |
| 32 | + but with 'memory' in the sense described above. |
| 33 | +""" |
| 34 | + |
| 35 | +import __future__ |
| 36 | +import warnings |
| 37 | + |
| 38 | +_features = [getattr(__future__, fname) |
| 39 | + for fname in __future__.all_feature_names] |
| 40 | + |
| 41 | +__all__ = ["compile_command", "Compile", "CommandCompiler"] |
| 42 | + |
| 43 | +# The following flags match the values from Include/cpython/compile.h |
| 44 | +# Caveat emptor: These flags are undocumented on purpose and depending |
| 45 | +# on their effect outside the standard library is **unsupported**. |
| 46 | +PyCF_DONT_IMPLY_DEDENT = 0x200 |
| 47 | +PyCF_ALLOW_INCOMPLETE_INPUT = 0x4000 |
| 48 | + |
| 49 | +def _maybe_compile(compiler, source, filename, symbol): |
| 50 | + # Check for source consisting of only blank lines and comments. |
| 51 | + for line in source.split("\n"): |
| 52 | + line = line.strip() |
| 53 | + if line and line[0] != '#': |
| 54 | + break # Leave it alone. |
| 55 | + else: |
| 56 | + if symbol != "eval": |
| 57 | + source = "pass" # Replace it with a 'pass' statement |
| 58 | + |
| 59 | + try: |
| 60 | + return compiler(source, filename, symbol) |
| 61 | + except SyntaxError: # Let other compile() errors propagate. |
| 62 | + pass |
| 63 | + |
| 64 | + # Catch syntax warnings after the first compile |
| 65 | + # to emit warnings (SyntaxWarning, DeprecationWarning) at most once. |
| 66 | + with warnings.catch_warnings(): |
| 67 | + warnings.simplefilter("error") |
| 68 | + |
| 69 | + try: |
| 70 | + compiler(source + "\n", filename, symbol) |
| 71 | + except SyntaxError as e: |
| 72 | + if "incomplete input" in str(e): |
| 73 | + return None |
| 74 | + raise |
| 75 | + |
| 76 | +def _is_syntax_error(err1, err2): |
| 77 | + rep1 = repr(err1) |
| 78 | + rep2 = repr(err2) |
| 79 | + if "was never closed" in rep1 and "was never closed" in rep2: |
| 80 | + return False |
| 81 | + if rep1 == rep2: |
| 82 | + return True |
| 83 | + return False |
| 84 | + |
| 85 | +def _compile(source, filename, symbol): |
| 86 | + return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT | PyCF_ALLOW_INCOMPLETE_INPUT) |
| 87 | + |
| 88 | +def compile_command(source, filename="<input>", symbol="single"): |
| 89 | + r"""Compile a command and determine whether it is incomplete. |
| 90 | +
|
| 91 | + Arguments: |
| 92 | +
|
| 93 | + source -- the source string; may contain \n characters |
| 94 | + filename -- optional filename from which source was read; default |
| 95 | + "<input>" |
| 96 | + symbol -- optional grammar start symbol; "single" (default), "exec" |
| 97 | + or "eval" |
| 98 | +
|
| 99 | + Return value / exceptions raised: |
| 100 | +
|
| 101 | + - Return a code object if the command is complete and valid |
| 102 | + - Return None if the command is incomplete |
| 103 | + - Raise SyntaxError, ValueError or OverflowError if the command is a |
| 104 | + syntax error (OverflowError and ValueError can be produced by |
| 105 | + malformed literals). |
| 106 | + """ |
| 107 | + return _maybe_compile(_compile, source, filename, symbol) |
| 108 | + |
| 109 | +class Compile: |
| 110 | + """Instances of this class behave much like the built-in compile |
| 111 | + function, but if one is used to compile text containing a future |
| 112 | + statement, it "remembers" and compiles all subsequent program texts |
| 113 | + with the statement in force.""" |
| 114 | + def __init__(self): |
| 115 | + self.flags = PyCF_DONT_IMPLY_DEDENT | PyCF_ALLOW_INCOMPLETE_INPUT |
| 116 | + |
| 117 | + def __call__(self, source, filename, symbol): |
| 118 | + codeob = compile(source, filename, symbol, self.flags, True) |
| 119 | + for feature in _features: |
| 120 | + if codeob.co_flags & feature.compiler_flag: |
| 121 | + self.flags |= feature.compiler_flag |
| 122 | + return codeob |
| 123 | + |
| 124 | +class CommandCompiler: |
| 125 | + """Instances of this class have __call__ methods identical in |
| 126 | + signature to compile_command; the difference is that if the |
| 127 | + instance compiles program text containing a __future__ statement, |
| 128 | + the instance 'remembers' and compiles all subsequent program texts |
| 129 | + with the statement in force.""" |
| 130 | + |
| 131 | + def __init__(self,): |
| 132 | + self.compiler = Compile() |
| 133 | + |
| 134 | + def __call__(self, source, filename="<input>", symbol="single"): |
| 135 | + r"""Compile a command and determine whether it is incomplete. |
| 136 | +
|
| 137 | + Arguments: |
| 138 | +
|
| 139 | + source -- the source string; may contain \n characters |
| 140 | + filename -- optional filename from which source was read; |
| 141 | + default "<input>" |
| 142 | + symbol -- optional grammar start symbol; "single" (default) or |
| 143 | + "eval" |
| 144 | +
|
| 145 | + Return value / exceptions raised: |
| 146 | +
|
| 147 | + - Return a code object if the command is complete and valid |
| 148 | + - Return None if the command is incomplete |
| 149 | + - Raise SyntaxError, ValueError or OverflowError if the command is a |
| 150 | + syntax error (OverflowError and ValueError can be produced by |
| 151 | + malformed literals). |
| 152 | + """ |
| 153 | + return _maybe_compile(self.compiler, source, filename, symbol) |
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