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154 lines
5.4 KiB
154 lines
5.4 KiB
r"""Utilities to compile possibly incomplete Python source code.
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This module provides two interfaces, broadly similar to the builtin
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function compile(), which take program text, a filename and a 'mode'
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and:
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- Return code object if the command is complete and valid
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- Return None if the command is incomplete
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- Raise SyntaxError, ValueError or OverflowError if the command is a
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syntax error (OverflowError and ValueError can be produced by
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malformed literals).
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The two interfaces are:
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compile_command(source, filename, symbol):
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Compiles a single command in the manner described above.
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CommandCompiler():
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Instances of this class have __call__ methods identical in
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signature to compile_command; the difference is that if the
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instance compiles program text containing a __future__ statement,
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the instance 'remembers' and compiles all subsequent program texts
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with the statement in force.
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The module also provides another class:
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Compile():
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Instances of this class act like the built-in function compile,
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but with 'memory' in the sense described above.
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"""
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import __future__
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import warnings
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_features = [getattr(__future__, fname)
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for fname in __future__.all_feature_names]
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__all__ = ["compile_command", "Compile", "CommandCompiler"]
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# The following flags match the values from Include/cpython/compile.h
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# Caveat emptor: These flags are undocumented on purpose and depending
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# on their effect outside the standard library is **unsupported**.
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PyCF_DONT_IMPLY_DEDENT = 0x200
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PyCF_ALLOW_INCOMPLETE_INPUT = 0x4000
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def _maybe_compile(compiler, source, filename, symbol):
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# Check for source consisting of only blank lines and comments.
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for line in source.split("\n"):
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line = line.strip()
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if line and line[0] != '#':
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break # Leave it alone.
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else:
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if symbol != "eval":
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source = "pass" # Replace it with a 'pass' statement
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try:
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return compiler(source, filename, symbol)
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except SyntaxError: # Let other compile() errors propagate.
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pass
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# Catch syntax warnings after the first compile
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# to emit warnings (SyntaxWarning, DeprecationWarning) at most once.
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with warnings.catch_warnings():
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warnings.simplefilter("error")
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try:
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compiler(source + "\n", filename, symbol)
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except SyntaxError as e:
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if "incomplete input" in str(e):
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return None
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raise
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def _is_syntax_error(err1, err2):
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rep1 = repr(err1)
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rep2 = repr(err2)
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if "was never closed" in rep1 and "was never closed" in rep2:
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return False
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if rep1 == rep2:
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return True
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return False
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def _compile(source, filename, symbol):
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return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT | PyCF_ALLOW_INCOMPLETE_INPUT)
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def compile_command(source, filename="<input>", symbol="single"):
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r"""Compile a command and determine whether it is incomplete.
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Arguments:
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source -- the source string; may contain \n characters
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filename -- optional filename from which source was read; default
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"<input>"
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symbol -- optional grammar start symbol; "single" (default), "exec"
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or "eval"
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Return value / exceptions raised:
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- Return a code object if the command is complete and valid
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- Return None if the command is incomplete
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- Raise SyntaxError, ValueError or OverflowError if the command is a
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syntax error (OverflowError and ValueError can be produced by
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malformed literals).
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"""
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return _maybe_compile(_compile, source, filename, symbol)
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class Compile:
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"""Instances of this class behave much like the built-in compile
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function, but if one is used to compile text containing a future
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statement, it "remembers" and compiles all subsequent program texts
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with the statement in force."""
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def __init__(self):
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self.flags = PyCF_DONT_IMPLY_DEDENT | PyCF_ALLOW_INCOMPLETE_INPUT
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def __call__(self, source, filename, symbol):
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codeob = compile(source, filename, symbol, self.flags, True)
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for feature in _features:
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if codeob.co_flags & feature.compiler_flag:
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self.flags |= feature.compiler_flag
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return codeob
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class CommandCompiler:
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"""Instances of this class have __call__ methods identical in
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signature to compile_command; the difference is that if the
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instance compiles program text containing a __future__ statement,
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the instance 'remembers' and compiles all subsequent program texts
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with the statement in force."""
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def __init__(self,):
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self.compiler = Compile()
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def __call__(self, source, filename="<input>", symbol="single"):
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r"""Compile a command and determine whether it is incomplete.
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Arguments:
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source -- the source string; may contain \n characters
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filename -- optional filename from which source was read;
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default "<input>"
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symbol -- optional grammar start symbol; "single" (default) or
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"eval"
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Return value / exceptions raised:
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- Return a code object if the command is complete and valid
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- Return None if the command is incomplete
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- Raise SyntaxError, ValueError or OverflowError if the command is a
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syntax error (OverflowError and ValueError can be produced by
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malformed literals).
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"""
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return _maybe_compile(self.compiler, source, filename, symbol)
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