mirror of
https://github.com/python/cpython
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1557a7314c
Currently, contains one function: compile_command(), which helps determining whether a source string is complete, incomplete or in error. This is useful when writing your own version of the Python read-eval-print loop.
53 lines
1.5 KiB
Python
53 lines
1.5 KiB
Python
"""Utilities dealing with code objects."""
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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 "<input>"
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symbol -- optional grammar start symbol; "single" (default) or "eval"
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Return value / exception 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 if the command is a syntax error
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Approach:
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Compile three times: as is, with \n, and with \n\n appended. If
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it compiles as is, it's complete. If it compiles with one \n
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appended, we expect more. If it doesn't compile either way, we
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compare the error we get when compiling with \n or \n\n appended.
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If the errors are the same, the code is broken. But if the errors
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are different, we expect more. Not intuitive; not even guaranteed
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to hold in future releases; but this matches the compiler's
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behavior in Python 1.4 and 1.5.
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"""
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err = err1 = err2 = None
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code = code1 = code2 = None
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try:
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code = compile(source, filename, symbol)
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except SyntaxError, err:
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pass
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try:
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code1 = compile(source + "\n", filename, symbol)
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except SyntaxError, err1:
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pass
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try:
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code2 = compile(source + "\n\n", filename, symbol)
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except SyntaxError, err2:
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pass
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if code:
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return code
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if not code1 and err1 == err2:
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raise SyntaxError, err1
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