codekingpro/portable-devtools

1r"""Utilities to compile possibly incomplete Python source code.2 3This module provides two interfaces, broadly similar to the builtin4function compile(), which take program text, a filename and a 'mode'5and:6 7- Return code object if the command is complete and valid8- Return None if the command is incomplete9- Raise SyntaxError, ValueError or OverflowError if the command is a10  syntax error (OverflowError and ValueError can be produced by11  malformed literals).12 13The two interfaces are:14 15compile_command(source, filename, symbol):16 17    Compiles a single command in the manner described above.18 19CommandCompiler():20 21    Instances of this class have __call__ methods identical in22    signature to compile_command; the difference is that if the23    instance compiles program text containing a __future__ statement,24    the instance 'remembers' and compiles all subsequent program texts25    with the statement in force.26 27The module also provides another class:28 29Compile():30 31    Instances of this class act like the built-in function compile,32    but with 'memory' in the sense described above.33"""34 35import __future__36import warnings37 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.h44# Caveat emptor: These flags are undocumented on purpose and depending45# on their effect outside the standard library is **unsupported**.46PyCF_DONT_IMPLY_DEDENT = 0x20047PyCF_ONLY_AST = 0x40048PyCF_ALLOW_INCOMPLETE_INPUT = 0x400049 50def _maybe_compile(compiler, source, filename, symbol, flags):51    # Check for source consisting of only blank lines and comments.52    for line in source.split("\n"):53        line = line.strip()54        if line and line[0] != '#':55            break               # Leave it alone.56    else:57        if symbol != "eval":58            source = "pass"     # Replace it with a 'pass' statement59 60    # Disable compiler warnings when checking for incomplete input.61    with warnings.catch_warnings():62        warnings.simplefilter("ignore", (SyntaxWarning, DeprecationWarning))63        try:64            compiler(source, filename, symbol, flags=flags)65        except SyntaxError:  # Let other compile() errors propagate.66            try:67                compiler(source + "\n", filename, symbol, flags=flags)68                return None69            except _IncompleteInputError as e:70                return None71            except SyntaxError as e:72                pass73                # fallthrough74 75    return compiler(source, filename, symbol, incomplete_input=False)76 77def _compile(source, filename, symbol, incomplete_input=True, *, flags=0):78    if incomplete_input:79        flags |= PyCF_ALLOW_INCOMPLETE_INPUT80        flags |= PyCF_DONT_IMPLY_DEDENT81    return compile(source, filename, symbol, flags)82 83def compile_command(source, filename="<input>", symbol="single", flags=0):84    r"""Compile a command and determine whether it is incomplete.85 86    Arguments:87 88    source -- the source string; may contain \n characters89    filename -- optional filename from which source was read; default90                "<input>"91    symbol -- optional grammar start symbol; "single" (default), "exec"92              or "eval"93 94    Return value / exceptions raised:95 96    - Return a code object if the command is complete and valid97    - Return None if the command is incomplete98    - Raise SyntaxError, ValueError or OverflowError if the command is a99      syntax error (OverflowError and ValueError can be produced by100      malformed literals).101    """102    return _maybe_compile(_compile, source, filename, symbol, flags)103 104class Compile:105    """Instances of this class behave much like the built-in compile106    function, but if one is used to compile text containing a future107    statement, it "remembers" and compiles all subsequent program texts108    with the statement in force."""109    def __init__(self):110        self.flags = PyCF_DONT_IMPLY_DEDENT | PyCF_ALLOW_INCOMPLETE_INPUT111 112    def __call__(self, source, filename, symbol, flags=0, **kwargs):113        flags |= self.flags114        if kwargs.get('incomplete_input', True) is False:115            flags &= ~PyCF_DONT_IMPLY_DEDENT116            flags &= ~PyCF_ALLOW_INCOMPLETE_INPUT117        codeob = compile(source, filename, symbol, flags, True)118        if flags & PyCF_ONLY_AST:119            return codeob  # this is an ast.Module in this case120        for feature in _features:121            if codeob.co_flags & feature.compiler_flag:122                self.flags |= feature.compiler_flag123        return codeob124 125class CommandCompiler:126    """Instances of this class have __call__ methods identical in127    signature to compile_command; the difference is that if the128    instance compiles program text containing a __future__ statement,129    the instance 'remembers' and compiles all subsequent program texts130    with the statement in force."""131 132    def __init__(self,):133        self.compiler = Compile()134 135    def __call__(self, source, filename="<input>", symbol="single"):136        r"""Compile a command and determine whether it is incomplete.137 138        Arguments:139 140        source -- the source string; may contain \n characters141        filename -- optional filename from which source was read;142                    default "<input>"143        symbol -- optional grammar start symbol; "single" (default) or144                  "eval"145 146        Return value / exceptions raised:147 148        - Return a code object if the command is complete and valid149        - Return None if the command is incomplete150        - Raise SyntaxError, ValueError or OverflowError if the command is a151          syntax error (OverflowError and ValueError can be produced by152          malformed literals).153        """154        return _maybe_compile(self.compiler, source, filename, symbol, flags=self.compiler.flags)155