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Viewing changes to pypy/interpreter/stablecompiler/future.py

  • Committer: Bazaar Package Importer
  • Author(s): Alexandre Fayolle
  • Date: 2007-04-13 09:33:09 UTC
  • Revision ID: james.westby@ubuntu.com-20070413093309-yoojh4jcoocu2krz
Tags: upstream-1.0.0
Import upstream version 1.0.0

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pypy/interpreter/stablecompiler/future.py
 
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"""Parser for future statements
 
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"""
 
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from pypy.interpreter.stablecompiler import ast, walk
 
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def is_future(stmt):
 
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    """Return true if statement is a well-formed future statement"""
 
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    if not isinstance(stmt, ast.From):
 
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        return 0
 
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    if stmt.modname == "__future__":
 
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        return 1
 
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    else:
 
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        return 0
 
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class FutureParser:
 
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    features = ("nested_scopes", "generators", "division")
 
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    def __init__(self):
 
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        self.found = {} # set
 
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    def visitModule(self, node):
 
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        stmt = node.node
 
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        for s in stmt.nodes:
 
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            if not self.check_stmt(s):
 
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                break
 
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    def check_stmt(self, stmt):
 
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        if is_future(stmt):
 
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            for name, asname in stmt.names:
 
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                if name in self.features:
 
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                    self.found[name] = 1
 
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                elif name=="*":
 
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                    raise SyntaxError(
 
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                        "future statement does not support import *",
 
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                        ( stmt.filename, stmt.lineno, 0, "" ) )
 
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                else:
 
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                    raise SyntaxError(
 
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                        "future feature %s is not defined" % name,
 
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                        ( stmt.filename, stmt.lineno, 0, "" ) )
 
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            stmt.valid_future = 1
 
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            return 1
 
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        return 0
 
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    def get_features(self):
 
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        """Return list of features enabled by future statements"""
 
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        return self.found.keys()
 
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class BadFutureParser:
 
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    """Check for invalid future statements
 
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    Those not marked valid are appearing after other statements
 
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    """
 
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    def visitFrom(self, node):
 
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        if hasattr(node, 'valid_future'):
 
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            return
 
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        if node.modname != "__future__":
 
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            return
 
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        raise SyntaxError( "from __future__ imports must occur at the beginning of the file",
 
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                           ( node.filename, node.lineno, 0, "" ) )
 
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def find_futures(node):
 
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    p1 = FutureParser()
 
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    p2 = BadFutureParser()
 
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    walk(node, p1)
 
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    walk(node, p2)
 
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    return p1.get_features()
 
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if __name__ == "__main__":
 
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    import sys
 
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    from pypy.interpreter.stablecompiler import parseFile, walk
 
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    for file in sys.argv[1:]:
 
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        print file
 
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        tree = parseFile(file)
 
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        v = FutureParser()
 
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        walk(tree, v)
 
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        print v.found
 
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        print