| """Parser for future statements
|
|
|
| """
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|
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| from compiler 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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| "absolute_import", "with_statement", "print_function",
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| "unicode_literals")
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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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| else:
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| raise SyntaxError, \
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| "future feature %s is not defined" % name
|
| stmt.valid_future = 1
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| return 1
|
| return 0
|
|
|
| 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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|
|
| def visitFrom(self, node):
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| if hasattr(node, 'valid_future'):
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| return
|
| if node.modname != "__future__":
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| return
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| raise SyntaxError, "invalid future statement " + repr(node)
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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 compiler 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
|
| print
|