| 1 | """Parser for future statements
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| 2 |
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| 3 | """
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| 4 |
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| 5 | from . import ast
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| 6 | from .visitor import walk
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| 7 |
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| 8 |
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| 9 | def is_future(stmt):
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| 10 | """Return true if statement is a well-formed future statement"""
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| 11 | if not isinstance(stmt, ast.From):
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| 12 | return 0
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| 13 | if stmt.modname == "__future__":
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| 14 | return 1
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| 15 | else:
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| 16 | return 0
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| 17 |
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| 18 | class FutureParser:
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| 19 |
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| 20 | features = ("nested_scopes", "generators", "division",
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| 21 | "absolute_import", "with_statement", "print_function",
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| 22 | "unicode_literals")
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| 23 |
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| 24 | def __init__(self):
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| 25 | self.found = {} # set
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| 26 |
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| 27 | def visitModule(self, node):
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| 28 | stmt = node.node
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| 29 | for s in stmt.nodes:
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| 30 | if not self.check_stmt(s):
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| 31 | break
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| 32 |
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| 33 | def check_stmt(self, stmt):
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| 34 | if is_future(stmt):
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| 35 | for name, asname in stmt.names:
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| 36 | if name in self.features:
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| 37 | self.found[name] = 1
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| 38 | else:
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| 39 | raise SyntaxError, \
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| 40 | "future feature %s is not defined" % name
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| 41 | stmt.valid_future = 1
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| 42 | return 1
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| 43 | return 0
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| 44 |
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| 45 | def get_features(self):
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| 46 | """Return list of features enabled by future statements"""
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| 47 | return self.found.keys()
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| 48 |
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| 49 | class BadFutureParser:
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| 50 | """Check for invalid future statements"""
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| 51 |
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| 52 | def visitFrom(self, node):
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| 53 | if hasattr(node, 'valid_future'):
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| 54 | return
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| 55 | if node.modname != "__future__":
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| 56 | return
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| 57 | raise SyntaxError, "invalid future statement " + repr(node)
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| 58 |
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| 59 | def find_futures(node):
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| 60 | p1 = FutureParser()
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| 61 | p2 = BadFutureParser()
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| 62 | walk(node, p1)
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| 63 | walk(node, p2)
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| 64 | return p1.get_features()
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| 65 |
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| 66 | if __name__ == "__main__":
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| 67 | import sys
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| 68 | from compiler import parseFile, walk
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| 69 |
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| 70 | for file in sys.argv[1:]:
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| 71 | print(file)
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| 72 | tree = parseFile(file)
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| 73 | v = FutureParser()
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| 74 | walk(tree, v)
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| 75 | print(v.found)
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| 76 | print()
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