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78 lines
1.8 KiB
Python
78 lines
1.8 KiB
Python
"""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",)
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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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if node.doc is None:
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off = 0
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else:
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off = 1
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stmt = node.node
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for s in stmt.nodes[off:]:
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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
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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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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, "invalid future statement"
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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
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print
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