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66 lines
2.6 KiB
Python
66 lines
2.6 KiB
Python
# this will implement noderange grammar
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# considered ast, but a number of things violate python grammar like [] in
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# the middle of strings and use of @ for anything is not in their syntax
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#construct custom grammer with pyparsing
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#>>> grammar = pyparsing.Word(pyparsing.alphanums+'/', pyparsing.alphanums+'[]-.*') | ',-' | ',' | '@'
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#>>> parser = pyparsing.nestedExpr('(',')',content=grammar)
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#>>> parser.parseString("(n1-n4,compute,(foo@bar),-bob,bob)").asList()
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#[['n1-n4', ',', 'compute', ',', ['foo', '@', 'bar'], ',-', 'bob', ',', 'bob']]
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import pyparsing
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import re
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class NodeRange(object):
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"""Iterate over a noderange
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:param noderange: string representing a noderange to evaluate
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:param verify: whether or not to perform lookups in the config
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"""
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_grammar = \
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pyparsing.Word(
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pyparsing.alphanums + '=', pyparsing.alphanums + '[]-.*+') | \
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',-' | ',' | '@'
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_parser = pyparsing.nestedExpr(content=_grammar)
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def __init__(self, noderange, verify=True):
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self.verify = verify
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elements = self._parser.parseString("(" + noderange + ")").asList()
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self._noderange = self._evaluate(elements)
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print self._noderange
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def _evaluate(self, parsetree):
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current_op = 0 # enum, 0 union, 1 subtract, 2 intersect
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current_range = set([])
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if not isinstance(parsetree,list): # down to a plain text thing
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return self._expandstring(parsetree)
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for elem in parsetree:
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if elem == ',-':
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current_op = 1
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elif elem == ',':
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current_op = 0
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elif elem == '@':
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current_op = 2
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elif current_op == 0:
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current_range |= self._evaluate(elem)
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elif current_op == 1:
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current_range -= self._evaluate(elem)
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elif current_op == 2:
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current_range &= self._evaluate(elem)
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return current_range
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def _expandstring(self, element):
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if self.verify:
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#this is where we would check for exactly this
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raise Exception("TODO: link with actual config")
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#this is where we would check for a literal groupname
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#ok, now time to understand the various things
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if '[' in element: #[] style expansion
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raise Exception("TODO: [] in expression")
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elif '-' in element: # *POSSIBLE* range, could just be part of name
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raise Exception("TODO: ranged expression")
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elif ':' in element: # : range for less ambiguity
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raise Exception("TODO: ranged expression")
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if not self.verify:
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return set([element])
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