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# Copyright (C) 2010, 2011 Google Inc.

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# This program is free software; you can redistribute it and/or modify

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# the Free Software Foundation; either version 2 of the License, or

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# General Public License for more details.

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"""Module for a simple query language

A query filter is always a list. The first item in the list is the operator

(e.g. C{[OP_AND, ...]}), while the other items depend on the operator. For

logic operators (e.g. L{OP_AND}, L{OP_OR}), they are subfilters whose results

are combined. Unary operators take exactly one other item (e.g. a subfilter for

L{OP_NOT} and a field name for L{OP_TRUE}). Binary operators take exactly two

operands, usually a field name and a value to compare against. Filters are

converted to callable functions by L{query._CompileFilter}.

"""

from ganeti import errors

# Logic operators with one or more operands, each of which is a filter on its

# own

OP_OR = "|"

OP_AND = "&"

# Unary operators with exactly one operand

OP_NOT = "!"

OP_TRUE = "?"

# Binary operators with exactly two operands, the field name and an

# operator-specific value

OP_EQUAL = "="

OP_NOT_EQUAL = "!="

OP_GLOB = "=*"

OP_REGEXP = "=~"

OP_CONTAINS = "=[]"

def MakeSimpleFilter(namefield, values):

  """Builds simple a filter.

  @param namefield: Name of field containing item name

  @param values: List of names

  """

  if values:

    return [OP_OR] + [[OP_EQUAL, namefield, i] for i in values]

  return None