Commit 341ff8e9 authored by Michael Hanselmann's avatar Michael Hanselmann
Browse files

qlang: Add some more documentation for filters

It's not perfect, but at least some more.
Signed-off-by: default avatarMichael Hanselmann <>
Reviewed-by: default avatarIustin Pop <>
parent 425e5bf0
# Copyright (C) 2010 Google Inc.
# Copyright (C) 2010, 2011 Google Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
......@@ -19,22 +19,34 @@
# 02110-1301, USA.
"""Module for a simple query language"""
"""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
# Logic operators with one or more operands, each of which is a filter on its
# own
OP_OR = "|"
OP_AND = "&"
# Unary operators
# Unary operators with exactly one operand
OP_NOT = "!"
OP_TRUE = "?"
# Binary operators
# Binary operators with exactly two operands, the field name and an
# operator-specific value
OP_EQUAL = "="
OP_GLOB = "=*"
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