From 341ff8e9dc1b10c17ecc0986118662fbbdca412e Mon Sep 17 00:00:00 2001
From: Michael Hanselmann <hansmi@google.com>
Date: Fri, 11 Mar 2011 17:08:49 +0100
Subject: [PATCH] qlang: Add some more documentation for filters
It's not perfect, but at least some more.
Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>
---
lib/qlang.py | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/lib/qlang.py b/lib/qlang.py
index d255ef353..02cdef1c2 100644
--- a/lib/qlang.py
+++ b/lib/qlang.py
@@ -1,7 +1,7 @@
#
#
-# 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_NOT_EQUAL = "!="
OP_GLOB = "=*"
--
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