proxy.py revision 3105 
1# Copyright (c) 2004-2006 The Regents of The University of Michigan
2# All rights reserved.
3#
4# Redistribution and use in source and binary forms, with or without
5# modification, are permitted provided that the following conditions are
6# met: redistributions of source code must retain the above copyright
7# notice, this list of conditions and the following disclaimer;
8# redistributions in binary form must reproduce the above copyright
9# notice, this list of conditions and the following disclaimer in the
10# documentation and/or other materials provided with the distribution;
11# neither the name of the copyright holders nor the names of its
12# contributors may be used to endorse or promote products derived from
13# this software without specific prior written permission.
14#
15# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
19# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
21# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26#
27# Authors: Steve Reinhardt
28#          Nathan Binkert
29
30#####################################################################
31#
32# Proxy object support.
33#
34#####################################################################
35
36class BaseProxy(object):
37    def __init__(self, search_self, search_up):
38        self._search_self = search_self
39        self._search_up = search_up
40        self._multiplier = None
41
42    def __setattr__(self, attr, value):
43        if not attr.startswith('_'):
44            raise AttributeError, \
45                  "cannot set attribute '%s' on proxy object" % attr
46        super(BaseProxy, self).__setattr__(attr, value)
47
48    # support multiplying proxies by constants
49    def __mul__(self, other):
50        if not isinstance(other, (int, long, float)):
51            raise TypeError, "Proxy multiplier must be integer"
52        if self._multiplier == None:
53            self._multiplier = other
54        else:
55            # support chained multipliers
56            self._multiplier *= other
57        return self
58
59    __rmul__ = __mul__
60
61    def _mulcheck(self, result):
62        if self._multiplier == None:
63            return result
64        return result * self._multiplier
65
66    def unproxy(self, base):
67        obj = base
68        done = False
69
70        if self._search_self:
71            result, done = self.find(obj)
72
73        if self._search_up:
74            while not done:
75                obj = obj._parent
76                if not obj:
77                    break
78                result, done = self.find(obj)
79
80        if not done:
81            raise AttributeError, \
82                  "Can't resolve proxy '%s' of type '%s' from '%s'" % \
83                  (self.path(), self._pdesc.ptype_str, base.path())
84
85        if isinstance(result, BaseProxy):
86            if result == self:
87                raise RuntimeError, "Cycle in unproxy"
88            result = result.unproxy(obj)
89
90        return self._mulcheck(result)
91
92    def getindex(obj, index):
93        if index == None:
94            return obj
95        try:
96            obj = obj[index]
97        except TypeError:
98            if index != 0:
99                raise
100            # if index is 0 and item is not subscriptable, just
101            # use item itself (so cpu[0] works on uniprocessors)
102        return obj
103    getindex = staticmethod(getindex)
104
105    def set_param_desc(self, pdesc):
106        self._pdesc = pdesc
107
108class AttrProxy(BaseProxy):
109    def __init__(self, search_self, search_up, attr):
110        super(AttrProxy, self).__init__(search_self, search_up)
111        self._attr = attr
112        self._modifiers = []
113
114    def __getattr__(self, attr):
115        # python uses __bases__ internally for inheritance
116        if attr.startswith('_'):
117            return super(AttrProxy, self).__getattr__(self, attr)
118        if hasattr(self, '_pdesc'):
119            raise AttributeError, "Attribute reference on bound proxy"
120        self._modifiers.append(attr)
121        return self
122
123    # support indexing on proxies (e.g., Self.cpu[0])
124    def __getitem__(self, key):
125        if not isinstance(key, int):
126            raise TypeError, "Proxy object requires integer index"
127        self._modifiers.append(key)
128        return self
129
130    def find(self, obj):
131        try:
132            val = getattr(obj, self._attr)
133        except:
134            return None, False
135        while isproxy(val):
136            val = val.unproxy(obj)
137        for m in self._modifiers:
138            if isinstance(m, str):
139                val = getattr(val, m)
140            elif isinstance(m, int):
141                val = val[m]
142            else:
143                assert("Item must be string or integer")
144            while isproxy(val):
145                val = val.unproxy(obj)
146        return val, True
147
148    def path(self):
149        p = self._attr
150        for m in self._modifiers:
151            if isinstance(m, str):
152                p += '.%s' % m
153            elif isinstance(m, int):
154                p += '[%d]' % m
155            else:
156                assert("Item must be string or integer")
157        return p
158
159class AnyProxy(BaseProxy):
160    def find(self, obj):
161        return obj.find_any(self._pdesc.ptype)
162
163    def path(self):
164        return 'any'
165
166def isproxy(obj):
167    if isinstance(obj, (BaseProxy, params.EthernetAddr)):
168        return True
169    elif isinstance(obj, (list, tuple)):
170        for v in obj:
171            if isproxy(v):
172                return True
173    return False
174
175class ProxyFactory(object):
176    def __init__(self, search_self, search_up):
177        self.search_self = search_self
178        self.search_up = search_up
179
180    def __getattr__(self, attr):
181        if attr == 'any':
182            return AnyProxy(self.search_self, self.search_up)
183        else:
184            return AttrProxy(self.search_self, self.search_up, attr)
185
186# global objects for handling proxies
187Parent = ProxyFactory(search_self = False, search_up = True)
188Self = ProxyFactory(search_self = True, search_up = False)
189
190# limit exports on 'from proxy import *'
191__all__ = ['Parent', 'Self']
192
193# see comment on imports at end of __init__.py.
194import params # for EthernetAddr
195