GDB (xrefs)

xmethod.py
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1 # Python side of the support for xmethods.
2 # Copyright (C) 2013-2018 Free Software Foundation, Inc.
3
4 # This program is free software; you can redistribute it and/or modify
5 # it under the terms of the GNU General Public License as published by
6 # the Free Software Foundation; either version 3 of the License, or
7 # (at your option) any later version.
8 #
9 # This program is distributed in the hope that it will be useful,
10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 # GNU General Public License for more details.
13 #
14 # You should have received a copy of the GNU General Public License
15 # along with this program. If not, see <http://www.gnu.org/licenses/>.
16
17 """Utilities for defining xmethods"""
18
19 import gdb
20 import re
21 import sys
22
23
24 if sys.version_info[0] > 2:
25 # Python 3 removed basestring and long
26 basestring = str
27 long = int
28
29
30 class XMethod(object):
31 """Base class (or a template) for an xmethod description.
32
33 Currently, the description requires only the 'name' and 'enabled'
34 attributes. Description objects are managed by 'XMethodMatcher'
35 objects (see below). Note that this is only a template for the
36 interface of the XMethodMatcher.methods objects. One could use
37 this class or choose to use an object which supports this exact same
38 interface. Also, an XMethodMatcher can choose not use it 'methods'
39 attribute. In such cases this class (or an equivalent) is not used.
40
41 Attributes:
42 name: The name of the xmethod.
43 enabled: A boolean indicating if the xmethod is enabled.
44 """
45
46 def __init__(self, name):
47 self.name = name
48 self.enabled = True
49
50
51 class XMethodMatcher(object):
52 """Abstract base class for matching an xmethod.
53
54 When looking for xmethods, GDB invokes the `match' method of a
55 registered xmethod matcher to match the object type and method name.
56 The `match' method in concrete classes derived from this class should
57 return an `XMethodWorker' object, or a list of `XMethodWorker'
58 objects if there is a match (see below for 'XMethodWorker' class).
59
60 Attributes:
61 name: The name of the matcher.
62 enabled: A boolean indicating if the matcher is enabled.
63 methods: A sequence of objects of type 'XMethod', or objects
64 which have at least the attributes of an 'XMethod' object.
65 This list is used by the 'enable'/'disable'/'info' commands to
66 enable/disable/list the xmethods registered with GDB. See
67 the 'match' method below to know how this sequence is used.
68 This attribute is None if the matcher chooses not have any
69 xmethods managed by it.
70 """
71
72 def __init__(self, name):
73 """
74 Args:
75 name: An identifying name for the xmethod or the group of
76 xmethods returned by the `match' method.
77 """
78 self.name = name
79 self.enabled = True
80 self.methods = None
81
82 def match(self, class_type, method_name):
83 """Match class type and method name.
84
85 In derived classes, it should return an XMethodWorker object, or a
86 sequence of 'XMethodWorker' objects. Only those xmethod workers
87 whose corresponding 'XMethod' descriptor object is enabled should be
88 returned.
89
90 Args:
91 class_type: The class type (gdb.Type object) to match.
92 method_name: The name (string) of the method to match.
93 """
94 raise NotImplementedError("XMethodMatcher match")
95
96
97 class XMethodWorker(object):
98 """Base class for all xmethod workers defined in Python.
99
100 An xmethod worker is an object which matches the method arguments, and
101 invokes the method when GDB wants it to. Internally, GDB first invokes the
102 'get_arg_types' method to perform overload resolution. If GDB selects to
103 invoke this Python xmethod, then it invokes it via the overridden
104 '__call__' method. The 'get_result_type' method is used to implement
105 'ptype' on the xmethod.
106
107 Derived classes should override the 'get_arg_types', 'get_result_type'
108 and '__call__' methods.
109 """
110
111 def get_arg_types(self):
112 """Return arguments types of an xmethod.
113
114 A sequence of gdb.Type objects corresponding to the arguments of the
115 xmethod are returned. If the xmethod takes no arguments, then 'None'
116 or an empty sequence is returned. If the xmethod takes only a single
117 argument, then a gdb.Type object or a sequence with a single gdb.Type
118 element is returned.
119 """
120 raise NotImplementedError("XMethodWorker get_arg_types")
121
122 def get_result_type(self, *args):
123 """Return the type of the result of the xmethod.
124
125 Args:
126 args: Arguments to the method. Each element of the tuple is a
127 gdb.Value object. The first element is the 'this' pointer
128 value. These are the same arguments passed to '__call__'.
129
130 Returns:
131 A gdb.Type object representing the type of the result of the
132 xmethod.
133 """
134 raise NotImplementedError("XMethodWorker get_result_type")
135
136 def __call__(self, *args):
137 """Invoke the xmethod.
138
139 Args:
140 args: Arguments to the method. Each element of the tuple is a
141 gdb.Value object. The first element is the 'this' pointer
142 value.
143
144 Returns:
145 A gdb.Value corresponding to the value returned by the xmethod.
146 Returns 'None' if the method does not return anything.
147 """
148 raise NotImplementedError("XMethodWorker __call__")
149
150
151 class SimpleXMethodMatcher(XMethodMatcher):
152 """A utility class to implement simple xmethod mathers and workers.
153
154 See the __init__ method below for information on how instances of this
155 class can be used.
156
157 For simple classes and methods, one can choose to use this class. For
158 complex xmethods, which need to replace/implement template methods on
159 possibly template classes, one should implement their own xmethod
160 matchers and workers. See py-xmethods.py in testsuite/gdb.python
161 directory of the GDB source tree for examples.
162 """
163
164 class SimpleXMethodWorker(XMethodWorker):
165 def __init__(self, method_function, arg_types):
166 self._arg_types = arg_types
167 self._method_function = method_function
168
169 def get_arg_types(self):
170 return self._arg_types
171
172 def __call__(self, *args):
173 return self._method_function(*args)
174
175
176 def __init__(self, name, class_matcher, method_matcher, method_function,
177 *arg_types):
178 """
179 Args:
180 name: Name of the xmethod matcher.
181 class_matcher: A regular expression used to match the name of the
182 class whose method this xmethod is implementing/replacing.
183 method_matcher: A regular expression used to match the name of the
184 method this xmethod is implementing/replacing.
185 method_function: A Python callable which would be called via the
186 'invoke' method of the worker returned by the objects of this
187 class. This callable should accept the object (*this) as the
188 first argument followed by the rest of the arguments to the
189 method. All arguments to this function should be gdb.Value
190 objects.
191 arg_types: The gdb.Type objects corresponding to the arguments that
192 this xmethod takes. It can be None, or an empty sequence,
193 or a single gdb.Type object, or a sequence of gdb.Type objects.
194 """
195 XMethodMatcher.__init__(self, name)
196 assert callable(method_function), (
197 "The 'method_function' argument to 'SimpleXMethodMatcher' "
198 "__init__ method should be a callable.")
199 self._method_function = method_function
200 self._class_matcher = class_matcher
201 self._method_matcher = method_matcher
202 self._arg_types = arg_types
203
204 def match(self, class_type, method_name):
205 cm = re.match(self._class_matcher, str(class_type.unqualified().tag))
206 mm = re.match(self._method_matcher, method_name)
207 if cm and mm:
208 return SimpleXMethodMatcher.SimpleXMethodWorker(
209 self._method_function, self._arg_types)
210
211
212 # A helper function for register_xmethod_matcher which returns an error
213 # object if MATCHER is not having the requisite attributes in the proper
214 # format.
215
216 def _validate_xmethod_matcher(matcher):
217 if not hasattr(matcher, "match"):
218 return TypeError("Xmethod matcher is missing method: match")
219 if not hasattr(matcher, "name"):
220 return TypeError("Xmethod matcher is missing attribute: name")
221 if not hasattr(matcher, "enabled"):
222 return TypeError("Xmethod matcher is missing attribute: enabled")
223 if not isinstance(matcher.name, basestring):
224 return TypeError("Attribute 'name' of xmethod matcher is not a "
225 "string")
226 if matcher.name.find(";") >= 0:
227 return ValueError("Xmethod matcher name cannot contain ';' in it")
228
229
230 # A helper function for register_xmethod_matcher which looks up an
231 # xmethod matcher with NAME in LOCUS. Returns the index of the xmethod
232 # matcher in 'xmethods' sequence attribute of the LOCUS. If NAME is not
233 # found in LOCUS, then -1 is returned.
234
235 def _lookup_xmethod_matcher(locus, name):
236 for i in range(0, len(locus.xmethods)):
237 if locus.xmethods[i].name == name:
238 return i
239 return -1
240
241
242 def register_xmethod_matcher(locus, matcher, replace=False):
243 """Registers a xmethod matcher MATCHER with a LOCUS.
244
245 Arguments:
246 locus: The locus in which the xmethods should be registered.
247 It can be 'None' to indicate that the xmethods should be
248 registered globally. Or, it could be a gdb.Objfile or a
249 gdb.Progspace object in which the xmethods should be
250 registered.
251 matcher: The xmethod matcher to register with the LOCUS. It
252 should be an instance of 'XMethodMatcher' class.
253 replace: If True, replace any existing xmethod matcher with the
254 same name in the locus. Otherwise, if a matcher with the same name
255 exists in the locus, raise an exception.
256 """
257 err = _validate_xmethod_matcher(matcher)
258 if err:
259 raise err
260 if not locus:
261 locus = gdb
262 if locus == gdb:
263 locus_name = "global"
264 else:
265 locus_name = locus.filename
266 index = _lookup_xmethod_matcher(locus, matcher.name)
267 if index >= 0:
268 if replace:
269 del locus.xmethods[index]
270 else:
271 raise RuntimeError("Xmethod matcher already registered with "
272 "%s: %s" % (locus_name, matcher.name))
273 if gdb.parameter("verbose"):
274 gdb.write("Registering xmethod matcher '%s' with %s' ...\n")
275 locus.xmethods.insert(0, matcher)
gdb.xmethod.XMethodWorker
Definition: xmethod.py:97
gdb.xmethod.XMethod.enabled
enabled
Definition: xmethod.py:48
gdb.xmethod.XMethodMatcher.match
def match(self, class_type, method_name)
Definition: xmethod.py:82
gdb.xmethod.XMethodWorker.get_result_type
def get_result_type(self, args)
Definition: xmethod.py:122
gdb.xmethod.SimpleXMethodMatcher.SimpleXMethodWorker
Definition: xmethod.py:164
gdb.xmethod.XMethod.name
name
Definition: xmethod.py:47
gdb.xmethod.SimpleXMethodMatcher.SimpleXMethodWorker.__init__
def __init__(self, method_function, arg_types)
Definition: xmethod.py:165
gdb.xmethod.XMethod
Definition: xmethod.py:30
gdb.xmethod.SimpleXMethodMatcher._method_matcher
_method_matcher
Definition: xmethod.py:201
gdb.xmethod.XMethodWorker.get_arg_types
def get_arg_types(self)
Definition: xmethod.py:111
gdb.xmethod.SimpleXMethodMatcher.match
def match(self, class_type, method_name)
Definition: xmethod.py:204
gdb.xmethod.SimpleXMethodMatcher._method_function
_method_function
Definition: xmethod.py:199
gdb.xmethod.XMethodMatcher.enabled
enabled
Definition: xmethod.py:79
gdb.xmethod.SimpleXMethodMatcher.SimpleXMethodWorker._method_function
_method_function
Definition: xmethod.py:167
gdb.xmethod.register_xmethod_matcher
def register_xmethod_matcher(locus, matcher, replace=False)
Definition: xmethod.py:242
gdb.xmethod.SimpleXMethodMatcher
Definition: xmethod.py:151
range
Definition: value.c:62
gdb.xmethod.SimpleXMethodMatcher.SimpleXMethodWorker.get_arg_types
def get_arg_types(self)
Definition: xmethod.py:169
gdb.xmethod.XMethodMatcher
Definition: xmethod.py:51
gdb.xmethod.XMethodMatcher.__init__
def __init__(self, name)
Definition: xmethod.py:72
gdb.xmethod.SimpleXMethodMatcher.SimpleXMethodWorker.__call__
def __call__(self, args)
Definition: xmethod.py:172
gdb.xmethod.XMethodWorker.__call__
def __call__(self, args)
Definition: xmethod.py:136
gdb.xmethod.XMethod.__init__
def __init__(self, name)
Definition: xmethod.py:46
gdb.xmethod.SimpleXMethodMatcher._arg_types
_arg_types
Definition: xmethod.py:202
gdb.xmethod.XMethodMatcher.methods
methods
Definition: xmethod.py:80
gdb.xmethod.SimpleXMethodMatcher._class_matcher
_class_matcher
Definition: xmethod.py:200
gdb.xmethod._validate_xmethod_matcher
def _validate_xmethod_matcher(matcher)
Definition: xmethod.py:216
gdb.xmethod._lookup_xmethod_matcher
def _lookup_xmethod_matcher(locus, name)
Definition: xmethod.py:235
gdb.xmethod.SimpleXMethodMatcher.SimpleXMethodWorker._arg_types
_arg_types
Definition: xmethod.py:166
gdb.xmethod.XMethodMatcher.name
name
Definition: xmethod.py:78