1# Pretty-printer utilities. 2# Copyright (C) 2010-2013 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 working with pretty-printers.""" 18 19import gdb 20import gdb.types 21import re 22import sys 23 24if sys.version_info[0] > 2: 25 # Python 3 removed basestring and long 26 basestring = str 27 long = int 28 29class PrettyPrinter(object): 30 """A basic pretty-printer. 31 32 Attributes: 33 name: A unique string among all printers for the context in which 34 it is defined (objfile, progspace, or global(gdb)), and should 35 meaningfully describe what can be pretty-printed. 36 E.g., "StringPiece" or "protobufs". 37 subprinters: An iterable object with each element having a `name' 38 attribute, and, potentially, "enabled" attribute. 39 Or this is None if there are no subprinters. 40 enabled: A boolean indicating if the printer is enabled. 41 42 Subprinters are for situations where "one" pretty-printer is actually a 43 collection of several printers. E.g., The libstdc++ pretty-printer has 44 a pretty-printer for each of several different types, based on regexps. 45 """ 46 47 # While one might want to push subprinters into the subclass, it's 48 # present here to formalize such support to simplify 49 # commands/pretty_printers.py. 50 51 def __init__(self, name, subprinters=None): 52 self.name = name 53 self.subprinters = subprinters 54 self.enabled = True 55 56 def __call__(self, val): 57 # The subclass must define this. 58 raise NotImplementedError("PrettyPrinter __call__") 59 60 61class SubPrettyPrinter(object): 62 """Baseclass for sub-pretty-printers. 63 64 Sub-pretty-printers needn't use this, but it formalizes what's needed. 65 66 Attributes: 67 name: The name of the subprinter. 68 enabled: A boolean indicating if the subprinter is enabled. 69 """ 70 71 def __init__(self, name): 72 self.name = name 73 self.enabled = True 74 75 76def register_pretty_printer(obj, printer, replace=False): 77 """Register pretty-printer PRINTER with OBJ. 78 79 The printer is added to the front of the search list, thus one can override 80 an existing printer if one needs to. Use a different name when overriding 81 an existing printer, otherwise an exception will be raised; multiple 82 printers with the same name are disallowed. 83 84 Arguments: 85 obj: Either an objfile, progspace, or None (in which case the printer 86 is registered globally). 87 printer: Either a function of one argument (old way) or any object 88 which has attributes: name, enabled, __call__. 89 replace: If True replace any existing copy of the printer. 90 Otherwise if the printer already exists raise an exception. 91 92 Returns: 93 Nothing. 94 95 Raises: 96 TypeError: A problem with the type of the printer. 97 ValueError: The printer's name contains a semicolon ";". 98 RuntimeError: A printer with the same name is already registered. 99 100 If the caller wants the printer to be listable and disableable, it must 101 follow the PrettyPrinter API. This applies to the old way (functions) too. 102 If printer is an object, __call__ is a method of two arguments: 103 self, and the value to be pretty-printed. See PrettyPrinter. 104 """ 105 106 # Watch for both __name__ and name. 107 # Functions get the former for free, but we don't want to use an 108 # attribute named __foo__ for pretty-printers-as-objects. 109 # If printer has both, we use `name'. 110 if not hasattr(printer, "__name__") and not hasattr(printer, "name"): 111 raise TypeError("printer missing attribute: name") 112 if hasattr(printer, "name") and not hasattr(printer, "enabled"): 113 raise TypeError("printer missing attribute: enabled") 114 if not hasattr(printer, "__call__"): 115 raise TypeError("printer missing attribute: __call__") 116 117 if obj is None: 118 if gdb.parameter("verbose"): 119 gdb.write("Registering global %s pretty-printer ...\n" % name) 120 obj = gdb 121 else: 122 if gdb.parameter("verbose"): 123 gdb.write("Registering %s pretty-printer for %s ...\n" % 124 (printer.name, obj.filename)) 125 126 if hasattr(printer, "name"): 127 if not isinstance(printer.name, basestring): 128 raise TypeError("printer name is not a string") 129 # If printer provides a name, make sure it doesn't contain ";". 130 # Semicolon is used by the info/enable/disable pretty-printer commands 131 # to delimit subprinters. 132 if printer.name.find(";") >= 0: 133 raise ValueError("semicolon ';' in printer name") 134 # Also make sure the name is unique. 135 # Alas, we can't do the same for functions and __name__, they could 136 # all have a canonical name like "lookup_function". 137 # PERF: gdb records printers in a list, making this inefficient. 138 i = 0 139 for p in obj.pretty_printers: 140 if hasattr(p, "name") and p.name == printer.name: 141 if replace: 142 del obj.pretty_printers[i] 143 break 144 else: 145 raise RuntimeError("pretty-printer already registered: %s" % 146 printer.name) 147 i = i + 1 148 149 obj.pretty_printers.insert(0, printer) 150 151 152class RegexpCollectionPrettyPrinter(PrettyPrinter): 153 """Class for implementing a collection of regular-expression based pretty-printers. 154 155 Intended usage: 156 157 pretty_printer = RegexpCollectionPrettyPrinter("my_library") 158 pretty_printer.add_printer("myclass1", "^myclass1$", MyClass1Printer) 159 ... 160 pretty_printer.add_printer("myclassN", "^myclassN$", MyClassNPrinter) 161 register_pretty_printer(obj, pretty_printer) 162 """ 163 164 class RegexpSubprinter(SubPrettyPrinter): 165 def __init__(self, name, regexp, gen_printer): 166 super(RegexpCollectionPrettyPrinter.RegexpSubprinter, self).__init__(name) 167 self.regexp = regexp 168 self.gen_printer = gen_printer 169 self.compiled_re = re.compile(regexp) 170 171 def __init__(self, name): 172 super(RegexpCollectionPrettyPrinter, self).__init__(name, []) 173 174 def add_printer(self, name, regexp, gen_printer): 175 """Add a printer to the list. 176 177 The printer is added to the end of the list. 178 179 Arguments: 180 name: The name of the subprinter. 181 regexp: The regular expression, as a string. 182 gen_printer: A function/method that given a value returns an 183 object to pretty-print it. 184 185 Returns: 186 Nothing. 187 """ 188 189 # NOTE: A previous version made the name of each printer the regexp. 190 # That makes it awkward to pass to the enable/disable commands (it's 191 # cumbersome to make a regexp of a regexp). So now the name is a 192 # separate parameter. 193 194 self.subprinters.append(self.RegexpSubprinter(name, regexp, 195 gen_printer)) 196 197 def __call__(self, val): 198 """Lookup the pretty-printer for the provided value.""" 199 200 # Get the type name. 201 typename = gdb.types.get_basic_type(val.type).tag 202 if not typename: 203 return None 204 205 # Iterate over table of type regexps to determine 206 # if a printer is registered for that type. 207 # Return an instantiation of the printer if found. 208 for printer in self.subprinters: 209 if printer.enabled and printer.compiled_re.search(typename): 210 return printer.gen_printer(val) 211 212 # Cannot find a pretty printer. Return None. 213 return None 214 215# A helper class for printing enum types. This class is instantiated 216# with a list of enumerators to print a particular Value. 217class _EnumInstance: 218 def __init__(self, enumerators, val): 219 self.enumerators = enumerators 220 self.val = val 221 222 def to_string(self): 223 flag_list = [] 224 v = long(self.val) 225 any_found = False 226 for (e_name, e_value) in self.enumerators: 227 if v & e_value != 0: 228 flag_list.append(e_name) 229 v = v & ~e_value 230 any_found = True 231 if not any_found or v != 0: 232 # Leftover value. 233 flag_list.append('<unknown: 0x%x>' % v) 234 return "0x%x [%s]" % (self.val, " | ".join(flag_list)) 235 236class FlagEnumerationPrinter(PrettyPrinter): 237 """A pretty-printer which can be used to print a flag-style enumeration. 238 A flag-style enumeration is one where the enumerators are or'd 239 together to create values. The new printer will print these 240 symbolically using '|' notation. The printer must be registered 241 manually. This printer is most useful when an enum is flag-like, 242 but has some overlap. GDB's built-in printing will not handle 243 this case, but this printer will attempt to.""" 244 245 def __init__(self, enum_type): 246 super(FlagEnumerationPrinter, self).__init__(enum_type) 247 self.initialized = False 248 249 def __call__(self, val): 250 if not self.initialized: 251 self.initialized = True 252 flags = gdb.lookup_type(self.name) 253 self.enumerators = [] 254 for field in flags.fields(): 255 self.enumerators.append((field.name, field.enumval)) 256 # Sorting the enumerators by value usually does the right 257 # thing. 258 self.enumerators.sort(key = lambda x: x.enumval) 259 260 if self.enabled: 261 return _EnumInstance(self.enumerators, val) 262 else: 263 return None 264