Coverage for python/lsst/pipe/base/configOverrides.py: 21%

90 statements  

« prev     ^ index     » next       coverage.py v7.2.5, created at 2023-05-12 02:03 -0700

1# This file is part of pipe_base. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (http://www.lsst.org). 

6# See the COPYRIGHT file at the top-level directory of this distribution 

7# for details of code ownership. 

8# 

9# This program is free software: you can redistribute it and/or modify 

10# it under the terms of the GNU General Public License as published by 

11# the Free Software Foundation, either version 3 of the License, or 

12# (at your option) any later version. 

13# 

14# This program is distributed in the hope that it will be useful, 

15# but WITHOUT ANY WARRANTY; without even the implied warranty of 

16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

17# GNU General Public License for more details. 

18# 

19# You should have received a copy of the GNU General Public License 

20# along with this program. If not, see <http://www.gnu.org/licenses/>. 

21 

22"""Module which defines ConfigOverrides class and related methods. 

23""" 

24 

25__all__ = ["ConfigOverrides"] 

26 

27import ast 

28import inspect 

29from enum import Enum 

30from operator import attrgetter 

31 

32from lsst.resources import ResourcePath 

33 

34from ._instrument import Instrument 

35 

36OverrideTypes = Enum("OverrideTypes", "Value File Python Instrument") 

37 

38 

39class ConfigExpressionParser(ast.NodeVisitor): 

40 """An expression parser that will be used to transform configuration 

41 strings supplied from the command line or a pipeline into a python 

42 object. 

43 

44 This is roughly equivalent to ast.literal_parser, but with the ability to 

45 transform strings that are valid variable names into the value associated 

46 with the name. Variables that should be considered valid are supplied to 

47 the constructor as a dictionary that maps a string to its corresponding 

48 value. 

49 

50 This class in an internal implementation detail, and should not be exposed 

51 outside this module. 

52 

53 Parameters 

54 ---------- 

55 namespace : `dict` of `str` to variable 

56 This is a mapping of strings corresponding to variable names, to the 

57 object that is associated with that name 

58 """ 

59 

60 def __init__(self, namespace): 

61 self.variables = namespace 

62 

63 def visit_Name(self, node): 

64 """This method gets called when the parser has determined a node 

65 corresponds to a variable name. 

66 """ 

67 # If the id (name) of the variable is in the dictionary of valid names, 

68 # load and return the corresponding variable. 

69 if node.id in self.variables: 

70 return self.variables[node.id] 

71 # If the node does not correspond to a valid variable, turn the name 

72 # into a string, as the user likely intended it as such. 

73 return f"{node.id}" 

74 

75 def visit_List(self, node): 

76 """This method is visited if the node is a list. Constructs a list out 

77 of the sub nodes. 

78 """ 

79 return [self.visit(elm) for elm in node.elts] 

80 

81 def visit_Tuple(self, node): 

82 """This method is visited if the node is a tuple. Constructs a list out 

83 of the sub nodes, and then turns it into a tuple. 

84 """ 

85 return tuple(self.visit_List(node)) 

86 

87 def visit_Constant(self, node): 

88 """This method is visited if the node is a constant""" 

89 return node.value 

90 

91 def visit_Dict(self, node): 

92 """This method is visited if the node is a dict. It builds a dict out 

93 of the component nodes. 

94 """ 

95 return {self.visit(key): self.visit(value) for key, value in zip(node.keys, node.values)} 

96 

97 def visit_Set(self, node): 

98 """This method is visited if the node is a set. It builds a set out 

99 of the component nodes. 

100 """ 

101 return {self.visit(el) for el in node.elts} 

102 

103 def visit_UnaryOp(self, node): 

104 """This method is visited if the node is a unary operator. Currently 

105 The only operator we support is the negative (-) operator, all others 

106 are passed to generic_visit method. 

107 """ 

108 if isinstance(node.op, ast.USub): 

109 value = self.visit(node.operand) 

110 return -1 * value 

111 self.generic_visit(node) 

112 

113 def generic_visit(self, node): 

114 """This method is called for all other node types. It will just raise 

115 a value error, because this is a type of expression that we do not 

116 support. 

117 """ 

118 raise ValueError("Unable to parse string into literal expression") 

119 

120 

121class ConfigOverrides: 

122 """Defines a set of overrides to be applied to a task config. 

123 

124 Overrides for task configuration need to be applied by activator when 

125 creating task instances. This class represents an ordered set of such 

126 overrides which activator receives from some source (e.g. command line 

127 or some other configuration). 

128 

129 Methods 

130 ---------- 

131 addFileOverride(filename) 

132 Add overrides from a specified file. 

133 addValueOverride(field, value) 

134 Add override for a specific field. 

135 applyTo(config) 

136 Apply all overrides to a `config` instance. 

137 

138 Notes 

139 ----- 

140 Serialization support for this class may be needed, will add later if 

141 necessary. 

142 """ 

143 

144 def __init__(self): 

145 self._overrides = [] 

146 

147 def addFileOverride(self, filename): 

148 """Add overrides from a specified file. 

149 

150 Parameters 

151 ---------- 

152 filename : convertible to `ResourcePath` 

153 Path or URI to the override file. All URI schemes supported by 

154 `ResourcePath` are supported. 

155 """ 

156 self._overrides.append((OverrideTypes.File, ResourcePath(filename))) 

157 

158 def addValueOverride(self, field, value): 

159 """Add override for a specific field. 

160 

161 This method is not very type-safe as it is designed to support 

162 use cases where input is given as string, e.g. command line 

163 activators. If `value` has a string type and setting of the field 

164 fails with `TypeError` the we'll attempt `eval()` the value and 

165 set the field with that value instead. 

166 

167 Parameters 

168 ---------- 

169 field : str 

170 Fully-qualified field name. 

171 value : 

172 Value to be given to a filed. 

173 """ 

174 self._overrides.append((OverrideTypes.Value, (field, value))) 

175 

176 def addPythonOverride(self, python_snippet: str) -> None: 

177 """Add Overrides by running a snippit of python code against a config. 

178 

179 Parameters 

180 ---------- 

181 python_snippet: str 

182 A string which is valid python code to be executed. This is done 

183 with config as the only local accessible value. 

184 """ 

185 self._overrides.append((OverrideTypes.Python, python_snippet)) 

186 

187 def addInstrumentOverride(self, instrument: Instrument, task_name: str) -> None: 

188 """Apply any overrides that an instrument has for a task 

189 

190 Parameters 

191 ---------- 

192 instrument: `Instrument` 

193 An instrument instance which will apply configs 

194 task_name: str 

195 The _DefaultName of a task associated with a config, used to look 

196 up overrides from the instrument. 

197 """ 

198 self._overrides.append((OverrideTypes.Instrument, (instrument, task_name))) 

199 

200 def _parser(self, value, configParser): 

201 try: 

202 value = configParser.visit(ast.parse(value, mode="eval").body) 

203 except Exception: 

204 # This probably means it is a specific user string such as a URI. 

205 # Let the value return as a string to attempt to continue to 

206 # process as a string, another error will be raised in downstream 

207 # code if that assumption is wrong 

208 pass 

209 

210 return value 

211 

212 def applyTo(self, config): 

213 """Apply all overrides to a task configuration object. 

214 

215 Parameters 

216 ---------- 

217 config : `pex.Config` 

218 Configuration to apply to; modified in place. 

219 

220 Raises 

221 ------ 

222 `Exception` is raised if operations on configuration object fail. 

223 """ 

224 # Look up a stack of variables people may be using when setting 

225 # configs. Create a dictionary that will be used akin to a namespace 

226 # for the duration of this function. 

227 vars = {} 

228 # pull in the variables that are declared in module scope of the config 

229 mod = inspect.getmodule(config) 

230 vars.update({k: v for k, v in mod.__dict__.items() if not k.startswith("__")}) 

231 # put the supplied config in the variables dictionary 

232 vars["config"] = config 

233 

234 # Create a parser for config expressions that may be strings 

235 configParser = ConfigExpressionParser(namespace=vars) 

236 

237 for otype, override in self._overrides: 

238 if otype is OverrideTypes.File: 

239 with override.open("r") as buffer: 

240 config.loadFromStream(buffer, filename=override.ospath) 

241 elif otype is OverrideTypes.Value: 

242 field, value = override 

243 if isinstance(value, str): 

244 value = self._parser(value, configParser) 

245 # checking for dicts and lists here is needed because {} and [] 

246 # are valid yaml syntax so they get converted before hitting 

247 # this method, so we must parse the elements. 

248 # 

249 # The same override would remain a string if specified on the 

250 # command line, and is handled above. 

251 if isinstance(value, dict): 

252 new = {} 

253 for k, v in value.items(): 

254 if isinstance(v, str): 

255 new[k] = self._parser(v, configParser) 

256 else: 

257 new[k] = v 

258 value = new 

259 elif isinstance(value, list): 

260 new = [] 

261 for v in value: 

262 if isinstance(v, str): 

263 new.append(self._parser(v, configParser)) 

264 else: 

265 new.append(v) 

266 value = new 

267 # The field might be a string corresponding to a attribute 

268 # hierarchy, attempt to split off the last field which 

269 # will then be set. 

270 parent, *child = field.rsplit(".", maxsplit=1) 

271 if child: 

272 # This branch means there was a hierarchy, get the 

273 # field to set, and look up the sub config for which 

274 # it is to be set 

275 finalField = child[0] 

276 tmpConfig = attrgetter(parent)(config) 

277 else: 

278 # There is no hierarchy, the config is the base config 

279 # and the field is exactly what was passed in 

280 finalField = parent 

281 tmpConfig = config 

282 # set the specified config 

283 setattr(tmpConfig, finalField, value) 

284 

285 elif otype is OverrideTypes.Python: 

286 # exec python string with the context of all vars known. This 

287 # both lets people use a var they know about (maybe a bit 

288 # dangerous, but not really more so than arbitrary python exec, 

289 # and there are so many other places to worry about security 

290 # before we start changing this) and any imports that are done 

291 # in a python block will be put into this scope. This means 

292 # other config setting branches can make use of these 

293 # variables. 

294 exec(override, None, vars) 

295 elif otype is OverrideTypes.Instrument: 

296 instrument, name = override 

297 instrument.applyConfigOverrides(name, config)