Coverage for python/lsst/pipe/base/configOverrides.py: 20%
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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/>.
22"""Module which defines ConfigOverrides class and related methods.
23"""
25__all__ = ["ConfigOverrides"]
27import ast
28from operator import attrgetter
30from lsst.utils import doImport
32import inspect
33from enum import Enum
35OverrideTypes = Enum("OverrideTypes", "Value File Python Instrument")
38class ConfigExpressionParser(ast.NodeVisitor):
39 """An expression parser that will be used to transform configuration
40 strings supplied from the command line or a pipeline into a python
41 object.
43 This is roughly equivalent to ast.literal_parser, but with the ability to
44 transform strings that are valid variable names into the value associated
45 with the name. Variables that should be considered valid are supplied to
46 the constructor as a dictionary that maps a string to its corresponding
47 value.
49 This class in an internal implementation detail, and should not be exposed
50 outside this module.
52 Parameters
53 ----------
54 namespace : `dict` of `str` to variable
55 This is a mapping of strings corresponding to variable names, to the
56 object that is associated with that name
57 """
59 def __init__(self, namespace):
60 self.variables = namespace
62 def visit_Name(self, node):
63 """This method gets called when the parser has determined a node
64 corresponds to a variable name.
65 """
66 # If the id (name) of the variable is in the dictionary of valid names,
67 # load and return the corresponding variable.
68 if node.id in self.variables:
69 return self.variables[node.id]
70 # If the node does not correspond to a valid variable, turn the name
71 # into a string, as the user likely intended it as such.
72 return f"{node.id}"
74 def visit_List(self, node):
75 """This method is visited if the node is a list. Constructs a list out
76 of the sub nodes.
77 """
78 return [self.visit(elm) for elm in node.elts]
80 def visit_Tuple(self, node):
81 """This method is visited if the node is a tuple. Constructs a list out
82 of the sub nodes, and then turns it into a tuple.
83 """
84 return tuple(self.visit_List(node))
86 def visit_Constant(self, node):
87 """This method is visited if the node is a constant
88 """
89 return node.value
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)}
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}
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)
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")
121class ConfigOverrides:
122 """Defines a set of overrides to be applied to a task config.
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).
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.
138 Notes
139 -----
140 Serialization support for this class may be needed, will add later if
141 necessary.
142 """
144 def __init__(self):
145 self._overrides = []
147 def addFileOverride(self, filename):
148 """Add overrides from a specified file.
150 Parameters
151 ----------
152 filename : str
153 Path to the override file.
154 """
155 self._overrides.append((OverrideTypes.File, filename))
157 def addValueOverride(self, field, value):
158 """Add override for a specific field.
160 This method is not very type-safe as it is designed to support
161 use cases where input is given as string, e.g. command line
162 activators. If `value` has a string type and setting of the field
163 fails with `TypeError` the we'll attempt `eval()` the value and
164 set the field with that value instead.
166 Parameters
167 ----------
168 field : str
169 Fully-qualified field name.
170 value :
171 Value to be given to a filed.
172 """
173 self._overrides.append((OverrideTypes.Value, (field, value)))
175 def addPythonOverride(self, python_snippet: str):
176 """Add Overrides by running a snippit of python code against a config.
178 Parameters
179 ----------
180 python_snippet: str
181 A string which is valid python code to be executed. This is done
182 with config as the only local accessible value.
183 """
184 self._overrides.append((OverrideTypes.Python, python_snippet))
186 def addInstrumentOverride(self, instrument: str, task_name: str):
187 """Apply any overrides that an instrument has for a task
189 Parameters
190 ----------
191 instrument: str
192 A string containing the fully qualified name of an instrument from
193 which configs should be loaded and applied
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 instrument_lib = doImport(instrument)()
199 self._overrides.append((OverrideTypes.Instrument, (instrument_lib, task_name)))
201 def _parser(self, value, configParser):
202 try:
203 value = configParser.visit(ast.parse(value, mode='eval').body)
204 except Exception:
205 # This probably means it is a specific user string such as a URI.
206 # Let the value return as a string to attempt to continue to
207 # process as a string, another error will be raised in downstream
208 # code if that assumption is wrong
209 pass
211 return value
213 def applyTo(self, config):
214 """Apply all overrides to a task configuration object.
216 Parameters
217 ----------
218 config : `pex.Config`
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
234 # Create a parser for config expressions that may be strings
235 configParser = ConfigExpressionParser(namespace=vars)
237 for otype, override in self._overrides:
238 if otype is OverrideTypes.File:
239 config.load(override)
240 elif otype is OverrideTypes.Value:
241 field, value = override
242 if isinstance(value, str):
243 value = self._parser(value, configParser)
244 # checking for dicts and lists here is needed because {} and []
245 # are valid yaml syntax so they get converted before hitting
246 # this method, so we must parse the elements.
247 #
248 # The same override would remain a string if specified on the
249 # command line, and is handled above.
250 if isinstance(value, dict):
251 new = {}
252 for k, v in value.items():
253 if isinstance(v, str):
254 new[k] = self._parser(v, configParser)
255 else:
256 new[k] = v
257 value = new
258 elif isinstance(value, list):
259 new = []
260 for v in value:
261 if isinstance(v, str):
262 new.append(self._parser(v, configParser))
263 else:
264 new.append(v)
265 value = new
266 # The field might be a string corresponding to a attribute
267 # hierarchy, attempt to split off the last field which
268 # will then be set.
269 parent, *child = field.rsplit(".", maxsplit=1)
270 if child:
271 # This branch means there was a hierarchy, get the
272 # field to set, and look up the sub config for which
273 # it is to be set
274 finalField = child[0]
275 tmpConfig = attrgetter(parent)(config)
276 else:
277 # There is no hierarchy, the config is the base config
278 # and the field is exactly what was passed in
279 finalField = parent
280 tmpConfig = config
281 # set the specified config
282 setattr(tmpConfig, finalField, value)
284 elif otype is OverrideTypes.Python:
285 # exec python string with the context of all vars known. This
286 # both lets people use a var they know about (maybe a bit
287 # dangerous, but not really more so than arbitrary python exec,
288 # and there are so many other places to worry about security
289 # before we start changing this) and any imports that are done
290 # in a python block will be put into this scope. This means
291 # other config setting branches can make use of these
292 # variables.
293 exec(override, None, vars)
294 elif otype is OverrideTypes.Instrument:
295 instrument, name = override
296 instrument.applyConfigOverrides(name, config)