Coverage for python/lsst/pipe/base/configOverrides.py: 23%
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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
28import inspect
29from enum import Enum
30from operator import attrgetter
32from lsst.utils import doImport
34OverrideTypes = Enum("OverrideTypes", "Value File Python Instrument")
37class ConfigExpressionParser(ast.NodeVisitor):
38 """An expression parser that will be used to transform configuration
39 strings supplied from the command line or a pipeline into a python
40 object.
42 This is roughly equivalent to ast.literal_parser, but with the ability to
43 transform strings that are valid variable names into the value associated
44 with the name. Variables that should be considered valid are supplied to
45 the constructor as a dictionary that maps a string to its corresponding
46 value.
48 This class in an internal implementation detail, and should not be exposed
49 outside this module.
51 Parameters
52 ----------
53 namespace : `dict` of `str` to variable
54 This is a mapping of strings corresponding to variable names, to the
55 object that is associated with that name
56 """
58 def __init__(self, namespace):
59 self.variables = namespace
61 def visit_Name(self, node):
62 """This method gets called when the parser has determined a node
63 corresponds to a variable name.
64 """
65 # If the id (name) of the variable is in the dictionary of valid names,
66 # load and return the corresponding variable.
67 if node.id in self.variables:
68 return self.variables[node.id]
69 # If the node does not correspond to a valid variable, turn the name
70 # into a string, as the user likely intended it as such.
71 return f"{node.id}"
73 def visit_List(self, node):
74 """This method is visited if the node is a list. Constructs a list out
75 of the sub nodes.
76 """
77 return [self.visit(elm) for elm in node.elts]
79 def visit_Tuple(self, node):
80 """This method is visited if the node is a tuple. Constructs a list out
81 of the sub nodes, and then turns it into a tuple.
82 """
83 return tuple(self.visit_List(node))
85 def visit_Constant(self, node):
86 """This method is visited if the node is a constant"""
87 return node.value
89 def visit_Dict(self, node):
90 """This method is visited if the node is a dict. It builds a dict out
91 of the component nodes.
92 """
93 return {self.visit(key): self.visit(value) for key, value in zip(node.keys, node.values)}
95 def visit_Set(self, node):
96 """This method is visited if the node is a set. It builds a set out
97 of the component nodes.
98 """
99 return {self.visit(el) for el in node.elts}
101 def visit_UnaryOp(self, node):
102 """This method is visited if the node is a unary operator. Currently
103 The only operator we support is the negative (-) operator, all others
104 are passed to generic_visit method.
105 """
106 if isinstance(node.op, ast.USub):
107 value = self.visit(node.operand)
108 return -1 * value
109 self.generic_visit(node)
111 def generic_visit(self, node):
112 """This method is called for all other node types. It will just raise
113 a value error, because this is a type of expression that we do not
114 support.
115 """
116 raise ValueError("Unable to parse string into literal expression")
119class ConfigOverrides:
120 """Defines a set of overrides to be applied to a task config.
122 Overrides for task configuration need to be applied by activator when
123 creating task instances. This class represents an ordered set of such
124 overrides which activator receives from some source (e.g. command line
125 or some other configuration).
127 Methods
128 ----------
129 addFileOverride(filename)
130 Add overrides from a specified file.
131 addValueOverride(field, value)
132 Add override for a specific field.
133 applyTo(config)
134 Apply all overrides to a `config` instance.
136 Notes
137 -----
138 Serialization support for this class may be needed, will add later if
139 necessary.
140 """
142 def __init__(self):
143 self._overrides = []
145 def addFileOverride(self, filename):
146 """Add overrides from a specified file.
148 Parameters
149 ----------
150 filename : str
151 Path to the override file.
152 """
153 self._overrides.append((OverrideTypes.File, filename))
155 def addValueOverride(self, field, value):
156 """Add override for a specific field.
158 This method is not very type-safe as it is designed to support
159 use cases where input is given as string, e.g. command line
160 activators. If `value` has a string type and setting of the field
161 fails with `TypeError` the we'll attempt `eval()` the value and
162 set the field with that value instead.
164 Parameters
165 ----------
166 field : str
167 Fully-qualified field name.
168 value :
169 Value to be given to a filed.
170 """
171 self._overrides.append((OverrideTypes.Value, (field, value)))
173 def addPythonOverride(self, python_snippet: str):
174 """Add Overrides by running a snippit of python code against a config.
176 Parameters
177 ----------
178 python_snippet: str
179 A string which is valid python code to be executed. This is done
180 with config as the only local accessible value.
181 """
182 self._overrides.append((OverrideTypes.Python, python_snippet))
184 def addInstrumentOverride(self, instrument: str, task_name: str):
185 """Apply any overrides that an instrument has for a task
187 Parameters
188 ----------
189 instrument: str
190 A string containing the fully qualified name of an instrument from
191 which configs should be loaded and applied
192 task_name: str
193 The _DefaultName of a task associated with a config, used to look
194 up overrides from the instrument.
195 """
196 instrument_lib = doImport(instrument)()
197 self._overrides.append((OverrideTypes.Instrument, (instrument_lib, task_name)))
199 def _parser(self, value, configParser):
200 try:
201 value = configParser.visit(ast.parse(value, mode="eval").body)
202 except Exception:
203 # This probably means it is a specific user string such as a URI.
204 # Let the value return as a string to attempt to continue to
205 # process as a string, another error will be raised in downstream
206 # code if that assumption is wrong
207 pass
209 return value
211 def applyTo(self, config):
212 """Apply all overrides to a task configuration object.
214 Parameters
215 ----------
216 config : `pex.Config`
218 Raises
219 ------
220 `Exception` is raised if operations on configuration object fail.
221 """
222 # Look up a stack of variables people may be using when setting
223 # configs. Create a dictionary that will be used akin to a namespace
224 # for the duration of this function.
225 vars = {}
226 # pull in the variables that are declared in module scope of the config
227 mod = inspect.getmodule(config)
228 vars.update({k: v for k, v in mod.__dict__.items() if not k.startswith("__")})
229 # put the supplied config in the variables dictionary
230 vars["config"] = config
232 # Create a parser for config expressions that may be strings
233 configParser = ConfigExpressionParser(namespace=vars)
235 for otype, override in self._overrides:
236 if otype is OverrideTypes.File:
237 config.load(override)
238 elif otype is OverrideTypes.Value:
239 field, value = override
240 if isinstance(value, str):
241 value = self._parser(value, configParser)
242 # checking for dicts and lists here is needed because {} and []
243 # are valid yaml syntax so they get converted before hitting
244 # this method, so we must parse the elements.
245 #
246 # The same override would remain a string if specified on the
247 # command line, and is handled above.
248 if isinstance(value, dict):
249 new = {}
250 for k, v in value.items():
251 if isinstance(v, str):
252 new[k] = self._parser(v, configParser)
253 else:
254 new[k] = v
255 value = new
256 elif isinstance(value, list):
257 new = []
258 for v in value:
259 if isinstance(v, str):
260 new.append(self._parser(v, configParser))
261 else:
262 new.append(v)
263 value = new
264 # The field might be a string corresponding to a attribute
265 # hierarchy, attempt to split off the last field which
266 # will then be set.
267 parent, *child = field.rsplit(".", maxsplit=1)
268 if child:
269 # This branch means there was a hierarchy, get the
270 # field to set, and look up the sub config for which
271 # it is to be set
272 finalField = child[0]
273 tmpConfig = attrgetter(parent)(config)
274 else:
275 # There is no hierarchy, the config is the base config
276 # and the field is exactly what was passed in
277 finalField = parent
278 tmpConfig = config
279 # set the specified config
280 setattr(tmpConfig, finalField, value)
282 elif otype is OverrideTypes.Python:
283 # exec python string with the context of all vars known. This
284 # both lets people use a var they know about (maybe a bit
285 # dangerous, but not really more so than arbitrary python exec,
286 # and there are so many other places to worry about security
287 # before we start changing this) and any imports that are done
288 # in a python block will be put into this scope. This means
289 # other config setting branches can make use of these
290 # variables.
291 exec(override, None, vars)
292 elif otype is OverrideTypes.Instrument:
293 instrument, name = override
294 instrument.applyConfigOverrides(name, config)