2 Module for managing and evaluation of Moe configuration variables.
4 .. todo:: (OPT) Cleanup of unused undefined variables.
5 .. todo:: (OPT) Better variable name checking (no name '.'-structural prefix of another)
6 .. todo:: (OPT) Implemet "subtree" listing.
9 import types, itertools, re, bisect
11 from moe import MoeError
14 "Allowed depth of recursion - includes ALL recursive calls, so should quite high."
17 "Maximum attained depth of recursion - for debug/testing"
20 "Variable name regexp, dots (separators) must be separated from edges and each other."
21 re_VARNAME = re.compile(r'\A([A-Za-z0-9_-]+\.)*[A-Za-z0-9_-]+\Z')
24 def check_depth(depth):
25 "Helper to check for recursion depth."
27 if depth > c_maxdepth:
28 raise CyclicConfigError('Too deep recursion in config evaluation (cyclic substitution?)')
29 if depth > debug_maxdepth:
30 debug_maxdepth = depth
33 class ConfigError(MoeError):
34 "Base class for moe.config errors"
37 class UndefinedError(ConfigError):
38 "Raised when no **SET** operation applies to evaluated variable."
41 class VariableNameError(ConfigError):
42 "Raised on invalid config variable name."
45 class VariableFixedError(ConfigError):
46 "Raised when modifying a fixed variable"
49 class CyclicConfigError(ConfigError):
50 "Raised when evaluation recursion is too deep"
54 class ParseProxy(list):
55 """Proxy helper class around values returned by `parse` and `parse_file`,
56 useful in "with" constructs."""
57 def __init__(self, config, parsed_ops):
58 super(ParseProxy, self).__init__(parsed_ops)
62 def __exit__(self, etype, value, traceback):
63 self.config.remove(list(self))
66 class ConfigTree(object):
68 Configuration environment containing the variables.
74 def lookup(self, key, create = True):
76 Lookup and return a variable.
77 If not found and `create` set, check the name and transparently create a new one.
79 if key not in self.variables:
80 if not re_VARNAME.match(key):
81 raise VariableNameError('Invalid variable identifier %r in config', key)
83 raise UndefinedError('Config variable %r undefined.', key)
84 self.variables[key] = ConfigVar(key)
85 return self.variables[key]
87 def __getitem__(self, key):
89 Return the value of an existing variable.
91 return self.lookup(key, create=False).value()
93 def dump(self, prefix=''):
95 Pretty printing of the tree.
96 Returns an iterator of lines (strings).
98 return itertools.chain(*[
99 self.variables[k].dump(prefix) for k in sorted(self.variables.keys())
103 "Fix value of variable or list of variables. Fixing undefined variable raises `UndefinedError`."
104 if isinstance(keys, types.StringTypes):
107 self.lookup(key, create=False).fix()
109 def unfix(self, keys):
110 "Unfix value of variable or list of variables. Unfixing undefined variable raises `UndefinedError`."
111 if isinstance(keys, types.StringTypes):
114 self.lookup(key, create=False).unfix()
116 def remove(self, parsed):
117 """Given a list [(varname, `Operation`)] as returned by `parse` or `parse_file`,
118 removes the operations from the respective variables config tree.
119 Variables/operations not present int the tree raise ValueError.
121 for vname, o in parsed:
122 v = self.lookup(vname, create = True)
123 v.remove_operation(o)
125 def parse(self, s, source=None, level=0, proxy=True):
126 """Parse `s` (stream/string) into the tree, see `moe.config_parser.ConfigParser` for details.
127 Returns list of parset operations: [(varname, `Operation`)].
128 By default returns a proxy list-like object that can be used in "with" constructs:
130 with config.parse("TEST='1'"):
134 import moe.config_parser
135 p = moe.config_parser.ConfigParser(s, self, source=source, level=level)
139 return ParseProxy(self, l)
141 def parse_file(self, filename, desc=None, level=0, proxy=True):
142 """Parse an utf-8 file into the tree using func:`parse`.
143 Names the source "`filename` <`desc`>". """
144 with open(filename, 'rt') as f:
146 filename += " <" + desc + ">"
147 return self.parse(f, source=filename, level=level, proxy=proxy)
150 class ConfigElem(object):
152 Base class for cached config elements - variables and conditions
155 def __init__(self, name):
156 # Full name with separators, definition for conditions
158 # Vars and conditions depending on value of this one
159 self.dependants = set([])
160 # Cached value (may be None in case of evaluation error)
162 self.cached_val = None
164 def invalidate(self, depth=0):
166 Invalidate cached data and invalidate all dependants.
167 Does nothing if not cached.
171 log.debug('invalidating %s', self)
173 for d in self.dependants:
174 d.invalidate(depth + 1)
176 def value(self, depth=0):
177 "Caching helper calling self.evaluate(), returns a value or throws an exception."
180 self.cached_val = self.evaluate(depth=depth+1)
182 if self.cached_val == None:
183 raise UndefinedError("Unable to evaluate %r."%(self.name,))
184 return self.cached_val
190 class ConfigCondition(ConfigElem):
192 Condition using equality and logic operators.
193 Formula is a tuple-tree in the following recursive form::
195 ('AND', c1, c1), ('OR', c1, c2), ('NOT', c1), ('==', e1, e2), ('!=', e1, e2)
197 where ``e1``, ``e2`` are :class:`ConfigExpression`, ``c1``, ``c2``, :class:`ConfigCondition`.
200 def __init__(self, formula, text=None, parent=None):
202 Condition defined by `text` (informative), `formula` as in class definition,
203 `parent` is the parent condition (if any).
206 text = self.formula_string(formula)
207 super(ConfigCondition, self).__init__(text)
208 self.formula = formula
210 # Setup dependencies on used variables (not on the parent condition)
211 for v in self.variables():
212 v.dependants.add(self)
214 self.parent.dependants.add(self)
216 def variables(self, cl=None):
217 "Return an iterator of variables used in formula `cl`"
220 if cl[0] in ['==','!=']:
221 return itertools.chain(cl[1].variables(), cl[2].variables())
222 if cl[0] in ['AND','OR']:
223 return itertools.chain(self.variables(cl[1]), self.variables(cl[2]))
224 return self.variables(cl[1]) # only 'NOT' left
226 def remove_dependencies(self):
227 "Remove self as a dependant from all used variables"
228 for v in self.variables():
229 v.dependants.discard(self)
231 self.parent.dependants.discard(self)
233 def evaluate(self, cl=None, depth=0):
234 """Evaluate formula `cl` (or the entire condition).
235 Partial evaluation for AND and OR. Tests the parent condition first."""
239 if self.parent and not self.parent.value():
241 if cl[0] in ['==','!=']:
242 v = cl[1].evaluate(depth=depth+1) == cl[2].evaluate(depth=depth+1)
243 if cl[0] == '!=': v = not v
245 v1 = self.evaluate(cl=cl[1], depth=depth+1)
248 if cl[0] == 'OR' and v1: return True
249 if cl[0] == 'AND' and not v1: return False
250 return self.evaluate(cl=cl[2], depth=depth+1)
252 def formula_string(self, formula):
253 "Create a string representation of a formula."
254 if formula[0] == 'AND':
255 return itertools.chain(['('], self.formula_string(formula[1]), [' and '], self.formula_string(formula[2]),[')'])
256 elif formula[0] == 'OR':
257 return itertools.chain(['('], self.formula_string(formula[1]), [' or '], self.formula_string(formula[2]),[')'])
258 elif formula[0] == 'NOT':
259 return itertools.chain(['(not '], self.formula_string(formula[1]),[')'])
260 elif formula[0] in ['==', '!=']:
261 return itertools.chain(formula[1], formula[0], formula[2])
262 return iter(['<invalid formula>'])
264 def str(self, parents=False):
265 "Retur the defining expression, if `parents` set, then prefixed with parent conditions."
266 if parents and self.parent:
267 return self.parent.str(parents=True) + u' && ' + self.name
271 return self.str(parents=False)
274 class Operation(object):
276 Helper class for operation data. Must be present at most once in at most one variable.
278 ``operation`` is either ``"SET"`` or ``"APPEND"``, ``condition`` is a :class:`ConfigCondition` instance or ``None``,
279 ``expression`` is a :class:`ConfigExpression` instance, ``level`` is the priority of the operation and ``source``
280 is an informative string describing the operation origin.
283 def __init__(self, operation, condition, expression, level=0, source='?'):
284 self.operation = operation
285 self.condition = condition
286 self.expression = expression
291 return "%s <%d, %s> [%s] %r" % ( {'SET':'=', 'APPEND':'+'}[self.operation], self.level, self.source,
292 (self.condition and self.condition.str(parents=True)) or '', unicode(self.expression))
295 class ConfigVar(ConfigElem):
296 "Class representing a single configuration variable"
298 def __init__(self, name):
299 super(ConfigVar, self).__init__(name)
300 # Ordered list of `Operations` (ascending by `level`)
302 # Fixed to value (may be None)
304 self.fixed_val = None
307 "Return a set of variables used in the expressions of the operations"
308 if not self.operations:
310 return set.union(*[ op.expression.variables() for op in self.operations ])
314 Fixes the value of the variable. Exception is raised should the variable
315 evaluate to a different value while fixed.
319 self.fixed_val = self.value()
323 "Make the variable modifiable again."
326 def value(self, depth=0):
327 "Handle the case when fixed, raise exc. on different evaluation"
328 val = super(ConfigVar,self).value(depth)
329 if self.fixed and self.fixed_val != val:
330 raise VariableFixedError("value of var %r was fixed to %r but evaluated to %r", self.name, self.fixed_val, val)
333 def add_operation(self, operation):
335 Inserts an operation. The operations are sorted by `level` (ascending), new operation goes last among
336 these with the same level.
337 Adds the variable as a dependant of the conditions and variables used in the expressions.
339 # Invalidate cached value
342 pos = bisect.bisect_right([o.level for o in self.operations], operation.level)
343 self.operations.insert(pos, operation)
344 # Create dependencies
345 for v in operation.expression.variables():
346 v.dependants.add(self)
347 if operation.condition:
348 operation.condition.dependants.add(self)
350 def remove_operation(self, operation):
352 Remove the Operation.
353 Also removes the variable as dependant from all conditions and variables used in this
354 operation that are no longer used.
356 # Invalidate cached value
358 # Remove the operation
359 self.operations.remove(operation)
360 # Remove dependencies on variables unused in other defining operations
361 vs = self.variables()
362 for v in operation.expression.variables():
364 v.dependants.remove(self)
365 # Remove the dependency on the conditions (if not used in another operation)
366 if operation.condition and operation.condition not in [op.condition for op in self.operations]:
367 operation.condition.dependants.remove(self)
369 def evaluate(self, depth=0):
371 Find the last 'SET' operation that applies and return the result of concatenating with all
372 subsequent applicable 'APPEND' operations. The result is the same as performing the operations
374 NOTE: undefined if some 'APPEND' apply but no 'SET' applies.
377 log.debug('evaluating var %r', self.name)
378 # List of strings to be concatenated
380 # Scan for last applicable expression - try each starting from the end, concatenate extensions
381 for i in range(len(self.operations)-1, -1, -1):
382 op = self.operations[i]
383 # Check the guarding condition
384 if (not op.condition) or op.condition.value(depth+1):
385 val.insert(0, op.expression.evaluate(depth=depth+1))
386 if op.operation == 'SET':
390 def dump(self, prefix=''):
392 Pretty printing of the variable. Includes all operations.
393 Returns iterator of lines (unicode strings).
395 # Try to evaluate the variable, but avoid undefined exceptions
398 v = self.value(depth=0)
401 yield prefix+u'%s = %r' % (self.name, v)
402 for op in self.operations:
403 #yield prefix+u' %s [%s] %s' % (op.operation, op.condition and op.condition.str(parents=True), op.expression)
404 yield prefix + u' ' + unicode(op)
407 class ConfigExpression(object):
409 String expression with some unexpanded config variables. Used in variable operations and conditions.
410 Expression is given as a list of unicode strings and ConfigVar variables to be expanded.
413 def __init__(self, exprlist, original = u'<unknown>'):
414 self.exprlist = list(exprlist)
415 # Original defining string
416 self.original = original
417 # Replace strings with unicode
418 for i in range(len(self.exprlist)):
420 if isinstance(e, types.StringTypes):
421 if not isinstance(e, unicode):
422 self.exprlist[i] = unicode(e, 'ascii')
425 "Return a set of variables used in the expression"
426 return set([e for e in self.exprlist if isinstance(e, ConfigVar)])
431 def evaluate(self, depth):
433 "Return unicode result of expansion of the variables."
435 for e in self.exprlist:
436 if isinstance(e, ConfigVar):
437 s.append(e.value(depth+1))
438 elif isinstance(e, unicode):
441 raise ConfigError('Invalid type %s in expression \'%s\'.'%(type(e), self))