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# $Id$
# coding=utf-8
#
# Copyright Š 2007 Bruce Frederiksen
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
from pyke import tmp_itertools as itertools
from pyke import knowledge_base
class StopProof(Exception): pass
class stopIterator(object):
def __init__(self, iterator):
self.iterator = iter(iterator)
def __iter__(self): return self
def next(self):
if self.iterator:
try:
return self.iterator.next()
except StopProof:
self.iterator = None
raise StopIteration
class rule_base(knowledge_base.knowledge_base):
def __init__(self, engine, name, parent = None, exclude_list = ()):
super(rule_base, self).__init__(engine, name, rule_list, False)
if name in engine.rule_bases:
raise AssertionError("rule_base %s already exists" % name)
if name in engine.knowledge_bases:
raise AssertionError("name clash between rule_base '%s' and "
"fact_base '%s'" % (name, name))
engine.rule_bases[name] = self
self.fc_rules = []
self.parent = parent
self.exclude_set = frozenset(exclude_list)
self.rules = {} # {name: rule}
def add_fc_rule(self, fc_rule):
if fc_rule.name in self.rules:
raise AssertionError("%s rule_base: duplicate rule name: %s" %
(self.name, fc_rule.name))
self.rules[fc_rule.name] = fc_rule
self.fc_rules.append(fc_rule)
def add_bc_rule(self, bc_rule):
if bc_rule.name in self.rules:
raise AssertionError("%s rule_base: duplicate rule name: %s" %
(self.name, bc_rule.name))
self.rules[bc_rule.name] = bc_rule
self.get_entity_list(bc_rule.goal_name).add_bc_rule(bc_rule)
def init2(self):
if not self.initialized:
self.initialized = True
if self.parent:
parent = self.engine.rule_bases.get(self.parent)
if parent is None:
raise KeyError("rule_base %s: parent %s not found" % \
(self.name, self.parent))
self.parent = parent
self.parent.init2()
self.root_name = self.parent.root_name
else:
self.root_name = self.name
def derived_from(self, rb):
parent = self.parent
while parent:
if parent == rb: return True
parent = parent.parent
return False
def register_fc_rules(self, stop_at_rb):
rb = self
while rb is not stop_at_rb:
for fc_rule in rb.fc_rules: fc_rule.register_rule()
if not rb.parent: break
rb = rb.parent
def run_fc_rules(self, stop_at_rb):
rb = self
while rb is not stop_at_rb:
for fc_rule in rb.fc_rules: fc_rule.run()
if not rb.parent: break
rb = rb.parent
def activate(self):
current_rb = self.engine.knowledge_bases.get(self.root_name)
if current_rb:
assert self.derived_from(current_rb), \
"%s.activate(): not derived from current rule_base, %s" % \
(self.name, current_rb.name)
self.engine.knowledge_bases[self.root_name] = self
self.register_fc_rules(current_rb)
self.run_fc_rules(current_rb)
def reset(self):
if self.root_name in self.engine.knowledge_bases:
del self.engine.knowledge_bases[self.root_name]
def gen_rule_lists_for(self, goal_name):
rule_base = self
while True:
rl = rule_base.entity_lists.get(goal_name)
if rl: yield rl
if rule_base.parent and goal_name not in rule_base.exclude_set:
rule_base = rule_base.parent
else:
break
def prove(self, bindings, pat_context, goal_name, patterns):
return stopIterator(
itertools.chain(
itertools.imap(
lambda rl: rl.prove(bindings, pat_context, patterns),
self.gen_rule_lists_for(goal_name))))
class rule_list(knowledge_base.knowledge_entity_list):
def __init__(self, name):
self.name = name
self.bc_rules = []
def add_bc_rule(self, bc_rule):
self.bc_rules.append(bc_rule)
def prove(self, bindings, pat_context, patterns):
""" Binds patterns to successive facts, yielding None for each
successful match. Undoes bindings upon continuation, so that no
bindings remain at StopIteration.
"""
return itertools.chain(bc_rule.bc_fn(bc_rule, patterns, pat_context)
for bc_rule in self.bc_rules)
def test():
import doctest
import sys
sys.exit(doctest.testmod()[0])
if __name__ == "__main__":
test()