ControlFlow.py

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"""
Classes for the implementation of the Control Flow Structure Syntax.
 
@see: https://github.com/lhcb/scheduling-event-model/tree/master/controlflow_syntax
"""
 
 
class ControlFlowNode(object):
    """
    Basic entry in the control flow graph.
    """
 
    def __and__(self, rhs):
        if rhs is CFTrue:
            return self
        elif rhs is CFFalse:
            return CFFalse
        return AndNode(self, rhs)
 
    def __or__(self, rhs):
        if rhs is CFFalse:
            return self
        elif rhs is CFTrue:
            return CFTrue
        return OrNode(self, rhs)
 
    def __invert__(self):
        return InvertNode(self)
 
    def __rshift__(self, rhs):
        return OrderedNode(self, rhs)
 
    def visitNode(self, visitor):
        visitor.enter(self)
        self._visitSubNodes(visitor)
        visitor.leave(self)
 
    def _visitSubNodes(self, visitor):
        pass
 
    def __eq__(self, other):
        return repr(self) == repr(other)
 
    def __hash__(self):
        """Return a unique identifier for this object.
 
        As we use the `repr` of this object to check for equality, we use it
        here to define uniqueness.
        """
        # The hash of the 1-tuple containing the repr of this object
        return hash((repr(self),))
 
    def getFullName(self):
        """
        Allow use of an expression as an algorihtm/sequence in a Gaudi job
        configuration.
 
        Convert the expression in nested sequencers and return the full name of
        the top one.
        """
        if not hasattr(self, "_fullname"):
            from GaudiKernel.Configurable import makeSequences
 
            self._fullname = makeSequences(self).getFullName()
        return self._fullname
 
 
class ControlFlowLeaf(ControlFlowNode):
    """
    Class used to identify a note without sub-nodes.
    """
 
    pass
 
 
class ControlFlowBool(ControlFlowLeaf):
    def __init__(self, value):
        self.value = value
 
    def __and__(self, rhs):
        return rhs if self.value else self
 
    def __or__(self, rhs):
        return self if self.value else rhs
 
    def __invert__(self):
        return CFFalse if self.value else CFTrue
 
    def __repr__(self):
        return "CFTrue" if self.value else "CFFalse"
 
 
CFTrue = ControlFlowBool(True)
CFFalse = ControlFlowBool(False)
del ControlFlowBool
 
 
class OrderedNode(ControlFlowNode):
    """
    Represent order of execution of nodes.
    """
 
    def __init__(self, lhs, rhs):
        self.lhs = lhs
        self.rhs = rhs
 
    def __repr__(self):
        return "(%r >> %r)" % (self.lhs, self.rhs)
 
    def _visitSubNodes(self, visitor):
        self.lhs.visitNode(visitor)
        self.rhs.visitNode(visitor)
 
 
class AndNode(ControlFlowNode):
    """
    And operation between control flow nodes.
    """
 
    def __init__(self, lhs, rhs):
        self.lhs = lhs
        self.rhs = rhs
 
    def __repr__(self):
        return "(%r & %r)" % (self.lhs, self.rhs)
 
    def _visitSubNodes(self, visitor):
        self.lhs.visitNode(visitor)
        self.rhs.visitNode(visitor)
 
 
class OrNode(ControlFlowNode):
    """
    Or operation between control flow nodes.
    """
 
    def __init__(self, lhs, rhs):
        self.lhs = lhs
        self.rhs = rhs
 
    def __repr__(self):
        return "(%r | %r)" % (self.lhs, self.rhs)
 
    def _visitSubNodes(self, visitor):
        self.lhs.visitNode(visitor)
        self.rhs.visitNode(visitor)
 
 
class InvertNode(ControlFlowNode):
    """
    Invert logic (negation) of a control flow node.
    """
 
    def __init__(self, item):
        self.item = item
 
    def __repr__(self):
        return "~%r" % self.item
 
    def _visitSubNodes(self, visitor):
        self.item.visitNode(visitor)
 
 
class ignore(ControlFlowNode):
    """
    Treat a control flow node as always successful, equivalent to (a | ~ a).
    """
 
    def __init__(self, item):
        self.item = item
 
    def __repr__(self):
        return "ignore(%r)" % self.item
 
    def _visitSubNodes(self, visitor):
        self.item.visitNode(visitor)
 
 
class par(ControlFlowNode):
    def __init__(self, item):
        self.item = item
 
    def __repr__(self):
        return "par(%r)" % self.item
 
    def _visitSubNodes(self, visitor):
        self.item.visitNode(visitor)
 
 
class seq(ControlFlowNode):
    def __init__(self, item):
        self.item = item
 
    def __repr__(self):
        return "seq(%r)" % self.item
 
    def _visitSubNodes(self, visitor):
        self.item.visitNode(visitor)
 
 
class line(object):
    def __init__(self, name, item):
        self.name = name
        self.item = item
 
    def __repr__(self):
        return "line(%r, %r)" % (self.name, self.item)
 
    def _visitSubNodes(self, visitor):
        self.item.visitNode(visitor)
 
 
class _TestVisitor(object):
    def __init__(self):
        self.depths = 0
 
    def enter(self, visitee):
        self.depths += 1
        print("%sEntering %s" % (self.depths * " ", type(visitee)))
        if isinstance(visitee, ControlFlowLeaf):
            print("%s Algorithm name: %s" % (" " * self.depths, visitee))
 
    def leave(self, visitee):
        print("%sLeaving %s" % (self.depths * " ", type(visitee)))
        self.depths -= 1
 
 
class _TestAlgorithm(ControlFlowLeaf):
    def __init__(self, name):
        self._name = name
 
    def __repr__(self):
        return self._name
 
    def name(self):
        return self._name
 
 
class DotVisitor(object):
    def __init__(self):
        self.nodes = []
        self.edges = []
        self.number = 0
        self.stack = []
        self.ids = {}
 
    def enter(self, visitee):
        if visitee not in self.ids:
            self.number += 1
            dot_id = self.ids[visitee] = "T%s" % self.number
        dot_id = self.ids[visitee]
        mother = None
        if self.is_needed(visitee):
            if isinstance(visitee, ControlFlowLeaf):
                entry = '%s [label="%s", shape=box]' % (dot_id, visitee.name())
            elif isinstance(visitee, OrNode):
                entry = '%s [label="OR", shape=invhouse]' % dot_id
            elif isinstance(visitee, AndNode):
                entry = '%s [label="AND", shape=invhouse]' % dot_id
            elif isinstance(visitee, OrderedNode):
                entry = '%s [label=">>", shape=point]' % dot_id
            elif isinstance(visitee, InvertNode):
                entry = '%s [label="NOT", shape=circle, color=red]' % dot_id
            elif isinstance(visitee, par):
                entry = '%s [label="PAR", shape=circle]' % dot_id
            elif isinstance(visitee, seq):
                entry = '%s [label="SEQ", shape=circle]' % dot_id
            else:
                entry = '%s [label="%s", shape=circle]' % (dot_id, type(visitee))
            self.nodes.append(entry)
            if len(self.stack) != 0:
                mother = self.collapse_identical_ancestors(type(self.stack[-1][0]))
                if not mother:
                    mother = self.stack[-1][1]
                edge = "%s->%s" % (dot_id, mother)
                self.edges.append(edge)
        self.stack.append((visitee, dot_id))
 
    def leave(self, visitee):
        self.stack.pop()
 
    def collapse_identical_ancestors(self, thetype):
        """
        If AND nodes are inside AND nodes, the graph could be simplified
        to not contain those (same true for OR and ordered)
        """
        if len(self.stack) != 0:
            mother = self.stack[-1][1]
            for entry in self.stack[::-1]:
                if not isinstance(entry[0], thetype):
                    break
                mother = entry[1]
            return mother
        return None
 
    def is_needed(self, visitee):
        """
        Check whether this node is actually needed
        """
        if len(self.stack) != 0:
            return not isinstance(visitee, type(self.stack[-1][0]))
        return True
 
    def write(self, filename):
        output = """
digraph graphname {
rankdir=LR
 
%s
 
%s
 
}
""" % (
            "\n".join(self.nodes),
            "\n".join(self.edges),
        )
 
        with open(filename, "w") as outfile:
            outfile.write(output)
 
 
def test():
    Algorithm = _TestAlgorithm
 
    a = Algorithm("a")
    b = Algorithm("b")
    c = Algorithm("c")
    d = Algorithm("d")
    e = Algorithm("e")
    f = Algorithm("f")
    g = Algorithm("g")
    sequence = seq(b >> a >> f)
    expression = sequence | ~c & par(d & e & g)
    a = expression == expression
    aLine = line("MyTriggerPath", expression)
    visitor = _TestVisitor()
    visitor2 = DotVisitor()
    print("\nPrinting trigger line:")
    print(aLine)
    print("\nPrinting expression:")
    print(expression)
    print("\nTraversing through expression:\n")
    expression.visitNode(visitor)
    expression.visitNode(visitor2)
    visitor2.write("out.dot")