The heat.engine.dependencies Module

exception heat.engine.dependencies.CircularDependencyException(**kwargs)

Bases: heat.common.exception.HeatException

msg_fmt = u'Circular Dependency Found: %(cycle)s'

class heat.engine.dependencies.Dependencies(edges=None)

Bases: object

Helper class for calculating a dependency graph.

graph(reverse=False)

Return a copy of the underlying dependency graph.

leaves()

Return an iterator over all of the leaf nodes in the graph.

required_by(last)

List the keys that require the specified node.

requires(target)

List the keys that require the specified node.

roots()

Return an iterator over all of the root nodes in the graph.

translate(transform)

Translate all of the nodes using a transform function.

Returns a new Dependencies object.

class heat.engine.dependencies.Graph(*args)

Bases: collections.defaultdict

A mutable mapping of objects to nodes in a dependency graph.

copy()

Return a copy of the graph.

edges()

Return an iterator over all of the edges in the graph.

map(func)

A dict mapping the supplied function onto each node in the graph.

Return a dictionary derived from mapping the supplied function onto each node in the graph.

reverse_copy()

Return a copy of the graph with the edges reversed.

static toposort(graph)

Return a topologically sorted iterator over a dependency graph.

This is a destructive operation for the graph.

class heat.engine.dependencies.Node(requires=None, required_by=None)

Bases: object

A node in a dependency graph.

copy()

Return a copy of the node.

disjoint()

Return True if this node is both a leaf and a stem.

required_by(source=None)

List the keys that require this node, and optionally add new one.

requires(target=None)

Add a key that this node requires, and optionally add a new one.

reverse_copy()

Return a copy of the node with the edge directions reversed.

stem()

Return True if this node is a stem (required by nothing).