eta.plan.PlanNode

class PlanNode(step)[source]

A node in the doubly linked list that represents the system’s plan.

Parameters:: step (PlanStep) – The plan step contained within this node.

step

The plan step contained within this node.

prev

The next plan node in the linked list.

next

The previous plan node in the linked list.

Methods

`add_schema_to_subplan`	Add the given schema to each plan step in the subplan headed by this node.
`add_superstep_to_subplan`	Add the step of a given plan node as a superstep of each node within the subplan headed by this node.
`add_supersteps`	Given a subplan bounded between a given start and end node, add each as a superstep of this node.
`bind`	Bind the given variable symbol to the given value throughout the entire plan structure.
`get_all_roots`	Get all root plan steps (i.e., the most abstract steps) reachable from the current plan.
`get_schemas`	Get all schemas of this plan.
`serialize_from_roots`	Format a string representing the subtrees of the plan structure reachable from each root step.
`serialize_subtree`	Format a string representing the subtree of the plan structure reachable from this node.
`status`	Format the plan structure as a status string showing the current, past, and future surface steps.
`to_graph`	Convert a plan structure to a standard graph object, i.e., a list of vertices and edges.
`unbind`	Unbind the given variable symbol throughout the entire plan structure.

add_superstep_to_subplan(node)[source]

Add the step of a given plan node as a superstep of each node within the subplan headed by this node.

Parameters:: node (PlanNode) – The node whose step should be added as a superstep.

add_supersteps(start_node, end_node)[source]

Given a subplan bounded between a given start and end node, add each as a superstep of this node.

Parameters:

start_node (PlanNode) – The beginning of the subplan whose steps should be added as a superstep.
end_node (PlanNode) – The end of the subplan whose steps should be added as a superstep.

add_schema_to_subplan(schema)[source]

Add the given schema to each plan step in the subplan headed by this node.

Parameters:: schema (Schema) – The schema object to add to the schema lists for each plan step.

get_all_roots()[source]: Get all root plan steps (i.e., the most abstract steps) reachable from the current plan.

bind(var, val)[source]: Bind the given variable symbol to the given value throughout the entire plan structure.

unbind(var)[source]: Unbind the given variable symbol throughout the entire plan structure.

status(before=3, after=5, schemas=False)[source]

Format the plan structure as a status string showing the current, past, and future surface steps.

Parameters:

before (int, default=3) – The number of past surface steps to show.
after (int, default=5) – The number of future surface steps to show.
schemas (bool, default=False) – Whether to also display schema predicates for each step.

Return type:

str

serialize_subtree(schemas=False)[source]

Format a string representing the subtree of the plan structure reachable from this node.

Parameters:: schemas (bool, default=False) – Whether to also display schema predicates for each step.
Return type:: str

serialize_from_roots(schemas=False)[source]

Format a string representing the subtrees of the plan structure reachable from each root step.

Parameters:: schemas (bool, default=False) – Whether to also display schema predicates for each step.
Return type:: str

to_graph(before=3, after=5, schemas=False)[source]

Convert a plan structure to a standard graph object, i.e., a list of vertices and edges.

Parameters:

before (int, default=3) – The number of past surface steps to include in the graph.
after (int, default=5) – The number of future surface steps to include in the graph.
schemas (bool, default=False) – Whether to also display schema predicates in the labels for each step.

Returns:

nodes (list[tuple[str, str]]) – A list of vertices/nodes in the resulting graph, where each node is an (<id>, <label>) tuple.
edges (list[tuple[str, str]]) – A list of edges in the resulting graph, where each edge is an (<id1>, <id2>) tuple.