Struct BacktrackingTraversal

Source

pub struct BacktrackingTraversal { /* private fields */ }

Expand description

A checked paired do-undo backtracking traversal.

§Examples

use automation_structures::BacktrackingTraversal;

let mut traversal = BacktrackingTraversal::new(2, 1, 0)?;
traversal.descend(1, 2)?;
traversal.visit()?;
traversal.ascend()?;
assert_eq!(traversal.choices(), &[]);

Implementations§

Source §

impl BacktrackingTraversal

Source

pub fn new( branch_factor: u64, max_depth: usize, initial_aux: u64, ) -> Result<Self, BacktrackingBuildError>

Validate and construct an empty traversal.

§Errors

Returns BacktrackingBuildError::InitialAuxOutOfRange when initial_aux is not in 0..3.

Examples found in repository ?

examples/catalog.rs (line 69)

21fn main() -> Result<(), Box<dyn Error>> {
22    // Primitives.
23    let mut budget = Budget::new(8);
24    assert!(budget.try_reserve(3));
25    budget.commit_reservation(3)?;
26
27    let mut hierarchy = QualityHierarchy::new(2, 2);
28    hierarchy.set_node_properties(0, 2, 1)?;
29    hierarchy.set_node_properties(1, 1, 2)?;
30    hierarchy.add_child(0, 1)?;
31
32    let mut registry = ResourceRegistry::new();
33    registry.insert(1, 10);
34    assert_eq!(registry.get(1), Some(10));
35
36    let mut hard = CompetitiveSelectionHard::new(2)?;
37    hard.update_score(0, 2)?;
38    hard.update_score(1, 1)?;
39    assert_eq!(hard.evaluate(), 0);
40
41    let mut exclusive = CompetitiveSelectionHardExclusive::new(1, 2, 2)?;
42    exclusive.update_score(0, 0, 2)?;
43    exclusive.update_score(0, 1, 1)?;
44    assert_eq!(exclusive.evaluate(0)?, 0);
45
46    let mut soft = CompetitiveSelectionSoft::begin(vec![3, 1], 4, 3)?;
47    assert_eq!(soft.assign_next()?, 0);
48
49    let mut ranked = CompetitiveSelectionRanked::new(vec![2, 1], 1, 2)?;
50    ranked.select();
51    assert_eq!(ranked.is_selected(0), Some(true));
52
53    let mut actuation = ActuationPass::new(vec![Some(7)]);
54    actuation.actuate(0)?;
55    actuation.finish()?;
56
57    let mut propagation = PropagationPass::new(1, 2, vec![], vec![0])?;
58    propagation.start_round()?;
59    propagation.update_node(0)?;
60    propagation.end_round()?;
61
62    let mut convergence = ConvergenceGovernor::new(2, 6, 2, 10)?;
63    assert_eq!(convergence.update(1)?, 1);
64
65    let mut audit = AuditSink::new(1);
66    assert!(audit.try_record(7));
67    assert!(audit.validate());
68
69    let mut backtracking = BacktrackingTraversal::new(2, 1, 0)?;
70    backtracking.descend(1, 1)?;
71    backtracking.visit()?;
72
73    // Named compositions.
74    let mut snapshot = AllocationSnapshot::new(3, 1);
75    snapshot.accept(0, 3)?;
76
77    let mut federated = FederatedBudget::new(4, 1);
78    assert!(federated.try_delegate(0, 4));
79    assert!(federated.try_allocate(0, 2));
80
81    let mut bisection = Bisection::new(4, 2)?;
82    bisection.converge();
83    assert!(bisection.is_converged());
84
85    let mut classes = EquivalenceClass::new(2, 1);
86    assert!(classes.union(0, 1)?);
87
88    let mut rate_limit = RateLimit::new(1, 1, 1)?;
89    assert!(rate_limit.try_acquire());
90
91    let mut reduction = Reduction::new(vec![2, 3])?;
92    reduction.process_next()?;
93
94    let mut graph = RelationshipGraph::new(2, 1);
95    assert!(graph.add_edge(0, 1, 1)?);
96
97    let mut sampler = Sampler::new(vec![1, 1], 1);
98    sampler.sample(0)?;
99
100    let mut select_then_actuate = SelectThenActuate::new(1, 2)?;
101    select_then_actuate.update_score(0, 0, 1)?;
102    assert_eq!(select_then_actuate.evaluate(0)?, 0);
103    select_then_actuate.actuate(0)?;
104    select_then_actuate.finish()?;
105
106    let mut signal = Signal::new(0, 2, 1)?;
107    assert!(signal.set_value(1)?);
108    signal.notify(0)?;
109
110    let mut traversal = TraversalEngine::new(1, 0, 2)?;
111    traversal.visit(0)?;
112    assert_eq!(traversal.accepted_cost(), 2);
113    traversal.terminate()?;
114
115    // Execution modalities.
116    let mut sequential = Sequential::new(1, 2, 0)?;
117    assert!(sequential.begin_step());
118    assert!(sequential.complete_step(1));
119
120    let mut fork_join = ForkJoin::new(1, 2, 0)?;
121    assert!(fork_join.start_worker(0));
122    assert!(fork_join.complete_worker(0, 1));
123    assert!(fork_join.barrier());
124    assert!(fork_join.produce_output());
125
126    let mut step_graph = StepGraph::new(1, vec![])?;
127    assert!(step_graph.start(0));
128    assert!(step_graph.complete(0));
129
130    let mut stream_graph = StreamGraph::new(3, 1, 1, 2)?;
131    assert!(stream_graph.ingest(1));
132    assert!(stream_graph.advance_first());
133    assert_eq!(stream_graph.consume(), Some(1));
134
135    // Connective roles.
136    let mut cursor = Cursor::new(0);
137    cursor.advance_to(1)?;
138
139    let mut accumulator = Accumulator::new(vec![1]);
140    assert_eq!(accumulator.advance(), Some(1));
141    assert_eq!(accumulator.accumulated(0), Some(1));
142
143    let mut marker = Marker::new(false);
144    assert!(marker.set());
145
146    let mut counter = Counter::new(0);
147    assert!(counter.try_increment());
148
149    let mut buffer = Buffer::new(1);
150    assert_eq!(buffer.push(1), Ok(()));
151    assert_eq!(buffer.pop(), Some(1));
152
153    assert!(projection_consistent(true, true));
154    assert!(strictly_before(0, 1));
155
156    assert_debuggable!(
157        budget,
158        hierarchy,
159        registry,
160        hard,
161        exclusive,
162        soft,
163        ranked,
164        actuation,
165        propagation,
166        convergence,
167        audit,
168        backtracking,
169        snapshot,
170        federated,
171        bisection,
172        classes,
173        rate_limit,
174        reduction,
175        graph,
176        sampler,
177        select_then_actuate,
178        signal,
179        traversal,
180        sequential,
181        fork_join,
182        step_graph,
183        stream_graph,
184        cursor,
185        accumulator,
186        marker,
187        counter,
188        buffer,
189    );
190
191    println!("all public automation structures constructed and exercised");
192    Ok(())
193}

Source

pub fn max_depth(&self) -> usize

Maximum admitted traversal depth.

Source

pub fn depth(&self) -> usize

Current path depth.

Source

pub fn auxiliary(&self) -> u64

Current auxiliary state.

Source

pub fn visited_count(&self) -> usize

Number of recorded leaves.

Source

pub fn is_leaf(&self) -> bool

Whether the current path is a full-depth leaf.

Source

pub fn choice(&self, depth: usize) -> Option<u64>

Read one current branch choice.

Source

pub fn descend( &mut self, choice: u64, delta: u64, ) -> Result<(), BacktrackingError>

Descend one level and record the paired undo token.

§Errors

Returns BacktrackingError at a leaf or for an invalid choice or delta.

Examples found in repository ?

examples/catalog.rs (line 70)

21fn main() -> Result<(), Box<dyn Error>> {
22    // Primitives.
23    let mut budget = Budget::new(8);
24    assert!(budget.try_reserve(3));
25    budget.commit_reservation(3)?;
26
27    let mut hierarchy = QualityHierarchy::new(2, 2);
28    hierarchy.set_node_properties(0, 2, 1)?;
29    hierarchy.set_node_properties(1, 1, 2)?;
30    hierarchy.add_child(0, 1)?;
31
32    let mut registry = ResourceRegistry::new();
33    registry.insert(1, 10);
34    assert_eq!(registry.get(1), Some(10));
35
36    let mut hard = CompetitiveSelectionHard::new(2)?;
37    hard.update_score(0, 2)?;
38    hard.update_score(1, 1)?;
39    assert_eq!(hard.evaluate(), 0);
40
41    let mut exclusive = CompetitiveSelectionHardExclusive::new(1, 2, 2)?;
42    exclusive.update_score(0, 0, 2)?;
43    exclusive.update_score(0, 1, 1)?;
44    assert_eq!(exclusive.evaluate(0)?, 0);
45
46    let mut soft = CompetitiveSelectionSoft::begin(vec![3, 1], 4, 3)?;
47    assert_eq!(soft.assign_next()?, 0);
48
49    let mut ranked = CompetitiveSelectionRanked::new(vec![2, 1], 1, 2)?;
50    ranked.select();
51    assert_eq!(ranked.is_selected(0), Some(true));
52
53    let mut actuation = ActuationPass::new(vec![Some(7)]);
54    actuation.actuate(0)?;
55    actuation.finish()?;
56
57    let mut propagation = PropagationPass::new(1, 2, vec![], vec![0])?;
58    propagation.start_round()?;
59    propagation.update_node(0)?;
60    propagation.end_round()?;
61
62    let mut convergence = ConvergenceGovernor::new(2, 6, 2, 10)?;
63    assert_eq!(convergence.update(1)?, 1);
64
65    let mut audit = AuditSink::new(1);
66    assert!(audit.try_record(7));
67    assert!(audit.validate());
68
69    let mut backtracking = BacktrackingTraversal::new(2, 1, 0)?;
70    backtracking.descend(1, 1)?;
71    backtracking.visit()?;
72
73    // Named compositions.
74    let mut snapshot = AllocationSnapshot::new(3, 1);
75    snapshot.accept(0, 3)?;
76
77    let mut federated = FederatedBudget::new(4, 1);
78    assert!(federated.try_delegate(0, 4));
79    assert!(federated.try_allocate(0, 2));
80
81    let mut bisection = Bisection::new(4, 2)?;
82    bisection.converge();
83    assert!(bisection.is_converged());
84
85    let mut classes = EquivalenceClass::new(2, 1);
86    assert!(classes.union(0, 1)?);
87
88    let mut rate_limit = RateLimit::new(1, 1, 1)?;
89    assert!(rate_limit.try_acquire());
90
91    let mut reduction = Reduction::new(vec![2, 3])?;
92    reduction.process_next()?;
93
94    let mut graph = RelationshipGraph::new(2, 1);
95    assert!(graph.add_edge(0, 1, 1)?);
96
97    let mut sampler = Sampler::new(vec![1, 1], 1);
98    sampler.sample(0)?;
99
100    let mut select_then_actuate = SelectThenActuate::new(1, 2)?;
101    select_then_actuate.update_score(0, 0, 1)?;
102    assert_eq!(select_then_actuate.evaluate(0)?, 0);
103    select_then_actuate.actuate(0)?;
104    select_then_actuate.finish()?;
105
106    let mut signal = Signal::new(0, 2, 1)?;
107    assert!(signal.set_value(1)?);
108    signal.notify(0)?;
109
110    let mut traversal = TraversalEngine::new(1, 0, 2)?;
111    traversal.visit(0)?;
112    assert_eq!(traversal.accepted_cost(), 2);
113    traversal.terminate()?;
114
115    // Execution modalities.
116    let mut sequential = Sequential::new(1, 2, 0)?;
117    assert!(sequential.begin_step());
118    assert!(sequential.complete_step(1));
119
120    let mut fork_join = ForkJoin::new(1, 2, 0)?;
121    assert!(fork_join.start_worker(0));
122    assert!(fork_join.complete_worker(0, 1));
123    assert!(fork_join.barrier());
124    assert!(fork_join.produce_output());
125
126    let mut step_graph = StepGraph::new(1, vec![])?;
127    assert!(step_graph.start(0));
128    assert!(step_graph.complete(0));
129
130    let mut stream_graph = StreamGraph::new(3, 1, 1, 2)?;
131    assert!(stream_graph.ingest(1));
132    assert!(stream_graph.advance_first());
133    assert_eq!(stream_graph.consume(), Some(1));
134
135    // Connective roles.
136    let mut cursor = Cursor::new(0);
137    cursor.advance_to(1)?;
138
139    let mut accumulator = Accumulator::new(vec![1]);
140    assert_eq!(accumulator.advance(), Some(1));
141    assert_eq!(accumulator.accumulated(0), Some(1));
142
143    let mut marker = Marker::new(false);
144    assert!(marker.set());
145
146    let mut counter = Counter::new(0);
147    assert!(counter.try_increment());
148
149    let mut buffer = Buffer::new(1);
150    assert_eq!(buffer.push(1), Ok(()));
151    assert_eq!(buffer.pop(), Some(1));
152
153    assert!(projection_consistent(true, true));
154    assert!(strictly_before(0, 1));
155
156    assert_debuggable!(
157        budget,
158        hierarchy,
159        registry,
160        hard,
161        exclusive,
162        soft,
163        ranked,
164        actuation,
165        propagation,
166        convergence,
167        audit,
168        backtracking,
169        snapshot,
170        federated,
171        bisection,
172        classes,
173        rate_limit,
174        reduction,
175        graph,
176        sampler,
177        select_then_actuate,
178        signal,
179        traversal,
180        sequential,
181        fork_join,
182        step_graph,
183        stream_graph,
184        cursor,
185        accumulator,
186        marker,
187        counter,
188        buffer,
189    );
190
191    println!("all public automation structures constructed and exercised");
192    Ok(())
193}

Source

pub fn visit(&mut self) -> Result<(), BacktrackingError>

Record the current leaf when it has not been visited.

§Errors

Returns BacktrackingError when the traversal is not at a fresh leaf.

Examples found in repository ?

examples/catalog.rs (line 71)

21fn main() -> Result<(), Box<dyn Error>> {
22    // Primitives.
23    let mut budget = Budget::new(8);
24    assert!(budget.try_reserve(3));
25    budget.commit_reservation(3)?;
26
27    let mut hierarchy = QualityHierarchy::new(2, 2);
28    hierarchy.set_node_properties(0, 2, 1)?;
29    hierarchy.set_node_properties(1, 1, 2)?;
30    hierarchy.add_child(0, 1)?;
31
32    let mut registry = ResourceRegistry::new();
33    registry.insert(1, 10);
34    assert_eq!(registry.get(1), Some(10));
35
36    let mut hard = CompetitiveSelectionHard::new(2)?;
37    hard.update_score(0, 2)?;
38    hard.update_score(1, 1)?;
39    assert_eq!(hard.evaluate(), 0);
40
41    let mut exclusive = CompetitiveSelectionHardExclusive::new(1, 2, 2)?;
42    exclusive.update_score(0, 0, 2)?;
43    exclusive.update_score(0, 1, 1)?;
44    assert_eq!(exclusive.evaluate(0)?, 0);
45
46    let mut soft = CompetitiveSelectionSoft::begin(vec![3, 1], 4, 3)?;
47    assert_eq!(soft.assign_next()?, 0);
48
49    let mut ranked = CompetitiveSelectionRanked::new(vec![2, 1], 1, 2)?;
50    ranked.select();
51    assert_eq!(ranked.is_selected(0), Some(true));
52
53    let mut actuation = ActuationPass::new(vec![Some(7)]);
54    actuation.actuate(0)?;
55    actuation.finish()?;
56
57    let mut propagation = PropagationPass::new(1, 2, vec![], vec![0])?;
58    propagation.start_round()?;
59    propagation.update_node(0)?;
60    propagation.end_round()?;
61
62    let mut convergence = ConvergenceGovernor::new(2, 6, 2, 10)?;
63    assert_eq!(convergence.update(1)?, 1);
64
65    let mut audit = AuditSink::new(1);
66    assert!(audit.try_record(7));
67    assert!(audit.validate());
68
69    let mut backtracking = BacktrackingTraversal::new(2, 1, 0)?;
70    backtracking.descend(1, 1)?;
71    backtracking.visit()?;
72
73    // Named compositions.
74    let mut snapshot = AllocationSnapshot::new(3, 1);
75    snapshot.accept(0, 3)?;
76
77    let mut federated = FederatedBudget::new(4, 1);
78    assert!(federated.try_delegate(0, 4));
79    assert!(federated.try_allocate(0, 2));
80
81    let mut bisection = Bisection::new(4, 2)?;
82    bisection.converge();
83    assert!(bisection.is_converged());
84
85    let mut classes = EquivalenceClass::new(2, 1);
86    assert!(classes.union(0, 1)?);
87
88    let mut rate_limit = RateLimit::new(1, 1, 1)?;
89    assert!(rate_limit.try_acquire());
90
91    let mut reduction = Reduction::new(vec![2, 3])?;
92    reduction.process_next()?;
93
94    let mut graph = RelationshipGraph::new(2, 1);
95    assert!(graph.add_edge(0, 1, 1)?);
96
97    let mut sampler = Sampler::new(vec![1, 1], 1);
98    sampler.sample(0)?;
99
100    let mut select_then_actuate = SelectThenActuate::new(1, 2)?;
101    select_then_actuate.update_score(0, 0, 1)?;
102    assert_eq!(select_then_actuate.evaluate(0)?, 0);
103    select_then_actuate.actuate(0)?;
104    select_then_actuate.finish()?;
105
106    let mut signal = Signal::new(0, 2, 1)?;
107    assert!(signal.set_value(1)?);
108    signal.notify(0)?;
109
110    let mut traversal = TraversalEngine::new(1, 0, 2)?;
111    traversal.visit(0)?;
112    assert_eq!(traversal.accepted_cost(), 2);
113    traversal.terminate()?;
114
115    // Execution modalities.
116    let mut sequential = Sequential::new(1, 2, 0)?;
117    assert!(sequential.begin_step());
118    assert!(sequential.complete_step(1));
119
120    let mut fork_join = ForkJoin::new(1, 2, 0)?;
121    assert!(fork_join.start_worker(0));
122    assert!(fork_join.complete_worker(0, 1));
123    assert!(fork_join.barrier());
124    assert!(fork_join.produce_output());
125
126    let mut step_graph = StepGraph::new(1, vec![])?;
127    assert!(step_graph.start(0));
128    assert!(step_graph.complete(0));
129
130    let mut stream_graph = StreamGraph::new(3, 1, 1, 2)?;
131    assert!(stream_graph.ingest(1));
132    assert!(stream_graph.advance_first());
133    assert_eq!(stream_graph.consume(), Some(1));
134
135    // Connective roles.
136    let mut cursor = Cursor::new(0);
137    cursor.advance_to(1)?;
138
139    let mut accumulator = Accumulator::new(vec![1]);
140    assert_eq!(accumulator.advance(), Some(1));
141    assert_eq!(accumulator.accumulated(0), Some(1));
142
143    let mut marker = Marker::new(false);
144    assert!(marker.set());
145
146    let mut counter = Counter::new(0);
147    assert!(counter.try_increment());
148
149    let mut buffer = Buffer::new(1);
150    assert_eq!(buffer.push(1), Ok(()));
151    assert_eq!(buffer.pop(), Some(1));
152
153    assert!(projection_consistent(true, true));
154    assert!(strictly_before(0, 1));
155
156    assert_debuggable!(
157        budget,
158        hierarchy,
159        registry,
160        hard,
161        exclusive,
162        soft,
163        ranked,
164        actuation,
165        propagation,
166        convergence,
167        audit,
168        backtracking,
169        snapshot,
170        federated,
171        bisection,
172        classes,
173        rate_limit,
174        reduction,
175        graph,
176        sampler,
177        select_then_actuate,
178        signal,
179        traversal,
180        sequential,
181        fork_join,
182        step_graph,
183        stream_graph,
184        cursor,
185        accumulator,
186        marker,
187        counter,
188        buffer,
189    );
190
191    println!("all public automation structures constructed and exercised");
192    Ok(())
193}