First revision of search stack.
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@ -1,3 +1,4 @@
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pub mod base;
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pub mod nav;
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pub mod mutators;
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@ -7,6 +7,8 @@ use ::hidden::base::*;
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use ::hidden::nav::{ChildList, ChildListIter, Edge, Node, ParentList, ParentListIter};
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use ::hidden::nav::{make_child_list, make_edge, make_node, make_parent_list};
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pub mod stack;
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/// Mutable handle to a graph vertex ("node handle").
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///
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/// This zipper-like type enables traversal of a graph along the vertex's
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205
src/hidden/mutators/stack.rs
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205
src/hidden/mutators/stack.rs
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@ -0,0 +1,205 @@
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use std::clone::Clone;
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use std::cmp::Eq;
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use std::error::Error;
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use std::fmt;
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use std::hash::Hash;
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use std::iter::Iterator;
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use ::{Graph, Target};
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use ::hidden::base::*;
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use ::hidden::mutators::MutNode;
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use ::hidden::nav::{Edge, Node, make_edge, make_node};
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enum Head {
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Vertex(StateId),
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Unexpanded(ArcId),
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}
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#[derive(Debug)]
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pub enum SearchError<E> where E: Error {
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Unexpanded,
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ChildBounds(usize, usize),
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ParentBounds(usize, usize),
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PredicateError(E),
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}
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impl<E> fmt::Display for SearchError<E> where E: Error {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match *self {
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SearchError::Unexpanded => write!(f, "Stack head is unexpanded"),
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SearchError::ChildBounds(i, len) => write!(f, "Search chose child {}/{}", i, len),
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SearchError::ParentBounds(i, len) => write!(f, "Search chose parent {}/{}", i, len),
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SearchError::PredicateError(ref e) => write!(f, "Error in search predicate: {}", e),
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}
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}
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}
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impl<E> Error for SearchError<E> where E: Error {
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fn description(&self) -> &str {
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match *self {
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SearchError::Unexpanded => "unexpanded",
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SearchError::ChildBounds(_, _) => "child out of bounds",
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SearchError::ParentBounds(_, _) => "parent out of bounds",
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SearchError::PredicateError(ref e) => e.description(),
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}
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}
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fn cause(&self) -> Option<&Error> {
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match *self {
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SearchError::PredicateError(ref e) => Some(e),
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_ => None,
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}
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}
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}
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pub struct SearchStack<'a, T, S, A> where T: 'a + Hash + Eq + Clone, S: 'a, A: 'a {
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graph: &'a mut Graph<T, S, A>,
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stack: Vec<(StateId, ArcId)>,
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head: Head,
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}
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pub struct SearchStackIter<'a, 's, T, S, A> where T: 'a + Hash + Eq + Clone, S: 'a, A: 'a, 'a: 's {
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stack: &'s SearchStack<'a, T, S, A>,
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position: usize,
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exhausted: bool,
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}
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pub enum StackItem<'a, T, S, A> where T: 'a + Hash + Eq + Clone, S: 'a, A: 'a {
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Item(Node<'a, T, S, A>, Edge<'a, T, S, A>),
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Head(Target<Node<'a, T, S, A>, Edge<'a, T, S, A>>),
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}
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impl<'a, T, S, A> SearchStack<'a, T, S, A> where T: 'a + Hash + Eq + Clone, S: 'a, A: 'a {
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pub fn new(node: MutNode<'a, T, S, A>) -> Self {
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SearchStack {
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graph: node.graph,
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stack: Vec::new(),
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head: Head::Vertex(node.id),
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}
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}
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pub fn len(&self) -> usize {
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self.stack.len() + 1
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}
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pub fn pop(&mut self) -> bool {
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match self.stack.pop() {
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Some((new_head, _)) => {
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self.head = Head::Vertex(new_head);
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true
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},
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None => false,
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}
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}
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pub fn head<'s>(&'s self) -> Target<Node<'s, T, S, A>, Edge<'s, T, S, A>> {
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match self.head {
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Head::Vertex(id) => Target::Expanded(make_node(self.graph, id)),
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Head::Unexpanded(id) => Target::Unexpanded(make_edge(self.graph, id)),
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}
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}
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pub fn is_head_expanded(&self) -> bool {
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match self.head {
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Head::Vertex(_) => true,
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Head::Unexpanded(_) => false,
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}
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}
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pub fn push_child<'s, F, E>(&'s mut self, f: F)
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-> Result<Option<Edge<'s, T, S, A>>, SearchError<E>>
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where F: Fn(Node<'s, T, S, A>) -> Result<Option<usize>, E>, E: Error {
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match self.head {
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Head::Vertex(head_id) => {
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let node = make_node(self.graph, head_id);
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let children = node.get_child_list();
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match f(node) {
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Ok(Some(i)) if i >= children.len() =>
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Err(SearchError::ChildBounds(i, children.len())),
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Ok(Some(i)) => {
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let child = children.get_edge(i);
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self.stack.push((head_id, ArcId(child.get_id())));
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self.head = match child.get_target() {
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Target::Expanded(n) => Head::Vertex(StateId(n.get_id())),
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Target::Unexpanded(()) => Head::Unexpanded(ArcId(child.get_id())),
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};
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Ok(Some(child))
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},
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Ok(None) => Ok(None),
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Err(e) => Err(SearchError::PredicateError(e)),
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}
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},
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Head::Unexpanded(_) => Err(SearchError::Unexpanded),
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}
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}
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pub fn push_parent<'s, F, E>(&'s mut self, f: F)
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-> Result<Option<Edge<'s, T, S, A>>, SearchError<E>>
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where F: Fn(Node<'s, T, S, A>) -> Result<Option<usize>, E>, E: Error {
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match self.head {
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Head::Vertex(head_id) => {
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let node = make_node(self.graph, head_id);
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let parents = node.get_parent_list();
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match f(node) {
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Ok(Some(i)) if i >= parents.len() =>
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Err(SearchError::ParentBounds(i, parents.len())),
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Ok(Some(i)) => {
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let parent = parents.get_edge(i);
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self.stack.push((head_id, ArcId(parent.get_id())));
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self.head = match parent.get_target() {
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Target::Expanded(n) => Head::Vertex(StateId(n.get_id())),
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Target::Unexpanded(()) => Head::Unexpanded(ArcId(parent.get_id())),
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};
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Ok(Some(parent))
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},
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Ok(None) => Ok(None),
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Err(e) => Err(SearchError::PredicateError(e)),
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}
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},
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Head::Unexpanded(_) => Err(SearchError::Unexpanded),
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}
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}
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pub fn iter<'s>(&'s self) -> SearchStackIter<'a, 's, T, S, A> {
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SearchStackIter::new(self)
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}
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}
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impl<'a, 's, T, S, A> SearchStackIter<'a, 's, T, S, A> where T: 'a + Hash + Eq + Clone, S: 'a, A: 'a, 'a: 's {
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fn new(stack: &'s SearchStack<'a, T, S, A>) -> Self {
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SearchStackIter {
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stack: stack,
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position: 0,
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exhausted: false,
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}
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}
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}
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impl<'a, 's, T, S, A> Iterator for SearchStackIter<'a, 's, T, S, A>
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where T: 'a + Hash + Eq + Clone, S: 'a, A: 'a, 'a: 's {
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type Item = StackItem<'s, T, S, A>;
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fn next(&mut self) -> Option<StackItem<'s, T, S, A>> {
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if self.position >= self.stack.stack.len() {
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if self.exhausted {
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None
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} else {
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self.exhausted = true;
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Some(StackItem::Head(match self.stack.head {
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Head::Vertex(id) => Target::Expanded(make_node(self.stack.graph, id)),
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Head::Unexpanded(id) => Target::Unexpanded(make_edge(self.stack.graph, id)),
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}))
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}
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} else {
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let (state_id, edge_id) = self.stack.stack[self.position];
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self.position += 1;
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Some(StackItem::Item(make_node(self.stack.graph, state_id),
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make_edge(self.stack.graph, edge_id)))
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}
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}
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fn size_hint(&self) -> (usize, Option<usize>) {
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let len = self.stack.len() - self.position - (if self.exhausted { 1 } else { 0 });
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(len, Some(len))
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}
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}
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@ -8,6 +8,7 @@ use self::hidden::mutators::make_mut_node;
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pub use self::hidden::nav::{ChildList, ChildListIter, Edge, Node, ParentList, ParentListIter};
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pub use self::hidden::mutators::{EdgeExpander, MutChildList, MutEdge, MutNode, MutParentList};
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pub use self::hidden::mutators::stack::{SearchError, SearchStack, SearchStackIter};
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/// A search graph.
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///
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