49 lines
1.1 KiB
Rust
49 lines
1.1 KiB
Rust
use crate::Node;
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use std::slice::Iter;
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/// An iterator that traverses an operator tree in pre-order.
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pub struct NodeIter<'a> {
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stack: Vec<Iter<'a, Node>>,
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}
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impl<'a> NodeIter<'a> {
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fn new(node: &'a Node) -> Self {
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NodeIter {
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stack: vec![node.children.iter()],
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}
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}
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}
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impl<'a> Iterator for NodeIter<'a> {
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type Item = &'a Node;
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fn next(&mut self) -> Option<Self::Item> {
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loop {
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let mut result = None;
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if let Some(last) = self.stack.last_mut() {
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if let Some(next) = last.next() {
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result = Some(next);
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} else {
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// Can not fail because we just borrowed last.
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self.stack.pop().unwrap();
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}
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} else {
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return None;
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}
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if let Some(result) = result {
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self.stack.push(result.children.iter());
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return Some(result);
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}
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}
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}
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}
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impl Node {
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/// Returns an iterator over all nodes in this tree.
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pub fn iter(&self) -> impl Iterator<Item = &Node> {
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NodeIter::new(self)
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}
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}
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