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use crate::collections::HashMap;
use crate::Component;
use std::mem;
#[derive(Default, Debug)]
struct Node {
/// If this is a terminating node that can be imported or not..
term: bool,
/// The children of this node.
children: HashMap<Component, Node>,
}
/// A tree of names.
#[derive(Default, Debug)]
pub struct Names {
root: Node,
}
impl Names {
/// Construct a collection of names.
pub fn new() -> Self {
Self::default()
}
/// Insert the given item as an import.
///
/// # Examples
///
/// ```rust
/// use runestick::Names;
///
/// let mut names = Names::new();
/// assert!(!names.contains(&["test"]));
/// assert!(names.insert(&["test"]));
/// assert!(names.contains(&["test"]));
/// assert!(!names.insert(&["test"]));
/// ```
pub fn insert<I>(&mut self, iter: I) -> bool
where
I: IntoIterator,
I::Item: Into<Component>,
{
let mut current = &mut self.root;
for c in iter {
current = current.children.entry(c.into()).or_default();
}
!mem::replace(&mut current.term, true)
}
/// Test if the given import exists.
///
/// # Examples
///
/// ```rust
/// use runestick::Names;
///
/// let mut names = Names::new();
/// assert!(!names.contains(&["test"]));
/// assert!(names.insert(&["test"]));
/// assert!(names.contains(&["test"]));
/// assert!(!names.insert(&["test"]));
/// ```
pub fn contains<I>(&self, iter: I) -> bool
where
I: IntoIterator,
I::Item: Into<Component>,
{
self.find_node(iter).map(|n| n.term).unwrap_or_default()
}
/// Test if we contain the given prefix.
pub fn contains_prefix<I>(&self, iter: I) -> bool
where
I: IntoIterator,
I::Item: Into<Component>,
{
self.find_node(iter).is_some()
}
/// Iterate over all known components immediately under the specified `iter`
/// path.
pub fn iter_components<'a, I>(&'a self, iter: I) -> impl Iterator<Item = &'a Component>
where
I: IntoIterator,
I::Item: Into<Component>,
{
let mut current = &self.root;
for c in iter {
let c = c.into();
current = match current.children.get(&c) {
Some(node) => node,
None => return IterComponents(None),
};
}
return IterComponents(Some(current.children.keys()));
struct IterComponents<I>(Option<I>);
impl<'a, I> Iterator for IterComponents<I>
where
I: Iterator<Item = &'a Component>,
{
type Item = &'a Component;
fn next(&mut self) -> Option<Self::Item> {
let mut iter = self.0.take()?;
let next = iter.next()?;
self.0 = Some(iter);
Some(next)
}
}
}
/// Find the node corresponding to the given path.
fn find_node<I>(&self, iter: I) -> Option<&Node>
where
I: IntoIterator,
I::Item: Into<Component>,
{
let mut current = &self.root;
for c in iter {
let c = c.into();
current = current.children.get(&c)?;
}
Some(current)
}
}