63 lines
2.3 KiB
Rust
63 lines
2.3 KiB
Rust
// Can't use pub const fn constructor due to Copy trait, so allow directly creating struct publicly for now.
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pub struct TrieNode<V: 'static + Copy> {
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// Using a children array of size 256 would probably be fastest, but waste too much memory and cause slow compiles
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// and large binaries. Instead, we only store the children between the first and last defined (see `gen/trie.ts`).
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// When getting a child, use `index - offset`.
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pub offset: usize,
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pub value: Option<V>,
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pub children: &'static [Option<&'static TrieNode<V>>],
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}
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pub enum TrieNodeMatch<V: 'static + Copy> {
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Found { len: usize, value: V },
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NotFound { reached: usize },
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}
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impl<V: 'static + Copy> TrieNodeMatch<V> {
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pub fn found(&self) -> bool {
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match self {
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TrieNodeMatch::Found { .. } => true,
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TrieNodeMatch::NotFound { .. } => false,
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}
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}
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}
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impl<V: 'static + Copy> TrieNode<V> {
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// Find the node that matches the shortest prefix of {@param text} and has a value, or the entire text.
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#[inline(always)]
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pub fn next_matching_node(&self, text: &[u8], from: usize) -> Option<(&TrieNode<V>, usize)> {
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let mut node: &TrieNode<V> = self;
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let mut next_pos = from;
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while let Some(&c) = text.get(next_pos) {
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match node.children.get((c as usize).wrapping_sub(node.offset)) {
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Some(Some(child)) => node = child,
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None | Some(None) => return None,
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};
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next_pos += 1;
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if node.value.is_some() {
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break;
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};
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};
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Some((node, next_pos))
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}
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#[inline(always)]
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pub fn longest_matching_prefix(&self, text: &[u8]) -> TrieNodeMatch<V> {
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let mut node: &TrieNode<V> = self;
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let mut value: Option<TrieNodeMatch<V>> = None;
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let mut pos = 0;
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while let Some(&c) = text.get(pos) {
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match node.children.get((c as usize).wrapping_sub(node.offset)) {
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Some(Some(child)) => node = child,
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None | Some(None) => break,
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};
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pos += 1;
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match node.value {
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Some(v) => value = Some(TrieNodeMatch::Found { len: pos, value: v }),
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None => {}
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};
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};
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value.unwrap_or(TrieNodeMatch::NotFound { reached: pos })
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}
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}
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