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67 lines
1.3 KiB
67 lines
1.3 KiB
//! Map iter
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use super::*;
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use std::{
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iter,
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collections::HashSet,
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hash::Hash,
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};
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//TODO: Feature flag for SHA256 hashing
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type HashOutput = u64;
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fn compute<H: Hash>(what: &H) -> HashOutput
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{
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use std::hash::Hasher;
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let mut hasher = std::collections::hash_map::DefaultHasher::new();
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what.hash(&mut hasher);
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hasher.finish()
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}
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pub struct DedupIter<I: Iterator>(I, HashSet<HashOutput>)
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where <I as Iterator>::Item: Hash;
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impl<I: Iterator> Iterator for DedupIter<I>
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where I::Item: Hash
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{
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type Item = I::Item;
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fn next(&mut self) -> Option<Self::Item>
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{
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if let Some(next) = self.0.next() {
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let hash = compute(&next);
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if self.1.insert(hash) {
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Some(next)
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} else {
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return self.next();
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}
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} else {
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None
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}
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}
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fn size_hint(&self) -> (usize, Option<usize>)
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{
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let (low, high) = self.0.size_hint();
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(if low < 1 {0} else {1}, high)
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}
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}
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pub trait DedupIterExt: Iterator + Sized
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where Self::Item: Hash
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{
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fn dedup(self) -> DedupIter<Self>;
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}
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impl<I: Iterator> DedupIterExt for I
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where I::Item: Hash
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{
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fn dedup(self) -> DedupIter<Self>
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{
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let set = match self.size_hint() {
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(0, Some(0)) | (0, None) => HashSet::new(),
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(_, Some(x)) | (x, None) => HashSet::with_capacity(x),
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};
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DedupIter(self, set)
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}
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}
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