Mercurial > lbo > hg > localmr
view src/util.rs @ 10:3f35e5705cc2
Make RecordIterator a generic type
Damn, I'm just too Gopher for Rust
author | Lewin Bormann <lbo@spheniscida.de> |
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date | Sat, 30 Jan 2016 22:18:15 +0000 |
parents | 020bfec8699f |
children |
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use mapreducer::Record; use std::fmt; /// Transforms an iterator<string> into an iterator<Record>. It yields /// records with the key being the position of the current record, starting with /// 1. Mainly used as input iterator in the mapping phase, from sources that only /// yield values (no keys). pub struct RecordIterator<I: Iterator<Item=String>> { i: I, counter: u64, } impl<I: Iterator<Item=String>> RecordIterator<I> { pub fn new(it: I) -> RecordIterator<I> { RecordIterator { i: it, counter: 0 } } } impl<I: Iterator<Item=String>> Iterator for RecordIterator<I> { type Item = Record; fn next(&mut self) -> Option<Record> { match self.i.next() { None => None, Some(val) => { self.counter += 1; Some(Record { key: fmt::format(format_args!("{}", self.counter)), value: val }) } } } }