Mercurial > lbo > hg > localmr
view src/mapreducer.rs @ 12:86b39697bc0e
Move util module; add lines module; update writelog mod
author | Lewin Bormann <lbo@spheniscida.de> |
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date | Sun, 31 Jan 2016 11:38:54 +0000 |
parents | 0d7cfea10370 |
children | 895d6a1771db |
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use std::collections::LinkedList; use std::clone::Clone; pub struct Record { pub key: String, pub value: String, } /// Input to a reducer function. pub struct MultiRecord { key: String, value: Box<Iterator<Item=String>>, } impl MultiRecord { /// Retrieves the key of the record. pub fn key<'a>(&'a self) -> &'a String { &self.key } } impl IntoIterator for MultiRecord { type Item = String; type IntoIter = Box<Iterator<Item=String>>; /// Allows iterating over all the values. fn into_iter(self) -> Self::IntoIter { self.value } } pub struct MEmitter { r: LinkedList<Record>, } impl MEmitter { pub fn new() -> MEmitter { MEmitter { r: LinkedList::new() } } pub fn emit(&mut self, key: String, val: String) { self.r.push_back(Record { key: key, value: val }) } pub fn _get(self) -> LinkedList<Record> { self.r } } pub struct REmitter { r: LinkedList<String>, } impl REmitter { pub fn new() -> REmitter { REmitter { r: LinkedList::new() } } pub fn emit(&mut self, val: String) { self.r.push_back(val) } pub fn _get(self) -> LinkedList<String> { self.r } } pub type MapperF = fn(&mut MEmitter, Record); pub type ReducerF = fn(&mut REmitter, MultiRecord); /// A type implementing map() and reduce() functions. pub trait MapReducer: Clone { /// Takes one <key,value> pair and an emitter. /// The emitter is used to yield results from the map phase. fn map(&self, em: &mut MEmitter, record: Record); fn reduce(&self, em: &mut REmitter, records: MultiRecord); }