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#![warn(missing_docs)]
extern crate rand;
extern crate rustc_serialize;
use std::borrow::ToOwned;
use std::collections::HashMap;
use std::collections::hash_map::Entry::{Occupied, Vacant};
use std::fs::File;
use std::hash::Hash;
use std::io::{BufReader, Error, ErrorKind, Result};
use std::io::prelude::*;
use std::iter::Map;
use std::path::Path;
use std::rc::Rc;
use rand::{Rng, thread_rng};
use rustc_serialize::{Decodable, Encodable};
use rustc_serialize::json::{decode, encode};
pub trait Chainable: Eq + Hash {}
impl<T> Chainable for T where T: Eq + Hash {}
#[derive(RustcEncodable, RustcDecodable, PartialEq, Debug)]
pub struct Chain<T> where T: Chainable {
map: HashMap<Rc<T>, HashMap<Rc<T>, usize>>,
start: Rc<T>,
end: Rc<T>,
}
impl<T> Chain<T> where T: Chainable {
pub fn new(start: T, end: T) -> Chain<T> {
let start = Rc::new(start);
let end = Rc::new(end);
Chain {
map: {
let mut map = HashMap::new();
map.insert(start.clone(), HashMap::new());
map
},
start: start, end: end
}
}
pub fn is_empty(&self) -> bool {
self.map[&self.start.clone()].is_empty()
}
pub fn feed(&mut self, tokens: Vec<T>) -> &mut Chain<T> {
if tokens.len() == 0 { return self }
let mut toks = Vec::new();
toks.push(self.start.clone());
toks.extend(tokens.into_iter().map(|token| {
let rc = Rc::new(token);
if !self.map.contains_key(&rc) {
self.map.insert(rc.clone(), HashMap::new());
}
rc
}));
toks.push(self.end.clone());
for p in toks.windows(2) {
self.map.get_mut(&p[0]).unwrap().add(p[1].clone());
}
self
}
pub fn generate(&self) -> Vec<Rc<T>> {
let mut ret = Vec::new();
let mut curs = self.start.clone();
while curs != self.end {
curs = self.map[&curs].next();
ret.push(curs.clone());
}
ret.pop();
ret
}
pub fn generate_from_token(&self, token: T) -> Vec<Rc<T>> {
let token = Rc::new(token);
if !self.map.contains_key(&token) { return Vec::new() }
let mut ret = vec![token.clone()];
let mut curs = token;
while curs != self.end {
curs = self.map[&curs].next();
ret.push(curs.clone());
}
ret.pop();
ret
}
pub fn iter(&self) -> InfiniteChainIterator<T> {
InfiniteChainIterator { chain: self }
}
pub fn iter_for(&self, size: usize) -> SizedChainIterator<T> {
SizedChainIterator { chain: self, size: size }
}
}
impl<T> Chain<T> where T: Decodable + Chainable {
pub fn load(path: &Path) -> Result<Chain<T>> {
let mut file = try!(File::open(path));
let mut data = String::new();
try!(file.read_to_string(&mut data));
decode(&data).map_err(|_|
Error::new(ErrorKind::InvalidInput, "Failed to decode markov chain.")
)
}
pub fn load_utf8(path: &str) -> Result<Chain<T>> {
Chain::load(&Path::new(path))
}
}
impl<T> Chain<T> where T: for<'a> Encodable + Chainable {
pub fn save(&self, path: &Path) -> Result<()> {
let mut f = try!(File::create(path));
try!(f.write_all(&try!(encode(self).map_err(|_|
Error::new(ErrorKind::InvalidInput, "Failed to encode markov chain.")
)).as_bytes()));
f.flush()
}
pub fn save_utf8(&self, path: &str) -> Result<()> {
self.save(&Path::new(path))
}
}
impl Chain<String> {
pub fn for_strings() -> Chain<String> {
Chain::new("\u{0002}".to_owned(), "\u{0003}".to_owned())
}
pub fn feed_str(&mut self, string: &str) -> &mut Chain<String> {
self.feed(string.split(" ").map(|s| s.to_owned()).collect())
}
pub fn feed_file(&mut self, path: &Path) -> &mut Chain<String> {
let reader = BufReader::new(File::open(path).unwrap());
for line in reader.lines() {
let line = line.unwrap();
let words: Vec<_> = line.split(&[' ', '\t', '\n', '\r'][..])
.filter(|word| !word.is_empty())
.collect();
self.feed(words.iter().map(|&s| s.to_owned()).collect());
}
self
}
fn vec_to_string(vec: Vec<Rc<String>>) -> String {
let mut ret = String::new();
for s in vec.iter() {
ret.push_str(&s);
ret.push_str(" ");
}
let len = ret.len();
if len > 0 {
ret.truncate(len - 1);
}
ret
}
pub fn generate_str(&self) -> String {
Chain::vec_to_string(self.generate())
}
pub fn generate_str_from_token(&self, string: &str) -> String {
Chain::vec_to_string(self.generate_from_token(string.to_owned()))
}
pub fn str_iter(&self) -> InfiniteChainStringIterator {
let vec_to_string: fn(Vec<Rc<String>>) -> String = Chain::vec_to_string;
self.iter().map(vec_to_string)
}
pub fn str_iter_for(&self, size: usize) -> SizedChainStringIterator {
let vec_to_string: fn(Vec<Rc<String>>) -> String = Chain::vec_to_string;
self.iter_for(size).map(vec_to_string)
}
}
pub type SizedChainStringIterator<'a> =
Map<SizedChainIterator<'a, String>, fn(Vec<Rc<String>>) -> String>;
pub struct SizedChainIterator<'a, T: Chainable + 'a> {
chain: &'a Chain<T>,
size: usize,
}
impl<'a, T> Iterator for SizedChainIterator<'a, T> where T: Chainable + 'a {
type Item = Vec<Rc<T>>;
fn next(&mut self) -> Option<Vec<Rc<T>>> {
if self.size > 0 {
self.size -= 1;
Some(self.chain.generate())
} else {
None
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.size, Some(self.size))
}
}
pub type InfiniteChainStringIterator<'a> =
Map<InfiniteChainIterator<'a, String>, fn(Vec<Rc<String>>) -> String>;
pub struct InfiniteChainIterator<'a, T: Chainable + 'a> {
chain: &'a Chain<T>
}
impl<'a, T> Iterator for InfiniteChainIterator<'a, T> where T: Chainable + 'a {
type Item = Vec<Rc<T>>;
fn next(&mut self) -> Option<Vec<Rc<T>>> {
Some(self.chain.generate())
}
}
trait States<T: PartialEq> {
fn add(&mut self, token: Rc<T>);
fn next(&self) -> Rc<T>;
}
impl<T> States<T> for HashMap<Rc<T>, usize> where T: Chainable {
fn add(&mut self, token: Rc<T>) {
match self.entry(token) {
Occupied(mut e) => *e.get_mut() += 1,
Vacant(e) => { e.insert(1); },
}
}
fn next(&self) -> Rc<T> {
let mut sum = 0;
for &value in self.values() {
sum += value;
}
let mut rng = thread_rng();
let cap = rng.gen_range(0, sum);
sum = 0;
for (key, &value) in self.iter() {
sum += value;
if sum > cap {
return key.clone()
}
}
unreachable!("The random number generator failed.")
}
}
#[cfg(test)]
mod test {
use super::Chain;
#[test]
fn new() {
Chain::new(0u8, 100);
Chain::for_strings();
}
#[test]
fn is_empty() {
let mut chain = Chain::new(0u8, 100);
assert!(chain.is_empty());
chain.feed(vec![1, 2, 3]);
assert!(!chain.is_empty());
}
#[test]
fn feed() {
let mut chain = Chain::new(0u8, 100);
chain.feed(vec![3, 5, 10]).feed(vec![5, 12]);
}
#[test]
fn generate() {
let mut chain = Chain::new(0u8, 100);
chain.feed(vec![3, 5, 10]).feed(vec![5, 12]);
let v = chain.generate().into_iter().map(|v| *v).collect();
assert!([vec![3, 5, 10], vec![3, 5, 12], vec![5, 10], vec![5, 12]].contains(&v));
}
#[test]
fn generate_from_token() {
let mut chain = Chain::new(0u8, 100);
chain.feed(vec![3, 5, 10]).feed(vec![5, 12]);
let v = chain.generate_from_token(5).into_iter().map(|v| *v).collect();
assert!([vec![5, 10], vec![5, 12]].contains(&v));
}
#[test]
fn generate_from_unfound_token() {
let mut chain = Chain::new(0u8, 100);
chain.feed(vec![3, 5, 10]).feed(vec![5, 12]);
let v: Vec<_> = chain.generate_from_token(9).into_iter().map(|v| *v).collect();
assert_eq!(v, vec![]);
}
#[test]
fn iter() {
let mut chain = Chain::new(0u8, 100);
chain.feed(vec![3, 5, 10]).feed(vec![5, 12]);
assert_eq!(chain.iter().size_hint().1, None);
}
#[test]
fn iter_for() {
let mut chain = Chain::new(0u8, 100);
chain.feed(vec![3, 5, 10]).feed(vec![5, 12]);
assert_eq!(chain.iter_for(5).collect::<Vec<_>>().len(), 5);
}
#[test]
fn feed_str() {
let mut chain = Chain::for_strings();
chain.feed_str("I like cats and dogs");
}
#[test]
fn generate_str() {
let mut chain = Chain::for_strings();
chain.feed_str("I like cats").feed_str("I hate cats");
assert!(["I like cats", "I hate cats"].contains(&&chain.generate_str()[..]));
}
#[test]
fn generate_str_from_token() {
let mut chain = Chain::for_strings();
chain.feed_str("I like cats").feed_str("cats are cute");
assert!(["cats", "cats are cute"].contains(&&chain.generate_str_from_token("cats")[..]));
}
#[test]
fn generate_str_from_unfound_token() {
let mut chain = Chain::for_strings();
chain.feed_str("I like cats").feed_str("cats are cute");
assert_eq!(chain.generate_str_from_token("test"), "");
}
#[test]
fn str_iter() {
let mut chain = Chain::for_strings();
chain.feed_str("I like cats and I like dogs");
assert_eq!(chain.str_iter().size_hint().1, None);
}
#[test]
fn str_iter_for() {
let mut chain = Chain::for_strings();
chain.feed_str("I like cats and I like dogs");
assert_eq!(chain.str_iter_for(5).collect::<Vec<_>>().len(), 5);
}
#[test]
fn save() {
let mut chain = Chain::for_strings();
chain.feed_str("I like cats and I like dogs");
chain.save_utf8("save.json").unwrap();
}
#[test]
fn load() {
let mut chain = Chain::for_strings();
chain.feed_str("I like cats and I like dogs");
chain.save_utf8("load.json").unwrap();
let other_chain: Chain<String> = Chain::load_utf8("load.json").unwrap();
assert_eq!(other_chain, chain);
}
}