2 use std::io::prelude::*;
3 use std::collections::HashMap;
5 pub fn read_file(path: &str) -> Result<String, std::io::Error> {
6 let mut s = String::new();
8 .read_to_string(&mut s)?;
12 // needs Copy trait, good for simple types
13 pub fn largest<T: PartialOrd + Copy>(list: &[T]) -> T {
14 let mut result = list[0];
23 // expensive for large strings, don't use that
24 pub fn largest_clone<T: PartialOrd + Clone>(list: &[T]) -> T {
25 let mut result = list[0].clone();
34 // good for everything, but more expensive for simple types
35 pub fn largest_ref<T: PartialOrd>(list: &[T]) -> &T {
36 let mut result = &list[0];
45 pub fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
46 if x.len() > y.len() {
53 /// Wrap and cache an expensive calculation
55 /// This calls a closure just once for every distinct argument. Any subsequent
56 /// call to `.value()` with the same argument uses the cached value.
57 pub struct Cacher<T, A, V>
60 A: Eq + Copy + std::hash::Hash,
64 values: HashMap<A, V>,
67 impl<T, A, V> Cacher<T, A, V>
70 A: Eq + Copy + std::hash::Hash,
73 pub fn new(calc: T) -> Cacher<T, A, V> {
74 Cacher { calc, values: HashMap::new() }
77 pub fn value(&mut self, arg: A) -> V {
78 match self.values.get(&arg) {
81 let v = (self.calc)(arg);
82 self.values.insert(arg, v);
94 pub fn new() -> Counter5 {
99 impl Iterator for Counter5 {
102 fn next(&mut self) -> Option<Self::Item> {