mod word_utils;
+mod lib;
use std::collections::HashMap;
use std::io::{prelude::*, ErrorKind};
use std::fs::{self, File};
+use lib::*;
use word_utils::{first_word, second_word};
fn test_strings() {
println!("scores after doubling: {:?}", scores);
// double scores of immutable hashmap (rebuild it)
- let collect_scores: HashMap<_, _> = collect_scores.iter()
+ let collect_scores: HashMap<_, _> = collect_scores.into_iter()
.map(|(k, v)| (k, 2 * v))
.collect();
println!("collect_scores after rebuilding with doubling: {:?}", collect_scores);
}
-fn read_file(path: &str) -> Result<String, std::io::Error> {
- let mut s = String::new();
- File::open(path)?
- .read_to_string(&mut s)?;
- Ok(s)
-}
-
fn test_files() {
if let Ok(mut f) = File::open("Cargo.toml") {
let mut contents = String::new();
}
}
-// needs Copy trait, good for simple types
-fn largest<T: PartialOrd + Copy>(list: &[T]) -> T {
- let mut result = list[0];
- for &i in list {
- if i > result {
- result = i;
- }
- }
- result
-}
-
-// expensive for large strings, don't use that
-fn largest_clone<T: PartialOrd + Clone>(list: &[T]) -> T {
- let mut result = list[0].clone();
- for i in list {
- if *i > result {
- result = i.clone();
- }
- }
- result
-}
-
-// good for everything, but more expensive for simple types
-fn largest_ref<T: PartialOrd>(list: &[T]) -> &T {
- let mut result = &list[0];
- for i in list {
- if i > result {
- result = i;
- }
- }
- result
-}
-
-fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
- if x.len() > y.len() {
- x
- } else {
- y
- }
-}
-
fn test_generics() {
let num_list = vec![3, 42, -7, 100, 0];
println!("largest number: {}", largest(&num_list));
println!("longest string: {}", l);
}
+fn test_closures() {
+ let mut expensive_int_result = Cacher::new(|x| {
+ println!("calculating expensive int result for {}", x);
+ 2 * x
+ });
+
+ println!("1st int call for value 1: {}", expensive_int_result.value(1));
+ println!("2nd int call for value 1: {}", expensive_int_result.value(1));
+ println!("1st int call for value 2: {}", expensive_int_result.value(2));
+
+ let mut expensive_str_result = Cacher::new(|x: &str| {
+ println!("calculating expensive str result for {}", x);
+ x.len()
+ });
+
+ println!("1st int call for value abc: {}", expensive_str_result.value("abc"));
+ println!("2nd int call for value abc: {}", expensive_str_result.value("abc"));
+ println!("1st int call for value defg: {}", expensive_str_result.value("defg"));
+}
+
+fn test_iterators() {
+ let v1 = vec!["Hello", "good", "world"];
+ // implied default is .into_iter() which consumes v1
+ for s in v1.iter() {
+ println!("element: {}", s);
+ }
+ // can still use it now
+ println!("v1: {:?}", &v1);
+
+ // manual iteration
+ let mut v1_iter = v1.iter();
+ while let Some(e) = v1_iter.next() {
+ println!("while loop over iter: {}", e);
+ }
+
+ for l_element in v1.iter().filter(|x| x.contains('l')) {
+ println!("v1 element containing 'l': {}", l_element);
+ }
+
+ let v2 = vec![1, 2, 3];
+ let double_v2: Vec<_> = v2.iter().map(|x| x * 2).collect();
+ println!("doubled v2: {:?}", double_v2);
+
+ for i in v2.into_iter().map(|x| x * 3) {
+ println!("for loop triplicating v2: {}", i);
+ }
+
+ for i in Counter5::new() {
+ println!("Counter 5 value: {}", i);
+ }
+}
+
fn main() {
test_strings();
test_vectors();
test_hashmaps();
test_files();
test_generics();
+ test_closures();
+ test_iterators();
}