+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() {
+ let s = String::from("Hello world");
+ println!("first word: '{}'", first_word(&s));
+ println!("second word: '{}'", second_word(&s).unwrap());
+
+ let s2 = "hello dude blah";
+ println!("second word of single: '{}'", second_word(s2).unwrap_or("(none)"));
+
+ match second_word(s2) {
+ Some(w) => println!("match: second word of '{}' exists: {}", s2, w),
+ None => println!("match: second word of '{}' does not exist", s2),
+ }
+}
+
+fn test_vectors() {
+ let v1 = vec![1, 2, 3];
+ println!("statically initialized vector: {:?}", v1);
+
+ let mut v2: Vec<String> = Vec::new();
+ v2.push("Hello".to_string());
+ v2.push(String::from("world"));
+ println!("dynamically built vector: {:?}", v2);
+ println!("first element: {}", v2[0]);
+ for el in &mut v2 {
+ *el += "xx";
+ }
+ for el in &v2 {
+ println!("{}", el);
+ }
+}
+
+fn test_hashmaps() {
+ let mut scores = HashMap::new();
+ scores.insert("john", 10);
+ scores.insert("mary", 20);
+
+ println!("scores: {:?}", scores);
+
+ // hash map with .collect()
+ let persons = vec![("homer", 42), ("marge", 30)];
+ let collect_scores: HashMap<_, _> = persons.into_iter().collect();
+ println!("collect_scores: {:?}", collect_scores);
+
+ for (p, s) in &collect_scores {
+ println!("person {}: score {}", p, s);
+ }
+
+ println!("john's score: {}", scores.get("john").unwrap());
+ println!("jake's score: {}", scores.get("jake").unwrap_or(&-1));
+
+ // double scores
+ for (_, v) in scores.iter_mut() {
+ *v *= 2;
+ }
+ println!("scores after doubling: {:?}", scores);
+
+ // double scores of immutable hashmap (rebuild it)
+ 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 test_files() {
+ if let Ok(mut f) = File::open("Cargo.toml") {
+ let mut contents = String::new();
+ match f.read_to_string(&mut contents) {
+ Ok(len) => println!("successfully opened Cargo.toml: {:?}, contents {} bytes:\n{}\n----------", f, len, contents),
+ Err(e) => panic!("could not read file: {:?}", e)
+ }
+ } else {
+ println!("could not open Cargo.toml");
+ }
+
+ // alternative form, more specific error checking
+ let mut f = File::open("Cargo.toml").unwrap_or_else(|e| {
+ if e.kind() == ErrorKind::NotFound {
+ println!("Cargo.toml not found, falling back to /dev/null");
+ // need to return a File
+ File::open("/dev/null").unwrap()
+ } else {
+ panic!("Could not open Cargo.toml: {:?}", e);
+ }
+ });
+ let mut contents = String::new();
+ let len = f.read_to_string(&mut contents).unwrap_or_else(|e| {
+ panic!("Could not read file: {:?}", e);
+ });
+ println!("successfully opened Cargo.toml with unwrap_or_else: {:?}, contents {} bytes:\n{}\n----------", f, len, contents);
+
+ // using the '?' operator
+ match read_file("Cargo.toml") {
+ Ok(s) => println!("Cargo.toml contents:\n{}\n-------------", s),
+ Err(e) => println!("Could not open Cargo.toml: {:?}", e)
+ }
+
+ // using std API
+ match fs::read_to_string("Cargo.toml") {
+ Ok(s) => println!("Cargo.toml contents:\n{}\n-------------", s),
+ Err(e) => println!("Could not open Cargo.toml: {:?}", e)
+ }
+}
+
+fn test_generics() {
+ let num_list = vec![3, 42, -7, 100, 0];
+ println!("largest number: {}", largest(&num_list));
+ println!("num_list: {:?}", num_list);
+
+ let char_list = vec!['a', 'y', 'q', 'm'];
+ println!("largest char: {}", largest(&char_list));
+
+ let str_list = vec!["hello", "world", "blue", "planet"];
+ println!("largest str: {}", largest(&str_list));
+ println!("str_list: {:?}", str_list);
+
+ let string_list = vec!["aaaa".to_string(), "xxxxx".to_string(), "ffff".to_string()];
+ println!("largest string (with cloning): {}", largest_clone(&string_list));
+ println!("largest string (with ref): {}", largest_ref(&string_list));
+ println!("string_list: {:?}", string_list);
+
+ let s1 = String::from("abcd");
+ let l;
+ {
+ let s2 = "efghi";
+ l = longest(&s1, s2);
+ }
+ 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();
+}
projects / learn-rust.git / commitdiff