X-Git-Url: https://piware.de/gitweb/?p=learn-rust.git;a=blobdiff_plain;f=src%2Fmain.rs;h=0ef1b16f4f9b19c7e9e1c71377abd4273acc0d1b;hp=e61306ac95077cf475e0b60fd11d573531a09e2d;hb=b6a408eb8944df04d6c6e876a9a00f6c425f47f1;hpb=98ca13fb871858f407a9b2682a4e439d0557a4f7

diff --git a/src/main.rs b/src/main.rs
index e61306a..0ef1b16 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,11 @@
 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() {
@@ -67,8 +71,97 @@ fn test_hashmaps() {
     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 main() {
     test_strings();
     test_vectors();
     test_hashmaps();
+    test_files();
+    test_generics();
+    test_closures();
 }