work on examples

Author: nikomatsakis

src/example0.rs

@@ -1,10 +1,6 @@
 use std::collections::HashMap;
 use std::f32::INFINITY;
 
-struct ShoppingList {
-    items: Vec<String>,
-}
-
 struct Store {
     name: String,
     prices: HashMap<String, f32>,
@@ -51,7 +47,8 @@ fn build_stores() -> Vec<Store> {
     stores
 }
 
-fn find_best_store<'a>(stores: &'a [Store], shopping_list: &ShoppingList) -> &'a Store {
+fn find_best_store(stores: Vec<Store>, shopping_list: &Vec<String>) -> String {
+    // EXERCISE 0
     assert!(stores.len() > 0);
     let mut best = None;
     let mut best_price = INFINITY;
@@ -60,22 +57,19 @@ fn find_best_store<'a>(stores: &'a [Store], shopping_list: &ShoppingList) -> &'a
                                      .map(|item_name| store.price(item_name))
                                      .fold(0.0, |v, u| v + u);
         if sum < best_price {
-            best = Some(store);
+            best = Some(store.name);
             best_price = sum;
         }
     }
     best.unwrap() // there will always be at least one store
 }
 
-fn main() {
-    let shopping_list = ShoppingList {
-        items: vec![format!("chocolate"),
-                    format!("doll"),
-                    format!("bike")]
-    };
-
+pub fn main() {
+    let shopping_list = vec![format!("chocolate"),
+                             format!("doll"),
+                             format!("bike")];
     let stores = build_stores();
-    let store = find_best_store(&stores, &shopping_list);
-    println!("Best store: {}", store.name);
+    let best_store = find_best_store(stores, &shopping_list);
+    println!("Best store: {}", best_store);
 }
 

src/example1.rs

@@ -0,0 +1,91 @@
+use std::collections::HashMap;
+use std::f32::INFINITY;
+
+struct ShoppingList {
+    items: Vec<String>,
+}
+
+struct Store {
+    name: String,
+    prices: HashMap<String, f32>,
+}
+
+impl Store {
+    fn new(name: String) -> Store {
+        Store {
+            name: name,
+            prices: HashMap::new(),
+        }
+    }
+
+    fn add_item(&mut self, name: String, price: f32) {
+        self.prices.insert(name, price);
+    }
+
+    fn price(&self, item_name: &str) -> f32 {
+        self.prices[item_name]
+    }
+}
+
+fn build_stores() -> Vec<Store> {
+    let mut stores = vec![];
+
+    let mut store = Store::new(format!("R-mart"));
+    store.add_item(format!("chocolate"), 5.0);
+    store.add_item(format!("doll"), 22.0);
+    store.add_item(format!("bike"), 150.0);
+    stores.push(store);
+
+    let mut store = Store::new(format!("Bullseye"));
+    store.add_item(format!("chocolate"), 2.0);
+    store.add_item(format!("doll"), 23.0);
+    store.add_item(format!("bike"), 145.0);
+    stores.push(store);
+
+    let mut store = Store::new(format!("Woolmart"));
+    store.add_item(format!("chocolate"), 2.0);
+    store.add_item(format!("doll"), 23.0);
+    store.add_item(format!("bike"), 146.0);
+    stores.push(store);
+
+    stores
+}
+
+fn find_best_store(stores: Vec<Store>, shopping_list: &ShoppingList) -> String {
+    let threads = stores.into_iter()
+                        .map(|store| {
+                            let shopping_list = shopping_list.clone();
+                            thread::spawn(move || {
+                                shopping_list.items.iter()
+                                                   .map(|item_name| store.price(item_name))
+                                                   .fold(0.0, |v, u| v + u)
+                            })
+                        })
+                        .collect();
+
+    // EXERCISE 0
+    assert!(stores.len() > 0);
+    let mut best = None;
+    let mut best_price = INFINITY;
+    for store in stores {
+        let sum = 
+        if sum < best_price {
+            best = Some(store);
+            best_price = sum;
+        }
+    }
+    best.unwrap() // there will always be at least one store
+}
+
+pub fn main() {
+    let shopping_list = ShoppingList {
+        items: vec![format!("chocolate"),
+                    format!("doll"),
+                    format!("bike")]
+    };
+
+    let stores = build_stores();
+    let store = find_best_store(&stores, &shopping_list);
+    println!("Best store: {}", store.name);
+}
+

src/lib.rs

@@ -0,0 +1,6 @@
+mod example0;
+
+fn main() {
+    println!("----------------------------------------------------------------------");
+    example0::main();
+}