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<h1 id="structs">Structs</h1>
<p>(Time: 10 minutes)</p>
<p>Goal: Implement the <code>total_price</code> method.</p>
<div class="sourceCode"><pre class="sourceCode rust"><code class="sourceCode rust"><span class="at">#![</span>allow<span class="at">(</span>dead_code<span class="at">)]</span>
<span class="kw">struct</span> Store {
name: <span class="dt">String</span>,
items: <span class="dt">Vec</span><Item>,
}
<span class="at">#[</span>derive<span class="at">(</span><span class="bu">Debug</span><span class="at">)]</span>
<span class="kw">struct</span> Item {
name: &<span class="ot">'static</span> <span class="dt">str</span>,
price: <span class="dt">f32</span>,
}
<span class="kw">impl</span> Store {
<span class="kw">fn</span> new(name: <span class="dt">String</span>) -> Store {
Store {
name: name,
items: <span class="pp">vec!</span>[],
}
}
<span class="kw">fn</span> add_item(&<span class="kw">mut</span> <span class="kw">self</span>, item: Item) {
<span class="kw">self</span>.items.push(item);
}
<span class="kw">fn</span> price(&<span class="kw">self</span>, item_name: &<span class="dt">str</span>) -> <span class="dt">Option</span><<span class="dt">f32</span>> {
<span class="kw">for</span> item <span class="kw">in</span> &<span class="kw">self</span>.items {
<span class="kw">if</span> item.name == item_name {
<span class="kw">return</span> <span class="cn">Some</span>(item.price);
}
}
<span class="cn">None</span>
}
<span class="kw">fn</span> total_price(&<span class="kw">self</span>, shopping_list: &[&<span class="dt">str</span>]) -> <span class="dt">Option</span><<span class="dt">f32</span>> {
<span class="co">// Goal: compute the total price of all items in the shopping</span>
<span class="co">// list. If any of the options are not present, return `None`.</span>
<span class="dv">0.0</span>
}
}
<span class="kw">fn</span> build_store() -> Store {
<span class="kw">let</span> <span class="kw">mut</span> store = Store::new(<span class="pp">format!</span>(<span class="st">"Rustmart"</span>));
store.add_item(Item { name: <span class="st">"chocolate"</span>, price: <span class="dv">5.0</span> });
store.add_item(Item { name: <span class="st">"socks"</span>, price: <span class="dv">23.0</span> });
store.add_item(Item { name: <span class="st">"plush Mozilla dinosaur"</span>, price: <span class="dv">13.0</span> });
store
}
<span class="at">#[</span>test<span class="at">]</span>
<span class="kw">fn</span> total_price() {
<span class="kw">let</span> store = build_store();
<span class="kw">let</span> list = <span class="pp">vec!</span>[<span class="st">"chocolate"</span>, <span class="st">"plush Mozilla dinosaur"</span>];
<span class="pp">assert_eq!</span>(store.total_price(&list), <span class="cn">Some</span>(<span class="dv">18.0</span>));
}
<span class="at">#[</span>test<span class="at">]</span>
<span class="kw">fn</span> total_price_missing() {
<span class="kw">let</span> store = build_store();
<span class="kw">let</span> list = <span class="pp">vec!</span>[<span class="st">"chocolate"</span>, <span class="st">"plush Mozilla dinosaur"</span>, <span class="st">"fork and knife"</span>];
<span class="pp">assert_eq!</span>(store.total_price(&list), <span class="cn">None</span>);
}</code></pre></div>
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