initial commit

Author: kokeshing

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2015 Gatsbyjs
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+<!-- AUTO-GENERATED-CONTENT:START (STARTER) -->
+<p align="center">
+  <a href="https://www.gatsbyjs.org">
+    <img alt="Gatsby" src="https://www.gatsbyjs.org/monogram.svg" width="60" />
+  </a>
+</p>
+<h1 align="center">
+  Gatsby's blog starter
+</h1>
+
+Kick off your project with this blog boilerplate. This starter ships with the main Gatsby configuration files you might need to get up and running blazing fast with the blazing fast app generator for React.
+
+_Have another more specific idea? You may want to check out our vibrant collection of [official and community-created starters](https://www.gatsbyjs.org/docs/gatsby-starters/)._
+
+## 🚀 Quick start
+
+1.  **Create a Gatsby site.**
+
+    Use the Gatsby CLI to create a new site, specifying the blog starter.
+
+    ```sh
+    # create a new Gatsby site using the blog starter
+    npx gatsby new my-blog-starter https://github.com/gatsbyjs/gatsby-starter-blog
+    ```
+
+1.  **Start developing.**
+
+    Navigate into your new site’s directory and start it up.
+
+    ```sh
+    cd my-blog-starter/
+    gatsby develop
+    ```
+
+1.  **Open the source code and start editing!**
+
+    Your site is now running at `http://localhost:8000`!
+
+    _Note: You'll also see a second link: _`http://localhost:8000/___graphql`_. This is a tool you can use to experiment with querying your data. Learn more about using this tool in the [Gatsby tutorial](https://www.gatsbyjs.org/tutorial/part-five/#introducing-graphiql)._
+
+    Open the `my-blog-starter` directory in your code editor of choice and edit `src/pages/index.js`. Save your changes and the browser will update in real time!
+
+## 🧐 What's inside?
+
+A quick look at the top-level files and directories you'll see in a Gatsby project.
+
+    .
+    ├── node_modules
+    ├── src
+    ├── .gitignore
+    ├── gatsby-browser.js
+    ├── gatsby-config.js
+    ├── gatsby-node.js
+    ├── gatsby-ssr.js
+    ├── LICENSE
+    ├── package-lock.json
+    ├── package.json
+    └── README.md
+
+1.  **`/node_modules`**: This directory contains all of the modules of code that your project depends on (npm packages) are automatically installed.
+
+2.  **`/src`**: This directory will contain all of the code related to what you will see on the front-end of your site (what you see in the browser) such as your site header or a page template. `src` is a convention for “source code”.
+
+3.  **`.gitignore`**: This file tells git which files it should not track / not maintain a version history for.
+
+4.  **`.prettierrc`**: This is a configuration file for [Prettier](https://prettier.io/). Prettier is a tool to help keep the formatting of your code consistent.
+
+5.  **`gatsby-browser.js`**: This file is where Gatsby expects to find any usage of the [Gatsby browser APIs](https://www.gatsbyjs.org/docs/browser-apis/) (if any). These allow customization/extension of default Gatsby settings affecting the browser.
+
+6.  **`gatsby-config.js`**: This is the main configuration file for a Gatsby site. This is where you can specify information about your site (metadata) like the site title and description, which Gatsby plugins you’d like to include, etc. (Check out the [config docs](https://www.gatsbyjs.org/docs/gatsby-config/) for more detail).
+
+7.  **`gatsby-node.js`**: This file is where Gatsby expects to find any usage of the [Gatsby Node APIs](https://www.gatsbyjs.org/docs/node-apis/) (if any). These allow customization/extension of default Gatsby settings affecting pieces of the site build process.
+
+8.  **`gatsby-ssr.js`**: This file is where Gatsby expects to find any usage of the [Gatsby server-side rendering APIs](https://www.gatsbyjs.org/docs/ssr-apis/) (if any). These allow customization of default Gatsby settings affecting server-side rendering.
+
+9.  **`LICENSE`**: Gatsby is licensed under the MIT license.
+
+10. **`package-lock.json`** (See `package.json` below, first). This is an automatically generated file based on the exact versions of your npm dependencies that were installed for your project. **(You won’t change this file directly).**
+
+11. **`package.json`**: A manifest file for Node.js projects, which includes things like metadata (the project’s name, author, etc). This manifest is how npm knows which packages to install for your project.
+
+12. **`README.md`**: A text file containing useful reference information about your project.
+
+## 🎓 Learning Gatsby
+
+Looking for more guidance? Full documentation for Gatsby lives [on the website](https://www.gatsbyjs.org/). Here are some places to start:
+
+- **For most developers, we recommend starting with our [in-depth tutorial for creating a site with Gatsby](https://www.gatsbyjs.org/tutorial/).** It starts with zero assumptions about your level of ability and walks through every step of the process.
+
+- **To dive straight into code samples, head [to our documentation](https://www.gatsbyjs.org/docs/).** In particular, check out the _Guides_, _API Reference_, and _Advanced Tutorials_ sections in the sidebar.
+
+## 💫 Deploy
+
+[![Deploy to Netlify](https://www.netlify.com/img/deploy/button.svg)](https://app.netlify.com/start/deploy?repository=https://github.com/gatsbyjs/gatsby-starter-blog)
+
+<!-- AUTO-GENERATED-CONTENT:END -->

content/assets/favcon.png

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+---
+title: rustのinput!マクロではじめからミュータブルな変数として読み込む
+date: "2018-12-09T03:30:57.284Z"
+tags: ["Rust"]
+---
+
+大掛かりそうに見えて具体的な解決策は10秒で終わります．
+
+`card:https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8`
+
+のマクロでmutで宣言したいねというお話です．
+シャドーイングとかもあるけどはじめから宣言しちゃいたいよね．
+
+上記事のマクロでは
+
+```rust
+// 18行辺りを抜粋
+($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
+        let $var = read_value!($iter, $t); // ここでimmutableな変数として宣言されている
+        input_inner!{$iter $($r)*}
+    };
+```
+
+のようにimmutableな変数に読み込まれてしまうので，
+
+```
+    input!{
+        n: usize,
+        mut a: [usize; n],
+    }
+```
+
+このようにmutキーワードがあるときはmutableにしてくれると嬉しいのでそのようにしてもらうようにします．
+
+```rust
+macro_rules! input_inner {
+    ($iter:expr) => {};
+    ($iter:expr, ) => {};
+
+    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
+        let $var = read_value!($iter, $t);
+        input_inner!{$iter $($r)*}
+    };
+
+    // mutキーワードがあるときにマッチする
+    ($iter:expr, mut $var:ident : $t:tt $($r:tt)*) => {
+        let mut $var = read_value!($iter, $t);
+        input_inner!{$iter $($r)*}
+    };
+}
+```
+
+これで以下のようなコードも可能になりました．
+
+```rust
+fn main() {
+    input!{
+        n: usize,
+        mut a: [usize; n],
+    }
+
+    a.sort(); // Errorにならない!!!!
+
+    println!("{:?}", a);
+}
+```
+
+不具合は多分ないと思います．
+
+以下，マクロ全体です．
+
+```rust
+macro_rules! input {
+    (source = $s:expr, $($r:tt)*) => {
+        let mut iter = $s.split_whitespace();
+        input_inner!{iter, $($r)*}
+    };
+    ($($r:tt)*) => {
+        let mut s = {
+            use std::io::Read;
+            let mut s = String::new();
+            std::io::stdin().read_to_string(&mut s).unwrap();
+            s
+        };
+        let mut iter = s.split_whitespace();
+        input_inner!{iter, $($r)*}
+    };
+}
+
+macro_rules! input_inner {
+    ($iter:expr) => {};
+    ($iter:expr, ) => {};
+
+    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
+        let $var = read_value!($iter, $t);
+        input_inner!{$iter $($r)*}
+    };
+
+    ($iter:expr, mut $var:ident : $t:tt $($r:tt)*) => {
+        let mut $var = read_value!($iter, $t);
+        input_inner!{$iter $($r)*}
+    };
+}
+
+macro_rules! read_value {
+    ($iter:expr, ( $($t:tt),* )) => {
+        ( $(read_value!($iter, $t)),* )
+    };
+
+    ($iter:expr, [ $t:tt ; $len:expr ]) => {
+        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
+    };
+
+    ($iter:expr, chars) => {
+        read_value!($iter, String).chars().collect::<Vec<char>>()
+    };
+
+    ($iter:expr, usize1) => {
+        read_value!($iter, usize) - 1
+    };
+
+    ($iter:expr, $t:ty) => {
+        $iter.next().unwrap().parse::<$t>().expect("Parse error")
+    };
+}
+```
+
+読めば読むほどこんなの自分には思いつかないですねと感じさせる非常によくできたマクロです．何を食べたらこんなマクロを書けるんでしょうか．
+
+