├── .gitignore ├── .travis.yml ├── Cargo.toml ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md ├── src └── lib.rs └── tests └── test.rs /.gitignore: -------------------------------------------------------------------------------- 1 | target 2 | *.ll 3 | *.s 4 | Cargo.lock 5 | -------------------------------------------------------------------------------- /.travis.yml: -------------------------------------------------------------------------------- 1 | language: rust 2 | rust: 3 | - nightly 4 | - beta 5 | - 1.0.0 6 | sudo: required 7 | 8 | before_script: 9 | - pip install 'travis-cargo<0.2' --user && export PATH=$HOME/.local/bin:$PATH 10 | script: 11 | - | 12 | travis-cargo build && 13 | travis-cargo test && 14 | travis-cargo bench && 15 | travis-cargo doc 16 | after_success: 17 | - travis-cargo --only 1.0.0 doc-upload 18 | - travis-cargo coveralls 19 | env: 20 | global: 21 | - secure: "hvui3Tu9M/ZMvE1rDDaxCn0jVUthUZpTsRN/3+BwldK9Gj9a/2atSyqp9dk0aYzPZqaSbdbMW+Ud4LiMIVgllNR2bGfA7nq1P80S/V+Pq/GfBTU1Aq3h+KU2Xnt1/paJIucKw41eXTyBepuNUYlrwg340GiJx9Sfow0B7y/Zt7o=" 22 | notifications: 23 | webhooks: http://huon.me:54856/travis 24 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | 3 | name = "cfor" 4 | version = "1.1.0" 5 | authors = ["Huon Wilson "] 6 | 7 | homepage = "https://github.com/huonw/cfor" 8 | repository = "https://github.com/huonw/cfor" 9 | documentation = "http://huonw.github.io/cfor/cfor/" 10 | license = "MIT/Apache-2.0" 11 | keywords = ["macro"] 12 | readme = "README.md" 13 | description = """ 14 | A macro that gives Rust a C-style for loop, with initialisation, 15 | condition and step. This correctly handles control-flow like continue 16 | and break. 17 | """ 18 | 19 | [dev-dependencies] 20 | rand = "0.3" 21 | 22 | [features] 23 | unstable = [] 24 | -------------------------------------------------------------------------------- /LICENSE-APACHE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. Definitions. 8 | 9 | "License" shall mean the terms and conditions for use, reproduction, 10 | and distribution as defined by Sections 1 through 9 of this document. 11 | 12 | "Licensor" shall mean the copyright owner or entity authorized by 13 | the copyright owner that is granting the License. 14 | 15 | "Legal Entity" shall mean the union of the acting entity and all 16 | other entities that control, are controlled by, or are under common 17 | control with that entity. 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IN NO EVENT 21 | SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 22 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR 24 | IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 25 | DEALINGS IN THE SOFTWARE. -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # A C-style for loop for Rust 2 | 3 | [![Build Status](https://travis-ci.org/huonw/cfor.png)](https://travis-ci.org/huonw/cfor) [![Coverage Status](https://coveralls.io/repos/huonw/cfor/badge.svg?branch=master)](https://coveralls.io/r/huonw/cfor?branch=master) 4 | 5 | A Rust macro implementing a C-style `for` loop. See 6 | [the docs](http://huonw.github.io/cfor/cfor/) for more information. 7 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | //! A C-style `for` loop in macro form. 2 | //! 3 | //! This takes the form `cfor!(initialiser; condition; step { body })`. 4 | //! 5 | //! - `initialiser` is a statement evaluated before any iterations of 6 | //! the loop. Any variables declared here are scoped to the `cfor!` 7 | //! invocation, that is, only usable inside `condition`, `step` and 8 | //! `body`. 9 | //! - `condition` is an boolean expression evaluated at the start of 10 | //! each iteration. If it evaluates to `false` iteration will stop. 11 | //! - `step` is an arbitrary expression which is executed at the end 12 | //! of each iteration (including if `continue` is called), before 13 | //! `condition` is checked. 14 | //! 15 | //! 16 | //! The initialiser and condition can be empty like C, but the step 17 | //! cannot unlike C. A `for` loop with no step is identical to a 18 | //! `while` loop. 19 | //! 20 | //! [*Source & issue tracker*](https://github.com/huonw/cfor/) 21 | //! 22 | //! # When should I use it? 23 | //! 24 | //! *Only* when `cfor!` is clearer than the more declarative built-in 25 | //! [iterators](http://doc.rust-lang.org/master/std/iter/), [their 26 | //! adaptors](http://doc.rust-lang.org/master/std/iter/trait.Iterator.html) 27 | //! and the `for` loop. For example, the built-in iterator 28 | //! functionality is more self-contained so there is less risk of 29 | //! accidentally writing `i` in a condition when `j` was meant (I 30 | //! personally get bitten by this semiregularly when writing nested 31 | //! "2D" loops in C). 32 | //! 33 | //! Furthermore, the adaptor methods linked above allow [one to 34 | //! write](http://huonw.github.io/2014/06/10/knn-rust.html) concise, 35 | //! performant, reusable "functional" code in a way that is not 36 | //! possible to achieve using C-style iteration. 37 | //! 38 | //! # How to use it? 39 | //! 40 | //! Add the repository as a normal cargo dependency, and include into 41 | //! your crate with `#[phase(plugin)]`. (See examples below.) 42 | //! 43 | //! ```toml 44 | //! [dependencies.cfor] 45 | //! cfor = "1.0" 46 | //! ``` 47 | //! 48 | //! # Examples 49 | //! 50 | //! ## Simple 51 | //! 52 | //! A non-additive condition is not handled extremely naturally by 53 | //! `std::iter`, but is straight-forward to handle directly. 54 | //! 55 | //! ```rust 56 | //! #[macro_use] extern crate cfor; 57 | //! 58 | //! fn main() { 59 | //! cfor!{let mut x = 1; x < 0x1000; x *= 2; { 60 | //! println!("power of 2: {}", x); 61 | //! }} 62 | //! } 63 | //! ``` 64 | //! 65 | //! ## Intrabody condition 66 | //! 67 | //! If a condition requires some extra computation to be checked (or 68 | //! if there is some code that should always be evaluated, even if the 69 | //! condition will be `false` for a given iteration), the condition in 70 | //! the `cfor` header can be omitted. 71 | //! 72 | //! ```rust 73 | //! #[macro_use] extern crate cfor; 74 | //! 75 | //! fn main() { 76 | //! cfor!{let mut x = 1; ; x *= 2; { 77 | //! // ... setup ... 78 | //! println!("handling power of 2: {}", x); 79 | //! 80 | //! if x < 0x1000 { break } 81 | //! 82 | //! // ... further handling ... 83 | //! println!("handling power of 2: {}", x); 84 | //! }} 85 | //! } 86 | //! ``` 87 | //! 88 | //! ## Out-of-loop initialisation 89 | //! 90 | //! Sometimes one may wish to have access to a variable outside the 91 | //! loop after it finishes so it has to be declared outside the loop, 92 | //! or one may be iterating over some presupplied/-computed value so 93 | //! there is no meaningful additional initialisation possible. The 94 | //! initialisation expression can be safely omitted in this case. 95 | //! 96 | //! ```rust 97 | //! #[macro_use] extern crate cfor; 98 | //! 99 | //! extern crate rand; 100 | //! 101 | //! fn main() { 102 | //! let mut x = 1u16; 103 | //! 104 | //! cfor!{; x < 0x1000; x *= 2; { 105 | //! println!("power of 2: {}", x); 106 | //! 107 | //! // sometimes quit early 108 | //! if x > rand::random() { break } 109 | //! }} 110 | //! 111 | //! println!("actually stopped at {}", x); 112 | //! } 113 | //! ``` 114 | //! 115 | //! # Handling `continue` 116 | //! 117 | //! (Or, "why is the macro so complicated?") 118 | //! 119 | //! Special effort is made to ensure that `continue` acts correctly, a 120 | //! naive macro defined as follows will cause `continue` to also skip 121 | //! evaluating `step`, likely leading to undesirable behaviour like 122 | //! infinite loops. 123 | //! 124 | //! ```rust 125 | //! # // avoid our crate being inserted automatically, which gets in 126 | //! # // the way of the feature above. 127 | //! # #[macro_use] extern crate cfor; 128 | //! // WARNING: this is broken. 129 | //! macro_rules! bad_cfor { 130 | //! ($init: stmt; $cond: expr; $step: expr; $body: block) => { 131 | //! { 132 | //! $init; 133 | //! while $cond { 134 | //! $body; 135 | //! 136 | //! $step; 137 | //! } 138 | //! } 139 | //! } 140 | //! } 141 | //! 142 | //! fn main() { 143 | //! let mut true_counter = 0; 144 | //! 145 | //! bad_cfor!{let mut i = 0; i < 10; i += 1; { 146 | //! 147 | //! // manually avoid the infinite loop 148 | //! if true_counter >= 50 { break } 149 | //! true_counter += 1; 150 | //! 151 | //! println!("i = {}", i); 152 | //! // try to skip just i == 4 153 | //! if i == 4 { 154 | //! // but this skips the i += 1 leaving us 155 | //! // on i == 4 forever. 156 | //! continue 157 | //! } 158 | //! // ...more code... 159 | //! }} 160 | //! } 161 | //! ``` 162 | //! 163 | //! This is invoked in the same manner as `cfor!`, but, if `$body` 164 | //! contains a `continue`, the `$step` at the end of the loop body 165 | //! will never be evaluated. 166 | //! 167 | //! # Handling multiple initializations and steps 168 | //! 169 | //! Like C loops, `cfor!` supports specfying multiple initializations and steps seperated by a comma. 170 | //! 171 | //! ```rust 172 | //! #[macro_use] extern crate cfor; 173 | //! 174 | //! fn main() { 175 | //! cfor!{let mut x = 0, let mut y = x; x <= 10 && y <= 100; x += 1, y += 10; { 176 | //! println!("x: {}, y: {}", x, y); 177 | //! }} 178 | //! } 179 | //! ``` 180 | 181 | 182 | /// A C-style `for` loop in macro form. 183 | /// 184 | /// See crates docs for more information. 185 | #[macro_export] 186 | macro_rules! cfor { 187 | // for (; ...; ...) { ... } 188 | (; $($rest: tt)*) => { 189 | cfor!((); $($rest)*) 190 | }; 191 | // for ($init; ; ...) { ... } 192 | ($($init: stmt),+; ; $($rest: tt)*) => { 193 | // avoid the `while true` lint 194 | cfor!($($init),+; !false; $($rest)*) 195 | }; 196 | 197 | // for ($init; $cond; ) { ... } 198 | ($($init: stmt),+; $cond: expr; ; $body: block) => { 199 | cfor!{$($init),+; $cond; (); $body} 200 | }; 201 | 202 | // for ($init; $cond; $step) { $body } 203 | ($($init: stmt),+; $cond: expr; $($step: expr),+; $body: block) => { 204 | { 205 | $($init;)+ 206 | while $cond { 207 | let mut _first = true; 208 | let mut _continue = false; 209 | // this loop runs once, allowing us to use `break` and 210 | // `continue` as `goto` to skip forward to the 211 | // condition. 212 | // 213 | // the booleans above are very transparent to the 214 | // optimiser, since they are modified exactly once, 215 | // with nice control flow, and this this optimises to 216 | // be similar to C for loop. 217 | loop { 218 | // if we *don't* hit this, there was a `break` in 219 | // the body (otherwise the loop fell-through or 220 | // was `continue`d.) 221 | if !_first { _continue = true; break } 222 | _first = false; 223 | 224 | $body 225 | } 226 | if !_continue { 227 | // the `if` wasn't hit, so we should propagate the 228 | // `break`. 229 | break 230 | } 231 | 232 | $($step;)+ 233 | } 234 | } 235 | }; 236 | } 237 | -------------------------------------------------------------------------------- /tests/test.rs: -------------------------------------------------------------------------------- 1 | #[macro_use] extern crate cfor; 2 | 3 | #[test] 4 | fn smoketest() { 5 | let mut tick = 0; 6 | cfor!{let mut i = 1; i <= 0b1000_0000; i *= 2; { 7 | tick += 1; 8 | }} 9 | 10 | assert_eq!(tick, 8); 11 | 12 | tick = 0; 13 | cfor!{let (mut a, mut b) = (0, 0); a + b < 20; { a += 1; b += 1; }; { 14 | tick += 1; 15 | }} 16 | assert_eq!(tick, 10); 17 | } 18 | 19 | #[test] 20 | #[should_panic] 21 | fn continue_updates() { 22 | cfor!(let i = 0; i < 10; panic!(); { 23 | // we *should* hit the step expression. 24 | continue 25 | }) 26 | } 27 | 28 | #[test] 29 | fn missing_parts() { 30 | let mut inside = false; 31 | cfor!{;; (); { 32 | inside = true; 33 | break 34 | }} 35 | assert!(inside); 36 | 37 | inside = false; 38 | cfor!{();; (); { 39 | inside = true; 40 | break 41 | }} 42 | assert!(inside); 43 | 44 | cfor!{; false; ; { 45 | panic!() 46 | }} 47 | } 48 | 49 | #[test] 50 | fn multi_dec() { 51 | cfor!(let x = true, let y = x, let z = false; false;; { 52 | assert!(x); 53 | assert_eq!(x, y); 54 | assert!(!z); 55 | }); 56 | } 57 | 58 | #[test] 59 | fn multi_step() { 60 | let mut x = 0; 61 | let mut y = 0; 62 | cfor!(; x < 10 && y < 100; x += 1, y += 10; {}); 63 | assert_eq!(x, 10); 64 | assert_eq!(y, 100); 65 | } 66 | --------------------------------------------------------------------------------