1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
12 #![allow(unused_imports)]
13 #![allow(non_snake_case)]
15 // ASCII art shape renderer. Demonstrates traits, impls, operator overloading,
16 // non-copyable struct, unit testing. To run execute: rustc --test shapes.rs &&
19 // Rust's std library is tightly bound to the language itself so it is
20 // automatically linked in. However the extra library is designed to be
21 // optional (for code that must run on constrained environments like embedded
22 // devices or special environments like kernel code) so it must be explicitly
25 // Extern mod controls linkage. Use controls the visibility of names to modules
26 // that are already linked in. Using WriterUtil allows us to use the write_line
30 use std::iter::repeat;
33 // Represents a position on a canvas.
34 #[derive(Copy, Clone)]
40 // Represents an offset on a canvas. (This has the same structure as a Point.
41 // but different semantics).
42 #[derive(Copy, Clone)]
48 #[derive(Copy, Clone)]
54 // Contains the information needed to do shape rendering via ASCII art.
59 lines: Vec<Vec<char> > ,
61 // This struct can be quite large so we'll disable copying: developers need
62 // to either pass these structs around via references or move them.
65 impl Drop for AsciiArt {
69 // It's common to define a constructor sort of function to create struct instances.
70 // If there is a canonical constructor it is typically named the same as the type.
71 // Other constructor sort of functions are typically named from_foo, from_bar, etc.
72 fn AsciiArt(width: usize, height: usize, fill: char) -> AsciiArt {
73 // Build a vector of vectors containing blank characters for each position in
75 let lines = vec![vec!['.'; width]; height];
77 // Rust code often returns values by omitting the trailing semi-colon
78 // instead of using an explicit return statement.
79 AsciiArt {width: width, height: height, fill: fill, lines: lines}
82 // Methods particular to the AsciiArt struct.
84 fn add_pt(&mut self, x: isize, y: isize) {
85 if x >= 0 && x < self.width as isize {
86 if y >= 0 && y < self.height as isize {
87 // Note that numeric types don't implicitly convert to each other.
91 // Vector subscripting will normally copy the element, but &v[i]
92 // will return a reference which is what we need because the
94 // 1) potentially large
95 // 2) needs to be modified
96 let row = &mut self.lines[v];
103 // Allows AsciiArt to be converted to a string using the libcore ToString trait.
104 // Note that the %s fmt! specifier will not call this automatically.
105 impl fmt::Display for AsciiArt {
106 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
107 // Convert each line into a string.
108 let lines = self.lines.iter()
109 .map(|line| line.iter().cloned().collect())
110 .collect::<Vec<String>>();
112 // Concatenate the lines together using a new-line.
113 write!(f, "{}", lines.join("\n"))
117 // This is similar to an interface in other languages: it defines a protocol which
118 // developers can implement for arbitrary concrete types.
120 fn add_point(&mut self, shape: Point);
121 fn add_rect(&mut self, shape: Rect);
123 // Unlike interfaces traits support default implementations.
124 // Got an ICE as soon as I added this method.
125 fn add_points(&mut self, shapes: &[Point]) {
126 for pt in shapes {self.add_point(*pt)};
130 // Here we provide an implementation of the Canvas methods for AsciiArt.
131 // Other implementations could also be provided (e.g. for PDF or Apple's Quartz)
132 // and code can use them polymorphically via the Canvas trait.
133 impl Canvas for AsciiArt {
134 fn add_point(&mut self, shape: Point) {
135 self.add_pt(shape.x, shape.y);
138 fn add_rect(&mut self, shape: Rect) {
139 // Add the top and bottom lines.
140 for x in shape.top_left.x..shape.top_left.x + shape.size.width {
141 self.add_pt(x, shape.top_left.y);
142 self.add_pt(x, shape.top_left.y + shape.size.height - 1);
145 // Add the left and right lines.
146 for y in shape.top_left.y..shape.top_left.y + shape.size.height {
147 self.add_pt(shape.top_left.x, y);
148 self.add_pt(shape.top_left.x + shape.size.width - 1, y);
153 // Rust's unit testing framework is currently a bit under-developed so we'll use
154 // this little helper.
155 pub fn check_strs(actual: &str, expected: &str) -> bool {
156 if actual != expected {
157 println!("Found:\n{}\nbut expected\n{}", actual, expected);
164 fn test_ascii_art_ctor() {
165 let art = AsciiArt(3, 3, '*');
166 assert!(check_strs(&art.to_string(), "...\n...\n..."));
171 let mut art = AsciiArt(3, 3, '*');
175 assert!(check_strs(&art.to_string(), "*..\n...\n.*."));
180 let mut art = AsciiArt(4, 4, '*');
181 art.add_rect(Rect {top_left: Point {x: 0, y: 0}, size: Size {width: 4, height: 4}});
182 art.add_point(Point {x: 2, y: 2});
183 assert!(check_strs(&art.to_string(), "****\n*..*\n*.**\n****"));
187 test_ascii_art_ctor();