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.
11 // ASCII art shape renderer. Demonstrates traits, impls, operator overloading,
12 // non-copyable struct, unit testing. To run execute: rustc --test shapes.rs &&
15 // Rust's std library is tightly bound to the language itself so it is
16 // automatically linked in. However the extra library is designed to be
17 // optional (for code that must run on constrained environments like embedded
18 // devices or special environments like kernel code) so it must be explicitly
21 // Extern mod controls linkage. Use controls the visibility of names to modules
22 // that are already linked in. Using WriterUtil allows us to use the write_line
26 use std::iter::repeat;
29 // Represents a position on a canvas.
35 impl Copy for Point {}
37 // Represents an offset on a canvas. (This has the same structure as a Point.
38 // but different semantics).
53 // Contains the information needed to do shape rendering via ASCII art.
58 lines: Vec<Vec<char> > ,
60 // This struct can be quite large so we'll disable copying: developers need
61 // to either pass these structs around via references or move them.
64 impl Drop for AsciiArt {
68 // It's common to define a constructor sort of function to create struct instances.
69 // If there is a canonical constructor it is typically named the same as the type.
70 // Other constructor sort of functions are typically named from_foo, from_bar, etc.
71 fn AsciiArt(width: uint, height: uint, fill: char) -> AsciiArt {
72 // Use an anonymous function to build a vector of vectors containing
73 // blank characters for each position in our canvas.
74 let mut lines = Vec::new();
75 for _ in range(0, height) {
76 lines.push(repeat('.').take(width).collect::<Vec<_>>());
79 // Rust code often returns values by omitting the trailing semi-colon
80 // instead of using an explicit return statement.
81 AsciiArt {width: width, height: height, fill: fill, lines: lines}
84 // Methods particular to the AsciiArt struct.
86 fn add_pt(&mut self, x: int, y: int) {
87 if x >= 0 && x < self.width as int {
88 if y >= 0 && y < self.height as int {
89 // Note that numeric types don't implicitly convert to each other.
93 // Vector subscripting will normally copy the element, but &v[i]
94 // will return a reference which is what we need because the
96 // 1) potentially large
97 // 2) needs to be modified
98 let row = &mut self.lines[v];
105 // Allows AsciiArt to be converted to a string using the libcore ToString trait.
106 // Note that the %s fmt! specifier will not call this automatically.
107 impl fmt::Show for AsciiArt {
108 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
109 // Convert each line into a string.
110 let lines = self.lines.iter()
111 .map(|line| line.iter().cloned().collect())
112 .collect::<Vec<String>>();
114 // Concatenate the lines together using a new-line.
115 write!(f, "{}", lines.connect("\n"))
119 // This is similar to an interface in other languages: it defines a protocol which
120 // developers can implement for arbitrary concrete types.
122 fn add_point(&mut self, shape: Point);
123 fn add_rect(&mut self, shape: Rect);
125 // Unlike interfaces traits support default implementations.
126 // Got an ICE as soon as I added this method.
127 fn add_points(&mut self, shapes: &[Point]) {
128 for pt in shapes.iter() {self.add_point(*pt)};
132 // Here we provide an implementation of the Canvas methods for AsciiArt.
133 // Other implementations could also be provided (e.g. for PDF or Apple's Quartz)
134 // and code can use them polymorphically via the Canvas trait.
135 impl Canvas for AsciiArt {
136 fn add_point(&mut self, shape: Point) {
137 self.add_pt(shape.x, shape.y);
140 fn add_rect(&mut self, shape: Rect) {
141 // Add the top and bottom lines.
142 for x in range(shape.top_left.x, shape.top_left.x + shape.size.width) {
143 self.add_pt(x, shape.top_left.y);
144 self.add_pt(x, shape.top_left.y + shape.size.height - 1);
147 // Add the left and right lines.
148 for y in range(shape.top_left.y, shape.top_left.y + shape.size.height) {
149 self.add_pt(shape.top_left.x, y);
150 self.add_pt(shape.top_left.x + shape.size.width - 1, y);
155 // Rust's unit testing framework is currently a bit under-developed so we'll use
156 // this little helper.
157 pub fn check_strs(actual: &str, expected: &str) -> bool {
158 if actual != expected {
159 println!("Found:\n{}\nbut expected\n{}", actual, expected);
166 fn test_ascii_art_ctor() {
167 let art = AsciiArt(3, 3, '*');
168 assert!(check_strs(art.to_string().as_slice(), "...\n...\n..."));
173 let mut art = AsciiArt(3, 3, '*');
177 assert!(check_strs(art.to_string().as_slice(), "*..\n...\n.*."));
182 let mut art = AsciiArt(4, 4, '*');
183 art.add_rect(Rect {top_left: Point {x: 0, y: 0}, size: Size {width: 4, height: 4}});
184 art.add_point(Point {x: 2, y: 2});
185 assert!(check_strs(art.to_string().as_slice(), "****\n*..*\n*.**\n****"));
189 test_ascii_art_ctor();