first_fit/
first_fit.rs

1extern crate text_layout;
2use std::fmt::{self, Write};
3use text_layout::{FirstFit, Item, ParagraphLayout};
4
5fn layout_paragraph<'a, P: ParagraphLayout>(
6    paragraph: &'a str,
7    layout: &P,
8    max_width: usize,
9) -> Vec<&'a str> {
10    // Process the paragraph into its items.
11    let mut items = Vec::new();
12    for c in paragraph.chars() {
13        items.push(if c.is_whitespace() && items.len() != 0 {
14            Item::Glue {
15                width: 1.0,
16                stretch: 1.0,
17                shrink: 0.0,
18                data: (),
19            }
20        } else {
21            Item::Box {
22                width: 1.0,
23                data: (),
24            }
25        });
26    }
27    items.push(Item::Glue {
28        width: 0.0,
29        stretch: 100000.0,
30        shrink: 0.0,
31        data: (),
32    });
33    items.push(Item::Penalty {
34        width: 0.0,
35        cost: f32::NEG_INFINITY,
36        flagged: true,
37        data: (),
38    });
39
40    // Calculate the paragraph's breaks.
41    let breaks = layout.layout_paragraph(&items, max_width as f32);
42
43    // Render the laid-out paragraph using the break positions.
44    let mut cursor = 0;
45    let mut lines = Vec::new();
46    let mut start = 0;
47    for (i, _) in paragraph.chars().enumerate() {
48        if i == breaks[cursor].break_at {
49            lines.push(&paragraph[start..i]);
50            start = i + 1;
51            cursor += 1;
52        }
53    }
54    lines.push(&paragraph[start..]);
55    lines
56}
57
58fn layout_text() -> Result<String, fmt::Error> {
59    let text = "  Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-two million miles is an utterly insignificant little blue-green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.";
60    let first_fit = FirstFit::new().with_threshold(f32::INFINITY);
61    let lines = layout_paragraph(&text, &first_fit, 80);
62    let mut result = String::new();
63    writeln!(&mut result, "┏{}┓", "━".repeat(80))?;
64    for l in lines {
65        let pad = 80 - l.chars().count();
66        writeln!(&mut result, "┃{}{}┃", l, " ".repeat(pad))?;
67    }
68    writeln!(&mut result, "┗{}┛", "━".repeat(80))?;
69    Ok(result)
70}
71
72fn main() -> Result<(), fmt::Error> {
73    print!("{}", layout_text()?);
74    Ok(())
75}
76
77#[cfg(test)]
78mod tests {
79    use super::*;
80
81    #[test]
82    fn readme() {
83        let expected = r#"┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
84┃  Far out in the uncharted backwaters of the unfashionable end of the western   ┃
85┃spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a ┃
86┃distance of roughly ninety-two million miles is an utterly insignificant little ┃
87┃blue-green planet whose ape-descended life forms are so amazingly primitive     ┃
88┃that they still think digital watches are a pretty neat idea.                   ┃
89┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
90"#;
91        let actual = layout_text().unwrap();
92        assert!(actual == expected);
93    }
94}
first_fit/first_fit.rs

first_fit/
first_fit.rs
