cli_justify/
justify_text.rs

1use crate::text_utils::{char_len, split_at_char};
2
3pub(crate) fn justify_line(line: &[&str], line_width: usize) -> String {
4  let word_len: usize = line.iter().map(|s| char_len(s)).sum();
5
6  if word_len >= line_width || line.len() <= 1 {
7    return line.join(" ");
8  }
9
10  let spaces = line_width - word_len;
11  let line_len_div = if line.len() > 1 { line.len() - 1 } else { 1 };
12  let each_space = spaces / line_len_div;
13  let extra_space = spaces % line_len_div;
14
15  let mut justified = String::new();
16  for (i, word) in line.iter().enumerate() {
17    justified.push_str(word);
18    if i < line.len() - 1 {
19      let mut space = " ".repeat(each_space);
20      if i < extra_space {
21        space.push(' ');
22      }
23      justified.push_str(&space);
24    }
25  }
26
27  justified
28}
29
30pub fn justify(text: &str, line_width: usize) -> Vec<String> {
31  let paragraphs: Vec<&str> = text.split("\n\n").collect();
32  let mut lines: Vec<String> = Vec::new();
33
34  for paragraph in paragraphs {
35    let raw_words: Vec<&str> = paragraph.split_whitespace().collect();
36    let mut words = vec![];
37
38    for mut word in raw_words {
39      while let (w1, Some(w2)) = split_at_char(word, line_width) {
40        words.push(w1);
41        word = w2;
42      }
43
44      words.push(word);
45    }
46
47    let mut line: Vec<&str> = Vec::new();
48    let mut len = 0;
49
50    for word in words {
51      let word_len = char_len(word);
52      let space_len = if line.is_empty() { 0 } else { 1 };
53      let new_len = len + space_len + word_len;
54
55      if new_len > line_width && !line.is_empty() {
56        lines.push(justify_line(&line, line_width));
57        line.clear();
58        len = 0;
59      }
60
61      line.push(word);
62      len = if line.len() == 1 { word_len } else { len + space_len + word_len };
63    }
64
65    if !line.is_empty() {
66      lines.push(line.join(" "));
67    }
68
69    lines.push(String::new());
70  }
71
72  lines
73}
74
75#[cfg(test)]
76mod tests {
77  use super::justify;
78  use crate::text_utils::char_len;
79
80  #[test]
81  fn handles_long_words() {
82    let input_text = r#"some text and a very loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong word but no cause to panic"#;
83    let result = justify(input_text, 10);
84    assert!(!result.is_empty());
85  }
86
87  #[test]
88  fn handles_line_longer_than_width() {
89    let input_text =
90      "This is a line that is definitely longer than the requested width";
91    let result = justify(input_text, 20);
92    assert!(!result.is_empty());
93  }
94
95  #[test]
96  fn splits_single_word_longer_than_width() {
97    let input_text = "supercalifragilisticexpialidocious";
98    let result = justify(input_text, 10);
99    assert!(!result.is_empty());
100    assert!(result.len() > 1);
101  }
102
103  #[test]
104  fn normal_justification_produces_full_lines() {
105    let input_text = "This is a test of the justification system. It should properly justify lines that need to be wrapped.";
106    let result = justify(input_text, 20);
107    assert!(!result.is_empty());
108
109    let mut found_justified = false;
110    for (i, line) in result.iter().enumerate() {
111      if !line.is_empty() && i < result.len() - 2 && char_len(line) == 20 {
112        found_justified = true;
113        break;
114      }
115    }
116    assert!(found_justified, "Should have at least one justified line");
117  }
118
119  #[test]
120  fn keeps_unicode_justification_width_stable() {
121    let input = "Chapter “Text” introduces Unicode-aware width handling.";
122    let result = justify(input, 24);
123    assert!(
124      result
125        .iter()
126        .filter(|line| !line.is_empty())
127        .take(result.len().saturating_sub(2))
128        .all(|line| char_len(line) <= 24),
129      "expected all non-final wrapped lines to fit char width, got: {result:?}"
130    );
131  }
132}
cli_justify/justify_text.rs

cli_justify/
justify_text.rs
