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Merged
leynos merged 3 commits into from
Jul 31, 2025
Merged

Move wrap tests to module #152

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13b2cfd
Extract tokenize helpers and move wrap tests
leynos Jul 31, 2025
37876fb
Add tokenization tests and helpers
leynos Jul 31, 2025
bf00f56
Add docs and inline helpers
leynos Jul 31, 2025
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318 changes: 14 additions & 304 deletions src/wrap.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,9 @@

use regex::{Captures, Regex};

mod tokenize;
pub(crate) use tokenize::{Token, tokenize_markdown};

static FENCE_RE: std::sync::LazyLock<Regex> =
std::sync::LazyLock::new(|| Regex::new(r"^\s*(```|~~~).*").unwrap());

Expand Down Expand Up @@ -70,210 +73,28 @@ static HANDLERS: &[PrefixHandler] = &[
},
];

/// Markdown token emitted by [`tokenize_markdown`].
#[derive(Debug, PartialEq)]
pub enum Token<'a> {
/// Line within a fenced code block, including the fence itself.
Fence(&'a str),
/// Inline code span without surrounding backticks.
Code(&'a str),
/// Plain text outside code regions.
Text(&'a str),
/// Line break separating tokens.
Newline,
}

fn parse_link_or_image(chars: &[char], mut i: usize) -> (String, usize) {
let start = i;
if chars[i] == '!' {
i += 1;
}
// skip initial '[' which we know is present
i += 1;
while i < chars.len() && chars[i] != ']' {
i += 1;
}
if i < chars.len() && chars[i] == ']' {
i += 1;
if i < chars.len() && chars[i] == '(' {
i += 1;
let mut depth = 1;
while i < chars.len() && depth > 0 {
match chars[i] {
'(' => depth += 1,
')' => depth -= 1,
_ => {}
}
i += 1;
}
let tok: String = chars[start..i].iter().collect();
return (tok, i);
}
}
let tok: String = chars[start..=start].iter().collect();
(tok, start + 1)
}

fn is_trailing_punctuation(c: char) -> bool {
matches!(
c,
'.' | ',' | ';' | ':' | '!' | '?' | ')' | ']' | '"' | '\''
)
}

fn tokenize_inline(text: &str) -> Vec<String> {
let mut tokens = Vec::new();
let chars: Vec<char> = text.chars().collect();
let mut i = 0;
while i < chars.len() {
let c = chars[i];
if c.is_whitespace() {
let start = i;
while i < chars.len() && chars[i].is_whitespace() {
i += 1;
}
tokens.push(chars[start..i].iter().collect());
} else if c == '`' {
let start = i;
let mut delim_len = 0;
while i < chars.len() && chars[i] == '`' {
i += 1;
delim_len += 1;
}
let mut end = i;
while end < chars.len() {
if chars[end] == '`' {
let mut j = end;
let mut count = 0;
while j < chars.len() && chars[j] == '`' {
j += 1;
count += 1;
}
if count == delim_len {
end = j;
break;
}
}
end += 1;
}
if end >= chars.len() {
tokens.push(chars[start..start + delim_len].iter().collect());
i = start + delim_len;
} else {
tokens.push(chars[start..end].iter().collect());
i = end;
}
} else if c == '[' || (c == '!' && i + 1 < chars.len() && chars[i + 1] == '[') {
let (tok, mut new_i) = parse_link_or_image(&chars, i);
tokens.push(tok);
let mut punct = String::new();
while new_i < chars.len() && is_trailing_punctuation(chars[new_i]) {
punct.push(chars[new_i]);
new_i += 1;
}
if !punct.is_empty() {
tokens.push(punct);
}
i = new_i;
} else {
let start = i;
while i < chars.len() && !chars[i].is_whitespace() && chars[i] != '`' {
i += 1;
}
tokens.push(chars[start..i].iter().collect());
}
}
tokens
}

/// Split the input string into [`Token`]s by analysing whitespace and
/// backtick delimiters.
///
/// The tokenizer groups consecutive whitespace into a single
/// [`Token::Text`] and recognises backtick sequences as inline code spans.
/// When a run of backticks is encountered the parser searches forward for an
/// identical delimiter, allowing nested backticks when the span uses a longer
/// fence. Unmatched delimiter sequences are treated as literal text.
///
/// ```rust,ignore
/// use mdtablefix::wrap::{Token, tokenize_markdown};
///
/// let tokens = tokenize_markdown("Example with `code`");
/// assert_eq!(
/// tokens,
/// vec![Token::Text("Example with "), Token::Code("code")]
/// );
/// ```
pub(crate) fn tokenize_markdown(input: &str) -> Vec<Token<'_>> {
let mut out = Vec::new();
let mut in_fence = false;
for line in input.split_inclusive('\n') {
let trimmed = line.trim_end_matches('\n');
if FENCE_RE.is_match(trimmed) {
out.push(Token::Fence(trimmed));
out.push(Token::Newline);
in_fence = !in_fence;
continue;
}
if in_fence {
out.push(Token::Fence(trimmed));
out.push(Token::Newline);
continue;
}
let mut rest = trimmed;
while let Some(pos) = rest.find('`') {
if pos > 0 {
out.push(Token::Text(&rest[..pos]));
}
if let Some(end) = rest[pos + 1..].find('`') {
out.push(Token::Code(&rest[pos + 1..pos + 1 + end]));
rest = &rest[pos + end + 2..];
} else {
out.push(Token::Text(&rest[pos..]));
rest = "";
break;
}
}
if !rest.is_empty() {
out.push(Token::Text(rest));
}
out.push(Token::Newline);
}
out.pop();
out
}

/// Determine if the current line should break at the last whitespace.
///
/// Returns `true` if `current_width` exceeds `width` and a whitespace split
/// position is available.
///
/// # Examples
///
/// ```ignore
/// use mdtablefix::wrap::should_break_line;
/// assert!(should_break_line(10, 12, Some(3)));
/// assert!(!should_break_line(10, 8, Some(3)));
/// ```
fn should_break_line(width: usize, current_width: usize, last_split: Option<usize>) -> bool {
current_width > width && last_split.is_some()
}

fn wrap_preserving_code(text: &str, width: usize) -> Vec<String> {
use unicode_width::UnicodeWidthStr;

let mut lines = Vec::new();
let mut current = String::new();
let mut current_width = 0;
let mut last_split: Option<usize> = None;
let tokens = tokenize_inline(text);
let tokens = tokenize::segment_inline(text);
let mut i = 0;
while i < tokens.len() {
let mut j = i + 1;
let mut group_width = UnicodeWidthStr::width(tokens[i].as_str());

if tokens[i].contains("](") && tokens[i].ends_with(')') {
while j < tokens.len() && tokens[j].chars().all(is_trailing_punctuation) {
while j < tokens.len()
&& tokens[j].chars().all(|c| {
matches!(
c,
'.' | ',' | ';' | ':' | '!' | '?' | ')' | ']' | '"' | '\''
)
})
{
group_width += UnicodeWidthStr::width(tokens[j].as_str());
j += 1;
}
Expand Down Expand Up @@ -306,7 +127,7 @@ fn wrap_preserving_code(text: &str, width: usize) -> Vec<String> {
continue;
}

if should_break_line(width, current_width + group_width, last_split) {
if current_width + group_width > width && last_split.is_some() {
let pos = last_split.unwrap();
let line = current[..pos].to_string();
let mut rest = current[pos..].trim_start().to_string();
Expand Down Expand Up @@ -549,115 +370,4 @@ pub fn wrap_text(lines: &[String], width: usize) -> Vec<String> {
}

#[cfg(test)]
mod tests {
use super::*;

#[test]
fn wrap_text_preserves_hyphenated_words() {
let input = vec!["A word that is very-long-word indeed".to_string()];
let wrapped = wrap_text(&input, 20);
assert_eq!(
wrapped,
vec![
"A word that is".to_string(),
"very-long-word".to_string(),
"indeed".to_string(),
]
);
}

#[test]
fn wrap_text_does_not_insert_spaces_in_hyphenated_words() {
let input = vec![
concat!(
"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec tincidunt ",
"elit-sed fermentum congue. Vivamus dictum nulla sed consectetur ",
"volutpat."
)
.to_string(),
];
let wrapped = wrap_text(&input, 80);
assert_eq!(
wrapped,
vec![
"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec tincidunt"
.to_string(),
"elit-sed fermentum congue. Vivamus dictum nulla sed consectetur volutpat."
.to_string(),
]
);
}

#[test]
fn wrap_text_preserves_code_spans() {
let input = vec![
"with their own escaping rules. On Windows, scripts default to `powershell -Command` \
unless the manifest's `interpreter` field overrides the setting."
.to_string(),
];
let wrapped = wrap_text(&input, 60);
assert_eq!(
wrapped,
vec![
"with their own escaping rules. On Windows, scripts default".to_string(),
"to `powershell -Command` unless the manifest's".to_string(),
"`interpreter` field overrides the setting.".to_string(),
]
);
}

#[test]
fn wrap_text_multiple_code_spans() {
let input = vec!["combine `foo bar` and `baz qux` in one line".to_string()];
let wrapped = wrap_text(&input, 25);
assert_eq!(
wrapped,
vec![
"combine `foo bar` and".to_string(),
"`baz qux` in one line".to_string(),
]
);
}

#[test]
fn wrap_text_nested_backticks() {
let input = vec!["Use `` `code` `` to quote backticks".to_string()];
let wrapped = wrap_text(&input, 20);
assert_eq!(
wrapped,
vec![
"Use `` `code` `` to".to_string(),
"quote backticks".to_string()
]
);
}

#[test]
fn wrap_text_unmatched_backticks() {
let input = vec!["This has a `dangling code span.".to_string()];
let wrapped = wrap_text(&input, 20);
assert_eq!(
wrapped,
vec!["This has a".to_string(), "`dangling code span.".to_string()]
);
}

#[test]
fn wrap_text_preserves_links() {
let input = vec![
"`falcon-pachinko` is an extension library for the".to_string(),
"[Falcon](https://falcon.readthedocs.io) web framework. It adds a structured"
.to_string(),
"approach to asynchronous WebSocket routing and background worker integration."
.to_string(),
];
let wrapped = wrap_text(&input, 80);
let joined = wrapped.join("\n");
assert_eq!(joined.matches("https://").count(), 1);
assert!(
wrapped
.iter()
.any(|l| l.contains("https://falcon.readthedocs.io"))
);
}
}
mod tests;
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