mdbook_lint_core/rules/standard/

md037.rs

use crate::Document;
use crate::error::Result;
use crate::rule::{Rule, RuleCategory, RuleMetadata};
use crate::violation::{Severity, Violation};

/// MD037 - Spaces inside emphasis markers
pub struct MD037;

impl MD037 {
    fn find_emphasis_violations(&self, line: &str, line_number: usize) -> Vec<Violation> {
        let mut violations = Vec::new();
        let chars: Vec<char> = line.chars().collect();

        // Look for patterns like "** text **", "* text *", etc.
        self.check_pattern(&chars, "**", line_number, &mut violations);
        self.check_pattern(&chars, "__", line_number, &mut violations);
        self.check_single_pattern(&chars, '*', line_number, &mut violations);
        self.check_single_pattern(&chars, '_', line_number, &mut violations);

        violations
    }

    fn check_pattern(
        &self,
        chars: &[char],
        marker: &str,
        line_number: usize,
        violations: &mut Vec<Violation>,
    ) {
        let marker_chars: Vec<char> = marker.chars().collect();
        let marker_len = marker_chars.len();
        let mut i = 0;

        while i + marker_len < chars.len() {
            // Check if we found the opening marker
            if chars[i..i + marker_len] == marker_chars {
                // Look for closing marker
                let mut j = i + marker_len;
                while j + marker_len <= chars.len() {
                    if chars[j..j + marker_len] == marker_chars {
                        // Found a pair, check for spaces
                        let content_start = i + marker_len;
                        let content_end = j;

                        if content_start < content_end {
                            let has_leading_space = chars[content_start].is_whitespace();
                            let has_trailing_space = chars[content_end - 1].is_whitespace();

                            if has_leading_space || has_trailing_space {
                                violations.push(self.create_violation(
                                    "Spaces inside emphasis markers".to_string(),
                                    line_number,
                                    i + 1,
                                    Severity::Warning,
                                ));
                            }
                        }

                        i = j + marker_len;
                        break;
                    }
                    j += 1;
                }

                if j + marker_len > chars.len() {
                    i += 1;
                }
            } else {
                i += 1;
            }
        }
    }

    fn check_single_pattern(
        &self,
        chars: &[char],
        marker: char,
        line_number: usize,
        violations: &mut Vec<Violation>,
    ) {
        let mut i = 0;

        while i < chars.len() {
            if chars[i] == marker {
                // Make sure this isn't part of a double marker
                if (i > 0 && chars[i - 1] == marker)
                    || (i + 1 < chars.len() && chars[i + 1] == marker)
                {
                    i += 1;
                    continue;
                }

                // Look for closing marker
                let mut j = i + 1;
                while j < chars.len() {
                    if chars[j] == marker {
                        // Make sure this isn't part of a double marker
                        if (j > 0 && chars[j - 1] == marker)
                            || (j + 1 < chars.len() && chars[j + 1] == marker)
                        {
                            j += 1;
                            continue;
                        }

                        // Found a pair, check for spaces
                        let content_start = i + 1;
                        let content_end = j;

                        if content_start < content_end {
                            let has_leading_space = chars[content_start].is_whitespace();
                            let has_trailing_space = chars[content_end - 1].is_whitespace();

                            if has_leading_space || has_trailing_space {
                                violations.push(self.create_violation(
                                    "Spaces inside emphasis markers".to_string(),
                                    line_number,
                                    i + 1,
                                    Severity::Warning,
                                ));
                            }
                        }

                        i = j + 1;
                        break;
                    }
                    j += 1;
                }

                if j >= chars.len() {
                    i += 1;
                }
            } else {
                i += 1;
            }
        }
    }
}

impl Rule for MD037 {
    fn id(&self) -> &'static str {
        "MD037"
    }

    fn name(&self) -> &'static str {
        "no-space-in-emphasis"
    }

    fn description(&self) -> &'static str {
        "Spaces inside emphasis markers"
    }

    fn metadata(&self) -> RuleMetadata {
        RuleMetadata::stable(RuleCategory::Formatting)
    }

    fn check_with_ast<'a>(
        &self,
        document: &Document,
        _ast: Option<&'a comrak::nodes::AstNode<'a>>,
    ) -> Result<Vec<Violation>> {
        let mut violations = Vec::new();
        let lines = document.content.lines();

        for (line_number, line) in lines.enumerate() {
            let line_number = line_number + 1;
            violations.extend(self.find_emphasis_violations(line, line_number));
        }

        Ok(violations)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::Document;
    use std::path::PathBuf;

    #[test]
    fn test_md037_no_violations() {
        let content = r#"Here is some **bold** text.

Here is some *italic* text.

Here is some more __bold__ text.

Here is some more _italic_ text.
"#;

        let document = Document::new(content.to_string(), PathBuf::from("test.md")).unwrap();
        let rule = MD037;
        let violations = rule.check(&document).unwrap();
        assert_eq!(violations.len(), 0);
    }

    #[test]
    fn test_md037_spaces_in_bold() {
        let content = r#"Here is some ** bold ** text.

Here is some __bold __ text.

Here is some __ bold__ text.
"#;

        let document = Document::new(content.to_string(), PathBuf::from("test.md")).unwrap();
        let rule = MD037;
        let violations = rule.check(&document).unwrap();
        assert_eq!(violations.len(), 3);
        assert_eq!(violations[0].line, 1);
        assert_eq!(violations[1].line, 3);
        assert_eq!(violations[2].line, 5);
    }

    #[test]
    fn test_md037_spaces_in_italic() {
        let content = r#"Here is some * italic * text.

Here is some _italic _ text.

Here is some _ italic_ text.
"#;

        let document = Document::new(content.to_string(), PathBuf::from("test.md")).unwrap();
        let rule = MD037;
        let violations = rule.check(&document).unwrap();
        assert_eq!(violations.len(), 3);
        assert_eq!(violations[0].line, 1);
        assert_eq!(violations[1].line, 3);
        assert_eq!(violations[2].line, 5);
    }

    #[test]
    fn test_md037_mixed_violations() {
        let content = r#"Here is ** bold ** and * italic * text.

Normal **bold** and *italic* are fine.

But __bold __ and _italic _ are not.
"#;

        let document = Document::new(content.to_string(), PathBuf::from("test.md")).unwrap();
        let rule = MD037;
        let violations = rule.check(&document).unwrap();
        assert_eq!(violations.len(), 4);
        assert_eq!(violations[0].line, 1); // ** bold **
        assert_eq!(violations[1].line, 1); // * italic *
        assert_eq!(violations[2].line, 5); // __bold __
        assert_eq!(violations[3].line, 5); // _italic _
    }

    #[test]
    fn test_md037_no_false_positives() {
        let content = r#"This line has * asterisk but not emphasis.

This line has ** two asterisks but not emphasis.

This has *proper* emphasis.

This has **proper** emphasis too.

Math: 2 times 3 times 4 = 24.
"#;

        let document = Document::new(content.to_string(), PathBuf::from("test.md")).unwrap();
        let rule = MD037;
        let violations = rule.check(&document).unwrap();
        assert_eq!(violations.len(), 0);
    }

    #[test]
    fn test_md037_nested_emphasis() {
        let content = r#"This has ** bold with *italic* inside ** which is wrong.

This has **bold with *italic* inside** which is correct.
"#;

        let document = Document::new(content.to_string(), PathBuf::from("test.md")).unwrap();
        let rule = MD037;
        let violations = rule.check(&document).unwrap();
        assert_eq!(violations.len(), 1);
        assert_eq!(violations[0].line, 1);
    }

    #[test]
    fn test_md037_emphasis_at_line_boundaries() {
        let content = r#"** bold at start **

**bold at end **

* italic at start *

*italic at end *
"#;

        let document = Document::new(content.to_string(), PathBuf::from("test.md")).unwrap();
        let rule = MD037;
        let violations = rule.check(&document).unwrap();
        assert_eq!(violations.len(), 4);
        assert_eq!(violations[0].line, 1);
        assert_eq!(violations[1].line, 3);
        assert_eq!(violations[2].line, 5);
        assert_eq!(violations[3].line, 7);
    }

    #[test]
    fn test_md037_multiple_spaces() {
        let content = r#"Here is some **  bold with multiple spaces  ** text.

Here is some *   italic with multiple spaces   * text.
"#;

        let document = Document::new(content.to_string(), PathBuf::from("test.md")).unwrap();
        let rule = MD037;
        let violations = rule.check(&document).unwrap();
        assert_eq!(violations.len(), 2);
        assert_eq!(violations[0].line, 1);
        assert_eq!(violations[1].line, 3);
    }
}