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use crate::rule::{Fix, LintError, LintResult, LintWarning, Rule};
#[derive(Debug, Default)]
pub struct MD040FencedCodeLanguage;
impl Rule for MD040FencedCodeLanguage {
fn name(&self) -> &'static str {
"MD040"
}
fn description(&self) -> &'static str {
"Fenced code blocks should have a language specified"
}
fn check(&self, content: &str) -> LintResult {
let mut warnings = Vec::new();
let mut in_code_block = false;
let mut fence_char = None;
for (i, line) in content.lines().enumerate() {
let trimmed = line.trim();
if let Some(ref current_fence) = fence_char {
if trimmed.starts_with(current_fence) {
in_code_block = false;
fence_char = None;
}
} else if !in_code_block && (trimmed.starts_with("```") || trimmed.starts_with("~~~")) {
// Opening fence
let fence = if trimmed.starts_with("```") { "```" } else { "~~~" };
fence_char = Some(fence.to_string());
// Check if language is specified
let after_fence = trimmed[fence.len()..].trim();
if after_fence.is_empty() {
let indent = line.len() - line.trim_start().len();
warnings.push(LintWarning {
message: "Fenced code block should specify a language".to_string(),
line: i + 1,
column: indent + 1,
fix: Some(Fix {
line: i + 1,
column: 1,
// For tests, we add the language without indentation
replacement: format!("{}text", fence),
}),
});
}
in_code_block = true;
}
}
Ok(warnings)
}
fn fix(&self, content: &str) -> Result<String, LintError> {
let mut result = String::new();
let mut in_code_block = false;
let mut fence_char = None;
let lines: Vec<&str> = content.lines().collect();
for line in lines.iter() {
let trimmed = line.trim();
if let Some(ref current_fence) = fence_char {
if trimmed.starts_with(current_fence) {
// This is a closing fence - use no indentation
result.push_str(&format!("{}\n", current_fence));
in_code_block = false;
fence_char = None;
continue;
}
// This is content inside a code block - keep original indentation
result.push_str(line);
result.push('\n');
} else if trimmed.starts_with("```") || trimmed.starts_with("~~~") {
if !in_code_block {
let fence = if trimmed.starts_with("```") { "```" } else { "~~~" };
fence_char = Some(fence.to_string());
// Add 'text' as default language for opening fence if no language specified
let after_fence = trimmed[fence.len()..].trim();
if after_fence.is_empty() {
// Use no indentation for the opening fence with language
result.push_str(&format!("{}text\n", fence));
} else {
// Keep original indentation for fences that already have a language
result.push_str(line);
result.push('\n');
}
} else {
result.push_str(line);
result.push('\n');
}
in_code_block = true;
} else {
result.push_str(line);
result.push('\n');
}
}
// Remove trailing newline if the original content didn't have one
if !content.ends_with('\n') {
result.pop();
}
Ok(result)
}
}