import { Rule } from './rule-interface';
/**
* MD048: Code fence style
*
* This rule is triggered when the code fence style in a document is inconsistent.
* In Markdown, code fences can be created using either backticks (```) or
* tildes (~~~). This rule ensures that only one style is used throughout the document.
*/
export const name = 'MD048';
export const description = 'Code fence style';
/**
* Check if a line is a code fence (either opening or closing)
* @param line The line to check
* @returns True if the line is a code fence
*/
function isCodeFence(line: string): boolean {
return /^(`{3,}|~{3,})/.test(line.trim());
}
/**
* Get the code fence style (backtick or tilde) from a line
* @param line The line to check
* @returns The code fence style character, or empty string if not a fence
*/
function getCodeFenceStyle(line: string): string {
const match = line.trim().match(/^(`{3,}|~{3,})/);
return match ? match[1][0] : '';
}
/**
* Fix code fence style by ensuring a consistent style throughout the document
* @param lines Array of string lines to fix
* @returns Fixed lines array with consistent code fence style
*/
export function fix(lines: string[]): string[] {
if (lines.length === 0) return lines;
// Find the first code fence to determine the preferred style
let preferredStyle = '`'; // Default to backtick if no code fence is found
for (const line of lines) {
if (isCodeFence(line)) {
preferredStyle = getCodeFenceStyle(line);
break;
}
}
// Now fix all code fences to match the preferred style
let inCodeBlock = false;
return lines.map(line => {
if (isCodeFence(line)) {
const style = getCodeFenceStyle(line);
if (style !== preferredStyle) {
// Need to replace the fence character
const trimmed = line.trim();
const indentation = line.slice(0, line.indexOf(trimmed));
// Find how many fence characters we have
const fenceCount = trimmed.match(/^(`{3,}|~{3,})/)?.[0].length || 3;
// Get any language specifier if it exists (for opening fences)
const language = !inCodeBlock ? trimmed.slice(fenceCount).trim() : '';
// Create the new fence with the preferred style
const newFence = preferredStyle.repeat(fenceCount);
// Toggle the inCodeBlock state
inCodeBlock = !inCodeBlock;
// Return the updated line
return `${indentation}${newFence}${language ? ' ' + language : ''}`;
} else {
// Toggle the inCodeBlock state if the style is already correct
inCodeBlock = !inCodeBlock;
}
}
return line;
});
}
/**
* Rule implementation for MD048
*/
export const rule: Rule = {
name,
description,
fix
};
export default rule;
