LibreChat/client/src/utils/latex.ts

// Regex to check if the processed content contains any potential LaTeX patterns
const containsLatexRegex =
  /\\\(.*?\\\)|\\\[.*?\\\]|\$.*?\$|\\begin\{equation\}.*?\\end\{equation\}/;

// Regex for inline and block LaTeX expressions
const inlineLatex = new RegExp(/\\\((.+?)\\\)/, 'g');
const blockLatex = new RegExp(/\\\[(.*?[^\\])\\\]/, 'gs');

// Function to restore code blocks
const restoreCodeBlocks = (content: string, codeBlocks: string[]) => {
  return content.replace(/<<CODE_BLOCK_(\d+)>>/g, (match, index) => codeBlocks[index]);
};

// Regex to identify code blocks and inline code
const codeBlockRegex = /(```[\s\S]*?```|`.*?`)/g;

export const processLaTeX = (_content: string) => {
  let content = _content;
  // Temporarily replace code blocks and inline code with placeholders
  const codeBlocks: string[] = [];
  let index = 0;
  content = content.replace(codeBlockRegex, (match) => {
    codeBlocks[index] = match;
    return `<<CODE_BLOCK_${index++}>>`;
  });

  // Escape dollar signs followed by a digit or space and digit
  let processedContent = content.replace(/(\$)(?=\s?\d)/g, '\\$');

  // If no LaTeX patterns are found, restore code blocks and return the processed content
  if (!containsLatexRegex.test(processedContent)) {
    return restoreCodeBlocks(processedContent, codeBlocks);
  }

  // Convert LaTeX expressions to a markdown compatible format
  processedContent = processedContent
    .replace(inlineLatex, (match: string, equation: string) => `$${equation}$`) // Convert inline LaTeX
    .replace(blockLatex, (match: string, equation: string) => `$$${equation}$$`); // Convert block LaTeX

  // Restore code blocks
  return restoreCodeBlocks(processedContent, codeBlocks);
};