Detect the programming language from a snippet

detect-programming-lang.ts

function detectPopularLanguages(codeSnippet: string): string[] {
  const languageKeywords: { [key: string]: RegExp } = {
    JavaScript: /\b(?:var|let|const|function|if|else|for|while|switch|case|break|return)\b/g,
    Python: /\b(?:def|if|elif|else|for|while|break|continue|return)\b/g,
    Java: /\b(?:public|private|protected|class|void|static|if|else|for|while|switch|case|break|return)\b/g,
    CSharp: /\b(?:public|private|protected|class|void|static|if|else|for|while|switch|case|break|return)\b/g,
    C: /\b(?:int|float|char|void|if|else|for|while|switch|case|break|return)\b/g,
    Ruby: /\b(?:def|if|else|elsif|unless|end|for|while|case|when)\b/g,
    PHP: /\b(?:public|private|protected|function|if|else|for|while|switch|case|break|return)\b/g,
    Swift: /\b(?:class|func|var|let|if|else|for|while|switch|case|break|return)\b/g,
    TypeScript: /\b(?:let|const|function|interface|class|if|else|for|while|switch|case|break|return)\b/g,
    Go: /\b(?:package|func|var|const|if|else|for|switch|case|break|return)\b/g,
    Rust: /\b(?:fn|let|const|if|else|for|while|match|return)\b/g,
    Kotlin: /\b(?:fun|val|var|if|else|for|while|when)\b/g,
    Scala: /\b(?:val|var|def|if|else|for|while|match|case)\b/g,
    HTML: /<[a-z][\s\S]*?>/gi,
    CSS: /{[\s\S]*?}/gi,
    SQL: /\b(?:SELECT|INSERT|UPDATE|DELETE|FROM|WHERE|JOIN)\b/g,
    Shell: /\b(?:echo|export|cd|ls|grep|awk|sed|chmod)\b/g,
    Lua: /\b(?:function|if|else|for|while|repeat|until|end)\b/g,
    Perl: /\b(?:my|sub|if|else|for|while|foreach|return)\b/g,
    R: /\b(?:function|if|else|for|while|return)\b/g,
  };

  const languageCount: { [key: string]: number } = {};

  for (const language in languageKeywords) {
    const regex = languageKeywords[language];
    const matches = codeSnippet.match(regex);
    if (matches && matches.length > 0) {
      languageCount[language] = matches.length;
    }
  }

  const sortedLanguages = Object.keys(languageCount).sort(
    (a, b) => languageCount[b] - languageCount[a]
  );

  const topLanguages = sortedLanguages.slice(0, 20);
  return topLanguages;
}

// Example usage:
const codeSnippet = `
fn factorial(n: u32) -> u32 {
    if n == 0 {
        1
    } else {
        n * factorial(n - 1)
    }
}

fn main() {
    let num = 5;
    let result = factorial(num);
    println!("Factorial of {} is: {}", num, result);
}
`;

const topLanguages = detectPopularLanguages(codeSnippet);
console.log("Top 20 Programming Languages:");
console.log(topLanguages);