fastparselite/deep.js

Super simple & fast DSL parser for lightweight config-like data using custom syntax.

const fs = require('fs');

function parseLiteData(text) {
  // First, remove all comments
  const cleanText = text.replace(/(#|\/\/).*$/gm, '');
  
  const result = {};
  // Split by blocks starting with @
  const blocks = cleanText.split('@').slice(1);

  blocks.forEach(block => {
    const firstBrace = block.indexOf('{');
    const lastBrace = block.lastIndexOf('}');
    
    if (firstBrace === -1 || lastBrace === -1) return;
    
    const name = block.substring(0, firstBrace).trim();
    const content = block.substring(firstBrace + 1, lastBrace).trim();
    
    result[name] = parseBlockContent(content);
  });

  return result;
}

function parseBlockContent(content) {
  const obj = {};
  let currentPos = 0;
  const len = content.length;

  while (currentPos < len) {
    // Skip whitespace
    while (currentPos < len && isWhitespace(content[currentPos])) {
      currentPos++;
    }
    if (currentPos >= len) break;

    // Find key
    const keyMatch = content.slice(currentPos).match(/^([a-zA-Z_]\w*):/);
    if (!keyMatch) break;

    const key = keyMatch[1];
    currentPos += key.length + 1; // Skip key and colon

    // Skip whitespace after colon
    while (currentPos < len && isWhitespace(content[currentPos])) {
      currentPos++;
    }
    if (currentPos >= len) break;

    // Determine value type
    if (content[currentPos] === '{') {
      // Nested object
      let depth = 1;
      let endPos = currentPos + 1;
      
      while (endPos < len && depth > 0) {
        if (content[endPos] === '{') depth++;
        if (content[endPos] === '}') depth--;
        endPos++;
      }
      
      const innerContent = content.substring(currentPos + 1, endPos - 1);
      obj[key] = parseBlockContent(innerContent);
      currentPos = endPos;
    } 
    else if (content[currentPos] === '[') {
      // Array
      let endPos = currentPos + 1;
      while (endPos < len && content[endPos] !== ']') {
        endPos++;
      }
      
      const arrayContent = content.substring(currentPos + 1, endPos);
      obj[key] = arrayContent.split(',').map(item => convertValue(item.trim()));
      currentPos = endPos + 1;
    } 
    else {
      // Primitive value
      let endPos = currentPos;
      while (endPos < len && !isWhitespace(content[endPos]) && content[endPos] !== '}') {
        endPos++;
      }
      
      const value = content.substring(currentPos, endPos).trim();
      obj[key] = convertValue(value);
      currentPos = endPos;
    }
  }

  return obj;
}

function isWhitespace(char) {
  return char === ' ' || char === '\n' || char === '\r' || char === '\t';
}

function convertValue(value) {
  if (value === 'true') return true;
  if (value === 'false') return false;
  if (!isNaN(value)) return Number(value);
  if ((value.startsWith('"') && value.endsWith('"')) || 
      (value.startsWith("'") && value.endsWith("'"))) {
    return value.slice(1, -1);
  }
  return value;
}

// // Test with your exact sample
// const input = `
// @user {
//   name: "Alice"
//   age: 25
  
//   address: {
//     city: "Chennai"
//     location: {
//       lat: 13.08
//       long: 80.27
//     }
//     description: "something"
//   }

//   skills: [Python, JavaScript, C++]
//   active: true
// }

// @demo {
//   name: "dinesh"
// }
// `;

// const parsed = parseLiteData(input);
// console.log(parsed.user)

// ======== Usage =========
const input = fs.readFileSync("sample.ld", "utf8");
const result = parseLiteData(input);

const flatUser = flatten(result);
// console.log("User name:", flatUser.name);
console.log("User active:", flatUser.active);
console.log("User address city:", flatUser.address_description);