fastparselite/cop.js

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

const fs = require("fs");

function removeComments(text) {
  return text
    .split("\n")
    .map(line => line.replace(/(#|\/\/).*/, "").trim())
    .filter(line => line.length > 0)
    .join("\n");
}



function parseObjectBlock(content) {
  const obj = {};
  let i = 0;
  const len = content.length;

  while (i < len) {
    // Skip whitespace and newlines
    while (i < len && (content[i] === ' ' || content[i] === '\n' || content[i] === '\r')) i++;
    if (i >= len) break;

    // Extract key
    const keyMatch = content.slice(i).match(/^([a-zA-Z_]\w*):/);
    if (!keyMatch) break;
    
    const key = keyMatch[1];
    i += key.length + 1; // Skip key and colon

    // Skip whitespace after colon
    while (i < len && (content[i] === ' ' || content[i] === '\n' || content[i] === '\r')) i++;
    if (i >= len) break;

    // Handle different value types
    if (content[i] === '{') {
      // Nested object
      let depth = 1;
      let j = i + 1;
      while (j < len && depth > 0) {
        if (content[j] === '{') depth++;
        else if (content[j] === '}') depth--;
        j++;
      }
      const innerContent = content.slice(i + 1, j - 1);
      obj[key] = parseObjectBlock(innerContent);
      i = j;
    } else if (content[i] === '[') {
      // Array
      let j = i + 1;
      while (j < len && content[j] !== ']') j++;
      const elements = content.slice(i + 1, j).split(',').map(el => el.trim());
      obj[key] = elements;
      i = j + 1;
    } else {
      // Primitive value
      let j = i;
      while (j < len && content[j] !== '\n' && content[j] !== '\r' && content[j] !== ' ') j++;
      let value = content.slice(i, j).trim();

      // Value type conversion
      if (value === 'true') value = true;
      else if (value === 'false') value = false;
      else if (!isNaN(value)) value = Number(value);
      else if ((value.startsWith('"') && value.endsWith('"')) || 
               (value.startsWith("'") && value.endsWith("'"))) {
        value = value.slice(1, -1);
      }

      obj[key] = value;
      i = j;
    }
  }
  // console.log(obj);

  return obj;
}


function parseLiteData(text) {
  const cleanText = removeComments(text);
  const data = {};
  const blocks = cleanText.match(/@(\w+)\s*{([\s\S]*?)}/g);

  if (!blocks) return data;

  for (const block of blocks) {
    const [, name, content] = block.match(/@(\w+)\s*{([\s\S]*)}/);
    data[name] = parseObjectBlock(content.trim());
  }

  return data;
}

function flatten(obj, prefix = "", result = {}) {
  for (const key in obj) {
    const value = obj[key];
    const newKey = prefix ? `${prefix}_${key}` : key;
    if (typeof value === "object" && !Array.isArray(value)) {
      flatten(value, newKey, result);
    } else {
      result[newKey] = value;
    }
  }
  return result;
}

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

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