tinyrulelang/index.js

/**
 * Adds a prefix to a string.
 * @param {string} str - The original string.
 * @param {string} prefix - The prefix to add.
 * @returns {string} The string with the prefix added.
 */
function addPrefix(str, prefix) {
  return prefix + str;
}

/**
 * Removes a prefix from a string.
 * @param {string} str - The original string.
 * @param {string} prefix - The prefix to remove.
 * @returns {string} The string with the prefix removed.
 */
function removePrefix(str, prefix) {
  if (str.startsWith(prefix)) {
    return str.slice(prefix.length);
  }
  return str;
}

/**
 * Adds a suffix to a string.
 * @param {string} str - The original string.
 * @param {string} suffix - The suffix to add.
 * @returns {string} The string with the suffix added.
 */
function addSuffix(str, suffix) {
  return str + suffix;
}

/**
 * Removes a suffix from a string.
 * @param {string} str - The original string.
 * @param {string} suffix - The suffix to remove.
 * @returns {string} The string with the suffix removed.
 */
function removeSuffix(str, suffix) {
  if (str.endsWith(suffix)) {
    return str.slice(0, -suffix.length);
  }
  return str;
}

/**
 * Tokenizes a string into tokens
 * @param {string} str 
 * @returns {Array<string>} tokens
 */
function tokenize(str) {
  const tokens = [];
  let currentToken = "";
  let inQuotes = false;
  let escapeNext = false;

  for (let i = 0; i < str.length; i++) {
    const char = str[i];

    if (escapeNext) {
      currentToken += char;
      escapeNext = false;
    } else if (char === "\\") {
      escapeNext = true;
    } else if (char === '"') {
      inQuotes = !inQuotes;
    } else if ((char === " " || char === "\n" || char === "\r") && !inQuotes) {
      if (currentToken !== "") {
        tokens.push(currentToken);
        currentToken = "";
      }
    } else {
      currentToken += char;
    }
  }

  if (currentToken !== "") {
    tokens.push(currentToken);
  }

  return tokens;
}

/**
 * Manipulates the filename based on rules
 * @param {string} string
 * @param {string} filename
 * @returns
 */
function manipulateFilename(string, filename) {
  /**
   * @type {{dimension: string, action: string, target:string, value: string}}  cmd
   */
  let cmd;

  /**
   * @type {Array<{dimension: string, action: string, target:string, value: string}>} commands
   */
  let commands = [];
  let state = "next";

  for (const token of tokenize(string)) {
    switch (state) {
      case "next":
        if (token === "for") {
          cmd = {};
          state = "dimension";
        } else {
          throw new Error("Syntax Error, command must start with 'for'");
        }
        break;
      case "dimension":
        if (token === "2D" || token === "3D") {
          cmd = { ...cmd, dimension: token };
          state = "action";
        } else {
          throw new Error("Syntax Error, command must be '2D' or '3D'");
        }
        break;
      case "action":
        if (token === "add" || token === "remove") {
          cmd = { ...cmd, action: token };
          state = "target";
        } else {
          throw new Error("Syntax Error, command must be 'add' or 'remove'");
        }
        break;
      case "target":
        if (token === "all" && cmd.action === "add") { 
          throw new Error(
            "Syntax Error, you cannot use an 'all' target with an 'add' action, only 'remove' is allowed"
          );
        } else if (token === "all" && cmd.action === "remove") {
          cmd = { ...cmd, target: token };
          state = "value";        
        } else if (token === "prefix" || token === "suffix") {
          cmd = { ...cmd, target: token };
          state = "value";
        } else {
          throw new Error(
            "Syntax Error, command must be 'prefix', 'suffix', or 'all'"
          );
        }
        break;
      case "value":
        cmd = { ...cmd, value: token };
        commands.push(cmd);
        state = "more";
      case "more":
        if (token === "and") {
          state = "next";
        }
        break;
      default:
        break;
    }
  }

  for (const command of commands) {
    if (command.target === "prefix" && command.action === "add") {
      filename = addPrefix(filename, command.value);
    }
    if (command.target === "prefix" && command.action === "remove") {
      filename = removePrefix(filename, command.value);
    }
    if (command.target === "suffix" && command.action === "add") {
      filename = addSuffix(filename, command.value);
    }
    if (command.target === "suffix" && command.action === "remove") {
      filename = removeSuffix(filename, command.value);
    }
    if (command.target === "all" && command.action === "remove") {
      filename = filename.replace(command.value, "");      
    }
  }

  return filename;
}

const cmdStr = `for 2D add prefix "hello-" and 
                for 2D add suffix "-3" and 
                for 2D add suffix "-3" and 
                for 2D add suffix "-4" and 
                for 2D add suffix "-5" and for 2D remove all "-3"`;
const filename = "example";
const result = manipulateFilename(cmdStr, filename);
console.log(result); // Output: "hello-example-3"