codePositionToIndex.mjs

import CodePosition from "./CodePosition.mjs";

/**
 * Converts a code position to a string index.
 * @kind function
 * @name codePositionToIndex
 * @param {CodePosition} codePosition Code position.
 * @param {string} code Code.
 * @returns {number} String index.
 * @ignore
 */
export default function codePositionToIndex(codePosition, code) {
  if (!(codePosition instanceof CodePosition))
    throw new TypeError(
      "Argument 1 `codePosition` must be a `CodePosition` instance."
    );

  if (typeof code !== "string")
    throw new TypeError("Argument 2 `code` must be a string.");

  if (code === "")
    throw new TypeError("Argument 2 `code` must be a populated string.");

  let index = 0;
  let line = 1;
  let column = 1;

  while (line < codePosition.line || column < codePosition.column) {
    if (code[index] === "\n") {
      line++;
      column = 1;
    } else column++;

    index++;
  }

  return index;
}