error.js

export default function makeError(code, message, options) {
  var line = options.line;
  var column = options.column;
  var filename = options.filename;
  var src = options.src;
  var fullMessage;
  var location = line + (column ? ":" + column : "");

  if (src && line >= 1 && line <= src.split("\n").length) {
    var lines = src.split("\n");
    var start = Math.max(line - 3, 0);
    var end = Math.min(lines.length, line + 3);
    // Error context
    var context = lines
      .slice(start, end)
      .map(function (text, i) {
        var curr = i + start + 1;
        var preamble = (curr == line ? "  > " : "    ") + curr + "| ";
        var out = preamble + text;
        if (curr === line && column > 0) {
          out += "\n";
          out += Array(preamble.length + column).join("-") + "^";
        }
        return out;
      })
      .join("\n");
    fullMessage = (filename || "Pug") + ":" + location + "\n" + context +
      "\n\n" + message;
  } else {
    fullMessage = (filename || "Pug") + ":" + location + "\n\n" + message;
  }

  var err = new Error(fullMessage);
  err.code = "PUG:" + code;
  err.msg = message;
  err.line = line;
  err.column = column;
  err.filename = filename;
  err.src = src;
  err.toJSON = function () {
    return {
      code: this.code,
      msg: this.msg,
      line: this.line,
      column: this.column,
      filename: this.filename,
    };
  };
  return err;
}