Flexible template parser

template-parser.ts

/**
 * Parses a templated expression for fields.
 * Token opening and closing delimiters can be customised.
 */
function parseTemplate({
  input,
  tokenDelimiters: {
    open,
    close,
  } = {
    open: "{",
    close: "}",
  }
}: {
  input: string,
  tokenDelimiters: {
    open: string;
    close: string;
  }
}) {
  const fieldPattern = new RegExp(
    [
      open,
      "(.*?)",
      close,
    ].join(""),
    "g"
  );
  
  const inputMatches = Array.from(input.matchAll(fieldPattern));
  
  return inputMatches;
}

const testParams = {
  input: `Good {timeOfDay}, {personName}.`,
  tokenDelimiters: {
    open: "{",
    close: "}"
  }
};

const result = parseTemplate(testParams);

console.log(result);

// Output:
// [
//   [
//     '<timeOfDay>',
//     'timeOfDay',
//     index: 5,
//     input: 'Good <timeOfDay>, <personName>.',
//     groups: undefined
//   ],
//   [
//     '<personName>',
//     'personName',
//     index: 18,
//     input: 'Good <timeOfDay>, <personName>.',
//     groups: undefined
//   ]
// ]