Clone this repo:
  1. 005fab6 Don't crash on surrogate pairs. (#5) by Natalie Weizenbaum · 5 months ago master 1.0.2
  2. 50d0424 Fix the expectChar() error text. (#3) by Natalie Weizenbaum · 12 months ago 1.0.1
  3. 42cb2dc Add breaking changes and release 1.0.0. by Natalie Weizenbaum · 1 year, 4 months ago 1.0.0
  4. f83ceb2 Add StringScanner.scanChar() and .expectChar(). by Natalie Weizenbaum · 1 year, 5 months ago 0.1.5
  5. 2d44ec8 Add SpanScanner.within(). by Natalie Weizenbaum · 1 year, 5 months ago

This package exposes a StringScanner type that makes it easy to parse a string using a series of Patterns. For example:

import 'dart:math';

import 'package:string_scanner/string_scanner.dart';

num parseNumber(String source) {
  // Scan a number ("1", "1.5", "-3").
  var scanner = new StringScanner(source);

  // [Scanner.scan] tries to consume a [Pattern] and returns whether or not it
  // succeeded. It will move the scan pointer past the end of the pattern.
  var negative = scanner.scan("-");

  // [Scanner.expect] consumes a [Pattern] and throws a [FormatError] if it
  // fails. Like [Scanner.scan], it will move the scan pointer forward.
  scanner.expect(new RegExp(r"\d+"));

  // [Scanner.lastMatch] holds the [MatchData] for the most recent call to
  // [Scanner.scan], [Scanner.expect], or [Scanner.matches].
  var number = int.parse(scanner.lastMatch[0]);

  if (scanner.scan(".")) {
    scanner.expect(new RegExp(r"\d+"));
    var decimal = scanner.lastMatch[0];
    number += int.parse(decimal) / math.pow(10, decimal.length);
  }

  // [Scanner.expectDone] will throw a [FormatError] if there's any input that
  // hasn't yet been consumed.
  scanner.expectDone();

  return (negative ? -1 : 1) * number;
}