0865979c31dfe1e7b21a471c73390241374c05de - string_scanner

commit	0865979c31dfe1e7b21a471c73390241374c05de	[log] [tgz]
author	nweiz@google.com <nweiz@google.com>	Mon Jun 23 21:10:55 2014 +0000
committer	nweiz@google.com <nweiz@google.com>	Mon Jun 23 21:10:55 2014 +0000
tree	abb2ef1599cceb1e453d4b1e1d8bd45fa9bf8606
parent	edf541b1787796679ec5520dc4259b082634737d [diff]

tree: abb2ef1599cceb1e453d4b1e1d8bd45fa9bf8606

README.md

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;
}