commit | 7377f1922b15b74878e6fe57c68cb21ff6d62402 | [log] [tgz] |
---|---|---|
author | nweiz@google.com <nweiz@google.com> | Wed Apr 02 20:30:09 2014 +0000 |
committer | nweiz@google.com <nweiz@google.com> | Wed Apr 02 20:30:09 2014 +0000 |
tree | 1526368e7a7ed6fa4bffb8f128288ead4d859c1a |
Add a string_scanner package. This code has been pulled out of the Shelf package. R=kevmoo@google.com Review URL: https://codereview.chromium.org//213833013 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/string_scanner@34665 260f80e4-7a28-3924-810f-c04153c831b5
This package exposes a StringScanner
type that makes it easy to parse a string using a series of Pattern
s. 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; }