commit | 42cb2dcd76ad8e613847af5e983cab73df1094a4 | [log] [tgz] |
---|---|---|
author | Natalie Weizenbaum <nweiz@google.com> | Tue Jun 14 16:21:23 2016 -0700 |
committer | Natalie Weizenbaum <nweiz@google.com> | Tue Jun 14 16:21:23 2016 -0700 |
tree | 18599481b474ddb28becfb2888fb3ed6753bc0f3 | |
parent | f83ceb2e84a60a6417c6aeb0cd2162931617461a [diff] |
Add breaking changes and release 1.0.0. This makes `.error()` default to empty spans rather than single-character ones. This better represents the semantics of failing at a particular position in the text. It also makes `lastMatch` reset whenever the scanner's position changes. This makes `.error()` behave more consistently when primarily doing character-based scanning, since it won't unexpectedly emit an error for stale match data. R=jmesserly@google.com Review URL: https://codereview.chromium.org//2056933002 .
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; }