| commit | ad926d6c2840dd1248f07ed9c0b640f2620d2449 | [log] [tgz] |
|---|---|---|
| author | Natalie Weizenbaum <[email protected]> | Wed Sep 02 18:45:35 2015 |
| committer | Natalie Weizenbaum <[email protected]> | Wed Sep 02 18:45:35 2015 |
| tree | 2a7cd91053a53deed1d4274dea21bdb3fdf1ad17 | |
| parent | 494684f167047b06ce910633e8b26958d56cadc0 [diff] |
Add new SpanScanner.eager(). This is more efficient for uses like the YAML parser, which uses the current line and especially column information frequently while parsing a file. [email protected] Review URL: https://codereview.chromium.org//1318603008 .
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; }