commit | 2d44ec8eb90ffa0d7d16048d6ff96702cc27f075 | [log] [tgz] |
---|---|---|
author | Natalie Weizenbaum <nweiz@google.com> | Mon Jun 06 16:22:28 2016 -0700 |
committer | Natalie Weizenbaum <nweiz@google.com> | Mon Jun 06 16:22:28 2016 -0700 |
tree | 87fe3d59c34a7401283d893b47743952de604254 | |
parent | f70fa170a5fc5507fdad0fa1ef8996a126cc5796 [diff] |
Add SpanScanner.within(). This is useful for doing more detailed parses of sub-sections of larger text. R=rnystrom@google.com Review URL: https://codereview.chromium.org//2039163002 .
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; }