commit | a40bbbd83f1176bcc0021b336f5841310f91d8cb | [log] [tgz] |
---|---|---|
author | Natalie Weizenbaum <nweiz@google.com> | Tue Jul 09 16:35:39 2024 -0700 |
committer | GitHub <noreply@github.com> | Tue Jul 09 16:35:39 2024 -0700 |
tree | 39199553a86a32d7a78f407adfe48a2d488ed5c1 | |
parent | 0de03b5279a04aa05052ce306f90fca473c6fd1a [diff] |
Add a `SpanScanner.spanFromPosition()` method (#78) Tracking raw ints can be more efficient than tracking `LineScannerState` objects, and allows users to do small manual manipulations on the resulting positions.
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' as math; import 'package:string_scanner/string_scanner.dart'; num parseNumber(String source) { // Scan a number ("1", "1.5", "-3"). final scanner = 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. final 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(RegExp(r'\d+')); // [Scanner.lastMatch] holds the [MatchData] for the most recent call to // [Scanner.scan], [Scanner.expect], or [Scanner.matches]. var number = num.parse(scanner.lastMatch![0]!); if (scanner.scan('.')) { scanner.expect(RegExp(r'\d+')); final 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; }