petitparser/lib/src/parser/predicate/pattern.dart

import '../../context/context.dart';
import '../../context/result.dart';
import '../../core/parser.dart';

/// A parser that uses a [Pattern] matcher for parsing.
///
/// This parser wraps [Pattern.matchAsPrefix] in a [Parser]. This works for
/// any implementation of [Pattern], but can lead to very inefficient parsers
/// when not used carefully.
class PatternParser extends Parser<Match> {
  PatternParser(this.pattern, this.message);

  /// The [Pattern] matcher this parser uses.
  final Pattern pattern;

  /// Error message to annotate parse failures with.
  final String message;

  @override
  Result<Match> parseOn(Context context) {
    final result = pattern.matchAsPrefix(context.buffer, context.position);
    return result != null
        ? context.success(result, result.end)
        : context.failure(message);
  }

  @override
  int fastParseOn(String buffer, int position) {
    final result = pattern.matchAsPrefix(buffer, position);
    return result != null ? result.end : -1;
  }

  @override
  String toString() => '${super.toString()}[$message]';

  @override
  PatternParser copy() => PatternParser(pattern, message);

  @override
  bool hasEqualProperties(PatternParser other) =>
      super.hasEqualProperties(other) &&
      pattern == other.pattern &&
      message == other.message;
}