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9e76983782
This is another reland of 4f8333e80e
.
Third time is the charm.
CoreLibraryReviewExempt: Reland of accepted CL.
Change-Id: I4ea8326af91c168b044d252162571d3fe697e4b0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/289826
Commit-Queue: Lasse Nielsen <lrn@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
145 lines
5 KiB
Dart
145 lines
5 KiB
Dart
// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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part of dart.core;
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/// An interface for basic searches within strings.
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abstract interface class Pattern {
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/// Matches this pattern against the string repeatedly.
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///
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/// If [start] is provided, matching will start at that index.
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///
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/// The returned iterable lazily finds non-overlapping matches
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/// of the pattern in the [string].
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/// If a user only requests the first match,
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/// this function should not compute all possible matches.
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///
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/// The matches are found by repeatedly finding the first match
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/// of the pattern in the string, initially starting from [start],
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/// and then from the end of the previous match (but always
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/// at least one position later than the *start* of the previous
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/// match, in case the pattern matches an empty substring).
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/// ```dart
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/// RegExp exp = RegExp(r'(\w+)');
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/// var str = 'Dash is a bird';
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/// Iterable<Match> matches = exp.allMatches(str, 8);
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/// for (final Match m in matches) {
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/// String match = m[0]!;
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/// print(match);
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/// }
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/// ```
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/// The output of the example is:
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/// ```
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/// a
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/// bird
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/// ```
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Iterable<Match> allMatches(String string, [int start = 0]);
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/// Matches this pattern against the start of `string`.
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///
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/// Returns a match if the pattern matches a substring of [string]
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/// starting at [start], and `null` if the pattern doesn't match
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/// at that point.
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///
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/// The [start] must be non-negative and no greater than `string.length`.
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/// ```dart
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/// final string = 'Dash is a bird';
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///
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/// var regExp = RegExp(r'bird');
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/// var match = regExp.matchAsPrefix(string, 10); // Match found.
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///
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/// regExp = RegExp(r'bird');
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/// match = regExp.matchAsPrefix(string); // null
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/// ```
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Match? matchAsPrefix(String string, [int start = 0]);
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}
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/// A result from searching within a string.
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///
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/// A `Match` or an [Iterable] of `Match` objects is returned from
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/// the [Pattern] matching methods
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/// ([Pattern.allMatches] and [Pattern.matchAsPrefix]).
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///
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/// The following example finds all matches of a [RegExp] in a [String]
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/// and iterates through the returned iterable of `Match` objects.
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/// ```dart
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/// final regExp = RegExp(r'(\w+)');
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/// const string = 'Parse my string';
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/// final matches = regExp.allMatches(string);
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/// for (final m in matches) {
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/// String match = m[0]!;
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/// print(match);
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/// }
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/// ```
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/// The output of the example is:
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/// ```
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/// Parse
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/// my
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/// string
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/// ```
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/// Some patterns, regular expressions in particular, may record substrings
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/// that were part of the matching. These are called _groups_ in the `Match`
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/// object. Some patterns may never have any groups, and their matches always
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/// have zero [groupCount].
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abstract interface class Match {
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/// The index in the string where the match starts.
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int get start;
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/// The index in the string after the last character of the match.
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int get end;
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/// The string matched by the given [group].
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///
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/// If [group] is 0, returns the entire match of the pattern.
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///
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/// The result may be `null` if the pattern didn't assign a value to it
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/// as part of this match.
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/// ```dart import:convert
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///
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/// final string = '[00:13.37] This is a chat message.';
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/// final regExp = RegExp(r'^\[\s*(\d+):(\d+)\.(\d+)\]\s*(.*)$');
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/// final match = regExp.firstMatch(string)!;
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/// final message = jsonEncode(match[0]!); // '[00:13.37] This is a chat message.'
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/// final hours = jsonEncode(match[1]!); // '00'
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/// final minutes = jsonEncode(match[2]!); // '13'
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/// final seconds = jsonEncode(match[3]!); // '37'
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/// final text = jsonEncode(match[4]!); // 'This is a chat message.'
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/// ```
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String? group(int group);
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/// The string matched by the given [group].
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///
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/// If [group] is 0, returns the match of the pattern.
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///
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/// Short alias for [Match.group].
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String? operator [](int group);
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/// A list of the groups with the given indices.
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///
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/// The list contains the strings returned by [group] for each index in
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/// [groupIndices].
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/// ```dart import:convert
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///
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/// final string = '[00:13.37] This is a chat message.';
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/// final regExp = RegExp(r'^\[\s*(\d+):(\d+)\.(\d+)\]\s*(.*)$');
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/// final match = regExp.firstMatch(string)!;
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/// final message = jsonEncode(match.groups([1, 2, 3, 4]));
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/// // ['00','13','37','This is a chat message.']
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/// ```
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List<String?> groups(List<int> groupIndices);
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/// Returns the number of captured groups in the match.
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///
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/// Some patterns may capture parts of the input that was used to
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/// compute the full match. This is the number of captured groups,
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/// which is also the maximal allowed argument to the [group] method.
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int get groupCount;
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/// The string on which this match was computed.
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String get input;
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/// The pattern used to search in [input].
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Pattern get pattern;
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}
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