[API Proposal]: ReadOnlySpan<char>.StartsWithAny(SearchValues<string>) and ReadOnlySpan<char>.EndsWithAny(SearchValues<string>)
Nobody has claimed this yet.
Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 35/100
Research direction
Start by reading the proposed MemoryExtensions APIs and the related issue #94155 to understand the existing SearchValues span extensions. Investigate the surrounding runtime API and testing conventions before deciding whether the proposal fits. Done means both StartsWithAny and EndsWithAny APIs are designed, implemented, and validated consistently with the existing extensions.
Written by the indexing model from the issue text.
Description
Background and motivation
There currently doesn't seem to be a means of checking whether the beginning or the end of a string equals to any of the values contained in a specified set of values in an optimized way using SearchValues<string> that was introduced in .NET 9. There are other specialized extension APIs involving ReadOnlySpan<char> and SearchValues<string> that were recently added (e.g. IndexOfAny<T>(ReadOnlySpan<char>, SearchValues<string>), ContainsAny(ReadOnlySpan<char>, SearchValues<string>) et al.) but this particular API seems to be missing.
One use case could be if you need to efficiently check whether a string starts with any one of a particular set of prefixes in order to determine whether your application code supports or handles that particular item.
See also #94155.
API Proposal
namespace System;
public static class MemoryExtensions
{
// Proposed
public static bool StartsWithAny(this System.ReadOnlySpan<char> span, System.Buffers.SearchValues<string> values);
public static bool EndsWithAny(this System.ReadOnlySpan<char> span, System.Buffers.SearchValues<string> values);
}
API Usage
var searchValues = SearchValues.Create(new[] { "P1", A99", "B44" }.AsSpan(), StringComparison.Ordinal);
var isSupported = "testValue".StartsWithAny(searchValues);
var isSupported2 = "testValue".EndsWithAny(searchValues);
Alternative Designs
N/A
Risks
N/A
- Dominant language
- C#
- Stars
- 18.3k
- Forks
- 5.6k
- PR merge metrics
- PR metrics pending
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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