[API Proposal]: `TextReader.ReadLines` and `ReadAllLines`

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
30/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
csharp
Domain
api

Research direction

Begin with TextReader's existing ReadLine and ReadToEnd APIs, then compare the System.IO.File.ReadLines and ReadAllLines counterparts. Resolve the proposed naming, return types, and async cancellation behavior before implementation; done means an agreed API design with matching tests.

Written by the indexing model from the issue text.

Description

api-suggestion area-System.IO
Background and motivation

Currently TextReader offers ReadLine and ReadToEnd methods (and their corresponding async variants). In many cases it is useful to read multiple lines until the end of stream.

Such APIs would be a counterpart to System.IO.File.ReadLines.

Underlying logic can utilize existing ReadLine implementation to enumerate until end of stream.

API Proposal
public class TextReader
{
   public virtual System.Collections.Generic.IEnumerable<string> ReadLines();
   public virtual System.Collections.Generic.IAsyncEnumerable<string> ReadLinesAsync(System.Threading.CancellationToken cancellationToken = default);

   public virtual IEnumrable<string> ReadAllLines();
   public virtual Task<IEnumerable<string>> ReadAllLinesAsync(System.Threading.CancellationToken cancellationToken = default);
}
API Usage
public async Task ProcessInput(StreamReader input)
{
    var lines = await input.ReadAllLines();
    var lineCount = lines.Length;
    ...
}
Alternative Designs
  • When the stream has already advanced, the meaning of ReadAllLines is not accurate. It might be better as ReadLinesToEnd and ReadLinesToEndAsync
  • ReadLinesToEnd return IEnumerable<string> whereas counterpart File.ReadAllLines returns string[] - not sure which is preferable
Dominant language
C#
Stars
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Forks
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