More cases to optimize linq

[jamesHargreaves12]

Adds support for the following transformations:

OrderBy(...).FirstOrDefault() => MinBy(...)
OrderByDescending(...).FirstOrDefault() => MaxBy(...)

Do not restrict Applying Demorgans laws to the cases when the inside of the All / Any invocation is of the form !(...) - We can invert any boolean expression using SyntaxLogicalInverter.

[josefpihrt]

@jamesHargreaves12 MinBy/MaxBy throws exception in case of no elements so it should be First not FirstOrDefault.

[josefpihrt]

This is not maintainable as .NET version will grow.

I suggest to check if the MinBy method is contained in Enumerable class, for example:

enumerableSymbol.FindMember<IMethodSymbol>("MinBy") is not null

[jamesHargreaves12]

I agree thats much better :)

[josefpihrt]

Move to First case.

[jamesHargreaves12]

I don't think MaxBy does throw in the case of an empty List:
https://learn.microsoft.com/en-us/dotnet/api/system.linq.enumerable.minby?view=net-6.0
https://dotnetfiddle.net/4cdut9

[josefpihrt]

Ok, it does not throw always when the sequence is empty but sometimes it does:

https://source.dot.net/#System.Linq/System/Linq/Max.cs,442

/// <para>If <typeparamref name="TKey" /> is a reference type and the source sequence is empty or contains only values that are <see langword="null" />, this method returns <see langword="null" />.</para>

https://dotnetfiddle.net/BxHq1P

[jamesHargreaves12]

I have messed about with this some more and the Csharp docs are wrong it should be TSource instead of TKey which is checked for reference type.

[josefpihrt]

You are right that the doc is wrong, but the bottom line is that MaxBy throws sometimes which must be taken into account when applying these LINQ optimizations.

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