feat: inline methods consisting of a single return statement or local variable declaration expression

[hartmair]

feat: inline methods consisting of a single return statement or local variable declaration expression

Description

• feat: inline methods consisting of a single return statement
• feat: inline methods consisting of a single local variable declaration

Fixes # (issue)

Checklist

• The existing code style is followed
• The commit message follows our guidelines
• Performed a self-review of my code
• Hard-to-understand areas of my code are commented
• The documentation is updated (as applicable)
• Unit tests are added/updated
• Integration tests are added/updated (as applicable, especially if feature/bug depends on roslyn or framework version in use)

[trejjam]

You can do this with current features:

Source:

[Mapper]
public static partial class Mapper
{
    private static partial System.Linq.IQueryable<B> Map(this System.Linq.IQueryable<A> source);

    [MapProperty(nameof(C.Value), nameof(D.Value), Use = nameof(GetComputedValue))]
    private static partial D MapToD(C v);

    [UserMapping(Default = false)]
    private static string GetComputedValue(string value) => value + "-mapped";
}

class A { public string StringValue { get; set; } public C NestedValue { get; set; } }
class B { public string StringValue { get; set; } public D NestedValue { get; set; } }
class C { public string Value { get; set; } }
class D { public string Value { get; set; } }

Generated

// <auto-generated />
#nullable enable


    public static partial class Mapper
    {
        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "0.0.1.0")]
        private static partial global::System.Linq.IQueryable<B> Map(this global::System.Linq.IQueryable<A> source)
        {
#nullable disable
            return System.Linq.Queryable.Select(source, x => new B()
            {
                StringValue = x.StringValue,
                NestedValue = new D()
                {
                    Value = x.NestedValue.Value + "-mapped",
                },
            });
#nullable enable
        }

        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "0.0.1.0")]
        private static partial D MapToD(C v)
        {
            var target = new D();
            target.Value = GetComputedValue(v.Value);
            return target;
        }
    }

[hartmair]

@trejjam I know that you can do this if you use an expression body. That's the point of this pull request. That you don't have to think about the code style. It just works regardlessly how you write your user mapping.

[latonz]

Thank you for this contribution!
As @trejjam pointed out this works already by using method expressions. I can understand that there are use-cases where one doesn't want to use expressions and I think it's nice that the Mapperly inlining just works out of the box 😊
I added my feedback.

[latonz]

Relates #1406