forki/linq.expression.optimizer

System.Linq.Expression expressions optimizer. http://thorium.github.io/Linq.Expression.Optimizer

Linq.Expression.Optimizer

Lightweight optimizer of System.Linq.Expression expressions. Just basic boolean algebra and reductions, constant and tuple/anonymous type eliminations. For side-effect free Expressions. No compilation-subjective optimizations. This is meant to be used with expressions that are not compiled but transferred to other domain.

Supported frameworks: Net 3.5, Net 4.5-... (and Mono), .NET Standard 1.6 (so also .NET Core)

Supported optimizations

Example as a quote. There are various other cases also.

• Replace constants comparisons: 3 < 4 -> true
• Remove anonymous types: new AnonymousObject(Item1 = x, Item2 = "").Item1 --> x
• Cut not used condition: if false then x else y -> y
• Remove not: not(false) -> true
• Binary tree balancing: a or (b or (c or (d or (e or (f or (g or h)))))) -> ((a or b) or (c or d)) or ((e or f) or (g or h))
• Captured closure constant ("free variable") evaluation: y = 3 and (y + x) -> (3 + x)
• Execute simple math: 5 * 3 -> 15
• Boolean algebra reductions:
  • gather (x or y) and (x or z) -> x or (y and z)
  • identity false or y -> y
  • annihilate true or x -> true
  • absorb x and (x or y) -> x
  • idempotence y or y -> y
  • complement x and not(x) -> false
  • doubleNegation not(not(y)) -> y
  • deMorgan not(x) and not(y) -> not(x or y)

Background

This is a side-track from SQLProvider, excelent tool that is kind of OR-mapper with auto-generated objects, so it compiles any databases to .NET-language, and works fast on design time in Visual Studio or other editors.

But I needed better SQL-queries. So this optimses .NET LINQ-expressions. These expressions were not ment to be compiled so Nessos LinqOptimizer was not the right tool. I thought that .NET would optimize these automatically, but no.

Read the Getting started tutorial to learn more.

Documentation: http://thorium.github.io/Linq.Expression.Optimizer

Maintainer(s)

• @thorium

If you want more optimizations, please feel free to send PRs!