https://github.com/thorium/linq.expression.optimizer

System.Linq.Expression expressions optimizer. http://thorium.github.io/Linq.Expression.Optimizer
https://github.com/thorium/linq.expression.optimizer

boolean-algebra expression-tree linq mathematical-expressions optimisation optimization reduction sql

Last synced: 13 days ago
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System.Linq.Expression expressions optimizer. http://thorium.github.io/Linq.Expression.Optimizer

• Host: GitHub
• URL: https://github.com/thorium/linq.expression.optimizer
• Owner: Thorium
• License: unlicense
• Created: 2016-08-27T21:15:30.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2024-10-30T19:59:53.000Z (14 days ago)
• Last Synced: 2024-10-30T20:23:42.629Z (13 days ago)
• Topics: boolean-algebra, expression-tree, linq, mathematical-expressions, optimisation, optimization, reduction, sql
• Language: F#
• Homepage:
• Size: 464 KB
• Stars: 104
• Watchers: 13
• Forks: 6
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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# 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 domains.

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](https://github.com/fsprojects/SQLProvider), excellent 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 optimises .NET LINQ-expressions.

These expressions were not meant to be compiled, so [Nessos LinqOptimizer](https://github.com/nessos/LinqOptimizer) was not the right tool.

I thought that .NET would optimize these automatically, but no.

   

Read the [Getting started tutorial](http://thorium.github.io/Linq.Expression.Optimizer/index.html#Getting-started) to learn more.

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

## Maintainer(s)

- [@thorium](https://github.com/thorium)

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