├── .gitignore ├── EqualityGenerator ├── EqualityGenerator.csproj └── RecordEqualityGenerator.cs ├── RecordsRemove.sln ├── RecordsRemove ├── Program.cs └── RecordsRemove.csproj └── readme.md /.gitignore: -------------------------------------------------------------------------------- 1 | ## Ignore Visual Studio temporary files, build results, and 2 | ## files generated by popular Visual Studio add-ons. 3 | ## 4 | ## Get latest from https://github.com/github/gitignore/blob/master/VisualStudio.gitignore 5 | 6 | # User-specific files 7 | *.rsuser 8 | *.suo 9 | *.user 10 | *.userosscache 11 | *.sln.docstates 12 | 13 | # User-specific files (MonoDevelop/Xamarin Studio) 14 | *.userprefs 15 | 16 | # Mono auto generated files 17 | mono_crash.* 18 | 19 | # Build results 20 | [Dd]ebug/ 21 | [Dd]ebugPublic/ 22 | [Rr]elease/ 23 | [Rr]eleases/ 24 | x64/ 25 | x86/ 26 | [Ww][Ii][Nn]32/ 27 | [Aa][Rr][Mm]/ 28 | [Aa][Rr][Mm]64/ 29 | bld/ 30 | [Bb]in/ 31 | [Oo]bj/ 32 | [Ll]og/ 33 | [Ll]ogs/ 34 | 35 | # Visual Studio 2015/2017 cache/options directory 36 | .vs/ 37 | # Uncomment if you have tasks that create the project's static files in wwwroot 38 | #wwwroot/ 39 | 40 | # Visual Studio 2017 auto generated files 41 | Generated\ Files/ 42 | 43 | # MSTest test Results 44 | [Tt]est[Rr]esult*/ 45 | [Bb]uild[Ll]og.* 46 | 47 | # NUnit 48 | *.VisualState.xml 49 | TestResult.xml 50 | nunit-*.xml 51 | 52 | # Build Results of an ATL Project 53 | [Dd]ebugPS/ 54 | [Rr]eleasePS/ 55 | dlldata.c 56 | 57 | # Benchmark Results 58 | BenchmarkDotNet.Artifacts/ 59 | 60 | # .NET 61 | project.lock.json 62 | project.fragment.lock.json 63 | artifacts/ 64 | 65 | # Tye 66 | .tye/ 67 | 68 | # ASP.NET Scaffolding 69 | ScaffoldingReadMe.txt 70 | 71 | # StyleCop 72 | StyleCopReport.xml 73 | 74 | # Files built by Visual Studio 75 | *_i.c 76 | *_p.c 77 | *_h.h 78 | *.ilk 79 | *.meta 80 | *.obj 81 | *.iobj 82 | *.pch 83 | *.pdb 84 | *.ipdb 85 | *.pgc 86 | *.pgd 87 | *.rsp 88 | *.sbr 89 | *.tlb 90 | *.tli 91 | *.tlh 92 | *.tmp 93 | *.tmp_proj 94 | *_wpftmp.csproj 95 | *.log 96 | *.vspscc 97 | *.vssscc 98 | .builds 99 | *.pidb 100 | *.svclog 101 | *.scc 102 | 103 | # Chutzpah Test files 104 | _Chutzpah* 105 | 106 | # Visual C++ cache files 107 | ipch/ 108 | *.aps 109 | *.ncb 110 | *.opendb 111 | *.opensdf 112 | *.sdf 113 | *.cachefile 114 | *.VC.db 115 | *.VC.VC.opendb 116 | 117 | # Visual Studio profiler 118 | *.psess 119 | *.vsp 120 | *.vspx 121 | *.sap 122 | 123 | # Visual Studio Trace Files 124 | *.e2e 125 | 126 | # TFS 2012 Local Workspace 127 | $tf/ 128 | 129 | # Guidance Automation Toolkit 130 | *.gpState 131 | 132 | # ReSharper is a .NET coding add-in 133 | _ReSharper*/ 134 | *.[Rr]e[Ss]harper 135 | *.DotSettings.user 136 | 137 | # TeamCity is a build add-in 138 | _TeamCity* 139 | 140 | # DotCover is a Code Coverage Tool 141 | *.dotCover 142 | 143 | # AxoCover is a Code Coverage Tool 144 | .axoCover/* 145 | !.axoCover/settings.json 146 | 147 | # Coverlet is a free, cross platform Code Coverage Tool 148 | coverage*.json 149 | coverage*.xml 150 | coverage*.info 151 | 152 | # Visual Studio code coverage results 153 | *.coverage 154 | *.coveragexml 155 | 156 | # NCrunch 157 | _NCrunch_* 158 | .*crunch*.local.xml 159 | nCrunchTemp_* 160 | 161 | # MightyMoose 162 | *.mm.* 163 | AutoTest.Net/ 164 | 165 | # Web workbench (sass) 166 | .sass-cache/ 167 | 168 | # Installshield output folder 169 | [Ee]xpress/ 170 | 171 | # DocProject is a documentation generator add-in 172 | DocProject/buildhelp/ 173 | DocProject/Help/*.HxT 174 | DocProject/Help/*.HxC 175 | DocProject/Help/*.hhc 176 | DocProject/Help/*.hhk 177 | DocProject/Help/*.hhp 178 | DocProject/Help/Html2 179 | DocProject/Help/html 180 | 181 | # Click-Once directory 182 | publish/ 183 | 184 | # Publish Web Output 185 | *.[Pp]ublish.xml 186 | *.azurePubxml 187 | # Note: Comment the next line if you want to checkin your web deploy settings, 188 | # but database connection strings (with potential passwords) will be unencrypted 189 | *.pubxml 190 | *.publishproj 191 | 192 | # Microsoft Azure Web App publish settings. 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build; native; contentfiles; analyzers; buildtransitive 14 | 15 | 16 | 17 | 18 | 19 | 20 | -------------------------------------------------------------------------------- /EqualityGenerator/RecordEqualityGenerator.cs: -------------------------------------------------------------------------------- 1 | using System.Diagnostics; 2 | using System.Text; 3 | using Microsoft.CodeAnalysis; 4 | using Microsoft.CodeAnalysis.CSharp; 5 | using Microsoft.CodeAnalysis.CSharp.Syntax; 6 | using Microsoft.CodeAnalysis.Text; 7 | 8 | [Generator] 9 | public class RecordEqualityGenerator : ISourceGenerator 10 | { 11 | private const string AttributeText = @" 12 | using System; 13 | namespace RecordEquality 14 | { 15 | [AttributeUsage(AttributeTargets.Parameter, Inherited = false, AllowMultiple = false)] 16 | [System.Diagnostics.Conditional(""EqualityAttribute_DEBUG"")] 17 | sealed class EqualityAttribute : Attribute 18 | { 19 | } 20 | } 21 | "; 22 | 23 | public void Initialize(GeneratorInitializationContext context) 24 | { 25 | // Register the attribute source 26 | context.RegisterForPostInitialization(i => i.AddSource("RecordEqualityAttribute", AttributeText)); 27 | context.RegisterForSyntaxNotifications(() => new SyntaxReceiver()); 28 | } 29 | 30 | public void Execute(GeneratorExecutionContext context) 31 | { 32 | if (!(context.SyntaxContextReceiver is SyntaxReceiver receiver)) 33 | return; 34 | 35 | Debugger.Break(); 36 | 37 | foreach (var record in receiver.Records) 38 | { 39 | var propertyEquals = string.Join(" && ", record.Properties 40 | .Select(p => $"{p} == other.{p}") 41 | .ToList()); 42 | 43 | var hashCode = new StringBuilder("\n"); 44 | for (var index = 0; index < record.Properties.Count; index++) { 45 | var property = record.Properties[index]; 46 | hashCode.AppendLine(index == 0 47 | ? $" var hashCode = {property}.GetHashCode();" 48 | : $" hashCode = (hashCode * 397) ^ {property}.GetHashCode();"); 49 | } 50 | hashCode.AppendLine(" return hashCode;"); 51 | 52 | var source = 53 | $@"// Auto-generated code for {record.Name} 54 | 55 | public partial record {record.Name} 56 | {{ 57 | public virtual bool Equals({record.Name}? other) 58 | {{ 59 | if (ReferenceEquals(null, other)) return false; 60 | if (ReferenceEquals(this, other)) return true; 61 | return {propertyEquals}; 62 | }} 63 | 64 | public override int GetHashCode() 65 | {{{hashCode} 66 | }} 67 | }}"; 68 | context.AddSource($"{record.Name}__equality.cs", SourceText.From(source, Encoding.UTF8)); 69 | } 70 | } 71 | 72 | class SyntaxReceiver : ISyntaxContextReceiver 73 | { 74 | public record RecordResult(string Name, List Properties); 75 | 76 | public List Records { get; } 77 | = new (); 78 | 79 | public void OnVisitSyntaxNode(GeneratorSyntaxContext context) 80 | { 81 | // any field with at least one attribute is a candidate for property generation 82 | if (context.Node is RecordDeclarationSyntax rds && 83 | rds.Modifiers.Any(m => m.IsKind(SyntaxKind.PartialKeyword))) 84 | { 85 | var record = ModelExtensions.GetDeclaredSymbol(context.SemanticModel, rds); 86 | if (record is null) return; 87 | 88 | var result = new RecordResult(record.Name, new List()); 89 | var addRecord = false; 90 | 91 | foreach (var parameter in rds.ParameterList.Parameters) 92 | { 93 | var ps = ModelExtensions.GetDeclaredSymbol(context.SemanticModel, 94 | parameter) as IParameterSymbol; 95 | 96 | if (ps.GetAttributes().Any(a => a.AttributeClass.ToDisplayString() == "RecordEquality.EqualityAttribute")) 97 | { 98 | result.Properties.Add(ps.Name); 99 | addRecord = true; 100 | } 101 | } 102 | 103 | if (addRecord) 104 | { 105 | Records.Add(result); 106 | } 107 | } 108 | } 109 | } 110 | } -------------------------------------------------------------------------------- /RecordsRemove.sln: -------------------------------------------------------------------------------- 1 |  2 | Microsoft Visual Studio Solution File, Format Version 12.00 3 | Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "RecordsRemove", "RecordsRemove\RecordsRemove.csproj", "{DFF08C16-7CBD-4291-8C76-F367E9B8807A}" 4 | EndProject 5 | Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EqualityGenerator", "EqualityGenerator\EqualityGenerator.csproj", "{B2B5EAA9-61AB-41AC-8102-B6F5F7D0D37F}" 6 | EndProject 7 | Global 8 | GlobalSection(SolutionConfigurationPlatforms) = preSolution 9 | Debug|Any CPU = Debug|Any CPU 10 | Release|Any CPU = Release|Any CPU 11 | EndGlobalSection 12 | GlobalSection(ProjectConfigurationPlatforms) = postSolution 13 | {DFF08C16-7CBD-4291-8C76-F367E9B8807A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 14 | {DFF08C16-7CBD-4291-8C76-F367E9B8807A}.Debug|Any CPU.Build.0 = Debug|Any CPU 15 | {DFF08C16-7CBD-4291-8C76-F367E9B8807A}.Release|Any CPU.ActiveCfg = Release|Any CPU 16 | {DFF08C16-7CBD-4291-8C76-F367E9B8807A}.Release|Any CPU.Build.0 = Release|Any CPU 17 | {B2B5EAA9-61AB-41AC-8102-B6F5F7D0D37F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 18 | {B2B5EAA9-61AB-41AC-8102-B6F5F7D0D37F}.Debug|Any CPU.Build.0 = Debug|Any CPU 19 | {B2B5EAA9-61AB-41AC-8102-B6F5F7D0D37F}.Release|Any CPU.ActiveCfg = Release|Any CPU 20 | {B2B5EAA9-61AB-41AC-8102-B6F5F7D0D37F}.Release|Any CPU.Build.0 = Release|Any CPU 21 | EndGlobalSection 22 | EndGlobal 23 | -------------------------------------------------------------------------------- /RecordsRemove/Program.cs: -------------------------------------------------------------------------------- 1 | using RecordEquality; 2 | using static System.Console; 3 | 4 | var items = new List 5 | { 6 | new(1, "The Witcher 3", 60m), 7 | new(2, "Elden Ring", 60m), 8 | new(3, "King of Fighters XV", 50m), 9 | new(4, "Street Fighter V", 30m) 10 | }; 11 | 12 | WriteLine($"Items in Cart (before): {items.Count}"); 13 | 14 | // remove record with value equality 15 | // not with reference equality 16 | var item = new CartItem(1, "The Witcher 3"); 17 | items.Remove(item); 18 | 19 | // before records, you'd have to do this 20 | // items.RemoveAll(i => i.Name == item.Name); 21 | 22 | WriteLine($"Items in Cart (after): {items.Count}"); 23 | 24 | public partial record CartItem( 25 | [Equality] int Id, 26 | [Equality] string Name = "", 27 | decimal Price = 0m); -------------------------------------------------------------------------------- /RecordsRemove/RecordsRemove.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | Exe 5 | net6.0 6 | enable 7 | enable 8 | 9 | 10 | 11 | 12 | all 13 | runtime; build; native; contentfiles; analyzers; buildtransitive 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | -------------------------------------------------------------------------------- /readme.md: -------------------------------------------------------------------------------- 1 | # Record Equality Source Generator 2 | 3 | This is a sample where I use an attribute to modify a records 4 | default equality operator using an `Equality` attribute and the 5 | use of the `partial` keyword. 6 | 7 | ## Reasoning 8 | 9 | Records use value equality, but often domain entities have identifiers 10 | that denote the `identity` of a record, and that's what we want to compare. 11 | Other values on the entity might be different, but logically they may be 12 | the same entity. 13 | 14 | ## Use Case 15 | 16 | The common use case is we want to look at an `Id` property. You'd use 17 | the source generator 18 | 19 | ```c# 20 | public partial record CartItem( 21 | [Equality] int Id, 22 | string Name = "", 23 | decimal Price = 0m); 24 | ``` 25 | 26 | Now when you compare two `CartItem` instances, they will compare based 27 | on the value of `Id` alone. 28 | You may also add the equality attribute on multiple properties for composite keys. 29 | 30 | ```c# 31 | public partial record CartItem( 32 | [Equality] int Id, 33 | [Equality] string Name = "", 34 | decimal Price = 0m); 35 | ``` 36 | 37 | ## Possible Improvements 38 | 39 | If you're interested in using this in your project, some other improvements might include: 40 | 41 | - Supporting Comparison types like `Oridinal` or `Ignore Case` on properties that support such comparers i.e. `string`. 42 | - Overriding the `EqualityContract` to support inheritance comparison properly. 43 | 44 | ## License 45 | 46 | The MIT License (MIT) 47 | Copyright © 2022 Khalid Abuhakmeh 48 | 49 | Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: 50 | 51 | The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. 52 | 53 | THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 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