DeepEqual.Generator 1.0.3

DeepEqual.Generator

A C# source generator that creates super-fast, allocation-free deep equality comparers for your classes and structs.

Stop writing Equals by hand. Stop serializing to JSON just to compare objects. Just add an attribute, and you get a complete deep comparer generated at compile time.

✨ Why use this?

• Simple – annotate your models, and you’re done.
• Flexible – opt-in options for unordered collections, numeric tolerances, string case sensitivity, custom comparers.
• Robust – covers tricky cases (cycles, sets, dictionaries, polymorphism) that manual code often misses.

⚡ Why is it faster than handwritten code?

• Compile-time codegen: emitted at build time as optimized IL — no reflection, no runtime expression building.
• Direct member access: expands equality checks into straight-line code instead of generic loops or helper calls.
• No allocations: avoids closures, iterators, or boxing that sneak into LINQ or naive implementations.

Result: consistently 5–7× faster than handwritten comparers, and orders of magnitude faster than JSON/library approaches.

🛡️ Why is it more robust?

• Covers corner cases: nested collections, dictionaries, sets, polymorphism, reference cycles.
• Deterministic: guarantees the same behavior regardless of field order or shape.
• Safer than manual: no risk of forgetting a property or comparing the wrong shape.

In short: you get the speed of hand-tuned code, but with the coverage of a well-tested library — and without runtime overhead.

📦 Installation

You need two packages:

dotnet add package DeepEqual.Generator.Shared
dotnet add package DeepEqual.Generator

• Shared → contains runtime comparers and attributes.
• Generator → analyzer that emits the equality code at compile time.

If you install only the generator, builds will fail because the generated code depends on the runtime package.

🚀 Quick start

Annotate your type:

using DeepEqual.Generator.Shared;

[DeepComparable]
public sealed class Person
{
    public string Name { get; set; } = "";
    public int Age { get; set; }
}

At compile time, a static helper is generated:

PersonDeepEqual.AreDeepEqual(personA, personB);

🔍 Supported comparisons

• Primitives & enums – by value.
• Strings – configurable (ordinal, ignore case, culture aware).
• DateTime / DateTimeOffset – strict (both Kind/Offset and Ticks must match).
• Guid, TimeSpan, DateOnly, TimeOnly – by value.
• Nullable<T> – compared only if both have a value.
• Arrays & collections – element by element.
• Dictionaries – key/value pairs deeply compared.
• Jagged & multidimensional arrays – handled correctly.
• Object properties – compared polymorphically if the runtime type has a generated helper.
• Dynamics / ExpandoObject – compared as dictionaries.
• Cycles – supported (can be turned off if you know your graph has no cycles).

🎛 Options

On the root type

[DeepComparable(OrderInsensitiveCollections = true, IncludeInternals = true, IncludeBaseMembers = true)]
public sealed class Order { … }

Defaults:

• OrderInsensitiveCollections → false
• IncludeInternals → false
• IncludeBaseMembers → true
• CycleTracking → true

On individual members

public sealed class Person
{
    [DeepCompare(Kind = CompareKind.Shallow)]
    public Address? Home { get; set; }

    [DeepCompare(OrderInsensitive = true)]
    public List<string>? Tags { get; set; }

    [DeepCompare(IgnoreMembers = new[] { "CreatedAt", "UpdatedAt" })]
    public AuditInfo Info { get; set; } = new();
}

📚 Ordered vs unordered collections

By default, collections are compared in order. If you want them compared ignoring order (like sets), you can:

• Enable globally:

[DeepComparable(OrderInsensitiveCollections = true)]
public sealed class OrderBatch
{
    public List<int> Ids { get; set; } = new();
}

• On specific members:

public sealed class TagSet
{
    [DeepCompare(OrderInsensitive = true)]
    public List<string> Tags { get; set; } = new();
}

• Or use key-based matching:

[DeepCompare(KeyMembers = new[] { "Id" })]
public sealed class Customer
{
    public string Id { get; set; } = "";
    public string Name { get; set; } = "";
}

⚡ Numeric & string options

var opts = new ComparisonOptions
{
    FloatEpsilon = 0f,
    DoubleEpsilon = 0d,
    DecimalEpsilon = 0m,
    TreatNaNEqual = false,
    StringComparison = StringComparison.Ordinal
};

Defaults: strict equality for numbers and case-sensitive ordinal for strings.

🌀 Cycles

Cyclic graphs are handled safely:

[DeepComparable]
public sealed class Node
{
    public string Id { get; set; } = "";
    public Node? Next { get; set; }
}

var a = new Node { Id = "a" };
var b = new Node { Id = "a" };
a.Next = a;
b.Next = b;

NodeDeepEqual.AreDeepEqual(a, b);

📊 Benchmarks

The generated comparer outperforms handwritten, JSON, and popular libraries by a wide margin:

✅ When to use

• Large object graphs (domain models, caches, trees).
• Unit/integration tests where you assert deep equality.
• Regression testing with snapshot objects.
• High-throughput APIs needing object deduplication.
• Anywhere you need correctness and speed.

📦 Roadmap

• Strict time semantics
• Numeric tolerances
• String comparison options
• Cycle tracking
• Include internals & base members
• Order-insensitive collections
• Key-based unordered matching
• Custom comparers
• Memory<T> / ReadOnlyMemory<T>
• Benchmarks & tests
• Analyzer diagnostics
• Developer guide & samples site

update the benchmark to use the unit next to the number and increase unit ns, ms, s, etc, based on the number size