implementation of IStructuralEquatable

object equatable.ps1

using namespace System.Collections

class PSCustomObjectEquatable : IEquatable[object] {
    hidden [object[]] $Properties
    hidden [object[]] $Values
    [object] $Instance

    PSCustomObjectEquatable([object] $Instance) {
        $psProperties    = $Instance.PSObject.Properties
        $this.Instance   = $Instance
        $this.Properties = @($psProperties.Name)
        $this.Values     = @($psProperties.Value)
    }

    [bool] Equals([object] $Other) {
        return [PSCustomObjectEquatable]::Equals($this, [PSCustomObjectEquatable] $Other)
    }

    hidden static [bool] Equals(
        [PSCustomObjectEquatable] $LHS,
        [PSCustomObjectEquatable] $RHS
    ) {
        if(-not $LHS.Properties.Count.Equals($RHS.Properties.Count)) {
            return $false
        }

        if(-not $LHS.Values.Count.Equals($RHS.Values.Count)) {
            return $false
        }

        $Comparer = [StructuralComparisons]::StructuralEqualityComparer

        return $Comparer.Equals($LHS.Properties, $RHS.Properties) -and
               $Comparer.Equals($LHS.Values, $RHS.Values)
    }

    [int] GetHashCode() {
        $comparer = [StructuralComparisons]::StructuralEqualityComparer

        return ([IStructuralEquatable] $this.Properties).GetHashCode($comparer) -bxor
               ([IStructuralEquatable] $this.Values).GetHashCode($comparer)
    }
}

$hash = [System.Collections.Generic.HashSet[PSCustomObjectEquatable]]::new()
$hash.Add([PSCustomObjectEquatable] [pscustomobject]@{ foo = 'hello'; bar = 'World'; baz = 123 }) # true
$hash.Add([PSCustomObjectEquatable] [pscustomobject]@{ foo = 'hello'; bar = 'World'; baz = 123 }) # false
$hash.Add([PSCustomObjectEquatable] [pscustomobject]@{ foo = 'HELLO'; bar = 'World'; baz = 123 }) # true

[PSCustomObjectEquatable] [pscustomobject]@{ foo = 'hello'; bar = 'World'; baz = 123 } -eq
[PSCustomObjectEquatable] [pscustomobject]@{ foo = 'HELLO'; bar = 'World'; baz = 123 } # false

[PSCustomObjectEquatable] [pscustomobject]@{ foo = 'hello'; bar = 'World'; baz = 123 } -eq
[PSCustomObjectEquatable] [pscustomobject]@{ foo = 'hello'; bar = 'World'; baz = 123 } # true