Join.psm1

<#PSScriptInfo
.VERSION 3.8.3
.GUID 54688e75-298c-4d4b-a2d0-d478e6069126
.AUTHOR Ronald Bode (iRon)
.DESCRIPTION Join-Object combines two object lists based on a related property between them.
.COMPANYNAME PowerSnippets.com
.COPYRIGHT Ronald Bode (iRon)
.TAGS Join-Object Join InnerJoin LeftJoin RightJoin FullJoin OuterJoin CrossJoin Update Merge Difference Combine Table
.LICENSEURI https://github.com/iRon7/Join-Object/LICENSE
.PROJECTURI https://github.com/iRon7/Join-Object
.ICONURI https://raw.githubusercontent.com/iRon7/Join-Object/master/Join-Object.png
.EXTERNALMODULEDEPENDENCIES
.REQUIREDSCRIPTS
.EXTERNALSCRIPTDEPENDENCIES
.RELEASENOTES To install the new Join module equivalent: Install-Module -Name JoinModule
.PRIVATEDATA
#>

<#
.SYNOPSIS
    Combines two object lists based on a related property between them.

.DESCRIPTION
    Combines properties from one or more objects. It creates a set that can be saved as a new object or used as it is.
    An object join is a means for combining properties from one (self-join) or more object lists by using values common
    to each.

    Main features:
    * An intuitive idiomatic PowerShell syntax
    * SQL like joining features
    * Smart property merging
    * Predefined join commands for updating, merging and specific join types
    * Well defined pipeline for the (left) input objects and output objects (streaming preserves memory)
    * Performs about twice as fast as Compare-Object on large object lists
    * Supports a list of (custom) objects, strings or primitives and dictionaries (e.g. hash tables) and data tables for input
    * Smart properties and calculated property expressions
    * Custom relation expressions
    * Module (Install-Module -Name JoinModule) or (dot-sourcing) Script version (`Install-Script -Name Join`)
    * Supports PowerShell for Windows (5.1) and PowerShell Core

    The Join-Object cmdlet reveals the following proxy commands with their own ([-JoinType] and [-Property]) defaults:
    * `InnerJoin-Object` (Alias `InnerJoin` or `Join`), combines the related objects
    * `LeftJoin-Object` (Alias `LeftJoin`), combines the related objects and adds the rest of the left objects
    * `RightJoin-Object` (Alias `RightJoin`), combines the related objects and adds the rest of the right objects
    * `OuterJoin-Object` (Alias `OuterJoin`), returns the symmetric difference of the unrelated objects
    * `FullJoin-Object` (Alias `FullJoin`), combines the related objects and adds the rest of the left and right objects
    * `CrossJoin-Object` (Alias `CrossJoin`), combines each left object with each right object
    * `Update-Object` (Alias `Update`), updates the left object with the related right object
    * `Merge-Object` (Alias `Merge`), updates the left object with the related right object and adds the rest of the
      new (unrelated) right objects
    * `Get-Difference` (Alias `Differs`), returns the symmetric different objects and their properties

.PARAMETER LeftObject
    The left object list, usually provided through the pipeline, to be joined.

    > **Note:** a self-join on the `LeftObject` list will be performed if the `RightObject` is omitted.

.PARAMETER RightObject
    The right object list, provided by the first argument, to be joined.

    > **Note:** a self-join on the `RightObject` list will be performed if the `LeftObject` is omitted.

.PARAMETER On
    The [-On] parameter defines which objects should be joined together.\
    If the [-Equals] parameter is omitted, the value(s) of the properties listed by the -On parameter should be
    equal at both sides in order to join the left object with the right object.\
    If the [-On] parameter contains an expression, the expression will be evaluted where `$_`, `$PSItem` and
    `$Left` contains the currect object. The result of the expression will be compared to right object property
    defined by the [-Equals] parameter.

    > **Note 1:** The list of properties defined by the [-On] parameter will be complemented with the list of
    properties defined by the [-Equals] parameter and vice versa.

    > **Note 2:** Related properties will be merged to a single property by default (see also the [-Property]
    parameter).

    > **Note 3:** If the [-On] and the [-Using] parameter are omitted, a side-by-side join is returned unless
    `OuterJoin` is performed where the default [-On] parameter value is * (all properties).

    > **Note 4:** if the left object is a scalar array, the [-On] parameters is used to name the scalar array

.PARAMETER Equals
    If the [-Equals] parameter is supplied, the value(s) of the left object properties listed by the [-On]
    parameter should be equal to the value(s)of the right object listed by the [-Equals] parameter in order to
    join the left object with the right object.\
    If the [-Equals] parameter contains an expression, the expression will be evaluted where `$_`, `$PSItem` and
    `$Right` contains the currect object. The result of the expression will be compared to left object property
    defined by the [-On] parameter.

    > **Note 1:** The list of properties defined by the [-Equal] parameter will be complemented with the list of
    properties defined by the -On parameter and vice versa. This means that by default value of the [-Equals]
    parameter is equal to the value supplied to the [-On] parameter

    > **Note 2:** A property will be omitted in the results if it exists on both sides and if the property at the
    other side is related to another property.

    > **Note 3:** The [-Equals] parameter can only be used with the [-On] parameter.

    > **Note 4:** if the right object is a scalar array, the [-Equals] parameters is used to name the scalar array

.PARAMETER Strict
    If the [-Strict] switch is set, the comparison between the related properties defined by the [-On] Parameter
    (and the [-Equals] parameter) is based on a strict equality (both type and value need to be equal).

.PARAMETER MatchCase
    If the [-MatchCase] (alias `-CaseSensitive`) switch is set, the comparison between the related properties
    defined by the [-On] Parameter (and the [-Equals] parameter) will case sensitive.

.PARAMETER Using
    Any conditional expression that requires to evaluate to true in order to join the left object with the
    right object.

    The following variables are exposed for a (ScriptBlock) expression:
    * `$_`: iterates each property name
    * `$Left`: a hash table representing the current left object (each self-contained [-LeftObject]).
      The hash table will be empty (`@{}`) in the outer part of a left join or full join.
    * `$LeftIndex`: the index of the left object (`$Null` in the outer part of a right- or full join)
    * `$Right`: a hash table representing the current right object (each self-contained [-RightObject])
      The hash table will be empty (`@{}`) in the outer part of a right join or full join.
    * `$RightIndex`: the index of the right object (`$Null` in the outer part of a left- or full join)


    > **Note 1:** The -Using parameter has the most complex comparison possibilities but is considerable slower
    than the [-On] parameter.

    > **Note 2:** The [-Using] parameter cannot be used with the [-On] parameter.

.PARAMETER Where
    An expression that defines the condition to be met for the objects to be returned. See the [-Using]
    parameter for available expression variables.

.PARAMETER Discern
    By default unrelated properties with the same name will be collected in a single object property.
    The [-Discern] parameter (alias [-NameItems])  defines how to rename the object properties and divide
    them over multiple properties. If a given name pattern contains an asterisks (`*`), the asterisks
    will be replaced with the original property name. Otherwise, the property name for each property
    item will be prefixed with the given name pattern.

    The property collection of multiple (chained) join commands can be divided in once from the last join
    command in the change. The rename patterns are right aligned, meaning that the last renamed pattern
    will be applied to the last object joined. If there are less rename patterns than property items,
    the rest of the (left most) property items will be put in a fixed array under the original property name.

    > **Note 1:** Only properties with the same name on both sides will not be renamed.

    > **Note 2:** Related properties (with an equal value defined by the [-On] parameter) will be merged to a single
    item.

.PARAMETER Property
    A hash table or list of property names (strings) and/or hash tables that define a new selection of
    property names and values

    Hash tables should be in the format `@{<PropertyName> = <Expression>}` where the `<Expression>` is a
    ScriptBlock or a smart property (string) and defines how the specific left and right properties should be
    merged. See the [-Using] parameter for available expression variables.

    The following smart properties are available:
    * A general property: '<Property Name>', where `<Property Name>` represents the property name of the left
      and/or right property, e.g. `@{ MyProperty = 'Name' }`. If the property exists on both sides, an array
      holding both values will be returned. In the outer join, the value of the property will be `$Null`.
      This smart property is similar to the expression: `@{ MyProperty = { @($Left['Name'], $Right['Name']) } }`
    * A general wildcard property: `'*'`, where `* `represents the property name of the current property, e.g.
      `MyProperty` in `@{ MyProperty = '*' }`. If the property exists on both sides:
      - and the properties are unrelated, an array holding both values will be returned
      - and the properties are related to each other, the (equal) values will be merged in one property value
      - and the property at the other side is related to an different property, the property is omitted
      The argument: `-Property *`, will apply a general wildcard on all left and right properties.
    * A left property: `;Left.<Property Name>'`, or right property: `;Right.<Property Name>'`, where
      `<Property Name>` represents the property name of the either the left or right property. If the property
      doesn't exist, the value of the property will be `$Null`.
    * A left wildcard property: `'Left.*'`, or right wildcard property: `Right.*`, where `*` represents the
      property name of the current the left or right property, e.g. `MyProperty` in `@{ MyProperty = 'Left.*' }`.
      If the property doesn't exist (in an outer join), the property with the same name at the other side will
      be taken. If the property doesn't exist on either side, the value of the property will be `$Null`.
      The argument: `-Property 'Left.*'`, will apply a left wildcard property on all the left object properties.

    If the [-Property] parameter and the [-Discern] parameter are omitted, a general wildcard property is applied
    on all the left and right properties.

    The last defined expression or smart property will overrule any previous defined properties.

.PARAMETER ValueName
    Defines the name of the added property in case a scalar array is joined with an object array.
    The default property name for each scalar is: `<Value>`.

    > **Note:** if two scalar (or collection) arrays are joined, an array of (psobject) collections is returned.
    Each collection is a concatenation of the left item (collection) and the right item (collection).

.PARAMETER JoinType
    Defines which unrelated objects should be included (see: [Description]).
    Valid values are: `Inner`, `Left`, `Right`, `Full` or `Cross`. The default is `Inner`.

    > **Note:** it is recommended to use the related proxy commands (`... |<JoinType>-Object ...`) instead.

.EXAMPLE
    # Common (inner) join
    The following example will show an inner join based on the `country` property.\
    Given the following object lists:

    PS C:\> $Employee

        Id Name    Country Department  Age ReportsTo
        -- ----    ------- ----------  --- ---------
         1 Aerts   Belgium Sales        40         5
         2 Bauer   Germany Engineering  31         4
         3 Cook    England Sales        69         1
         4 Duval   France  Engineering  21         5
         5 Evans   England Marketing    35
         6 Fischer Germany Engineering  29         4

    PS C:\> $Department

        Name        Country
        ----        -------
        Engineering Germany
        Marketing   England
        Sales       France
        Purchase    France


    PS C:\> $Employee |Join $Department -On Country |Format-Table

        Id Name                   Country Department  Age ReportsTo
        -- ----                   ------- ----------  --- ---------
         2 {Bauer, Engineering}   Germany Engineering  31         4
         3 {Cook, Marketing}      England Sales        69         1
         4 {Duval, Sales}         France  Engineering  21         5
         4 {Duval, Purchase}      France  Engineering  21         5
         5 {Evans, Marketing}     England Marketing    35
         6 {Fischer, Engineering} Germany Engineering  29         4

.EXAMPLE
    # Full join overlapping column names

    The example below does a full join of the tables mentioned in the first example based
    on the `department` name and splits the duplicate (`country`) names over differend properties.

    PS C:\> $Employee |InnerJoin $Department -On Department -Equals Name -Discern Employee, Department |Format-Table

        Id Name    EmployeeCountry DepartmentCountry Department  Age ReportsTo
        -- ----    --------------- ----------------- ----------  --- ---------
         1 Aerts   Belgium         France            Sales        40         5
         2 Bauer   Germany         Germany           Engineering  31         4
         3 Cook    England         France            Sales        69         1
         4 Duval   France          Germany           Engineering  21         5
         5 Evans   England         England           Marketing    35
         6 Fischer Germany         Germany           Engineering  29         4

.EXAMPLE
    # merge a table with updates

    This example merges the following `$Changes` list into the `$Employee` list of the first example.

    PS C:\> $Changes

        Id Name    Country Department  Age ReportsTo
        -- ----    ------- ----------  --- ---------
         3 Cook    England Sales        69         5
         6 Fischer France  Engineering  29         4
         7 Geralds Belgium Sales        71         1

    PS C:\> # Apply the changes to the employees
    PS C:\> $Employee |Merge $Changes -On Id |Format-Table

        Id Name    Country Department  Age ReportsTo
        -- ----    ------- ----------  --- ---------
         1 Aerts   Belgium Sales        40         5
         2 Bauer   Germany Engineering  31         4
         3 Cook    England Sales        69         5
         4 Duval   France  Engineering  21         5
         5 Evans   England Marketing    35
         6 Fischer France  Engineering  29         4
         7 Geralds Belgium Sales        71         1

.EXAMPLE
    # Self join

    This example shows a (self)join where each employee is connected with another employee on the country.

    PS C:\> $Employee | Join -On Country -Discern *1,*2 |Format-Table *

        Id1 Id2 Name1   Name2   Country Department1 Department2 Age1 Age2 ReportsTo1 ReportsTo2
        --- --- -----   -----   ------- ----------- ----------- ---- ---- ---------- ----------
          2   6 Bauer   Fischer Germany Engineering Engineering   31   29          4          4
          3   5 Cook    Evans   England Sales       Marketing     69   35          1
          5   3 Evans   Cook    England Marketing   Sales         35   69                     1
          6   2 Fischer Bauer   Germany Engineering Engineering   29   31          4          4

.EXAMPLE
    # Join a scalar array

    This example adds an Id to the department list.\
    note that the default column name of (nameless) scalar array is `<Value>` this will show when the [-ValueName] parameter is ommited.

    PS C:\> 1..9 |Join $Department -ValueName Id

        Id Name        Country
        -- ----        -------
         1 Engineering Germany
         2 Marketing   England
         3 Sales       France
         4 Purchase    France

.EXAMPLE
    # Transpose arrays

    The following example, the `join-Object` cmdlet (`... |Join`) joins multiple arrays to a collection array.\
    The [Foreach-Object] cmdlet iterates over the rows and the `-Join` operator concatinates the item collections

    PS C:\> $a = 'a1', 'a2', 'a3', 'a4'
    PS C:\> $b = 'b1', 'b2', 'b3', 'b4'
    PS C:\> $c = 'c1', 'c2', 'c3', 'c4'
    PS C:\> $d = 'd1', 'd2', 'd3', 'd4'

    PS C:\> $a |Join $b |Join $c |Join $d |% { $_ -Join '|' }

        a1|b1|c1|d1
        a2|b2|c2|d2
        a3|b3|c3|d3
        a4|b4|c4|d4

.EXAMPLE
    # Arrays to objects

    This example will change the collections of the previous example into objects with named properties.

    PS C:\> $a |Join $b |Join $c |Join $d -Name a, b, c, d

        a  b  c  d
        -  -  -  -
        a1 b1 c1 d1
        a2 b2 c2 d2
        a3 b3 c3 d3
        a4 b4 c4 d4

.LINK
    https://www.powershellgallery.com/packages/Join
    https://www.powershellgallery.com/packages/JoinModule
    https://github.com/iRon7/Join-Object
    https://github.com/PowerShell/PowerShell/issues/14994 (Please give a thumbs up if you like to support the proposal to "Add a Join-Object cmdlet to the standard PowerShell equipment")
#>

function Join-Object {
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute('InjectionRisk.Create', '', Scope = 'Function')]
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute('InjectionRisk.ForeachObjectInjection', '', Scope = 'Function')]
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSUseLiteralInitializerForHashtable', '', Scope = 'Function')]
    [CmdletBinding(DefaultParameterSetName = 'Default')][OutputType([Object[]])] param(

        [Parameter(ValueFromPipeLine = $True, ParameterSetName = 'Default')]
        [Parameter(ValueFromPipeLine = $True, ParameterSetName = 'On')]
        [Parameter(ValueFromPipeLine = $True, ParameterSetName = 'Using')]
        $LeftObject,

        [Parameter(Position = 0, ParameterSetName = 'Default')]
        [Parameter(Position = 0, ParameterSetName = 'On')]
        [Parameter(Position = 0, ParameterSetName = 'Using')]
        $RightObject,

        [Parameter(Position = 1, ParameterSetName = 'On')]
        [array]$On = @(),

        [Parameter(Position = 1, ParameterSetName = 'Using')]
        [scriptblock]$Using,

        [Parameter(ParameterSetName = 'On')]
        [Alias('Eq')][array]$Equals = @(),

        [Parameter(Position = 2, ParameterSetName = 'Default')]
        [Parameter(Position = 2, ParameterSetName = 'On')]
        [Parameter(Position = 2, ParameterSetName = 'Using')]
        [Alias('NameItems')][AllowEmptyString()][String[]]$Discern,

        [Parameter(ParameterSetName = 'Default')]
        [Parameter(ParameterSetName = 'On')]
        [Parameter(ParameterSetName = 'Using')]
        $Property,

        [Parameter(Position = 3, ParameterSetName = 'Default')]
        [Parameter(Position = 3, ParameterSetName = 'On')]
        [Parameter(Position = 3, ParameterSetName = 'Using')]
        [scriptblock]$Where,

        [Parameter(ParameterSetName = 'Default')]
        [Parameter(ParameterSetName = 'On')]
        [Parameter(ParameterSetName = 'Using')]
        [ValidateSet('Inner', 'Left', 'Right', 'Full', 'Outer', 'Cross')][String]$JoinType = 'Inner',

        [Parameter(ParameterSetName = 'Default')]
        [Parameter(ParameterSetName = 'On')]
        [Parameter(ParameterSetName = 'Using')]
        [string]$ValueName = '<Value>',

        [Parameter(ParameterSetName = 'On')]
        [switch]$Strict,

        [Parameter(ParameterSetName = 'On')]
        [Alias('CaseSensitive')][switch]$MatchCase
    )
    begin {
        $Esc = "`u{1B}``"
        function StopError($Exception, $Id = 'IncorrectArgument', $Group = [Management.Automation.ErrorCategory]::SyntaxError, $Object){
            if ($Exception -isnot [Exception]) { $Exception = [ArgumentException]$Exception }
            $PSCmdlet.ThrowTerminatingError([System.Management.Automation.ErrorRecord]::new($Exception, $Id, $Group, $Object))
        }
        function AsDictionary {
            param(
                [Parameter(ValueFromPipeLine = $True)]$Object,
                $ValueName
            )
            begin {
                $Keys = $Null
            }
            process {
                if ($Null -eq $Keys) {
                    $Keys =
                        if ($Null -eq $Object) { ,@() }
                        elseif ($Object.GetType().GetElementType() -and $Object.get_Count() -eq 0) { $Null }
                        else {
                            $1 = $Object |Select-Object -First 1
                            if ($1 -is [string] -or $1 -is [ValueType] -or $1 -is [Array]) { $Null }
                            elseif ($1 -is [Collections.ObjectModel.Collection[psobject]]) { $Null }
                            elseif ($1 -is [Data.DataRow]) { ,@($1.Table.Columns.ColumnName) }
                            elseif ($1 -is [System.Collections.IDictionary]) { ,@($1.Get_Keys()) }
                            elseif ($1) { ,@($1.PSObject.Properties.Name) }
                        }
                }
                foreach ($Item in $Object) {
                    if ($Item -is [Collections.IDictionary]) { $Object; Break }
                    elseif ( $Null -eq $Keys ) { [ordered]@{ $ValueName = $Item } }
                    else {
                        $Dictionary = [ordered]@{}
                        if ($Null -ne $Item) {
                            foreach ($Key in @($Keys)) {
                                if ($Null -eq $Key) { $Key = $ValueName }
                                $Dictionary.Add($Key, $Item.psobject.properties[$Key].Value)
                            }
                        }
                        $Dictionary
                    }
                }
            }
        }
        function SetExpression ($Key = '*', $Keys, $Expression) {
            $Wildcard = if ($Key -is [ScriptBlock]) { $Keys } else {
                if (!$Keys.Contains($Key)) {
                    if ($Key.Trim() -eq '*') { $Keys }
                    else {
                        $Side, $Asterisks = $Key.Split('.', 2)
                        if ($Null -ne $Asterisks -and $Asterisks.Trim() -eq '*') {
                            if ($Side -eq 'Left') { $LeftKeys } elseif ($Side -eq 'Right') { $RightKeys }
                        }
                    }
                }
            }
            if ($Null -ne $Wildcard) {
                if ($Null -eq $Expression) { $Expression = $Key }
                foreach ($Key in $Wildcard) {
                    if ($Null -ne $Key -and !$Expressions.Contains($Key)) {
                        $Expressions[$Key] = $Expression
                    }
                }
            }
            else { $Expressions[$Key] = if ($Expression) { $Expression } else { ' * ' } }
        }
        function Combine {
            param(
                [Parameter(ValueFromPipeLine = $True)]$Item,
                $Where,
                $Expressions,
                $Discern,
                $ValueName,
                $LeftRight,
                $RightLeft
            )
            begin {
                if ($Where) { $Where = [ScriptBlock]::Create($Where) } # Pull into the current (module) scope
            }
            process {
                $Left = $Item.Left
                $Right = $Item.Right
                $LeftIndex = $Item.LeftIndex
                $RightIndex = $Item.RightIndex

                if (!$Where -or (& $Where)) {
                    $Nodes = [Ordered]@{}
                    foreach ($Name in $Expressions.Get_Keys()) {
                        $Tuple =
                            if ($Expressions[$Name] -is [ScriptBlock]) { @{ 0 = $Name.foreach{&$Expressions[$Name]}[0] } }
                            else {
                                $Key = $Expressions[$Name]
                                if ($Left.Contains($Key) -or $Right.Contains($Key)) {
                                    if ($Left.Contains($Key) -and $Right.Contains($Key)) { @{ 0 = $Left[$Key]; 1 = $Right[$Key] } }
                                    elseif ($Left.Contains($Key)) { @{ 0 = $Left[$Key] } }
                                    else { @{ 0 = $Right[$Key] } } # if($Right.Contains($Name))
                                }
                                elseif ($Key.Trim() -eq '*') {
                                    if ($Left.Contains($Name) -and $Right.Contains($Name)) {
                                        if ($LeftRight.Contains($Name) -and $LeftRight[$Name] -eq $Name) {
                                            if ($Null -ne $LeftIndex -and $Left.Contains($Name)) { @{ 0 = $Left[$Name] } } else { @{ 0 = $Right[$Name] } }
                                        }
                                        elseif (!$LeftRight.Contains($Name) -and $RightLeft.Contains($Name)) { @{ 0 = $Left[$Name] } }
                                        elseif ($LeftRight.Contains($Name) -and !$RightLeft.Contains($Name)) { @{ 0 = $Right[$Name] } }
                                        else { @{ 0 = $Left[$Name]; 1 = $Right[$Name] } }
                                    }
                                    elseif ($Left.Contains($Name))  {
                                        if ($Null -ne $LeftIndex -and $Left.Contains($Name)) { @{ 0 = $Left[$Name] } }
                                        elseif ($LeftRight.Contains($Name)) { @{ 0 = $Right[$LeftRight[$Name]] } }
                                    }
                                    elseif ($Right.Contains($Name)) {
                                        if ($Null -ne $RightIndex -and $Right.Contains($Name)) { @{ 0 = $Right[$Name] } }
                                        elseif ($RightLeft.Contains($Name)) { @{ 0 = $Left[$RightLeft[$Name]] } }
                                    }
                                }
                                else {
                                    $Side, $Key = $Key.Split('.', 2)
                                    if ($Null -ne $Key) {
                                        if ($Side[0] -eq 'L') {
                                            if ($Left.Contains($Key)) { @{ 0 = $Left[$Key] } }
                                            elseif ($Key -eq '*') {
                                                if ($Null -ne $LeftIndex -and $Left.Contains($Name)) { @{ 0 = $Left[$Name] } }
                                                elseif ($Null -ne $RightIndex -and $Right.Contains($Name)) { @{ 0 = $Right[$Name] } }
                                            }
                                        }
                                        if ($Side[0] -eq 'R') {
                                            if ($Right.Contains($Key)) { @{ 0 = $Right[$Key] } }
                                            elseif ($Key -eq '*') {
                                                if ($Null -ne $RightIndex -and $Right.Contains($Name)) { @{ 0 = $Right[$Name] } }
                                                elseif ($Null -ne $LeftIndex -and $Left.Contains($Name)) { @{ 0 = $Left[$Name] } }
                                            }
                                        }
                                    } else { StopError "The property '$Key' doesn't exists" 'MissingProperty' }
                                }
                            }
                        if ($Tuple -isnot [Collections.IDictionary] ) { $Node = $Null }
                        elseif ($Tuple.Count -eq 1) { $Node = $Tuple[0] }
                        else {
                            $Node = [Collections.ObjectModel.Collection[psobject]]::new()
                            if ($Tuple[0] -is [Collections.ObjectModel.Collection[psobject]]) { foreach ($Value in $Tuple[0]) { $Node.Add($Value) } } else { $Node.Add($Tuple[0]) }
                            if ($Tuple[1] -is [Collections.ObjectModel.Collection[psobject]]) { foreach ($Value in $Tuple[1]) { $Node.Add($Value) } } else { $Node.Add($Tuple[1]) }
                        }
                        if ($Null -ne $Discern -and $Node -is [Collections.ObjectModel.Collection[psobject]]) {
                            if ($Node.get_Count() -eq $Discern.Count + 1) { $Nodes[$Name] = $Node[$Node.get_Count() - $Discern.Count - 1] }
                            if ($Node.get_Count() -gt $Discern.Count + 1) { $Nodes[$Name] = $Node[0..($Node.get_Count() - $Discern.Count - 1)] }
                            for ($i = [math]::Min($Node.get_Count(), $Discern.Count); $i -gt 0; $i--) {
                                $Rename = $Discern[$Discern.Count - $i]
                                $Rename = if ($Rename.Contains('*')) { ([regex]"\*").Replace($Rename, $Name, 1) } elseif ($Name -eq $ValueName) { $Rename } else { $Rename + $Name }
                                if (!$Rename) { $Rename = $ValueName}
                                $Nodes[$Rename] = if ($Nodes.Contains($Rename)) { @($Nodes[$Rename]) + $Node[$Node.get_Count() - $i] } else { $Node[$Node.get_Count() - $i] }
                            }
                        } elseif ($Null -ne $Discern -and $Name -eq $ValueName) {
                            $Nodes[$Discern[0]] = $Node
                        } else {
                            $Nodes[$Name] = $Node
                        }
                    }
                    if ($Nodes.get_Count()) {
                        if ($Nodes.get_Count() -eq 1 -and $Nodes.Contains($ValueName)) { ,$Nodes[$ValueName] } # return scalar array
                        else { [PSCustomObject]$Nodes }
                    }
                }
            }
        }
        function ProcessObject {
            [Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSReviewUnusedParameter', 'Discern', Justification = 'False positive as rule does not scan child scopes')]
            [Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSReviewUnusedParameter', 'Where',   Justification = 'False positive as rule does not scan child scopes')]
            param(
                $RightObject,
                [array]$On = @(),
                $Using,
                [array]$Equals = @(),
                $Discern,
                $Property,
                $Where,
                $JoinType,
                $ValueName,
                [switch]$Strict,
                [switch]$MatchCase,
                [Switch]$SkipSameIndex,
                [Parameter(ValueFromPipeLine = $True)]$LeftObject
            )
            begin {
                $Expressions = [Ordered]@{}
                $StringComparer = if ($MatchCase) { [StringComparer]::Ordinal } Else { [StringComparer]::OrdinalIgnoreCase }
                $Keys, $LeftKeys, $RightKeys, $Pipeline, $LeftList, $AsDictionary = $Null
                $InnerRight = [System.Collections.Generic.HashSet[int]]::new()
                $RightIndices = [Collections.Generic.Dictionary[string, object]]::new($StringComparer)
                $LeftRight = @{}; $RightLeft = @{}; $LeftNull = [ordered]@{}; $RightNull = [ordered]@{}
                $LeftIndex = 0
                if ($RightObject -is [Collections.IDictionary]) { $RightList = @($RightObject) }
                else {
                    $RightName = if ($Equals.Count -eq 0 -and $On.Count -eq 1  -and "$($On[0])".Trim() -ne '*') { $On[0] }
                                 elseif ($Equals.Count -eq 1 -and "$($Equals[0])".Trim() -ne '*') { $Equals[0] } else { $ValueName }
                    $RightList = @(AsDictionary $RightObject -ValueName $RightName)
                }
                if ($RightList.Count) { $RightKeys = $RightList[0].get_Keys() } else { $RightKeys = @() }
                if ($Using) { $Using = [ScriptBlock]::Create($Using) } # Pull into the current (module) scope
                $Combine = $null
            }
            process {
                if (!$AsDictionary) {
                    $LeftName = if ($On.Count -eq 1 -and "$($On[0])".Trim() -ne '*') { $On[0] } else { $ValueName }
                    $AsDictionary = { AsDictionary -ValueName $LeftName }.GetSteppablePipeline()
                    $AsDictionary.Begin($True)
                }
                $Left = if ($LeftObject -is[Collections.IDictionary]) { $LeftObject }elseif ($Null -ne $LeftObject) { $AsDictionary.Process((,$LeftObject))[0] }
                if (!$LeftKeys) {
                    if ($Null -ne $Left) { $LeftKeys = $Left.get_Keys() } else { $LeftKeys = @() }
                    $Keys = [System.Collections.Generic.HashSet[string]]::new([string[]](@($LeftKeys) + @($RightKeys)), [StringComparer]::InvariantCultureIgnoreCase)
                }
                if ($Null -eq $Combine) {
                    if ($On.Count) {
                        $OnWildCard     = $On.Count     -eq 1 -and "$($On[0])".Trim()     -eq '*' # Use e.g. -On ' * ' if there exists an '*' property
                        $EqualsWildCard = $Equals.Count -eq 1 -and "$($Equals[0])".Trim() -eq '*'
                        if ($OnWildCard) {
                            if ($Equals.Count -and !$EqualsWildCard) { $On = $Equals }
                            else { $On = $LeftKeys.Where{ $RightKeys -eq $_ } }
                        }
                        elseif ($EqualsWildCard) { $Equals = $On }
                        if     ($On.Count -gt $Equals.Count) { $Equals += $On[($Equals.Count)..($On.Count - 1)] }
                        elseif ($On.Count -lt $Equals.Count) { $On     += $Equals[($On.Count)..($Equals.Count - 1)] }
                        if ($Null -ne $Left) {
                            for ($i = 0; $i -lt $On.Count; $i++) {
                                if ( $On[$i] -is [ScriptBlock] ) { if ( $On[$i] -Like '*$Right*' ) { Write-Warning 'Use the -Using parameter for comparison expressions' } }
                                else {
                                    if ($On[$i] -notin $LeftKeys) { StopError "The property $($On[$i]) cannot be found on the left object." 'MissingLeftProperty' }
                                    $LeftRight[$On[$i]] = $Equals[$i]
                                }
                                if ( $Equals[$i] -is [ScriptBlock] ) { if ( $On[$i] -Like '*$Left*' ) { Write-Warning 'Use the -Using parameter for comparison expressions' } }
                                else {
                                    if ($Equals[$i] -notin $RightKeys) { StopError "The property $($Equals[$i]) cannot be found on the right object." 'MissingRightProperty' }
                                    $RightLeft[$Equals[$i]] = $On[$i]
                                }
                            }
                        }
                        $RightIndex = 0
                        foreach ($Right in $RightList) {
                            $Dictionary = $RightIndices # $Dictionary references the $RightList
                            $Count = $Equals.Count
                            foreach ($Name in $Equals) {
                                $Value = if ($Name -is [ScriptBlock]) { $Right |ForEach-Object $Name } else { $Right[$Name] }
                                $Key = # WET performance: https://github.com/orgs/PowerShell/discussions/19322
                                    if ( $Null -eq $Value ) { "$Esc`$Null" }
                                    else {
                                        $Type = if ($Strict) { "$($Value.GetType())" }
                                        if ($Value -is [String]) { $Value }
                                        elseif ($Value -is [ValueType]) { "$Type$Value" }
                                        elseif ($Value -is [System.MarshalByRefObject]) { "$Esc$Type[$($Value |Select-Object *)]" }
                                        elseif ($Value -is [PSCustomObject]) { "$Esc$Type[$Value]" }
                                        elseif ($Value -is [System.Collections.IDictionary]) { "$Esc$Type{$($Value.GetEnumerator())}" }
                                        elseif ($Value -is [Array]) { "$Esc$Type($Value)" }
                                        else { "$Esc$Type$Value" }
                                    }
                                if (-Not --$Count) { break }
                                if (!$Dictionary.ContainsKey($Key)) { $Dictionary[$Key] = [Collections.Generic.Dictionary[string, object]]::new($StringComparer) }
                                $Dictionary = $Dictionary[$Key]
                            }
                            if ($Dictionary.ContainsKey($Key)) { $Dictionary[$Key].Add($RightIndex++) }
                            else { $Dictionary[$Key] = [Collections.Generic.List[Int]]$RightIndex++ }
                        }
                    }
                    foreach ($Key in $LeftKeys) {
                        if ($Left[$Key] -isnot [Collections.ObjectModel.Collection[psobject]]) { $LeftNull[$Key] = $Null }
                        else { $LeftNull[$Key] = [Collections.ObjectModel.Collection[psobject]]( ,$Null * $Left[$Key].Count) }
                    }
                    foreach ($Key in $RightKeys) {
                        $RightNull[$Key] = if ($RightList) {
                            if ($RightList[0][$Key] -isnot [Collections.ObjectModel.Collection[psobject]]) { $Null }
                            else { [Collections.ObjectModel.Collection[psobject]]( ,$Null * $Left[$Key].Count) }
                        }
                    }
                    if ($Property) {
                        foreach ($Item in @($Property)) {
                            if ($Item -is [System.Collections.IDictionary]) { foreach ($Key in $Item.Get_Keys()) { SetExpression -Key $Key -Keys $Keys -Expression $Item[$Key] } }
                            else { SetExpression -Key $Item -Keys $Keys }
                        }
                    } else { SetExpression -Keys $Keys }
                    foreach ($Key in @($Expressions.get_Keys())) {
                        if ($Expressions[$Key] -is [ScriptBlock]) { $Expressions[$Key] = [scriptblock]::Create($Expressions[$Key]) }
                    }
                    $Combine = { Combine -LeftRight $LeftRight -RightLeft $RightLeft -Where $Where -Expression $Expressions -Discern $Discern -ValueName $ValueName }.GetSteppablePipeline()
                    $Combine.Begin($True)
                }
                if ($Null -ne $Left) {
                    $InnerLeft = $False
                    $Indices =
                        if ($On.Count) {
                            $Dictionary = $RightIndices
                            foreach ($Name in $On) {
                                $Value = if ($Name -is [ScriptBlock]) { $Left |ForEach-Object $Name } else { $Left[$Name] }
                                $Key = # WET performance: https://github.com/orgs/PowerShell/discussions/19322
                                    if ( $Null -eq $Value ) { "$Esc`$Null" }
                                    else {
                                        $Type = if ($Strict) { "$($Value.GetType())" }
                                        if ($Value -is [String]) { $Value }
                                        elseif ($Value -is [ValueType]) { "$Type$Value" }
                                        elseif ($Value -is [System.MarshalByRefObject]) { "$Esc$Type[$($Value |Select-Object *)]" }
                                        elseif ($Value -is [PSCustomObject]) { "$Esc$Type[$Value]" }
                                        elseif ($Value -is [System.Collections.IDictionary]) { "$Esc$Type{$($Value.GetEnumerator())}" }
                                        elseif ($Value -is [Array]) { "$Esc$Type($Value)" }
                                        else { "$Esc$Type$Value" }                            }
                                $Dictionary = if ($Dictionary.ContainsKey($Key)) { $Dictionary[$Key] }
                                if ($Null -eq $Dictionary) { break }
                            }
                            if ($Null -ne $Dictionary) { $Dictionary }
                        }
                        elseif ($Using) {
                            if ($JoinType -eq 'Cross') { StopError 'The Using parameter cannot be used on a cross join.' 'CrossUsing' }
                            for ($RightIndex = 0; $RightIndex -lt $RightList.Count; $RightIndex++) {
                                $Right = $RightList[$RightIndex]
                                if (& $Using) { $RightIndex }
                            }
                        }
                        elseif ($JoinType -eq 'Cross') { 0..($RightList.Length - 1) }
                        elseif ($LeftIndex -lt $RightList.Count) { $LeftIndex } else { $Null }
                    foreach ($RightIndex in $Indices) {
                        if ($SkipSameIndex -and $LeftIndex -eq $RightIndex) {
                            $InnerLeft = $True
                            $Null = $InnerRight.Add($RightIndex)
                        }
                        else {
                            $Object = $Combine.Process(@{ Left = $Left; Right = $RightList[$RightIndex]; LeftIndex = $LeftIndex; RightIndex = $RightIndex })
                            if ($Null -ne $Object -and $Object.get_Count() -gt 0) {
                                if ($JoinType -ne 'Outer') { $Object }
                                $InnerLeft = $True
                                $Null = $InnerRight.Add($RightIndex)
                            }
                        }
                    }
                }
                else {
                    $InnerLeft = $True
                    for ($RightIndex = 0; $RightIndex -lt $RightList.Count; $RightIndex++) {
                        if (!$InnerRight.Contains($RightIndex)) {
                            $Combine.Process(@{ Left = $LeftNull; Right = $RightList[$RightIndex]; LeftIndex = $Null; RightIndex = $RightIndex })
                        }
                    }
                }
                if (!$InnerLeft -and ($JoinType -in 'Left', 'Full', 'Outer')) {
                    $Combine.Process(@{ Left = $Left; Right = $RightNull; LeftIndex = $LeftIndex; RightIndex = $Null })
                }
                $LeftIndex++
            }
            end {
                if ($AsDictionary) { $AsDictionary.End() }
                if($Combine) { $Combine.End() }
            }
        }

        $Parameters = [System.Collections.Generic.Dictionary[String,Object]]::new($PSBoundParameters)
        $Parameters['ValueName']     = $ValueName
        if ($Parameters.TryGetValue('OutBuffer', [ref]$Null))          { $Parameters['OutBuffer']   = 1   }
        if ($Parameters.ContainsKey('Discern') -and !$Discern)         { $Parameters['Discern']     = @() }
        if ($JoinType -eq 'Outer' -and !$Parameters.ContainsKey('On')) { $Parameters['On']          = '*' }

        $LeftList, $Pipeline = $Null
    }

    process {
        # The Process block is invoked (once) if the pipeline is omitted but not if it is empty: @()
        # if ($Null -eq $LeftKeys) { $LeftKeys = GetKeys $LeftObject }

        if ($Null -eq $Pipeline) {
            if ($Null -ne $_ -and $Parameters.ContainsKey('RightObject')) {
                $Pipeline = { ProcessObject @Parameters }.GetSteppablePipeline()
                $Pipeline.Begin($PSCmdlet)
            }
            else {
                $Pipeline = $False
                $LeftList = [Collections.Generic.List[Object]]::New()
            }
        }
        if ($Pipeline) { $Pipeline.Process($_) }  else { $LeftList.Add($_) }
    }
    end {
        if (!($Parameters.ContainsKey('LeftObject') -or $LeftList) -and !$Parameters.ContainsKey('RightObject')) {
             StopError 'A value for either the LeftObject, pipeline or the RightObject is required.' 'MissingObject'
        }
        if ($Pipeline -eq $False) { # Not yet streamed/processed
            if (!$LeftList) {
                if ($Parameters.ContainsKey('LeftObject'))   {
                    $LeftList = $LeftObject
                }
                else { # Right self-join
                    if ($Parameters.ContainsKey('On') -and !$Parameters.ContainsKey('Equal')) { $Parameters['SkipSameIndex'] = $True }
                    $LeftList = $RightObject
                }
            }
            if ($Parameters.ContainsKey('LeftObject')) { $Null = $Parameters.remove('LeftObject') }
            if (!$Parameters.ContainsKey('RightObject')) { # Left self-join
                if ($Parameters.ContainsKey('On') -and !$Parameters.ContainsKey('Equal')) { $Parameters['SkipSameIndex'] = $True }
                $Parameters['RightObject'] = $LeftList
            }
            $Pipeline = { ProcessObject @Parameters }.GetSteppablePipeline()
            $Pipeline.Begin($True)
            foreach ($Left in $LeftList) { $Pipeline.Process($Left) }
        }
        if ('Right', 'Full', 'Outer' -eq $JoinType) {
            if ($Null -eq $Pipeline) {
                if ($Parameters.ContainsKey('LeftObject')) { $Null = $Parameters.remove('LeftObject') }
                $Pipeline = { ProcessObject @Parameters }.GetSteppablePipeline()
                $PipeLine.Begin($True)
            }
            $Pipeline.Process($Null)
        }
        if ($Pipeline) { $Pipeline.End() }
    }
}; Set-Alias Join Join-Object

$JoinCommand = Get-Command Join-Object
$MetaData = [System.Management.Automation.CommandMetadata]$JoinCommand
$ProxyCommand = [System.Management.Automation.ProxyCommand]::Create($MetaData)
$ParamBlock, $ScriptBlock = $ProxyCommand -Split '\r?\n(?=begin\r?\n)', 2

$Proxies =
    @{ Name = 'InnerJoin-Object'; Alias = 'InnerJoin'; Default = "JoinType = 'Inner'" },
    @{ Name = 'LeftJoin-Object';  Alias = 'LeftJoin';  Default = "JoinType = 'Left'" },
    @{ Name = 'RightJoin-Object'; Alias = 'RightJoin'; Default = "JoinType = 'Right'" },
    @{ Name = 'FullJoin-Object';  Alias = 'FullJoin';  Default = "JoinType = 'Full'" },
    @{ Name = 'OuterJoin-Object'; Alias = 'OuterJoin'; Default = "JoinType = 'Outer'" },
    @{ Name = 'CrossJoin-Object'; Alias = 'CrossJoin'; Default = "JoinType = 'Cross'" },
    @{ Name = 'Update-Object';    Alias = 'Update';    Default = "JoinType = 'Left'",  "Property = @{ '*' = 'Right.*' }" },
    @{ Name = 'Merge-Object';     Alias = 'Merge';     Default = "JoinType = 'Full'",  "Property = @{ '*' = 'Right.*' }" },
    @{ Name = 'Get-Difference';   Alias = 'Differs';   Default = "JoinType = 'Outer'", "Property = @{ '*' = 'Right.*' }" }

foreach ($Proxy in $Proxies) {
    $ProxyCommand = @(
        $ParamBlock
        'DynamicParam  {'
        foreach ($Default in @($Proxy.Default)) { '    $PSBoundParameters.' + $Default }
        '}'
        $ScriptBlock
    ) -Join [Environment]::NewLine
    $Null = New-Item -Path Function:\ -Name $Proxy.Name -Value $ProxyCommand -Force
    Set-Alias $Proxy.Alias $Proxy.Name
}