Join-Keys.ps1

<#
.SYNOPSIS
Combines dictionaries together into a single dictionary.

.INPUTS
System.Collections.IDictionary to combine.

.OUTPUTS
System.Collections.IDictionary combining the inputs.

.FUNCTIONALITY
Dictionary

.EXAMPLE
Join-Keys.ps1 @{a=1;b=2} @{b=0;c=3}

Name                           Value
----                           -----
b                              2
c                              3
a                              1

.EXAMPLE
@{b=0;c=3},@{c=4;d=5} |Join-Keys.ps1 @{a=1;b=2} -Force |foreach {$_ |ConvertTo-Json -Compress}

{"c":3,"b":0,"a":1}
{"d":5,"b":2,"c":4,"a":1}

.EXAMPLE
@{b=0;c=3},@{c=4;d=5} |Join-Keys.ps1 @{a=1;b=2} -Force -Accumulate |foreach {$_ |ConvertTo-Json -Compress}

{"c":3,"b":0,"a":1}
{"c":4,"b":0,"d":5,"a":1}

.EXAMPLE
@{b=0;c=3},@{c=4;d=5} |Join-Keys.ps1 -Accumulate |select -Last 1

Name                           Value
----                           -----
c                              3
b                              0
d                              5
#>

#Requires -Version 3
[CmdletBinding()][OutputType([Collections.IDictionary])] Param(
# Initial dictionary value to combine.
[Parameter(Position=0)][Collections.IDictionary] $ReferenceObject = @{},
# Hashtables or other dictionaries to combine.
[Parameter(Position=1,Mandatory=$true,ValueFromPipeline=$true)][Collections.IDictionary] $InputObject,
<#
Indicates that the ReferenceObject should be updated with each input dictionary,
rather than the default behavior of combining the original ReferenceObject with each.
#>
[switch] $Accumulate,
<#
For matching keys, overwrites old values with new ones.
By default, only new keys are added.
#>
[switch] $Force
)
Begin {if($Accumulate) {$value = $ReferenceObject.Clone()}}
Process
{
	if(!$Accumulate) {$value = $ReferenceObject.Clone()}
	foreach($key in $InputObject.Keys)
	{
		if(!$value.ContainsKey($key)) {$value.Add($key,$InputObject[$key])}
		elseif($Force) {$value[$key] = $InputObject[$key]}
	}
	return $value
}