Mc2it.Hcon

1.1.0

Sources/Hcon.ps1

using namespace System.Diagnostics.CodeAnalysis
using namespace System.Management.Automation
using namespace System.Text.RegularExpressions

<#
.SYNOPSIS
    Converts a HCON-formatted string to a hash table.
.INPUTS
    The HCON-formatted string to convert.
.OUTPUTS
    The hash table corresponding to the specified HCON-formatted string.
#>
function ConvertFrom-Hcon {
    [CmdletBinding()]
    [OutputType([System.Management.Automation.OrderedHashtable])]
    [SuppressMessage("PSAvoidUsingEmptyCatchBlock", "")]
    param (
        # The HCON-formatted string to convert.
        [Parameter(Mandatory, Position = 1, ValueFromPipeline)]
        [AllowEmptyString()]
        [string] $InputObject,

        # The maximum depth the HCON input is allowed to have.
        [ValidateRange("Positive")]
        [int] $Depth = 1024
    )

    begin {
        # The pattern used to tokenize HCON-formatted strings.
        $hconPattern = "(?:""([^""]+)""|'([^']+)'|([^\s,:]+))(?:\s*:\s*(?:""([^""]*)""|'([^']*)'|<((?:[^/]|\/(?!>))+)\/>|([^\s,]+)))?(?=\s|,|$)"

        # Gets the value of the capturing group with the specified index in a given regular expression match.
        $getMatchGroup = { param ([Match] $match, [int] $index)
            $value = $match.Groups[$index].Value
            $value.Length ? $value : $null
        }
    }

    process {
        $hcon = $InputObject.Trim()
        if (-not $hcon) { return [OrderedHashtable]::new() }
        if ($hcon -like "{*") { return ConvertFrom-Json $hcon -AsHashtable -Depth $Depth }

        $target = [OrderedHashtable]::new()
        foreach ($match in [regex]::Matches($hcon, $hconPattern)) {
            $doubleQuotedKey = & $getMatchGroup $match 1 # "key"
            $singleQuotedKey = & $getMatchGroup $match 2 # 'key'
            $bareKey = & $getMatchGroup $match 3 # key
            $doubleQuotedValue = & $getMatchGroup $match 4 # "value"
            $singleQuotedValue = & $getMatchGroup $match 5 # 'value'
            $hyperscriptValue = & $getMatchGroup $match 6 # <value/>
            $bareValue = & $getMatchGroup $match 7 # value

            $key = $doubleQuotedKey ?? $singleQuotedKey ?? $bareKey
            $value = ($doubleQuotedValue ?? $singleQuotedValue ?? $hyperscriptValue ?? $bareValue ?? "true").Trim()
            try { $value = ConvertFrom-Json $value -AsHashtable -Depth $Depth -ErrorAction Stop } catch {}

            if ($bareKey -notlike "*.*") {
                $hashtable = [OrderedHashtable]::new()
                $hashtable[$key] = $value
                Merge-HconHashtable $hashtable $target
            }
            else {
                $source = $value
                $segments = $key -split "\."
                foreach ($index in ($segments.Count - 1)..0) {
                    $hashtable = [OrderedHashtable]::new()
                    $hashtable[$segments[$index]] = $source
                    $source = $hashtable
                }

                Merge-HconHashtable $source $target
            }
        }

        return $target
    }
}

<#
.SYNOPSIS
    Deep-merges a source hash table into a target hash table.
.INPUTS
    The source hash table.
.OUTPUTS
    The target hash table.
#>
function Merge-HconHashtable {
    [CmdletBinding()]
    [OutputType([void])]
    param (
        # The source hash table.
        [Parameter(Mandatory, Position = 1, ValueFromPipeline)]
        [hashtable] $Source,

        # The target hash table.
        [Parameter(Mandatory, Position = 2)]
        [hashtable] $Target
    )

    process {
        foreach ($key in $Source.Keys) {
            $value = $Source[$key]
            if (($value -is [hashtable]) -and ($Target[$key] -is [hashtable])) { Merge-HconHashtable $value $Target[$key] }
            else { $Target[$key] = $value }
        }
    }
}