ConvertFrom-YamlMapping.ps1

function ConvertFrom-YamlMapping {
    <#
        .SYNOPSIS
        Parses a YAML block-style mapping into a PSCustomObject or OrderedDictionary.
    #>
    [CmdletBinding()]
    [OutputType([System.Collections.Specialized.OrderedDictionary], [pscustomobject])]
    param(
        [Parameter(Mandatory)] [pscustomobject] $Context,
        [Parameter(Mandatory)] [int] $Indent,
        [Parameter(Mandatory)] [int] $Depth
    )

    $lines = $Context.Lines
    $map = [ordered]@{}

    while ($Context.Index -lt $lines.Count) {
        $line = $lines[$Context.Index]
        if ($line.Indent -lt $Indent) { break }
        if ($line.Indent -gt $Indent) {
            throw "ConvertFrom-Yaml: unexpected indentation at line $($line.Number)."
        }
        if ($line.Content.StartsWith('- ') -or $line.Content -eq '-') {
            # A sequence at the same indent as a mapping key is a sibling, not part of mapping.
            break
        }

        $colonIdx = Find-YamlMappingColon -Content $line.Content
        if ($colonIdx -lt 0) {
            throw "ConvertFrom-Yaml: expected mapping key at line $($line.Number): '$($line.Content)'."
        }

        $rawKey = $line.Content.Substring(0, $colonIdx).Trim()
        if ($rawKey.Length -ge 2 -and $rawKey[0] -eq "'" -and $rawKey[-1] -eq "'") {
            $key = ($rawKey.Substring(1, $rawKey.Length - 2)) -replace "''", "'"
        } elseif ($rawKey.Length -ge 2 -and $rawKey[0] -eq '"' -and $rawKey[-1] -eq '"') {
            $key = Expand-YamlDoubleQuoted -Text ($rawKey.Substring(1, $rawKey.Length - 2))
        } else {
            $key = $rawKey
        }
        $rest = $line.Content.Substring($colonIdx + 1).Trim()

        $Context.Index++

        if ($rest.Length -gt 0) {
            if ($rest -ceq '{}') {
                $map[$key] = if ($Context.AsHashtable) { [ordered]@{} } else { [pscustomobject][ordered]@{} }
            } elseif ($rest -ceq '[]') {
                $map[$key] = @()
            } else {
                $map[$key] = ConvertFrom-YamlScalar -Raw $rest
            }
            continue
        }

        # Value on subsequent indented lines (mapping or sequence) or null.
        if ($Context.Index -ge $lines.Count) {
            $map[$key] = $null
            continue
        }

        $next = $lines[$Context.Index]
        if ($next.Indent -lt $Indent) {
            $map[$key] = $null
            continue
        }
        if ($next.Indent -eq $Indent) {
            # Indentless sequences: YAML allows a sequence to start at the same indent as the
            # parent mapping key (e.g. "key:\n- a\n- b"). Parse these as the key's value.
            if ($next.Content.StartsWith('- ') -or $next.Content -eq '-') {
                $map[$key] = ConvertFrom-YamlSequence -Context $Context -Indent $Indent -Depth ($Depth + 1)
                continue
            }
            $map[$key] = $null
            continue
        }

        $childIndent = $next.Indent
        $value = ConvertFrom-YamlNode -Context $Context -Indent $childIndent -Depth ($Depth + 1)
        $map[$key] = $value
    }

    if ($Context.AsHashtable) {
        return $map
    }

    return [pscustomobject]$map
}