Requirements

2.2.6

src/core.ps1


$ErrorActionPreference = "Stop"
."$PSScriptRoot\types.ps1"

# idempotently applies a requirement
function applyRequirement([Requirement]$Requirement) {
  $result = $false
  if ($Requirement.Test) {
    [RequirementEvent]::new($Requirement, "Test", "Start")
    $result = &$Requirement.Test
    [RequirementEvent]::new($Requirement, "Test", "Stop", $result)
  }
  if (-not $result) {
    if ($Requirement.Set) {
      [RequirementEvent]::new($Requirement, "Set", "Start")
      $result = &$Requirement.Set
      [RequirementEvent]::new($Requirement, "Set", "Stop", $result)
    }
    if ($Requirement.Test -and $Requirement.Set) {
      [RequirementEvent]::new($Requirement, "Validate", "Start")
      $result = &$Requirement.Test
      [RequirementEvent]::new($Requirement, "Validate", "Stop", $result)
      if (-not $result) {
        Write-Error "Failed to apply Requirement '$($Requirement.Name)'"
      }
    }
  }
}

# applies an array of requirements
function applyRequirements([Requirement[]]$Requirements) {
  $Requirements | % { applyRequirement $_ }
}

# run the Test method of a requirement
function testRequirement([Requirement]$Requirement) {
  if ($Requirement.Test) {
    [RequirementEvent]::new($Requirement, "Test", "Start")
    $result = &$Requirement.Test
    [RequirementEvent]::new($Requirement, "Test", "Stop", $result)
  }
}

# tests an array of requirements
function testRequirements([Requirement[]]$Requirements) {
  $Requirements | % { testRequirement $_ }
}

# sorts an array of Requirements in topological order
function sortRequirements([Requirement[]]$Requirements) {
  $stages = @()
  while ($Requirements) {
    $nextStages = $Requirements `
    | ? { -not ($_.DependsOn | ? { $_ -notin $stages.Name }) }
    if (-not $nextStages) {
      throw "Could not resolve the dependencies for Requirements with names: $($Requirements.Name -join ', ')"
    }
    $Requirements = $Requirements | ? { $_.Name -notin $nextStages.Name }
    $stages += $nextStages
  }
  $stages
}