Tools/CronParser.ps1
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function Get-CronFields { return @( 'Minute', 'Hour', 'DayOfMonth', 'Month', 'DayOfWeek' ) } function Get-CronFieldConstraints { return @{ 'MinMax' = @( @(0, 59), @(0, 23), @(1, 31), @(1, 12), @(0, 6) ); 'DaysInMonths' = @( 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ); 'Months' = @( 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December' ) } } function Get-CronPredefined { return @{ # normal '@minutely' = '* * * * *'; '@hourly' = '0 * * * *'; '@daily' = '0 0 * * *'; '@weekly' = '0 0 * * 0'; '@monthly' = '0 0 1 * *'; '@quaterly' = '0 0 1 1,4,8,7,10'; '@yearly' = '0 0 1 1 *'; '@annually' = '0 0 1 1 *'; # twice '@twice-hourly' = '0,30 * * * *'; '@twice-daily' = '0,12 0 * * *'; '@twice-weekly' = '0 0 * * 0,4'; '@twice-monthly' = '0 0 1,15 * *'; '@twice-yearly' = '0 0 1 1,6 *'; '@twice-annually' = '0 0 1 1,6 *'; } } function Get-CronFieldAliases { return @{ 'Month' = @{ 'Jan' = 1; 'Feb' = 2; 'Mar' = 3; 'Apr' = 4; 'May' = 5; 'Jun' = 6; 'Jul' = 7; 'Aug' = 8; 'Sep' = 9; 'Oct' = 10; 'Nov' = 11; 'Dec' = 12; }; 'DayOfWeek' = @{ 'Sun' = 0; 'Mon' = 1; 'Tue' = 2; 'Wed' = 3; 'Thu' = 4; 'Fri' = 5; 'Sat' = 6; }; } } function ConvertFrom-CronExpression { param ( [Parameter(Mandatory=$true)] [ValidateNotNullOrEmpty()] [string] $Expression ) $Expression = $Expression.Trim() # check predefineds $predef = Get-CronPredefined if (!(Test-Empty $predef[$Expression])) { $Expression = $predef[$Expression] } # split and check atoms length $atoms = @($Expression -isplit '\s+') if ($atoms.Length -ne 5) { throw "Cron expression should only consist of 5 parts: $($Expression)" } # basic variables $aliasRgx = '(?<tag>[a-z]{3})' # get cron obj and validate atoms $fields = Get-CronFields $constraints = Get-CronFieldConstraints $aliases = Get-CronFieldAliases $cron = @{} for ($i = 0; $i -lt $atoms.Length; $i++) { $_cronExp = @{ 'Range' = $null; 'Values' = $null; 'Constraints' = $null; 'Random' = $false; } $_atom = $atoms[$i] $_field = $fields[$i] $_constraint = $constraints.MinMax[$i] $_aliases = $aliases[$_field] # replace day of week and months with numbers switch ($_field) { { $_field -ieq 'month' -or $_field -ieq 'dayofweek' } { while ($_atom -imatch $aliasRgx) { $_alias = $_aliases[$Matches['tag']] if ($null -eq $_alias) { throw "Invalid $($_field) alias found: $($Matches['tag'])" } $_atom = $_atom -ireplace $Matches['tag'], $_alias $_atom -imatch $aliasRgx | Out-Null } } } # ensure atom is a valid value if (!($_atom -imatch '^[\d|/|*|\-|,r]+$')) { throw "Invalid atom character: $($_atom)" } # replace * with min/max constraint $_atom = $_atom -ireplace '\*', ($_constraint -join '-') # parse the atom for either a literal, range, array, or interval # literal if ($_atom -imatch '^(\d+|r)$') { # check if it's random if ($_atom -ieq 'r') { $_cronExp.Values = @(Get-Random -Minimum $_constraint[0] -Maximum ($_constraint[1] + 1)) $_cronExp.Random = $true } else { $_cronExp.Values = @([int]$_atom) } } # range elseif ($_atom -imatch '^(?<min>\d+)\-(?<max>\d+)$') { $_cronExp.Range = @{ 'Min' = [int]($Matches['min'].Trim()); 'Max' = [int]($Matches['max'].Trim()); } } # array elseif ($_atom -imatch '^[\d,]+$') { $_cronExp.Values = [int[]](@($_atom -split ',').Trim()) } # interval elseif ($_atom -imatch '(?<start>(\d+|\*))\/(?<interval>(\d+|r))$') { $start = $Matches['start'] $interval = $Matches['interval'] if ($interval -ieq '0') { $interval = '1' } if ([string]::IsNullOrWhiteSpace($start) -or $start -ieq '*') { $start = '0' } # set the initial trigger value $_cronExp.Values = @([int]$start) # check if it's random if ($interval -ieq 'r') { $_cronExp.Random = $true } else { # loop to get all next values $next = [int]$start + [int]$interval while ($next -le $_constraint[1]) { $_cronExp.Values += $next $next += [int]$interval } } } # error else { throw "Invalid cron atom format found: $($_atom)" } # ensure cron expression values are valid if ($null -ne $_cronExp.Range) { if ($_cronExp.Range.Min -gt $_cronExp.Range.Max) { throw "Min value for $($_field) should not be greater than the max value" } if ($_cronExp.Range.Min -lt $_constraint[0]) { throw "Min value '$($_cronExp.Range.Min)' for $($_field) is invalid, should be greater than/equal to $($_constraint[0])" } if ($_cronExp.Range.Max -gt $_constraint[1]) { throw "Max value '$($_cronExp.Range.Max)' for $($_field) is invalid, should be less than/equal to $($_constraint[1])" } } if ($null -ne $_cronExp.Values) { $_cronExp.Values | ForEach-Object { if ($_ -lt $_constraint[0] -or $_ -gt $_constraint[1]) { throw "Value '$($_)' for $($_field) is invalid, should be between $($_constraint[0]) and $($_constraint[1])" } } } # assign value $_cronExp.Constraints = $_constraint $cron[$_field] = $_cronExp } # post validation for month/days in month if ($null -ne $cron['Month'].Values -and $null -ne $cron['DayOfMonth'].Values) { foreach ($mon in $cron['Month'].Values) { foreach ($day in $cron['DayOfMonth'].Values) { if ($day -gt $constraints.DaysInMonths[$mon - 1]) { throw "$($constraints.Months[$mon - 1]) only has $($constraints.DaysInMonths[$mon - 1]) days, but $($day) was supplied" } } } } # flag if this cron contains a random atom $cron['Random'] = (($cron.Values | Where-Object { $_.Random } | Measure-Object).Count -gt 0) # return the parsed cron expression return $cron } function Reset-RandomCronExpression { param ( [Parameter(Mandatory=$true)] [ValidateNotNull()] $Expression ) function Reset-Atom($Atom) { if (!$Atom.Random) { return $Atom } if ($Atom.Random) { $Atom.Values = @(Get-Random -Minimum $Atom.Constraints[0] -Maximum ($Atom.Constraints[1] + 1)) } return $Atom } if (!$Expression.Random) { return $Expression } $Expression.Minute = (Reset-Atom -Atom $Expression.Minute) $Expression.Hour = (Reset-Atom -Atom $Expression.Hour) $Expression.DayOfMonth = (Reset-Atom -Atom $Expression.DayOfMonth) $Expression.Month = (Reset-Atom -Atom $Expression.Month) $Expression.DayOfWeek = (Reset-Atom -Atom $Expression.DayOfWeek) return $Expression } function Test-CronExpression { param ( [Parameter(Mandatory=$true)] [ValidateNotNull()] $Expression, [Parameter()] $DateTime = $null ) function Test-RangeAndValue($AtomContraint, $NowValue) { if ($null -ne $AtomContraint.Range) { if ($NowValue -lt $AtomContraint.Range.Min -or $NowValue -gt $AtomContraint.Range.Max) { return $false } } elseif ($AtomContraint.Values -inotcontains $NowValue) { return $false } return $true } # current time if ($null -eq $DateTime) { $DateTime = [datetime]::Now } # check day of week and day of month (both must fail) if (!(Test-RangeAndValue -AtomContraint $Expression.DayOfWeek -NowValue ([int]$DateTime.DayOfWeek)) -and !(Test-RangeAndValue -AtomContraint $Expression.DayOfMonth -NowValue $DateTime.Day)) { return $false } # check month if (!(Test-RangeAndValue -AtomContraint $Expression.Month -NowValue $DateTime.Month)) { return $false } # check hour if (!(Test-RangeAndValue -AtomContraint $Expression.Hour -NowValue $DateTime.Hour)) { return $false } # check minute if (!(Test-RangeAndValue -AtomContraint $Expression.Minute -NowValue $DateTime.Minute)) { return $false } # date is valid return $true } |