PipeScript

0.1.1

Transpilers/Syntax/Dot.psx.ps1

<#
.SYNOPSIS
    Dot Notation
.DESCRIPTION
    Dot Notation simplifies multiple operations on one or more objects.

    Any command named . (followed by a letter) will be treated as the name of a method or property.

    .Name will be considered the name of a property or method

    If it is followed by parenthesis, these will be treated as method arguments.

    If it is followed by a ScriptBlock, a dynamic property will be created that will return the result of that script block.

    If any other arguments are found before the next .Name, they will be considered arguments to a method.
.EXAMPLE
    .> {
        [DateTime]::now | .Month .Day .Year
    }
.EXAMPLE
    .> {
        "abc", "123", "abc123" | .Length
    }
.EXAMPLE
    .> { 1.99 | .ToString 'C' [CultureInfo]'gb-gb' }
.EXAMPLE
    .> { 1.99 | .ToString('C') }
.EXAMPLE
    .> { 1..5 | .Number { $_ } .Even { -not ($_ % 2) } .Odd { ($_ % 2) -as [bool]} }
.EXAMPLE
    .> { .ID { Get-Random } .Count { 0 } .Total { 10 }}
.EXAMPLE
    .> {
        # Declare a new object
        .Property = "ConstantValue" .Numbers = 1..100 .Double = {
            param($n)
            $n * 2
        } .EvenNumbers = {
            $this.Numbers | Where-Object { -not ($_ % 2)}
        } .OddNumbers = {
            $this.Numbers | Where-Object { $_ % 2}
        }
    }
#>
[ValidateScript({
    $commandAst = $_
    $DotChainPattern = '^\.\p{L}'
    if ($commandAst.CommandElements[0].Value -match '^\.\p{L}') {
        return $true
    }
    return $false
})]
param(
[Parameter(Mandatory,ParameterSetName='Command',ValueFromPipeline)]
[Management.Automation.Language.CommandAst]
$CommandAst
)

begin {
    $DotProperty = {        
if ($in.PSObject.Methods[$PropertyName].OverloadDefinitions -match '\(\)$') {
    $in.$PropertyName.Invoke()
} elseif ($in.PSObject.Properties[$PropertyName]) {
    $in.$PropertyName
}
    }

    $DotMethod = { $in.$MethodName($MethodArguments) }
}

process {

    # Create a collection for the entire chain of operations and their arguments.
    $DotChain     = @()
    $DotArgsAst   = @()
    $DotChainPart = ''
    $DotChainPattern = '^\.\p{L}'

    # Then, walk over each element of the commands
    $CommandElements = $CommandAst.CommandElements
    for ( $elementIndex =0 ; $elementIndex -lt $CommandElements.Count; $elementIndex++) {
        # If we are on the first element, or the command element starts with the DotChainPattern
        if ($elementIndex -eq 0 -or $CommandElements[$elementIndex].Value -match $DotChainPattern) {
            if ($DotChainPart) {
                $DotChain += [PSCustomObject]@{
                    PSTypeName = 'PipeScript.Dot.Chain'
                    Name       = $DotChainPart
                    Arguments  = $DotArgsAst
                }
            }

            $DotArgsAst = @()

            # A given step started with dots can have more than one step in the chain specified.
            $elementDotChain = $CommandElements[$elementIndex].Value.Split('.')
            [Array]::Reverse($elementDotChain)
            $LastElement, $otherElements = $elementDotChain
            if ($otherElements) {
                foreach ($element in $otherElements) {
                    $DotChain += [PSCustomObject]@{
                        PSTypeName = 'PipeScript.Dot.Chain'
                        Name       = $element
                        Arguments  = @()
                    }
                }
            }
            
            $DotChainPart = $LastElement
        }
        # If we are not on the first index or the element does not start with a dot, it is an argument.
        else {
            $DotArgsAst += $CommandElements[$elementIndex]
        }
    }

    if ($DotChainPart) {
        $DotChain += [PSCustomObject]@{
            PSTypeName = 'PipeScript.Dot.Chain'
            Name       = $DotChainPart
            Arguments  = $DotArgsAst
        }
    }


    $NewScript = @()
    $indent    = 0
    $WasPipedTo =
        $CommandAst.Parent -and 
        $CommandAst.Parent.PipelineElements -and 
        $CommandAst.Parent.PipelineElements.IndexOf($CommandAst) -gt 0
        

    # By default, we are not creating a property bag.
    # This default will change if:
    # * More than one property is defined
    # * A property is explicitly assigned
    $isPropertyBag = $false

    # If we were piped to, adjust indent (for now)
    if ($WasPipedTo ) {
        $indent += 4
    }

    # Declare the start of the chain (even if we don't use it)
    $propertyBagStart = (' ' * $indent) + '[PSCustomObject][Ordered]@{'
    # and keep track of all items we must post process.
    $PostProcess      = @()

    # If more than one item was in the chain
    if ($DotChain.Length -ge 0) { 
        $indent += 4 # adjust indentation
    }   

    # Walk thru all items in the chain of properties.
    foreach ($Dot in $DotChain) {
        $firstDotArg, $secondDotArg, $restDotArgs = $dot.Arguments
        # Determine what will be the segment of the dot chain.
        $thisSegement =
            # If the dot chain has no arguments, treat it as a property
            if (-not $dot.Arguments) {                
                $DotProperty -replace '\$PropertyName', "'$($dot.Name)'"
            }
            # If the dot chain's first argument is an assignment
            elseif ($firstDotArg -is [Management.Automation.Language.StringConstantExpressionAst] -and 
                $firstDotArg.Value -eq '=') {
                $isPropertyBag = $true
                # and the second is a script block
                if ($secondDotArg -is [Management.Automation.Language.ScriptBlockExpressionAst]) {
                    # it will become either a [ScriptMethod] or [ScriptProperty]
                    $secondScriptBlock = [ScriptBlock]::Create(
                        $secondDotArg.Extent.ToString() -replace '^\{' -replace '\}$'
                    )
                                    
                    # If the script block had parameters (even if they were empty parameters)
                    # It should become a ScriptMethod
                    if ($secondScriptBlock.Ast.ParamBlock) {
                        "[PSScriptMethod]::New('$($dot.Name)', $secondDotArg)"
                    } else {
                        # Otherwise, it will become a ScriptProperty
                        "[PSScriptProperty]::New('$($dot.Name)', $secondDotArg)"
                    }
                    $PostProcess += $dot.Name
                }
                # If we had an array of arguments, and both elements were ScriptBlocks
                elseif ($secondDotArg -is [Management.Automation.Language.ArrayLiteralAst] -and 
                    $secondDotArg.Elements.Count -eq 2 -and 
                    $secondDotArg.Elements[0] -is [Management.Automation.Language.ScriptBlockExpressionAst] -and
                    $secondDotArg.Elements[1] -is [Management.Automation.Language.ScriptBlockExpressionAst]
                ) {
                    # Then we will treat this as a settable script block
                    $PostProcess += $dot.Name
                    "[PSScriptProperty]::New('$($dot.Name)', $($secondDotArg.Elements[0]), $($secondDotArg.Elements[1]))"
                }
                elseif (-not $restDotArgs) {
                    # Otherwise, if we only have one argument, use the expression directly
                    $secondDotArg.Extent.ToString()
                } elseif ($restDotArgs) {
                    # Otherwise, if we had multiple values, create a list.
                    @(
                        $secondDotArg.Extent.ToString()
                        foreach ($otherDotArg in $restDotArgs) {
                            $otherDotArg.Extent.Tostring()
                        }
                    ) -join ','
                }                
            }
            # If the dot chain's first argument is a ScriptBlock
            elseif ($firstDotArg -is [Management.Automation.Language.ScriptBlockExpressionAst]) 
            {
                # Run that script block
                "& $($firstDotArg.Extent.ToString())"
            } 
            elseif ($firstDotArg -is [Management.Automation.Language.ParenExpressionAst]) {
                # If the first argument is a parenthesis, assume the contents to be method arguments
                $DotMethod -replace '\$MethodName', $dot.Name -replace '\(\$MethodArguments\)',$firstDotArg.ToString()
            }
            else {
                # If the first argument is anything else, assume all remaining arguments to be method parameters.
                $DotMethod -replace '\$MethodName', $dot.Name -replace '\(\$MethodArguments\)',(
                    '(' + ($dot.Arguments -join ',') + ')'
                )                        
            }
        
        # Now we add the segment to the total script
        $NewScript +=            
            if (-not $isPropertyBag -and $DotChain.Length -eq 1 -and $thisSegement -notmatch '^\[PS') {
                # If the dot chain is a single item, and not part of a property bag, include it directly
                "$(' ' * ($indent - 4))$thisSegement"
            } else {
                
                $isPropertyBag = $true
                # Otherwise include this segment as a hashtable assignment with the correct indentation.
                $thisSegement = @($thisSegement -split '[\r\n]+' -ne '' -replace '$', (' ' * 8)) -join [Environment]::NewLine
                @"
$(' ' * $indent)'$($dot.Name.Replace("'","''"))' =
$(' ' * ($indent + 4))$thisSegement
"@
            }
    }

 
    # If we were generating a property bag
    if ($isPropertyBag) {
        if ($WasPipedTo) { # and it was piped to
            # Add the start of the pipeline and the property bag start to the top of the script.
            $NewScript = @('& { process {') + ((' ' * $indent) + '$in = $this = $_') + $propertyBagStart + $NewScript 
        } else {
            # If it was not piped to, just add the start of the property bag
            $newScript = @($propertyBagStart) + $NewScript
        }
    } elseif ($WasPipedTo)  {
        # If we were piped to (but were not a property bag)
        $indent -= 4
        # add the start of the pipeline to the top of the script.
        $newScript = @('& { process {') + ((' ' * $indent) + '$in = $this = $_') + $NewScript
    }
    
    # If we were a property bag
    if ($isPropertyBag) {
        # close out the script
        $NewScript += ($(' ' * $indent) + '}')
        $indent -= 4
    }

    # If there was post processing
    if ($PostProcess) {
        # Change the property bag start to assign it to a variable
        $NewScript = $newScript -replace ($propertyBagStart -replace '\W', '\$0'), "`$Out = $propertyBagStart"
        foreach ($post in $PostProcess) {
            # and change any [PSScriptProperty] or [PSScriptMethod] into a method on that object.
            $newScript += "`$Out.PSObject.Members.Add(`$out.$Post)"
        }
        # Then output.
        $NewScript += '$Out'
    }
    
    # If we were piped to
    if ($WasPipedTo) {   
        # close off the script.
        $NewScript += '} }'
    } else {
        # otherwise, make it a subexpression
        $NewScript = '$(' + ($NewScript -join [Environment]::NewLine) + ')'
    }

    $NewScript = $NewScript -join [Environment]::Newline

    # Return the created script.
    [scriptblock]::Create($NewScript)
}