UDF: _ExpandEnvStrings()

[blindwig]

I ran into some quirks while trying to control environmental variable expansion using the ExpandEnvStrings option, so I wrote a function to parse a string and return an expanded version of that string:

CODE

Func _ExpandEnvStrings($sInput)

Dim $aPart = StringSplit($sInput,'%')

If @error Then

SetError(1)

Return $sInput

EndIf

Dim $sOut = $aPart[1], $i = 2, $env = ''

;loop through the parts

While $i <= $aPart[0]

$env = EnvGet($aPart[$i])

If $env <> '' Then ;this part is an expandable environment variable

$sOut = $sOut & $env

$i = $i + 1

If $i <= $aPart[0] Then $sOut = $sOut & $aPart[$i]

ElseIf $aPart[$i] = '' Then ;a double-percent is used to force a single percent

$sOut = $sOut & '%'

$i = $i + 1

If $i <= $aPart[0] Then $sOut = $sOut & $aPart[$i]

Else ;this part is to be returned literally

$sOut = $sOut & '%' & $aPart[$i]

EndIf

$i = $i + 1

WEnd

Return $sOut

EndFunc

Example:

CODE

MsgBox(0, '', _ExpandEnvStrings('the file "%comspec%" is your command interpreter'), 5)

[FuryCell]

Awesome function!

Just tried on this string.

"Path=%PATH% %%"

It even knew to take the two %'s literally.

Better than Opt("ExpandEnvStrings",1) becuase as you said it's not quirky and it does not affect all strings , only the ones you want.

Good Job!

P.S. I might make an _ExpandVariables func like this if you woundn't mind me using your idea.

Edited June 12, 2005 by SolidSnake

[blindwig]

Awesome function!   

Just tried on this string.

"Path=%PATH% %%"

It even knew to take the two %'s literally.

Better than Opt("ExpandEnvStrings",1) becuase as you said it's not quirky and it does not affect all strings , only the ones you want.

Good Job!

P.S. I might make an _ExpandVariables func like this if you woundn't mind me using your idea.

<{POST_SNAPBACK}>

Yup, I tested it and tried to make it as close to "normal" (ie, as the command intrepreter would handle it) as I could. It successfully handles these tricky ones:

'%%path%%'

'%path%path%'

If you want to make a generic version (one that can use any character to "wrap" a variable), Change the header:

Func _ExpandEnvStrings($sInput, $Delim='%')

And then replace any '%' in the function with $Delim.

Replace the EnvGet with your own function, or I'd recommend using my table UDF to store your own variables.

[blindwig]

OK, I just added another feature to this routine. Now, in addition to looking for variables like %SystemDir%, it also looks for passes parameters, such as %1 %2 %3 etc. It takes an optional array of parameters (this array is assumed to be 1-base, like the $CmdLine built-in) and replaces %1 with element 1 of the array, %2 with the element 2, etc.

I am now working on wrapping it to find default commands for a particular filetype (so that I don't have to do a ShellExecute, I can actually look at the shell command and execute it myself)

Here's the code:

CODE

;Expands environment variables in a string, such as %COMSPEC% etc

;Also looks for %1 %2 %3 etc and substitutes from $aParameter, which is a 1-based 1-dimensional array

Func _ExpandEnvStrings($sInput, $aParameter=0)

Dim $aPart = StringSplit($sInput,'%')

If @error Then

SetError(1)

Return $sInput

EndIf

Dim $sOut = $aPart[1], $i = 2, $env = ''

;loop through the parts

While $i <= $aPart[0]

$env = EnvGet($aPart[$i])

If $env <> '' Then ;this part is an expandable environment variable

$sOut = $sOut & $env

$i = $i + 1

If $i <= $aPart[0] Then $sOut = $sOut & $aPart[$i]

ElseIf $aPart[$i] = '' Then ;a double-percent is used to force a single percent

$sOut = $sOut & '%'

$i = $i + 1

If $i <= $aPart[0] Then $sOut = $sOut & $aPart[$i]

Else ;this part may be literal, or may request a parameter

;first check for a parameter request

if Not UBound($aParameter,0) = 1 Then

If IsString($aParameter) Then

$aParameter = _ArrayCreate(1, $aParameter)

Else

Local $aParameter[1]

EndIf

EndIf

Local $j = 1, $num

While $j <= StringLen($aPart[$i]) And StringIsDigit(stringmid($aPart[$i], $j, 1))

$j = $j + 1

WEnd

$Num = StringLeft($aPart[$i], $j - 1)

If StringIsInt($num) Then ;parameter requested

If Int($num)<=$aParameter[0] Then ;allowed

$sOut = $sOut & $aParameter[int($num)] & StringTrimLeft($aPart[$i], $j - 1)

Else ;denied

$sOut = $sOut & StringTrimLeft($aPart[$i], $j - 1)

EndIf

Else ;return literal

$sOut = $sOut & '%' & $aPart[$i]

EndIf

EndIf

$i = $i + 1

WEnd

Return $sOut

EndFunc

[MAli]

Here is another example using RegEx:

Func _ExpandEnvStrings($sExpr)
    Local Const $sPattern = "\%[\d\w()_]+\%"
    Local $a
    Local $sEnv
    Local $p1, $p2
    Local $sMatch
    Local $sMatchStripPct
    Local $sResult

    $a = StringRegExp ($sExpr, $sPattern, 3)
    $sResult = $sExpr

    If IsArray($a) Then
        For $sMatch In $a
            $p1 = StringInStr($sMatch, "%", 0, 1)
            $p2 = StringInStr($sMatch, "%", 0, 2)
            $sMatchStripPct = StringMid($sMatch, $p1+1, $p2-$p1-1)
            $sEnv = EnvGet($sMatchStripPct)
            If $sEnv = "" Then $sEnv = $sMatch
            $sResult = StringReplace($sResult, $sMatch, $sEnv, 1)
        Next
    EndIf

    Return $sResult
EndFunc

Edited March 19, 2013 by MAli

[Melba23]

MAli,

Oh come on! The post above yours dates from nearly 8 years ago. Please pay attention when you post - we do not approve of resurrecting threds this old as the language has changed so much since then.

M23

P.S. Welcome to the AutoIt forum anyway - just be more careful in future.

Edited March 19, 2013 by Melba23
Fixed BB tags