How to parse out base file name using Script-Fu

问题:

Using Gimp 2.6.6 for MAC OS X (under X11) as downloaded from gimp.org.

I'm trying to automate a boring manual process with Script-Fu. I needed to parse the image file name to save off various layers as new files using a suffix on the original file name.

My original attempts went like this but failed because (string-search ...) doesn't seem to be available under 2.6 (a change to the scripting engine?).

(set! basefilename (substring filename 0 (string-search "." filename))) 

Then I tried to use this information to parse out the base file name using regex but (re-match-nth ...) is not recognized either.

(if (re-match "^(.*)[.]([^.]+)$" filename buffer)
    (set! basefilename (re-match-nth orig-name buffer 1))
    )

And while pulling the value out of the vector ran without error, the resulting value is not considered a string when it is passed into (string-append ...).

(if (re-match "^(.*)[.]([^.]+)$" filename buffer)
    (set! basefilename (vector-ref buffer 1))
    ) 

So I guess my question is, how would I parse out the base file name?

回答1:

Context

GIMP 2.6.6 Windows Vista SP2

Goal

Extract the basename of the original filename without its extension.

Symptom

Error: eval: unbound variable: re-match-nth

Possible suggestion

GIMP menu "Filters" > "Script-Fu" > "Console"

In the input box, paste the following Script-Fu definition of function then hit the ENTER key:

(define (filename-basename orig-name)
    (car (strbreakup orig-name "."))
    ; Nimmzo 09/09/30: the string split function strbreakup is defined 
    ; in the compatibility file from SIOD to TinyScheme:
    ; C:\Program Files\GIMP\share\gimp\2.0\scripts\script-fu-compat.init
) ; end  filename-basename

To test the function, enter:

(filename-basename "screen.xcf")

The Script-Fu Console answers:

"screen"

回答2:

Not really a correct solution:

> (filename-basename "this.is.a.long.filename.jpg")

"this"

A better implementation:

(define (morph-filename orig-name new-extension)
 (let* ((buffer (vector "" "" "")))
  (if (re-match "^(.*)[.]([^.]+)$" orig-name buffer)
   (string-append (substring orig-name 0 (car (vector-ref buffer 2))) new-extension)
  )
 )
)

回答3:

My version splits the filename (f) into parts delimited by separator ("." in this case); drops last part; and re-combines them with separator again

(define (pc-drop-extension f) 
  (unbreakupstr (butlast (strbreakup f ".")) ".")  )

so

(pc-drop-extension "ab.cd.efi") -> "ab.cd"

and

(pc-drop-extension "ab/cd.ef/ghi.jkl.mno") -> "ab/cd.ef/ghi.jkl"

回答4:

Many thanks philcolbourn for pointing out a "simple" way to do this. Unfortunately, the butlast function is deprecated: http://www.gimp.org/docs/script-fu-update.html#deprecated

Here is philcolbourn's version with the suggested replacement:

(define (drop-extension filename)
  (unbreakupstr (reverse (cdr (reverse (strbreakup filename ".")))) ".")
)

回答5:

As in Gimp 2.8 "gimp-image-get-uri" has to be used to get the filename of a JPG file, but gimp-image-get-uri delivers the complete path, I used this function to extract just the name of the pic (without the suffix ".jpg"):

(let* (
(uriname (car (gimp-image-get-uri IMAGE)))
(basename (car (reverse (strbreakup (car (strbreakup uriname ".")) "/"))))
...
)
...
)

回答6:

For those looking for a true string-replace functionality, here is a function I wrote for use in Script Fu

(define (string-replace strIn strReplace strReplaceWith)
    (let*
        (
            (curIndex 0)
            (replaceLen (string-length strReplace))
            (replaceWithLen (string-length strReplaceWith))
            (inLen (string-length strIn))
            (result strIn)
        )
        ;loop through the main string searching for the substring
        (while (<= (+ curIndex replaceLen) inLen)
            ;check to see if the substring is a match
            (if (substring-equal? strReplace result curIndex (+ curIndex replaceLen))
                (begin
                    ;create the result string
                    (set! result (string-append (substring result 0 curIndex) strReplaceWith (substring result (+ curIndex replaceLen) inLen)))
                    ;now set the current index to the end of the replacement. it will get incremented below so take 1 away so we don't miss anything
                    (set! curIndex (-(+ curIndex replaceWithLen) 1))
                    ;set new length for inLen so we can accurately grab what we need
                    (set! inLen (string-length result))
                )
            )
            (set! curIndex (+ curIndex 1))
        )
       (string-append result "")
    )
)