!define StrRep "!insertmacro StrRep"
!macro StrRep output string old new
    Push `${string}`
    Push `${old}`
    Push `${new}`
    !ifdef __UNINSTALL__
        Call un.StrRep
    !else
        Call StrRep
    !endif
    Pop ${output}
!macroend

!macro Func_StrRep un
    Function ${un}StrRep
        Exch $R2 ;new
        Exch 1
        Exch $R1 ;old
        Exch 2
        Exch $R0 ;string
        Push $R3
        Push $R4
        Push $R5
        Push $R6
        Push $R7
        Push $R8
        Push $R9

        StrCpy $R3 0
        StrLen $R4 $R1
        StrLen $R6 $R0
        StrLen $R9 $R2
        loop:
            StrCpy $R5 $R0 $R4 $R3
            StrCmp $R5 $R1 found
            StrCmp $R3 $R6 done
            IntOp $R3 $R3 + 1 ;move offset by 1 to check the next character
            Goto loop
        found:
            StrCpy $R5 $R0 $R3
            IntOp $R8 $R3 + $R4
            StrCpy $R7 $R0 "" $R8
            StrCpy $R0 $R5$R2$R7
            StrLen $R6 $R0
            IntOp $R3 $R3 + $R9 ;move offset by length of the replacement string
            Goto loop
        done:

        Pop $R9
        Pop $R8
        Pop $R7
        Pop $R6
        Pop $R5
        Pop $R4
        Pop $R3
        Push $R0
        Push $R1
        Pop $R0
        Pop $R1
        Pop $R0
        Pop $R2
        Exch $R1
    FunctionEnd
!macroend
!insertmacro Func_StrRep ""
!insertmacro Func_StrRep "un."

Function RIF

  ClearErrors  ; want to be a newborn

  Exch $0      ; REPLACEMENT
  Exch
  Exch $1      ; SEARCH_TEXT
  Exch 2
  Exch $2      ; SOURCE_FILE

  Push $R0     ; SOURCE_FILE file handle
  Push $R1     ; temporary file handle
  Push $R2     ; unique temporary file name
  Push $R3     ; a line to sar/save
  Push $R4     ; shift puffer

  IfFileExists $2 +1 RIF_error      ; knock-knock
  FileOpen $R0 $2 "r"               ; open the door

  GetTempFileName $R2               ; who's new?
  FileOpen $R1 $R2 "w"              ; the escape, please!

  RIF_loop:                         ; round'n'round we go
    FileRead $R0 $R3                ; read one line
    IfErrors RIF_leaveloop          ; enough is enough
    RIF_sar:                        ; sar - search and replace
      Push "$R3"                    ; (hair)stack
      Push "$1"                     ; needle
      Push "$0"                     ; blood
      Call StrRep                   ; do the bartwalk
      StrCpy $R4 "$R3"              ; remember previous state
      Pop $R3                       ; gimme s.th. back in return!
      StrCmp "$R3" "$R4" +1 RIF_sar ; loop, might change again!
    FileWrite $R1 "$R3"             ; save the newbie
  Goto RIF_loop                     ; gimme more

  RIF_leaveloop:                    ; over'n'out, Sir!
    FileClose $R1                   ; S'rry, Ma'am - clos'n now
    FileClose $R0                   ; me 2

    Delete "$2.old"                 ; go away, Sire
    Rename "$2" "$2.old"            ; step aside, Ma'am
    Rename "$R2" "$2"               ; hi, baby!

    ClearErrors                     ; now i AM a newborn
    Goto RIF_out                    ; out'n'away

  RIF_error:                        ; ups - s.th. went wrong...
    SetErrors                       ; ...so cry, boy!

  RIF_out:                          ; your wardrobe?
  Pop $R4
  Pop $R3
  Pop $R2
  Pop $R1
  Pop $R0
  Pop $2
  Pop $0
  Pop $1

FunctionEnd

!macro _ReplaceInFile SOURCE_FILE SEARCH_TEXT REPLACEMENT
  Push "${SOURCE_FILE}"
  Push "${SEARCH_TEXT}"
  Push "${REPLACEMENT}"
  Call RIF
!macroend