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Index > Macroinstructions > [fasmg] question about matching

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zhak



Joined: 12 Apr 2005
Posts: 490
Location: Belarus
zhak
Let's say I define data types as
Code:
byte      ; the same as rb 1
byte [?] ; the same as rb 1
byte [3] ; the same as rb 3
byte [4] 5 ; the same as db 4 dup 5
etc.
    

Also, I add naturally aligned data types as
Code:
aligned word
aligned dword [4]
etc.
    


For this aligned types I use struc
Code:
struc aligned? args&
  match =byte?, args
    label .
    byte [1]
  else match =byte? more, args
    label .
    byte more
  else match =word?, args
    align 2
    label .
    word [1]
  else match =word? more, args
    align 2
    label .
    word more
  end match
end struc
    

Here I must always match two variants: if data type has parameters following it or not.
Is it possible to somehow match only the beginning of the string so that it doesn't matter if 'more' is empty or not?
Post 12 Feb 2017, 15:52
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7801
Location: Kraków, Poland
Tomasz Grysztar
zhak wrote:
Is it possible to somehow match only the beginning of the string so that it doesn't matter if 'more' is empty or not?
While MATCH does not allow to match names with empty content, it is usually possible to deal with this using some tricks, though that may depend on context. For example:
Code:
    match =word? more, args :
        align 2
        label .
        match value :, more
                word value
        else
                word [1]
        end match
    end match    
Post 12 Feb 2017, 16:14
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