The gobble Package

(1)

The

gobble

Package

Martin Scharrer

martin@scharrer-scharrer.de

CTAN:

http://www.ctan.org/pkg/gobble

VC:

https://bitbucket.org/martin_scharrer/gobble

Version v0.2 – 2019/01/04

Abstract

ThegobbleLA_{TEX package provides more macros to discard (gobble) macro}

arguments. These macros are by default only for package and class writers, but are exported to the user level by thegobble-userpackage. The macros are also available as generic packages for other TEX formats.

1 Macros

1.1 Macros for Package/Class Writers

The following macros are provided by the genericgobble.texand the LA_{TEX package}

gobble. Some are already provided by the LA_{TEX kernel.} \@gobble

\@gobbletwo \@gobblethree \@gobblefour

Gobbles one, two, three or four mandatory arguments.

\@gobbleopt \@gobbletwoopt \@gobbleallopt

Gobbles one, two or all found optional arguments if present.

\@gobbletwoopttwo

(2)

\@firstofone

Reads one argument and expands to it, i.e. removes the braces around it.

\@firstoftwo

Reads two arguments and expands to the first one while discarding the second one.

\@secondoftwo

Reads two arguments and expands to the second one while discarding the first one.

\@firstofthree \@secondofthree \@thirdofthree

These macros read three arguments and expand to the first, second or third one, respectively, while discarding the other.

\@gobbletofi{〈code〉}〈discarded code〉\fi \@gobbletoelse{〈code〉}〈discarded code〉\else \@gobbletoor{〈code〉}〈discarded code〉\or

These macros read one argument and then gobble everything to the next\fi,\else

or\or, respectively. Afterwards they expand to the first argument. This allows to

break out of an\if.. or\ifcasebranch, which is sometimes required if code

should be executed after the conditional.

1.2 User Level Macros

The following macros are provided by the genericgobble-user.texand the LA_TEX

packagegobble-user. These also load thegobble.texfile or packagegobble

package, respectively.

They macros are identical to the corresponding versions with the leading ‘@’, but

can be used freely in a user document.

(3)

(4)

2 Implementation

1 % <! C O P Y R I G H T > 2 \ N e e d s T e X F o r m a t { L a T e X 2 e } [ 1 9 9 9 / 1 2 / 0 1 ] 3 \ P r o v i d e s P a c k a g e { g o b b l e }[% 4 % <! DATE > 5 % <! VERSION > 6 % <* DRIVER > 7 2 0 9 9 / 0 1 / 0 1 d e v e l o p 8 % </ DRIVER > 9 P r o v i d e s m o r e g o b b l e m a c r o s ] 10 \ i n p u t { g o b b l e } 11 % <! C O P Y R I G H T > 12 \ N e e d s T e X F o r m a t { L a T e X 2 e } [ 1 9 9 9 / 1 2 / 0 1 ] 13 \ P r o v i d e s P a c k a g e { gobble - u s e r }[% 14 % <! DATE > 15 % <! VERSION > 16 % <* DRIVER > 17 2 0 9 9 / 0 1 / 0 1 d e v e l o p 18 % </ DRIVER > 19 P r o v i d e s u s e r l e v e l m a c r o s ] 20 \ R e q u i r e P a c k a g e { g o b b l e } 21 \ i n p u t { gobble - u s e r } 22 \ e x p a n d a f t e r \ ifx \ c s n a m e g o b b l e . tex l o a d e d \ e n d c s n a m e \. r e l a x 23 \ e x p a n d a f t e r \ def \ c s n a m e g o b b l e . tex l o a d e d \. e n d c s n a m e {1}% 24 \ e l s e 25 \ e x p a n d a f t e r \ e n d i n p u t 26 \ fi \gobbletex@catcode 27 \ e x p a n d a f t e r \ e d e f \ c s n a m e g o b b l e t e x @ c a t c o d e \ e n d c s n a m e {. %

28 \ catcode ‘\ n o e x p a n d \ @ =\ the \ catcode ‘\ @% 29 }%

(5)

(6)

(7)

\@secondoftwo 71 \ l o n g \ def \ @ f i r s t o f t w o # 1 # 2 { # 1 }% 72 \ l o n g \ def \ @ s e c o n d o f t w o # 1 # 2 { # 2 }% \@firstofthree \@secondofthree \@thirdofthree 73 \ l o n g \ def \ @ f i r s t o f t h r e e # 1 # 2 # 3 { # 1 }% 74 \ l o n g \ def \ @ s e c o n d o f t h r e e # 1 # 2 # 3 { # 2 }% 75 \ l o n g \ def \ @ t h i r d o f t h r e e # 1 # 2 # 3 { # 3 }% \@gobbletofi \@gobbletoelse \@gobbletoor 76 \ l o n g \ def \ @ g o b b l e t o f i # 1 # 2 \ fi {\ fi #1}% 77 \ l o n g \ def \ @ g o b b l e t o e l s e # 1 # 2 \ e l s e {\ e l s e #1}% 78 \ l o n g \ def \ @ g o b b l e t o o r # 1 # 2 \ or {\ or #1}% 79 \ g o b b l e t e x @ c a t c o d e

80 \ e x p a n d a f t e r \ ifx \ c s n a m e gobble - u s e r . tex l o a d e d \. e n d c s n a m e \ r e l a x

81 \ e x p a n d a f t e r \ def \ c s n a m e gobble - u s e r . tex l o a d e d \. e n d c s n a m e {1}%

82 \ e l s e

83 \ e x p a n d a f t e r \ e n d i n p u t 84 \ fi

(8)

\gobbletex@catcode

86 \ e x p a n d a f t e r \ e d e f \ c s n a m e g o b b l e t e x @ c a t c o d e \ e n d c s n a m e {.

%

(9)