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Diff for /mandoc/roff.7 between version 1.47 and 1.48

version 1.47, 2014/02/14 23:50:57 version 1.48, 2014/03/08 04:43:54
Line 677  Its syntax is equivalent to
Line 677  Its syntax is equivalent to
 .Sx \&if .  .Sx \&if .
 .Ss \&if  .Ss \&if
 Begins a conditional.  Begins a conditional.
 Right now, the conditional evaluates to true  This request has the following syntax:
 if and only if it starts with the letter  .Bd -literal -offset indent
 .Sy n ,  \&.if COND BODY
 indicating processing in nroff style as opposed to troff style.  .Ed
   .Bd -literal -offset indent
   \&.if COND \e{BODY
   BODY...\e}
   .Ed
   .Bd -literal -offset indent
   \&.if COND \e{\e
   BODY...
   \&.\e}
   .Ed
   .Pp
   COND is a conditional statement.
   Currently,
   .Xr mandoc 1
   supports the following subset of roff conditionals:
   .Bl -bullet
   .It
   If
   .Sq \&!
   is prefixed to COND, the condition is logically inverted.
   .It
   If the first character of COND is
   .Sq n
   .Pq nroff mode
   or
   .Sq o
   .Pq odd page ,
   COND evaluates to true.
   .It
   If the first character of COND is
   .Sq c
   .Pq character available ,
   .Sq d
   .Pq string defined ,
   .Sq e
   .Pq even page ,
   .Sq r
   .Pq register accessed ,
   or
   .Sq t
   .Pq troff mode ,
   COND evaluates to false.
   .It
   If COND starts with a digit, optionally prefixed by a minus sign,
   it is evaluated as a numerical expression of the form
   .Ar number operator number ,
   where
   .Ar operator
   is one of
   .Sq < ,
   .Sq <= ,
   .Sq = ,
   .Sq >= ,
   or
   .Sq > .
   .It
   Otherwise, the first character of COND is regarded as a delimiter
   and COND evaluates to true if the string extending from its first
   to its second occurrence is equal to the string extending from its
   second to its third occurrence.
   .It
   If COND cannot be parsed, it evaluates to false.
   .El
   .Pp
 If a conditional is false, its children are not processed, but are  If a conditional is false, its children are not processed, but are
 syntactically interpreted to preserve the integrity of the input  syntactically interpreted to preserve the integrity of the input
 document.  document.
Line 698  will continue to syntactically interpret to the block 
Line 761  will continue to syntactically interpret to the block 
 conditional.  conditional.
 Sub-conditionals, in this case, obviously inherit the truth value of  Sub-conditionals, in this case, obviously inherit the truth value of
 the parent.  the parent.
 This request has the following syntax:  
 .Bd -literal -offset indent  
 \&.if COND \e{\e  
 BODY...  
 \&.\e}  
 .Ed  
 .Bd -literal -offset indent  
 \&.if COND \e{ BODY  
 BODY... \e}  
 .Ed  
 .Bd -literal -offset indent  
 \&.if COND \e{ BODY  
 BODY...  
 \&.\e}  
 .Ed  
 .Bd -literal -offset indent  
 \&.if COND \e  
 BODY  
 .Ed  
 .Pp  .Pp
 COND is a conditional statement.  
 roff allows for complicated conditionals; mandoc is much simpler.  
 At this time, mandoc supports only  
 .Sq n ,  
 evaluating to true;  
 and  
 .Sq t ,  
 .Sq e ,  
 and  
 .Sq o ,  
 evaluating to false.  
 All other invocations are read up to the next end of line or space and  
 evaluate as false.  
 .Pp  
 If the BODY section is begun by an escaped brace  If the BODY section is begun by an escaped brace
 .Sq \e{ ,  .Sq \e{ ,
 scope continues until a closing-brace escape sequence  scope continues until the end of the input line containing the
 .Sq \.\e} .  matching closing-brace escape sequence
   .Sq \e} .
 If the BODY is not enclosed in braces, scope continues until  If the BODY is not enclosed in braces, scope continues until
 the end of the line.  the end of the line.
 If the COND is followed by a BODY on the same line, whether after a  If the COND is followed by a BODY on the same line, whether after a
Legend:
Removed from v.1.47  
changed lines
  Added in v.1.48
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