* Copyright (c) 1980 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
static char sccsid
[] = "@(#)rval.c 5.1 (Berkeley) %G%";
* pxp - Pascal execution profiler
* Version 1.2 January 1979
#define alph(c) ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
* Rvalue reformats an expression.
* Par is a flag indicating that the expression
* should be parenthesized if it is non-atomic.
* if child is relational (bogus) or adding operator,
* this has the unaesthetic property that
* --i prints as -(-i), but is needed to catch
* -(a+b) which must print as -(a+b), not as -a+b.
* otherwise child has higher precedence
* and need not be parenthesized.
ppop(r
[0] == T_PLUS
? "+" : "-");
rvalue(r
[2], prec(al
) <= prec(r
) || full
);
* if child is of lesser precedence
* (i.e. not another not operator)
* nested not operators need not be parenthesized
* because it's a prefix operator.
rvalue(r
[2], prec(al
) < prec(r
) || full
);
* make the aesthetic choice to
* fully parenthesize relational expressions,
* in spite of left to right associativity.
* note: there are no operators with lower precedence.
rvalue(al
, prec(al
) <= prec(r
) || full
);
* need not parenthesize left child
* if it has equal precedence,
* due to left to right associativity.
* right child needs to be parenthesized
* if it has equal (or lesser) precedence.
rvalue(al
, prec(al
) < prec(r
) || full
);
rvalue(al
, prec(al
) <= prec(r
) || full
);
* Prec returns the precedence of an operator,
* with larger numbers indicating stronger binding.
* This is used to determine when parenthesization
* is needed on subexpressions.