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some cosmetic changes+fix in calculator

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ceriel 1987-11-13 15:11:37 +00:00
parent 4359c699dc
commit 57b1a2757e
1 changed files with 13 additions and 14 deletions
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27
doc/LLgen/LLgen.n
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@ -896,36 +896,35 @@ stat { int ident, val; } :
; ;
expr(int level, *val;) { int expr; } : expr(int level, *val;) { int expr; } :
%if (level <= MAXPRIO) factor(val)
/* The grammar is ambiguous here. If level > MAXPRIO, [ %while (prio(tok.t_tokno) >= level)
* this invocation will only scan one factor
*/
expr(MAXPRIO+1,val)
[ %while (prio(tok.t_tokno) >= level)
/* Swallow operators as long as their priority is /* Swallow operators as long as their priority is
* larger than or equal to the level of this invocation * larger than or equal to the level of this invocation
*/ */
'+' expr(prio('+')+1,&expr) '+' expr(prio('+')+1,&expr)
{ *val += expr; } { *val += expr; }
/* This states that '+' groups left to right. If it /* This states that '+' groups left to right. If it
* should group right to left, the rule should read: * should group right to left, the rule should read:
* '+' expr(prio('+'),&expr) * '+' expr(prio('+'),&expr)
*/ */
| '-' expr(prio('-'),&expr) | '-' expr(prio('-')+1,&expr)
{ *val -= expr; } { *val -= expr; }
| '*' expr(prio('*'),&expr) | '*' expr(prio('*')+1,&expr)
{ *val *= expr; } { *val *= expr; }
| '/' expr(prio('/'),&expr) | '/' expr(prio('/')+1,&expr)
{ *val /= expr; } { *val /= expr; }
| '%' expr(prio('%'),&expr) | '%' expr(prio('%')+1,&expr)
{ *val %= expr; } { *val %= expr; }
| '&' expr(prio('&'),&expr) | '&' expr(prio('&')+1,&expr)
{ *val &= expr; } { *val &= expr; }
| '|' expr(prio('|'),&expr) | '|' expr(prio('|')+1,&expr)
{ *val |= expr; } { *val |= expr; }
]* ]*
/* Notice the "*" here. It is important. /* Notice the "*" here. It is important.
*/ */
;
factor(int *val;):
| '(' expr(1,val) ')' | '(' expr(1,val) ')'
| '-' expr(MAXPRIO+1,val) | '-' expr(MAXPRIO+1,val)
{ *val = -*val; } { *val = -*val; }