floop.txt

.syntax [ arglist arglistp assignst block floop breakst callarglist
          callarglistp callexpr callst compare expr factor foreverst
          ifst intst loopst pmain printlnst printst proc continuest
          returnst st term ] floop
          
arglistp = ',' .id < ', int ' * > ;
arglist = '(' < '(int ' > .id < * > $(arglistp) ')' ':' < ')' > ;

intst = 'int' .id { 'int ' * ' = 0;' } ;

assignst = .id < '' * ' = ' > '<-' expr { ';' } ;

printst = 'print' (.id      { 'printf("%d ",' * ');' }
                  | .string { 'printf("' * ');'      }) ;

printlnst = 'println' (.id      { 'printf("%d\n",' * ');' }
                      | .string { 'puts("' * ');'     }) ;


ifst = 'if' < '' 'if (' >
       expr { ') {' } .lm+
       ',' 'then' ':'
       st ';' .lm- { '} else { ' } .lm+
       st .lm- { '}' } ;

continuest = 'continue' { 'continue;' } ;
breakst = 'break' { 'f = 0;' } ;

loopst = 'loop' 'at' 'most' < '' 'for(int i = 0, f = 1; i < ' >
         expr  { ' && f; i++) {' } .lm+
         'times' ':'
         block
         .lm- { '}' } ;

foreverst = 'forever' ':'
           { '{' } .lm+
             { 'int f = 1;' } < '' 'while(1 && f)' > { ' {' } .lm+
             block
             .lm- { '}' }
           .lm- { '}' } ;

st = printlnst | printst | ifst     | loopst | foreverst | continuest |
     breakst   | block   | returnst | callst | assignst ;

block = 'begin'
         $(intst ';' )
         { 'do {' } .lm+ st $(';' st) .lm- { '} while (0);' }
         'end' ;

proc = 'def' .id < 'int ' * > arglist { ' {' } .lm+
       $(.string)
       block
       .lm- { '}' } ;

pmain = 'main' { 'int main(void) {' } .lm+ block .lm- { '}' } ;

expr = factor $ (('+' < ' + ' > factor)
              |  ('-' < ' - ' > factor)) ;

term = callexpr
     |  (.id | .number)     < * >
     | '(' < '(' > expr ')' < ')' > ;

compare = term $ (('<'  < ' < '  > term)
               |  ('>'  < ' > '  > term)
               |  ('='  < ' == ' > term)
               |  ('>=' < ' >='  > term)
               |  ('<=' < ' <='  > term)) ;

factor = compare $ ('*' < ' * ' > compare) ;

callarglistp = ',' < ', ' > expr ;
callarglist = '(' < '(' > expr $(callarglistp) ')' < ')' > ;

callst = 'do' .id < '' * > callarglist { ';' } ;

returnst = 'return' < '' 'return ' > expr { ';' } ;

callexpr = 'do' .id < '' * > callarglist ;

floop = {
'#include <stdio.h>
#include <stdlib.h>
' }
$(proc | .string)  pmain ;

.end