oceani: add "remainder" operator.

a % b
treats a and b as integers, does a division, and reports
the remainder.

Signed-off-by: NeilBrown <neil@brown.name>

diff --git a/csrc/oceani.mdc b/csrc/oceani.mdc
index 9e1ce020eb7ff0b265938b5f76b525244131128c..68e5b603038a94b4ab27bbd739f671e12bf104de 100644 (file)
--- a/csrc/oceani.mdc
+++ b/csrc/oceani.mdc
@@ -47,7 +47,7 @@ Elements which are present to make a usable language are:
 
  - "blocks" of multiple statements.
  - `pass`: a statement which does nothing.
- - expressions: `+`, `-`, `*`, `/` can apply to numbers and `++` can
+ - expressions: `+`, `-`, `*`, `/`, `%` can apply to numbers and `++` can
    catenate strings.  `and`, `or`, `not` manipulate Booleans, and
    normal comparison operators can work on all three types.
  - `print`: will print the values in a list of expressions.
@@ -2069,7 +2069,7 @@ precedence is handled better I might be able to discard this.
 
 ###### Binode types
        Plus, Minus,
-       Times, Divide,
+       Times, Divide, Rem,
        Concat,
        Absolute, Negate,
        Bracket,
@@ -2119,6 +2119,7 @@ precedence is handled better I might be able to discard this.
 
        Top ->    * ${ $0.op = Times; }$
                | / ${ $0.op = Divide; }$
+               | % ${ $0.op = Rem; }$
                | ++ ${ $0.op = Concat; }$
 
 ###### print binode cases
@@ -2127,13 +2128,15 @@ precedence is handled better I might be able to discard this.
        case Times:
        case Divide:
        case Concat:
+       case Rem:
                print_exec(b->left, indent, 0);
                switch(b->op) {
-               case Plus:   printf(" + "); break;
-               case Minus:  printf(" - "); break;
-               case Times:  printf(" * "); break;
-               case Divide: printf(" / "); break;
-               case Concat: printf(" ++ "); break;
+               case Plus:   fputs(" + ", stdout); break;
+               case Minus:  fputs(" - ", stdout); break;
+               case Times:  fputs(" * ", stdout); break;
+               case Divide: fputs(" / ", stdout); break;
+               case Rem:    fputs(" % ", stdout); break;
+               case Concat: fputs(" ++ ", stdout); break;
                default: abort();
                }
                print_exec(b->right, indent, 0);
@@ -2156,6 +2159,7 @@ precedence is handled better I might be able to discard this.
        case Plus:
        case Minus:
        case Times:
+       case Rem:
        case Divide:
                /* both must be numbers, result is Tnum */
        case Absolute:
@@ -2207,6 +2211,20 @@ precedence is handled better I might be able to discard this.
                right = interp_exec(b->right);
                mpq_div(rv.num, rv.num, right.num);
                break;
+       case Rem: {
+               mpz_t l, r, rem;
+
+               left = interp_exec(b->left);
+               right = interp_exec(b->right);
+               mpz_init(l); mpz_init(r); mpz_init(rem);
+               mpz_tdiv_q(l, mpq_numref(left.num), mpq_denref(left.num));
+               mpz_tdiv_q(r, mpq_numref(right.num), mpq_denref(right.num));
+               mpz_tdiv_r(rem, l, r);
+               rv = val_init(Tnum);
+               mpq_set_z(rv.num, rem);
+               mpz_clear(r); mpz_clear(l); mpz_clear(rem);
+               break;
+       }
        case Negate:
                rv = interp_exec(b->right);
                mpq_neg(rv.num, rv.num);