oceani: add a 'length' operator

[ocean] / csrc / oceani.mdc

diff --git a/csrc/oceani.mdc b/csrc/oceani.mdc
index 891ce74c2e4d097b0cb9e4143f9dac97c0ec1e77..fb154be366f3c5759231c29fd7a0309daa001581 100644 (file)
--- a/csrc/oceani.mdc
+++ b/csrc/oceani.mdc
@@ -2576,7 +2576,7 @@ with a const size by whether they are prepared at parse time or not.
        } }$
 
 ###### Binode types
-       Index,
+       Index, Length,
 
 ###### term grammar
 
@@ -2588,6 +2588,13 @@ with a const size by whether they are prepared at parse time or not.
                $0 = b;
        } }$
 
+       | Term [ ] ${ {
+               struct binode *b = new(binode);
+               b->op = Length;
+               b->left = $<Term;
+               $0 = b;
+       } }$
+
 ###### print binode cases
        case Index:
                print_exec(b->left, -1, bracket);
@@ -2596,6 +2603,11 @@ with a const size by whether they are prepared at parse time or not.
                printf("]");
                break;
 
+       case Length:
+               print_exec(b->left, -1, bracket);
+               printf("[]");
+               break;
+
 ###### propagate binode cases
        case Index:
                /* left must be an array, right must be a number,
@@ -2615,6 +2627,20 @@ with a const size by whether they are prepared at parse time or not.
                }
                break;
 
+       case Length:
+               /* left must be an array, result is a number
+                */
+               t = propagate_types(b->left, c, perr, NULL, 0);
+               if (!t || t->compat != array_compat) {
+                       type_err(c, "error: %1 cannot provide length", prog, t, 0, NULL);
+                       return NULL;
+               }
+               if (!type_compat(type, Tnum, rules))
+                       type_err(c, "error: have %1 but need %2", prog,
+                                        Tnum, rules, type);
+               return Tnum;
+               break;
+
 ###### interp binode cases
        case Index: {
                mpz_t q;
@@ -2640,6 +2666,13 @@ with a const size by whether they are prepared at parse time or not.
                ltype = NULL;
                break;
        }
+       case Length: {
+               lleft = linterp_exec(c, b->left, &ltype);
+               mpq_set_ui(rv.num, ltype->array.size, 1);
+               ltype = NULL;
+               rvtype = Tnum;
+               break;
+       }
 
 #### Structs