list: Implement comparison operators.

py/objlist.c

@@ -62,6 +62,61 @@ static mp_obj_t list_make_new(mp_obj_t type_in, int n_args, const mp_obj_t *args
     return NULL;
 }
 
+// Don't pass RT_COMPARE_OP_NOT_EQUAL here
+static bool list_cmp_helper(int op, mp_obj_t self_in, mp_obj_t another_in) {
+    assert(MP_OBJ_IS_TYPE(self_in, &list_type));
+    if (!MP_OBJ_IS_TYPE(another_in, &list_type)) {
+        return false;
+    }
+    mp_obj_list_t *self = self_in;
+    mp_obj_list_t *another = another_in;
+    if (op == RT_COMPARE_OP_EQUAL && self->len != another->len) {
+        return false;
+    }
+
+    // Let's deal only with > & >=
+    if (op == RT_COMPARE_OP_LESS || op == RT_COMPARE_OP_LESS_EQUAL) {
+        mp_obj_t t = self;
+        self = another;
+        another = t;
+        if (op == RT_COMPARE_OP_LESS) {
+            op = RT_COMPARE_OP_MORE;
+        } else {
+            op = RT_COMPARE_OP_MORE_EQUAL;
+        }
+    }
+
+    int len = self->len < another->len ? self->len : another->len;
+    bool eq_status = true; // empty lists are equal
+    bool rel_status;
+    for (int i = 0; i < len; i++) {
+        eq_status = mp_obj_equal(self->items[i], another->items[i]);
+        if (op == RT_COMPARE_OP_EQUAL && !eq_status) {
+            return false;
+        }
+        rel_status = (rt_binary_op(op, self->items[i], another->items[i]) == mp_const_true);
+        if (!eq_status && !rel_status) {
+            return false;
+        }
+    }
+
+    // If we had tie in the last element...
+    if (eq_status) {
+        // ... and we have lists of different lengths...
+        if (self->len != another->len) {
+            if (self->len < another->len) {
+                // ... then longer list length wins (we deal only with >)
+                return false;
+            }
+        } else if (op == RT_COMPARE_OP_MORE) {
+            // Otherwise, if we have strict relation, equality means failure
+            return false;
+        }
+    }
+
+    return true;
+}
+
 static mp_obj_t list_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
     mp_obj_list_t *o = lhs;
     switch (op) {
@@ -105,6 +160,15 @@ static mp_obj_t list_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
             }
             return s;
         }
+        case RT_COMPARE_OP_EQUAL:
+        case RT_COMPARE_OP_LESS:
+        case RT_COMPARE_OP_LESS_EQUAL:
+        case RT_COMPARE_OP_MORE:
+        case RT_COMPARE_OP_MORE_EQUAL:
+            return MP_BOOL(list_cmp_helper(op, lhs, rhs));
+        case RT_COMPARE_OP_NOT_EQUAL:
+            return MP_BOOL(!list_cmp_helper(RT_COMPARE_OP_EQUAL, lhs, rhs));
+
         default:
             // op not supported
             return NULL;