1 files changed, 58 insertions, 0 deletions
diff --git a/py/objfilter.c b/py/objfilter.c
new file mode 100644
index 0000000000..18225ac102
--- /dev/null
+++ b/py/objfilter.c
@@ -0,0 +1,58 @@
+#include <stdlib.h>
+#include <assert.h>
+
+#include "nlr.h"
+#include "misc.h"
+#include "mpconfig.h"
+#include "mpqstr.h"
+#include "obj.h"
+#include "runtime.h"
+
+typedef struct _mp_obj_filter_t {
+    mp_obj_base_t base;
+    mp_obj_t fun;
+    mp_obj_t iter;
+} mp_obj_filter_t;
+
+static mp_obj_t filter_make_new(mp_obj_t type_in, int n_args, const mp_obj_t *args) {
+    /* NOTE: args are backwards */
+    if (n_args != 2) {
+        nlr_jump(mp_obj_new_exception_msg(MP_QSTR_TypeError, "filter expected 2 arguments"));
+    }
+    assert(n_args == 2);
+    mp_obj_filter_t *o = m_new_obj(mp_obj_filter_t);
+    o->base.type = &filter_type;
+    o->fun = args[1];
+    o->iter = rt_getiter(args[0]);
+    return o;
+}
+
+static mp_obj_t filter_getiter(mp_obj_t self_in) {
+    return self_in;
+}
+
+static mp_obj_t filter_iternext(mp_obj_t self_in) {
+    assert(MP_OBJ_IS_TYPE(self_in, &filter_type));
+    mp_obj_filter_t *self = self_in;
+    mp_obj_t next;
+    while ((next = rt_iternext(self->iter)) != mp_const_stop_iteration) {
+        mp_obj_t val;
+        if (self->fun != mp_const_none) {
+            val = rt_call_function_n(self->fun, 1, &next);
+        } else {
+            val = next;
+        }
+        if (rt_is_true(val)) {
+            return next;
+        }
+    }
+    return mp_const_stop_iteration;
+}
+
+const mp_obj_type_t filter_type = {
+    { &mp_const_type },
+    "filter",
+    .make_new = filter_make_new,
+    .getiter = filter_getiter,
+    .iternext = filter_iternext,
+};