added filter()

py/mpqstrraw.h

@@ -42,6 +42,7 @@ Q(complex)
 Q(dict)
 Q(divmod)
 Q(enumerate)
+Q(filter)
 Q(float)
 Q(hash)
 Q(int)

py/obj.h

@@ -300,6 +300,9 @@ extern const mp_obj_type_t map_type;
 // enumerate
 extern const mp_obj_type_t enumerate_type;
 
+// filter
+extern const mp_obj_type_t filter_type;
+
 // dict
 extern const mp_obj_type_t dict_type;
 uint mp_obj_dict_len(mp_obj_t self_in);

py/objfilter.c

@@ -0,0 +1,53 @@
+#include <stdlib.h>
+#include <assert.h>
+
+#include "misc.h"
+#include "mpconfig.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 */
+    mp_obj_filter_t *o = m_new_obj(mp_obj_filter_t);
+    assert(n_args == 2);
+    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,
+};

py/py.mk

@@ -79,6 +79,7 @@ PY_O_BASENAME = \
 	objdict.o \
 	objenumerate.o \
 	objexcept.o \
+	objfilter.o \
 	objfloat.o \
 	objfun.o \
 	objgenerator.o \

py/runtime.c

@@ -106,6 +106,7 @@ void rt_init(void) {
 #endif
     mp_map_add_qstr(&map_builtins, MP_QSTR_dict, (mp_obj_t)&dict_type);
     mp_map_add_qstr(&map_builtins, MP_QSTR_enumerate, (mp_obj_t)&enumerate_type);
+    mp_map_add_qstr(&map_builtins, MP_QSTR_filter, (mp_obj_t)&filter_type);
 #if MICROPY_ENABLE_FLOAT
     mp_map_add_qstr(&map_builtins, MP_QSTR_float, (mp_obj_t)&float_type);
 #endif

tests/basics/tests/filter.py

@@ -0,0 +1,2 @@
+print(list(filter(lambda x: x & 1, range(-3, 4))))
+print(list(filter(None, range(-3, 4))))