extmod/ure: Support search/match() pos and endpos parameters

MICROPY_PY_URE_MATCH_SPAN_START_END is used to enable the functionality
since it's similar.

extmod/modure.c

@@ -178,6 +178,35 @@ STATIC mp_obj_t ure_exec(bool is_anchored, uint n_args, const mp_obj_t *args) {
     size_t len;
     subj.begin = mp_obj_str_get_data(args[1], &len);
     subj.end = subj.begin + len;
+#if MICROPY_PY_URE_MATCH_SPAN_START_END
+    if (n_args > 2) {
+        const mp_obj_type_t *self_type = mp_obj_get_type(args[1]);
+        mp_int_t str_len = MP_OBJ_SMALL_INT_VALUE(mp_obj_len_maybe(args[1]));
+        const byte *begin = (const byte *)subj.begin;
+
+        int pos = mp_obj_get_int(args[2]);
+        if (pos >= str_len) {
+            return mp_const_none;
+        }
+        if (pos < 0) {
+            pos = 0;
+        }
+        const byte *pos_ptr = str_index_to_ptr(self_type, begin, len, MP_OBJ_NEW_SMALL_INT(pos), true);
+
+        const byte *endpos_ptr = (const byte *)subj.end;
+        if (n_args > 3) {
+            int endpos = mp_obj_get_int(args[3]);
+            if (endpos <= pos) {
+                return mp_const_none;
+            }
+            // Will cap to length
+            endpos_ptr = str_index_to_ptr(self_type, begin, len, args[3], true);
+        }
+
+        subj.begin = (const char *)pos_ptr;
+        subj.end = (const char *)endpos_ptr;
+    }
+#endif
     int caps_num = (self->re.sub + 1) * 2;
     mp_obj_match_t *match = m_new_obj_var(mp_obj_match_t, char*, caps_num);
     // cast is a workaround for a bug in msvc: it treats const char** as a const pointer instead of a pointer to pointer to const char

py/objstr.c

@@ -408,6 +408,15 @@ mp_obj_t mp_obj_str_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_i
 
 #if !MICROPY_PY_BUILTINS_STR_UNICODE
 // objstrunicode defines own version
+size_t str_offset_to_index(const mp_obj_type_t *type, const byte *self_data, size_t self_len,
+                           size_t offset) {
+    if (offset > self_len) {
+        mp_raise_ValueError(translate("offset out of bounds"));
+    }
+
+    return offset;
+}
+
 const byte *str_index_to_ptr(const mp_obj_type_t *type, const byte *self_data, size_t self_len,
                              mp_obj_t index, bool is_slice) {
     size_t index_val = mp_get_index(type, self_len, index, is_slice);

py/objstr.h

@@ -71,6 +71,8 @@ mp_obj_t mp_obj_new_str_of_type(const mp_obj_type_t *type, const byte* data, siz
 mp_obj_t mp_obj_str_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in);
 mp_int_t mp_obj_str_get_buffer(mp_obj_t self_in, mp_buffer_info_t *bufinfo, mp_uint_t flags);
 
+size_t str_offset_to_index(const mp_obj_type_t *type, const byte *self_data, size_t self_len,
+                           size_t offset);
 const byte *str_index_to_ptr(const mp_obj_type_t *type, const byte *self_data, size_t self_len,
                              mp_obj_t index, bool is_slice);
 const byte *find_subbytes(const byte *haystack, size_t hlen, const byte *needle, size_t nlen, int direction);

py/objstrunicode.c

@@ -112,6 +112,26 @@ STATIC mp_obj_t uni_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
     }
 }
 
+size_t str_offset_to_index(const mp_obj_type_t *type, const byte *self_data, size_t self_len,
+                           size_t offset) {
+    if (offset > self_len) {
+        mp_raise_ValueError(translate("offset out of bounds"));
+    }
+
+    if (type == &mp_type_bytes) {
+        return offset;
+    }
+
+    size_t index_val = 0;
+    const byte *s = self_data;
+    for (size_t i = 0; i < offset; i++, s++) {
+        if (!UTF8_IS_CONT(*s)) {
+            ++index_val;
+        }
+    }
+    return index_val;
+}
+
 // Convert an index into a pointer to its lead byte. Out of bounds indexing will raise IndexError or
 // be capped to the first/last character of the string, depending on is_slice.
 const byte *str_index_to_ptr(const mp_obj_type_t *type, const byte *self_data, size_t self_len,