Updated _advance() iter methods. Some have signed offsets.

utf8_peek()/utf8_peek_off() added/changed.

1 files changed, 10 insertions, 4 deletions

diff --git a/include/stc/csview.h b/include/stc/csview.h
index 54a4c4cc..2e90c69b 100644
--- a/include/stc/csview.h
+++ b/include/stc/csview.h
@@ -78,15 +78,21 @@ STC_INLINE csview_iter csview_begin(const csview* self) {
     return c_make(csview_iter){.u8 = {{self->str, utf8_chr_size(self->str)},
                                       self->str + self->size}};
 }
-
-STC_INLINE csview_iter csview_end(const csview* self) 
-    { return c_make(csview_iter){.u8 = {{NULL}, self->str + self->size}}; }
-
+STC_INLINE csview_iter csview_end(const csview* self) {
+    return c_make(csview_iter){.u8 = {{NULL}, self->str + self->size}};
+}
 STC_INLINE void csview_next(csview_iter* it) {
     it->ref += it->u8.chr.size;
     it->u8.chr.size = utf8_chr_size(it->ref);
     if (it->ref == it->u8.end) it->ref = NULL;
 }
+STC_INLINE csview_iter csview_advance(csview_iter it, isize_t pos) {
+    int inc = -1;
+    if (pos > 0) pos = -pos, inc = 1;
+    while (pos && it.ref != it.u8.end) pos += (*(it.ref += inc) & 0xC0) != 0x80;
+    it.u8.chr.size = utf8_chr_size(it.ref);
+    return it;
+}
 
 
 /* utf8 */