bstr: add bstrspn()

core/bstr.c

@@ -82,6 +82,15 @@ int bstrcspn(struct bstr str, const char *reject)
     return i;
 }
 
+int bstrspn(struct bstr str, const char *accept)
+{
+    int i;
+    for (i = 0; i < str.len; i++)
+        if (!strchr(accept, str.start[i]))
+            break;
+    return i;
+}
+
 int bstr_find(struct bstr haystack, struct bstr needle)
 {
     for (int i = 0; i < haystack.len; i++)

core/bstr.h

@@ -58,6 +58,7 @@ int bstrcmp(struct bstr str1, struct bstr str2);
 int bstrcasecmp(struct bstr str1, struct bstr str2);
 int bstrchr(struct bstr str, int c);
 int bstrrchr(struct bstr str, int c);
+int bstrspn(struct bstr str, const char *accept);
 int bstrcspn(struct bstr str, const char *reject);
 
 int bstr_find(struct bstr haystack, struct bstr needle);