tokenizing hello.zig

src/buffer.cpp

@@ -23,3 +23,24 @@ Buf *buf_sprintf(const char *format, ...) {
 
     return buf;
 }
+
+void buf_appendf(Buf *buf, const char *format, ...) {
+    va_list ap, ap2;
+    va_start(ap, format);
+    va_copy(ap2, ap);
+
+    int len1 = vsnprintf(nullptr, 0, format, ap);
+    assert(len1 >= 0);
+
+    size_t required_size = len1 + 1;
+
+    int orig_len = buf_len(buf);
+
+    buf_resize(buf, orig_len + required_size);
+
+    int len2 = vsnprintf(buf_ptr(buf) + orig_len, required_size, format, ap2);
+    assert(len2 == len1);
+
+    va_end(ap2);
+    va_end(ap);
+}