libc/src/stdio/scanf_core/reader.cpp

   1 //===-- Reader definition for scanf -----------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/stdio/scanf_core/reader.h"
  10 #include <stddef.h>
  11
  12 namespace LIBC_NAMESPACE {
  13 namespace scanf_core {
  14
  15 void Reader::ungetc(char c) {
  16   --cur_chars_read;
  17   if (rb != nullptr && rb->buff_cur > 0) {
  18     // While technically c should be written back to the buffer, in scanf we
  19     // always write the character that was already there. Additionally, the
  20     // buffer is most likely to contain a string that isn't part of a file,
  21     // which may not be writable.
  22     --(rb->buff_cur);
  23     return;
  24   }
  25   stream_ungetc(static_cast<int>(c), input_stream);
  26 }
  27 } // namespace scanf_core
  28 } // namespace LIBC_NAMESPACE