libc/src/stdio/printf_core/string_writer.h

   1 //===-- String Writer definition for printf ---------------------*- 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 #ifndef LLVM_LIBC_SRC_STDIO_PRINTF_CORE_STRING_WRITER_H
  10 #define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_STRING_WRITER_H
  11
  12 #include "src/__support/CPP/string_view.h"
  13 #include "src/string/memory_utils/memcpy_implementations.h"
  14 #include <stddef.h>
  15
  16 namespace __llvm_libc {
  17 namespace printf_core {
  18
  19 class StringWriter {
  20   char *__restrict cur_buffer;
  21   size_t available_capacity;
  22
  23 public:
  24   // StringWriter is intended to take a copy of the cur_buffer pointer, as well
  25   // as the maximum length of the string. This maximum length should not include
  26   // the null terminator, since that's written separately.
  27   StringWriter(char *__restrict buffer, size_t max_len = ~size_t(0))
  28       : cur_buffer(buffer), available_capacity(max_len) {}
  29
  30   void write(cpp::string_view new_string);
  31   void write(char new_char, size_t len);
  32   void write(char new_char);
  33
  34   // Terminate should only be called if the original max length passed to
  35   // snprintf was greater than 0. It writes a null byte to the end of the
  36   // cur_buffer, regardless of available_capacity.
  37   void terminate() { *cur_buffer = '\0'; }
  38
  39   // These write functions take a StringWriter as a void* in raw_pointer, and
  40   // call the appropriate write function on it.
  41   static int write_str(void *raw_pointer, cpp::string_view new_string);
  42   static int write_chars(void *raw_pointer, char new_char, size_t len);
  43   static int write_char(void *raw_pointer, char new_char);
  44 };
  45
  46 } // namespace printf_core
  47 } // namespace __llvm_libc
  48
  49 #endif // LLVM_LIBC_SRC_STDIO_PRINTF_CORE_STRING_WRITER_H