gdbsupport/byte-vector.h

   1 /* Copyright (C) 2017-2022 Free Software Foundation, Inc.
   2
   3    This file is part of GDB.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef COMMON_BYTE_VECTOR_H
  19 #define COMMON_BYTE_VECTOR_H
  20
  21 #include "gdbsupport/def-vector.h"
  22
  23 namespace gdb {
  24
  25 /* byte_vector is a gdb_byte std::vector with a custom allocator that
  26    unlike std::vector<gdb_byte> does not zero-initialize new elements
  27    by default when the vector is created/resized.  This is what you
  28    usually want when working with byte buffers, since if you're
  29    creating or growing a buffer you'll most surely want to fill it in
  30    with data, in which case zero-initialization would be a
  31    pessimization.  For example:
  32
  33      gdb::byte_vector buf (some_large_size);
  34      fill_with_data (buf.data (), buf.size ());
  35
  36    On the odd case you do need zero initialization, then you can still
  37    call the overloads that specify an explicit value, like:
  38
  39      gdb::byte_vector buf (some_initial_size, 0);
  40      buf.resize (a_bigger_size, 0);
  41
  42    (Or use std::vector<gdb_byte> instead.)
  43
  44    Note that unlike std::vector<gdb_byte>, function local
  45    gdb::byte_vector objects constructed with an initial size like:
  46
  47      gdb::byte_vector buf (some_size);
  48      fill_with_data (buf.data (), buf.size ());
  49
  50    usually compile down to the exact same as:
  51
  52      std::unique_ptr<byte[]> buf (new gdb_byte[some_size]);
  53      fill_with_data (buf.get (), some_size);
  54
  55    with the former having the advantage of being a bit more readable,
  56    and providing the whole std::vector API, if you end up needing it.
  57 */
  58 using byte_vector = gdb::def_vector<gdb_byte>;
  59 using char_vector = gdb::def_vector<char>;
  60
  61 } /* namespace gdb */
  62
  63 #endif /* COMMON_DEF_VECTOR_H */