[vlc-devel] [PATCH 20/20] mkv: Reimplemented MkvTree and moved it to `Util.hpp`

[Filip Roséen]

Because the whole point of the new code is to get rid of the dynamic
allocation if that is possible, using a std::string for the same thing would
require an allocator with static storage - and introducing such would in my
opinion by far too complex to be worth it.

The current implementation is cleaner than conditionally using a std::string
(which indirectly will do dynamic initialization).

/F

------------------------------------------------------------------------------

On 16/03/07 11:05, Denis Charmet wrote:

> Hi,
> 
> On 2016-03-04 17:04, Filip Roséen wrote:
> >+void MkvTree_va( demux_t& demuxer, int i_level, const char* fmt, va_list args)
> >+{
> >+    static char const * indent = "|    ";
> >+    static char const * prefix = "+ ";
> >+    static int  const   indent_len = strlen( indent );
> >+    static int  const   prefix_len = strlen( prefix );
> >+
> >+    char   fixed_buffer[256] = {};
> >+    size_t const  static_len = sizeof( fixed_buffer );
> >+    char *            buffer = fixed_buffer;
> >+    size_t         total_len = indent_len * i_level + prefix_len +
> >strlen( fmt );
> >+
> >+    if( total_len >= static_len ) {
> >+        buffer = new (std::nothrow) char[total_len] ();
> >+
> >+        if (buffer == NULL) {
> >+            msg_Err (&demuxer, "Unable to allocate memory for format string");
> >+            return;
> >+        }
> >+    }
> 
> Since you're cpping everything why not using std::string? :)
> 
> >+
> >+    char * dst = buffer;
> >+
> >+    for (int i = 0; i < i_level; ++i, dst += indent_len)
> >+        memcpy( dst, indent, indent_len );
> >+
> >+    strcat( dst, prefix );
> >+    strcat( dst, fmt );
> >+
> >+    msg_GenericVa( &demuxer, VLC_MSG_DBG, buffer, args );
> >+
> >+    if (buffer != fixed_buffer)
> >+        delete [] buffer;
> >+}
> >+
> >+void MkvTree( demux_t & demuxer, int i_level, const char *psz_format, ... )
> >+{
> >+    va_list args; va_start( args, psz_format );
> >+    MkvTree_va( demuxer, i_level, psz_format, args );
> >+    va_end( args );
> >+}
> >diff --git a/modules/demux/mkv/util.hpp b/modules/demux/mkv/util.hpp
> >index 8c6cc6a..5867d1d 100644
> >--- a/modules/demux/mkv/util.hpp
> >+++ b/modules/demux/mkv/util.hpp
> >@@ -90,3 +90,7 @@ public:
> > };
> >
> > block_t * packetize_wavpack( mkv_track_t *, uint8_t *, size_t);
> >+
> >+/* helper functions to print the mkv parse tree */
> >+void MkvTree_va( demux_t& demuxer, int i_level, const char* fmt, va_list args);
> >+void MkvTree( demux_t & demuxer, int i_level, const char *psz_format, ... );
> 
> Regards,
> -- 
> Denis Charmet - TypX
> Le mauvais esprit est un art de vivre
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