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Constexpr adventures
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@myrsloik
myrsloik committed Apr 10, 2024
1 parent bf7901e commit 22a4c51
Showing 1 changed file with 64 additions and 35 deletions.
99 changes: 64 additions & 35 deletions src/avisynth.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -369,17 +369,9 @@ static AVSValue __cdecl CreateBSAudioSource(AVSValue Args, void *UserData, IScri
return new AvisynthAudioSource(Source, Track, AdjustDelay, Threads, EnableDrefs, UseAbsolutePath, DrcScale, CacheMode, CachePath, CacheSize, Env);
}

// Now some fun magic to parse things from Avisynth arg strings at compile time

// FIXME, basically this needs C++20 and consteval/constinit to be evaluated at compile time without being too annoying to write
static constexpr std::array BSArgNames = { "source", "atrack", "vtrack", "fpsnum", "fpsden", "rff", "threads", "seekpreroll", "enable_drefs", "use_absolute_path", "cachemode", "cachepath", "acachesize", "vcachesize", "hwdevice", "extrahwframes", "timecodes", "start_number", "adjustdelay", "drc_scale" };
static constexpr std::array BSVArgNames = { "source", "track", "fpsnum", "fpsden", "rff", "threads", "seekpreroll", "enable_drefs", "use_absolute_path", "cachemode", "cachepath", "cachesize", "hwdevice", "extrahwframes", "timecodes", "start_number" };
static constexpr std::array BSAArgNames = { "source", "track", "adjustdelay", "threads", "enable_drefs", "use_absolute_path", "drc_scale", "cachemode", "cachepath", "cachesize" };

static constexpr char BSVideoSourceAvsArgs[] = "[source]s[track]i[fpsnum]i[fpsden]i[rff]b[threads]i[seekpreroll]i[enable_drefs]b[use_absolute_path]b[cachemode]i[cachepath]s[cachesize]i[hwdevice]s[extrahwframes]i[timecodes]s[start_number]i";
static constexpr char BSAudioSourceAvsArgs[] = "[source]s[track]i[adjustdelay]i[threads]i[enable_drefs]b[use_absolute_path]b[drc_scale]f[cachemode]i[cachepath]s[cachesize]i";
static constexpr char BSSourceAvsArgs[] = "[source]s[atrack]i[vtrack]i[fpsnum]i[fpsden]i[rff]b[threads]i[seekpreroll]i[enable_drefs]b[use_absolute_path]b[cachemode]i[cachepath]s[acachesize]i[vcachesize]i[hwdevice]s[extrahwframes]i[timecodes]s[start_number]i[adjustdelay]i[drc_scale]f";

static constexpr size_t CountNumArguments(const char *Args) {
static constexpr size_t GetNumAvsArgs(const char *Args) {
size_t NumArgs = 0;
while (*Args) {
if (*Args == '[')
Expand All @@ -389,46 +381,83 @@ static constexpr size_t CountNumArguments(const char *Args) {
return NumArgs;
}

static constexpr int GetVideoArgPos(size_t Position) {
for (size_t i = 0; i < BSArgNames.size(); i++)
if (!strcmp(BSVArgNames[Position], BSArgNames[i]) || BSArgNames[i][0] == 'v' && !strcmp(BSVArgNames[Position], BSArgNames[i] + 1))
return static_cast<int>(i);
return -1;
template<const char Args[], size_t Size>
static constexpr std::array<std::string_view, GetNumAvsArgs(Args)> PopulateArgNames() {
std::array<std::string_view, GetNumAvsArgs(Args)> Result;
size_t Arg = 0;
const char *Start = Args + 1;
const char *Cur = Start;
while (Cur < (Args + Size)) {
if (*Cur == ']') {
Result[Arg++] = std::string_view(Start, Cur - Start);
Start = Cur + 3;
Cur = Start;
} else {
++Cur;
}
}
return Result;
}

static constexpr char BSVideoSourceAvsArgs[] = "[source]s[track]i[fpsnum]i[fpsden]i[rff]b[threads]i[seekpreroll]i[enable_drefs]b[use_absolute_path]b[cachemode]i[cachepath]s[cachesize]i[hwdevice]s[extrahwframes]i[timecodes]s[start_number]i";
static constexpr char BSAudioSourceAvsArgs[] = "[source]s[track]i[adjustdelay]i[threads]i[enable_drefs]b[use_absolute_path]b[drc_scale]f[cachemode]i[cachepath]s[cachesize]i";
static constexpr char BSSourceAvsArgs[] = "[source]s[atrack]i[vtrack]i[fpsnum]i[fpsden]i[rff]b[threads]i[seekpreroll]i[enable_drefs]b[use_absolute_path]b[cachemode]i[cachepath]s[acachesize]i[vcachesize]i[hwdevice]s[extrahwframes]i[timecodes]s[start_number]i[adjustdelay]i[drc_scale]f";

static constexpr std::array BSVArgNames = PopulateArgNames<BSVideoSourceAvsArgs, sizeof(BSVideoSourceAvsArgs)>();
static constexpr std::array BSAArgNames = PopulateArgNames<BSAudioSourceAvsArgs, sizeof(BSAudioSourceAvsArgs)>();
static constexpr std::array BSArgNames = PopulateArgNames<BSSourceAvsArgs, sizeof(BSSourceAvsArgs)>();

static_assert(BSVArgNames.size() + 4 == BSArgNames.size()); //avtrack, avcachesize, adjustdelay and drc_scale

static constexpr std::array<int, BSVArgNames.size()> GetVideoArgMapping() {
auto GetArgPos = [](size_t Position) {
for (size_t i = 0; i < BSArgNames.size(); i++)
if (BSVArgNames[Position] == BSArgNames[i] || (BSArgNames[i].substr(0, 1) == "v" && BSVArgNames[Position] == BSArgNames[i].substr(1)))
return static_cast<int>(i);
return -1;
};
std::array<int, BSVArgNames.size()> Result{};
for (size_t i = 0; i < BSVArgNames.size(); i++)
Result[i] = GetArgPos(i);
return Result;
}

static constexpr int GetAudioArgPos(size_t Position) {
for (size_t i = 0; i < BSArgNames.size(); i++)
if (!strcmp(BSAArgNames[Position], BSArgNames[i]) || BSArgNames[i][0] == 'a' && !strcmp(BSAArgNames[Position], BSArgNames[i] + 1))
return static_cast<int>(i);
return -1;
static constexpr std::array<int, BSAArgNames.size()> GetAudioArgMapping() {
auto GetArgPos = [](size_t Position) {
for (size_t i = 0; i < BSArgNames.size(); i++)
if (BSAArgNames[Position] == BSArgNames[i] || (BSArgNames[i].substr(0, 1) == "a" && BSAArgNames[Position] == BSArgNames[i].substr(1)))
return static_cast<int>(i);
return -1;
};
std::array<int, BSAArgNames.size()> Result{};
for (size_t i = 0; i < BSAArgNames.size(); i++)
Result[i] = GetArgPos(i);
return Result;
}

static AVSValue __cdecl CreateBSSource(AVSValue Args, void *UserData, IScriptEnvironment *Env) {
static_assert(BSArgNames.size() == CountNumArguments(BSSourceAvsArgs), "Arg error");
static constexpr std::array VideoArgMapping = GetVideoArgMapping();
static constexpr std::array AudioArgMapping = GetAudioArgMapping();

AVSValue BSVArgs[] = { Args[GetVideoArgPos(0)], Args[GetVideoArgPos(1)], Args[GetVideoArgPos(2)], Args[GetVideoArgPos(3)],
Args[GetVideoArgPos(4)], Args[GetVideoArgPos(5)], Args[GetVideoArgPos(6)], Args[GetVideoArgPos(7)], Args[GetVideoArgPos(8)],
Args[GetVideoArgPos(9)], Args[GetVideoArgPos(10)], Args[GetVideoArgPos(11)], Args[GetVideoArgPos(12)], Args[GetVideoArgPos(13)],
Args[GetVideoArgPos(14)], Args[15] };
static_assert((sizeof(BSVArgs) / sizeof(BSVArgs[0])) == CountNumArguments(BSVideoSourceAvsArgs), "Arg error");
AVSValue BSVArgs[] = { Args[VideoArgMapping[0]], Args[VideoArgMapping[1]], Args[VideoArgMapping[2]], Args[VideoArgMapping[3]],
Args[VideoArgMapping[4]], Args[VideoArgMapping[5]], Args[VideoArgMapping[6]], Args[VideoArgMapping[7]], Args[VideoArgMapping[8]],
Args[VideoArgMapping[9]], Args[VideoArgMapping[10]], Args[VideoArgMapping[11]], Args[VideoArgMapping[12]], Args[VideoArgMapping[13]],
Args[VideoArgMapping[14]], Args[VideoArgMapping[15]] };
static_assert((sizeof(BSVArgs) / sizeof(BSVArgs[0])) == BSVArgNames.size(), "Arg error");

AVSValue Video = Env->Invoke("BSVideoSource", AVSValue(BSVArgs, sizeof(BSVArgs) / sizeof(BSVArgs[0])), BSVArgNames.data());

bool WithAudio = Args[1].Defined();
AVSValue Video = Env->Invoke("BSVideoSource", AVSValue(BSVArgs, sizeof(BSVArgs) / sizeof(BSVArgs[0])));

if (WithAudio) {
AVSValue BSAArgs[] = { Args[GetAudioArgPos(0)], Args[GetAudioArgPos(1)], Args[GetAudioArgPos(2)], Args[GetAudioArgPos(3)],
Args[GetAudioArgPos(4)], Args[GetAudioArgPos(5)], Args[GetAudioArgPos(6)], Args[GetAudioArgPos(7)], Args[GetAudioArgPos(8)], Args[GetAudioArgPos(9)]};
try {
AVSValue BSAArgs[] = { Args[AudioArgMapping[0]], Args[AudioArgMapping[1]], Args[AudioArgMapping[2]], Args[AudioArgMapping[3]],
Args[AudioArgMapping[4]], Args[AudioArgMapping[5]], Args[AudioArgMapping[6]], Args[AudioArgMapping[7]], Args[AudioArgMapping[8]], Args[AudioArgMapping[9]] };

static_assert((sizeof(BSAArgs) / sizeof(BSAArgs[0])) == CountNumArguments(BSAudioSourceAvsArgs), "Arg error");
static_assert((sizeof(BSAArgs) / sizeof(BSAArgs[0])) == BSAArgNames.size(), "Arg error");

AVSValue Audio = Env->Invoke("BSAudioSource", AVSValue(BSAArgs, sizeof(BSAArgs) / sizeof(BSAArgs[0])), BSAArgNames.data());
AVSValue Audio = Env->Invoke("BSAudioSource", AVSValue(BSAArgs, sizeof(BSAArgs) / sizeof(BSAArgs[0])));

AVSValue AudioDubArgs[] = { Video, Audio };
return Env->Invoke("AudioDubEx", AVSValue(AudioDubArgs, sizeof(AudioDubArgs) / sizeof(AudioDubArgs[0])));
} else {
} catch(...) {
return Video;
}
}
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