Rename Maybe and its members more like std::optional of C++17

src/BlockFile.cpp

@@ -545,9 +545,9 @@ size_t BlockFile::CommonReadData(
    SFFile sf;
 
    {
-      Maybe<wxLogNull> silence{};
+      Optional<wxLogNull> silence{};
       if (mSilentLog)
-         silence.create();
+         silence.emplace();
 
       const auto fullPath = fileName.GetFullPath();
       if (wxFile::Exists(fullPath) && f.Open(fullPath)) {
@@ -756,9 +756,9 @@ bool AliasBlockFile::ReadSummary(ArrayOf<char> &data)
    wxFFile summaryFile(mFileName.GetFullPath(), wxT("rb"));
 
    {
-      Maybe<wxLogNull> silence{};
+      Optional<wxLogNull> silence{};
       if (mSilentLog)
-         silence.create();
+         silence.emplace();
 
       if (!summaryFile.IsOpened()){
 

src/DirManager.cpp

@@ -204,16 +204,16 @@ int DirManager::RecursivelyEnumerateWithProgress(const FilePath &dirPath,
                                              int progress_count,
                                              const TranslatableString &message)
 {
-   Maybe<ProgressDialog> progress{};
+   Optional<ProgressDialog> progress{};
 
    if (!message.empty())
-      progress.create( XO("Progress"), message );
+      progress.emplace( XO("Progress"), message );
 
    int count = RecursivelyEnumerate(
                   dirPath, filePathArray, dirspec,filespec,
                   bFiles, bDirs,
                   progress_count, 0,
-                  progress.get());
+                  progress ? &*progress : nullptr);
 
    return count;
 }
@@ -289,11 +289,11 @@ void DirManager::RecursivelyRemove(const FilePaths& filePathArray, int count, in
    bool bFiles= (flags & kCleanFiles) != 0;
    bool bDirs = (flags & kCleanDirs) != 0;
    bool bDirsMustBeEmpty = (flags & kCleanDirsOnlyIfEmpty) != 0;
-   Maybe<ProgressDialog> progress{};
+   Optional<ProgressDialog> progress{};
 
 
    if (!message.empty())
-      progress.create( XO("Progress"), message );
+      progress.emplace( XO("Progress"), message );
 
    auto nn = filePathArray.size();
    for ( size_t ii = 0; ii < nn; ++ii ) {
@@ -568,7 +568,7 @@ struct DirManager::ProjectSetter::Impl
 
    // Another RAII object
    // Be prepared to un-create directory on failure
-   Maybe<DirCleaner> dirCleaner;
+   Optional<DirCleaner> dirCleaner;
    
    // State variables to carry over into Commit()
    // Remember old path to be cleaned up in case of successful move
@@ -646,7 +646,7 @@ DirManager::ProjectSetter::Impl::Impl(
 
    // Be prepared to un-create directory on failure
    if (bCreate)
-      dirCleaner.create( committed, dirManager.projFull );
+      dirCleaner.emplace( committed, dirManager.projFull );
 
    /* Hard-link or copy all files into this NEW directory.
 

src/FFmpeg.cpp

@@ -335,7 +335,7 @@ streamContext *import_ffmpeg_read_next_frame(AVFormatContext* formatContext,
    }
 
    // Copy the frame to the stream context
-   sc->m_pkt.create(std::move(pkt));
+   sc->m_pkt.emplace(std::move(pkt));
 
    sc->m_pktDataPtr = sc->m_pkt->data;
    sc->m_pktRemainingSiz = sc->m_pkt->size;

src/FFmpeg.h

@@ -1005,7 +1005,7 @@ struct streamContext
    AVStream            *m_stream{};                        // an AVStream *
    AVCodecContext      *m_codecCtx{};                      // pointer to m_stream->codec
 
-   Maybe<AVPacketEx>    m_pkt;                           // the last AVPacket we read for this stream
+   Optional<AVPacketEx>    m_pkt;                           // the last AVPacket we read for this stream
    uint8_t             *m_pktDataPtr{};                    // pointer into m_pkt.data
    int                  m_pktRemainingSiz{};
 

src/FreqWindow.cpp

@@ -1012,9 +1012,9 @@ void FrequencyPlotDialog::Recalc()
    // controls while the plot was being recalculated.  This doesn't appear to be necessary
    // so just use the the top level window instead.
    {
-      Maybe<wxWindowDisabler> blocker;
+      Optional<wxWindowDisabler> blocker;
       if (IsShown())
-         blocker.create(this);
+         blocker.emplace(this);
       wxYieldIfNeeded();
 
       mAnalyst->Calculate(alg, windowFunc, mWindowSize, mRate,

src/MemoryX.h

@@ -185,16 +185,15 @@ public:
 };
 
 /**
-  \class Maybe
+  \class Optional
   \brief Like a smart pointer, allows for object to not exist (nullptr)
+  \brief emulating some of std::optional of C++17
 
-  template class Maybe<X>
+  template class Optional<X>
   Can be used for monomorphic objects that are stack-allocable, but only conditionally constructed.
   You might also use it as a member.
-  Initialize with create(), then use like a smart pointer,
+  Initialize with emplace(), then use like a smart pointer,
-  with *, ->, get(), reset(), or in if()
+  with *, ->, reset(), or in if()
-
-  Like std::optional of C++17 but with other member naming conventions
  */
 
 // Placement-NEW is used below, and that does not cooperate with the DEBUG_NEW for Visual Studio
@@ -206,41 +205,43 @@ public:
 
 
 template<typename X>
-class Maybe {
+class Optional {
 public:
 
+   using value_type = X;
+
    // Construct as NULL
-   Maybe() {}
+   Optional() {}
 
    // Supply the copy and move, so you might use this as a class member too
-   Maybe(const Maybe &that)
+   Optional(const Optional &that)
    {
-      if (that.get())
+      if (that)
-         create(*that);
+         emplace(*that);
    }
 
-   Maybe& operator= (const Maybe &that)
+   Optional& operator= (const Optional &that)
    {
       if (this != &that) {
-         if (that.get())
+         if (that)
-            create(*that);
+            emplace(*that);
          else
             reset();
       }
       return *this;
    }
 
-   Maybe(Maybe &&that)
+   Optional(Optional &&that)
    {
-      if (that.get())
+      if (that)
-         create(::std::move(*that));
+         emplace(::std::move(*that));
    }
 
-   Maybe& operator= (Maybe &&that)
+   Optional& operator= (Optional &&that)
    {
       if (this != &that) {
-         if (that.get())
+         if (that)
-            create(::std::move(*that));
+            emplace(::std::move(*that));
          else
             reset();
       }
@@ -253,16 +254,17 @@ public:
    /// NULL state -- giving exception safety but only weakly
    /// (previous value was lost if present)
    template<typename... Args>
-   void create(Args&&... args)
+   X& emplace(Args&&... args)
    {
       // Lose any old value
       reset();
-      // Create NEW value
+      // emplace NEW value
       pp = safenew(address()) X(std::forward<Args>(args)...);
+      return **this;
    }
 
    // Destroy any object that was built in it
-   ~Maybe()
+   ~Optional()
    {
       reset();
    }
@@ -280,11 +282,6 @@ public:
       return pp;
    }
 
-   X* get() const
-   {
-      return pp;
-   }
-
    void reset()
    {
       if (pp)
@@ -297,6 +294,11 @@ public:
       return pp != nullptr;
    }
 
+   bool has_value() const
+   {
+      return pp != nullptr;
+   }
+
 private:
    X* address()
    {

src/ProjectFileManager.cpp

@@ -515,7 +515,7 @@ bool ProjectFileManager::DoSave (const bool fromSaveAs,
 
    {
    std::vector<std::unique_ptr<WaveTrack::Locker>> lockers;
-   Maybe<DirManager::ProjectSetter> pSetter;
+   Optional<DirManager::ProjectSetter> pSetter;
    bool moving = true;
 
    if (fromSaveAs && !bWantSaveCopy) {
@@ -536,7 +536,7 @@ bool ProjectFileManager::DoSave (const bool fromSaveAs,
 
       // This renames the project directory, and moves or copies
       // all of our block files over.
-      pSetter.create( dirManager, projPath, projName, true, moving );
+      pSetter.emplace( dirManager, projPath, projName, true, moving );
 
       if (!pSetter->Ok()){
          success = false;

src/ShuttleGui.cpp

@@ -1561,7 +1561,7 @@ void ShuttleGuiBase::StartRadioButtonGroup( const ChoiceSetting &Setting )
 
    // Configure the generic type mechanism to use OUR string.
    mRadioValueString = Setting.Default().Internal();
-   mRadioValue.create( mRadioValueString );
+   mRadioValue.emplace( mRadioValueString );
 
    // Now actually start the radio button group.
    mRadioSettingName = Setting.Key();

src/ShuttleGui.h

@@ -570,7 +570,7 @@ private:
 
    std::vector<EnumValueSymbol> mRadioSymbols;
    wxString mRadioSettingName; /// The setting controlled by a group.
-   Maybe<WrappedType> mRadioValue;  /// The wrapped value associated with the active radio button.
+   Optional<WrappedType> mRadioValue;  /// The wrapped value associated with the active radio button.
    int mRadioCount;       /// The index of this radio item.  -1 for none.
    wxString mRadioValueString; /// Unwrapped string value.
    wxRadioButton * DoAddRadioButton(

src/blockfile/LegacyBlockFile.cpp

@@ -73,11 +73,11 @@ void ComputeLegacySummaryInfo(const wxFileName &fileName,
 
    int read;
    {
-      Maybe<wxLogNull> silence{};
+      Optional<wxLogNull> silence{};
       const wxString fullPath{ fileName.GetFullPath() };
       wxFFile summaryFile(fullPath, wxT("rb"));
       if (Silent)
-         silence.create();
+         silence.emplace();
 
       // FIXME: TRAP_ERR no report to user of absent summary files.
       if (!summaryFile.IsOpened()) {
@@ -160,9 +160,9 @@ bool LegacyBlockFile::ReadSummary(ArrayOf<char> &data)
    wxFFile summaryFile(mFileName.GetFullPath(), wxT("rb"));
    size_t read;
    {
-      Maybe<wxLogNull> silence{};
+      Optional<wxLogNull> silence{};
       if (mSilentLog)
-         silence.create();
+         silence.emplace();
 
       if (!summaryFile.IsOpened()) {
 

src/blockfile/SimpleBlockFile.cpp

@@ -356,9 +356,9 @@ bool SimpleBlockFile::ReadSummary(ArrayOf<char> &data)
       wxFFile file(mFileName.GetFullPath(), wxT("rb"));
 
       {
-         Maybe<wxLogNull> silence{};
+         Optional<wxLogNull> silence{};
          if (mSilentLog)
-            silence.create();
+            silence.emplace();
          // FIXME: TRAP_ERR no report to user of absent summary files?
          // filled with zero instead.
          if (!file.IsOpened()){

src/commands/CommandType.cpp

@@ -41,7 +41,7 @@ CommandSignature &OldStyleCommandType::GetSignature()
 {
    if (!mSignature)
    {
-      mSignature.create();
+      mSignature.emplace();
       BuildSignature(*mSignature);
    }
    return *mSignature;

src/commands/CommandType.h

@@ -43,7 +43,7 @@ class OldStyleCommandType : public AudacityCommand
 {
 private:
    ComponentInterfaceSymbol mSymbol;
-   Maybe<CommandSignature> mSignature;
+   Optional<CommandSignature> mSignature;
 
 public:
    OldStyleCommandType();

src/effects/FindClipping.cpp

@@ -105,7 +105,7 @@ bool EffectFindClipping::SetAutomationParameters(CommandParameters & parms)
 bool EffectFindClipping::Process()
 {
    std::shared_ptr<AddedAnalysisTrack> addedTrack;
-   Maybe<ModifiedAnalysisTrack> modifiedTrack;
+   Optional<ModifiedAnalysisTrack> modifiedTrack;
    const wxString name{ _("Clipping") };
 
    auto clt = *inputTracks()->Any< const LabelTrack >().find_if(
@@ -115,7 +115,7 @@ bool EffectFindClipping::Process()
    if (!clt)
       addedTrack = (AddAnalysisTrack(name)), lt = addedTrack->get();
    else
-      modifiedTrack.create(ModifyAnalysisTrack(clt, name)),
+      modifiedTrack.emplace(ModifyAnalysisTrack(clt, name)),
       lt = modifiedTrack->get();
 
    int count = 0;

src/effects/VST/VSTEffect.cpp

@@ -517,7 +517,7 @@ unsigned VSTEffectsModule::DiscoverPluginsAtPath(
    wxString effectIDs = wxT("0;");
    wxStringTokenizer effectTzr(effectIDs, wxT(";"));
 
-   Maybe<wxProgressDialog> progress{};
+   Optional<wxProgressDialog> progress{};
    size_t idCnt = 0;
    size_t idNdx = 0;
 
@@ -577,7 +577,7 @@ unsigned VSTEffectsModule::DiscoverPluginsAtPath(
                idCnt = effectTzr.CountTokens();
                if (idCnt > 3)
                {
-                  progress.create( _("Scanning Shell VST"),
+                  progress.emplace( _("Scanning Shell VST"),
                         wxString::Format(_("Registering %d of %d: %-64.64s"), 0, idCnt,
                                          proc.GetSymbol().Translation()),
                         static_cast<int>(idCnt),

src/effects/nyquist/Nyquist.cpp

@@ -789,9 +789,9 @@ bool NyquistEffect::Process()
          XO("Nyquist Error") );
    }
 
-   Maybe<TrackIterRange<WaveTrack>> pRange;
+   Optional<TrackIterRange<WaveTrack>> pRange;
    if (!bOnePassTool)
-      pRange.create(mOutputTracks->Selected< WaveTrack >() + &Track::IsLeader);
+      pRange.emplace(mOutputTracks->Selected< WaveTrack >() + &Track::IsLeader);
 
    // Keep track of whether the current track is first selected in its sync-lock group
    // (we have no idea what the length of the returned audio will be, so we have

src/import/ImportFFmpeg.cpp

@@ -667,7 +667,7 @@ ProgressResult FFmpegImportFileHandle::Import(TrackFactory *trackFactory,
       for (int i = 0; i < mNumStreams; i++)
       {
          auto sc = scs[i].get();
-         sc->m_pkt.create();
+         sc->m_pkt.emplace();
          if (DecodeFrame(sc, true) == 0)
          {
             WriteData(sc);

src/menus/EditMenus.cpp

@@ -93,7 +93,7 @@ bool DoPasteNothingSelected(AudacityProject &project)
 
       Track* pFirstNewTrack = NULL;
       for (auto pClip : clipTrackRange) {
-         Maybe<WaveTrack::Locker> locker;
+         Optional<WaveTrack::Locker> locker;
 
          Track::Holder uNewTrack;
          Track *pNewTrack;
@@ -102,7 +102,7 @@ bool DoPasteNothingSelected(AudacityProject &project)
                if ((clipboard.Project() != &project))
                   // Cause duplication of block files on disk, when copy is
                   // between projects
-                  locker.create(wc);
+                  locker.emplace(wc);
                uNewTrack = trackFactory.NewWaveTrack(
                   wc->GetSampleFormat(), wc->GetRate()),
                pNewTrack = uNewTrack.get();
@@ -505,7 +505,7 @@ void OnPaste(const CommandContext &context)
             ff = n;
          
          wxASSERT( n && c && n->SameKindAs(*c) );
-         Maybe<WaveTrack::Locker> locker;
+         Optional<WaveTrack::Locker> locker;
 
          n->TypeSwitch(
             [&](WaveTrack *wn){
@@ -513,7 +513,7 @@ void OnPaste(const CommandContext &context)
                if (clipboard.Project() != &project)
                   // Cause duplication of block files on disk, when copy is
                   // between projects
-                  locker.create(wc);
+                  locker.emplace(wc);
                bPastedSomething = true;
                wn->ClearAndPaste(t0, t1, wc, true, true);
             },
@@ -583,11 +583,11 @@ void OnPaste(const CommandContext &context)
    {
       const auto wc =
          *clipboard.GetTracks().Any< const WaveTrack >().rbegin();
-      Maybe<WaveTrack::Locker> locker;
+      Optional<WaveTrack::Locker> locker;
       if (clipboard.Project() != &project && wc)
          // Cause duplication of block files on disk, when copy is
          // between projects
-         locker.create(static_cast<const WaveTrack*>(wc));
+         locker.emplace(static_cast<const WaveTrack*>(wc));
 
       tracks.Any().StartingWith(*pN).Visit(
          [&](WaveTrack *wt, const Track::Fallthrough &fallthrough) {

src/menus/TrackMenus.cpp

@@ -347,7 +347,7 @@ class ASAProgress final : public SAProgress {
    long mTotalCells; // how many matrix cells?
    long mCellCount; // how many cells so far?
    long mPrevCellCount; // cell_count last reported with Update()
-   Maybe<ProgressDialog> mProgress;
+   Optional<ProgressDialog> mProgress;
    #ifdef COLLECT_TIMING_DATA
       FILE *mTimeFile;
       wxDateTime mStartTime;
@@ -409,7 +409,7 @@ class ASAProgress final : public SAProgress {
                     work[1], mFrames[1], is_audio[1]);
             wxFprintf(mTimeFile, "work2 = %g, work3 = %g\n", work2, work3);
          #endif
-         mProgress.create(XO("Synchronize MIDI with Audio"),
+         mProgress.emplace(XO("Synchronize MIDI with Audio"),
                                XO("Synchronizing MIDI and Audio Tracks"));
       } else if (i < 3) {
          wxFprintf(mTimeFile,

src/ondemand/ODDecodeFFmpegTask.cpp

@@ -428,7 +428,7 @@ int ODFFmpegDecoder::Decode(SampleBuffer & data, sampleFormat & format, sampleCo
       for (int i = 0; i < mChannels.size(); i++)
       {
          sc = scs[i].get();
-         sc->m_pkt.create();
+         sc->m_pkt.emplace();
          if (DecodeFrame(sc, true) == 0)
          {
             sc->m_pkt.reset();

src/widgets/OverlayPanel.cpp

@@ -95,8 +95,8 @@ void OverlayPanel::DrawOverlays(bool repaint_all, wxDC *pDC)
       } while (!done);
    }
 
-   Maybe<wxClientDC> myDC;
+   Optional<wxClientDC> myDC;
-   auto &dc = pDC ? *pDC : (myDC.create(this), *myDC);
+   auto &dc = pDC ? *pDC : (myDC.emplace(this), *myDC);
 
    // Erase
    auto it2 = pairs.begin();