Don't use an internal iterator in Tags

src/Tags.cpp

@@ -394,30 +394,9 @@ wxString Tags::GetTag(const wxString & name)
    return mMap[iter->second];
 }
 
-bool Tags::GetFirst(wxString & name, wxString & value)
+Tags::Iterators Tags::GetRange() const
 {
-   mIter = mMap.begin();
-   if (mIter == mMap.end()) {
-      return false;
-   }
-
-   name = mIter->first;
-   value = mIter->second;
-
-   return true;
-}
-
-bool Tags::GetNext(wxString & name, wxString & value)
-{
-   ++mIter;
-   if (mIter == mMap.end()) {
-      return false;
-   }
-
-   name = mIter->first;
-   value = mIter->second;
-
-   return true;
+   return std::make_pair(mMap.begin(), mMap.end());
 }
 
 void Tags::SetTag(const wxString & name, const wxString & value)
@@ -510,8 +489,9 @@ void Tags::WriteXML(XMLWriter &xmlFile)
 {
    xmlFile.StartTag(wxT("tags"));
 
-   wxString n, v;
-   for (bool cont = GetFirst(n, v); cont; cont = GetNext(n, v)) {
+   for (const auto &pair : GetRange()) {
+      const auto &n = pair.first;
+      const auto &v = pair.second;
       xmlFile.StartTag(wxT("tag"));
       xmlFile.WriteAttr(wxT("name"), n);
       xmlFile.WriteAttr(wxT("value"), v);
@@ -863,8 +843,6 @@ bool TagsEditor::TransferDataFromWindow()
 bool TagsEditor::TransferDataToWindow()
 {
    size_t i;
-   wxString n;
-   wxString v;
    TagMap popTagMap;
 
    // Disable redrawing until we're done
@@ -895,12 +873,14 @@ bool TagsEditor::TransferDataToWindow()
    }
 
    // Populate the rest
-   for (bool cont = mLocal.GetFirst(n, v); cont; cont = mLocal.GetNext(n, v)) {
-      if ( popTagMap.find(n) == popTagMap.end() ) {
+   for (const auto &pair : mLocal.GetRange()) {
+      const auto &n = pair.first;
+      const auto &v = pair.second;
+      if (popTagMap.find(n) == popTagMap.end()) {
          mGrid->AppendRows();
          mGrid->SetCellValue(i, 0, n);
          mGrid->SetCellValue(i, 1, v);
-	 i++;
+         i++;
       }
    }
 
@@ -1186,8 +1166,9 @@ void TagsEditor::OnSaveDefaults(wxCommandEvent & WXUNUSED(event))
    gPrefs->DeleteGroup(wxT("/Tags"));
 
    // Write out each tag
-   wxString n, v;
-   for (bool cont = mLocal.GetFirst(n, v); cont; cont = mLocal.GetNext(n, v)) {
+   for (const auto &pair : mLocal.GetRange()) {
+      const auto &n = pair.first;
+      const auto &v = pair.second;
       gPrefs->Write(wxT("/Tags/") + n, v);
    }
    gPrefs->Flush();

src/Tags.h

@@ -33,6 +33,7 @@
 #include "widgets/Grid.h"
 #include "xml/XMLTagHandler.h"
 
+#include <utility>
 #include <wx/dialog.h>
 #include <wx/hashmap.h>
 #include <wx/notebook.h>
@@ -99,8 +100,14 @@ class AUDACITY_DLL_API Tags: public XMLTagHandler {
    bool HasTag(const wxString & name);
    wxString GetTag(const wxString & name);
 
-   bool GetFirst(wxString & name, wxString & value);
-   bool GetNext(wxString & name, wxString & value);
+   using IterPair = std::pair<TagMap::const_iterator, TagMap::const_iterator>;
+   struct Iterators : public IterPair {
+      Iterators(IterPair p) : IterPair(p) {}
+      // Define begin() and end() for convenience in range-for
+      auto begin() -> decltype(first) const { return first; }
+      auto end() -> decltype(second) const { return second; }
+   };
+   Iterators GetRange() const;
 
    void SetTag(const wxString & name, const wxString & value);
    void SetTag(const wxString & name, const int & value);
@@ -111,7 +118,6 @@ class AUDACITY_DLL_API Tags: public XMLTagHandler {
  private:
    void LoadDefaults();
 
-   TagMap::iterator mIter;
    TagMap mXref;
    TagMap mMap;
 

src/export/ExportFLAC.cpp

@@ -388,8 +388,10 @@ bool ExportFLAC::GetMetadata(AudacityProject *project, Tags *tags)
 
    mMetadata = ::FLAC__metadata_object_new(FLAC__METADATA_TYPE_VORBIS_COMMENT);
 
-   wxString n, v;
-   for (bool cont = tags->GetFirst(n, v); cont; cont = tags->GetNext(n, v)) {
+   wxString n;
+   for (const auto &pair : tags->GetRange()) {
+      n = pair.first;
+      const auto &v = pair.second;
       if (n == TAG_YEAR) {
          n = wxT("DATE");
       }

src/export/ExportMP2.cpp

@@ -344,8 +344,9 @@ int ExportMP2::AddTags(AudacityProject * WXUNUSED(project), char **buffer, bool
 #ifdef USE_LIBID3TAG
    struct id3_tag *tp = id3_tag_new();
 
-   wxString n, v;
-   for (bool cont = tags->GetFirst(n, v); cont; cont = tags->GetNext(n, v)) {
+   for (const auto &pair : tags->GetRange()) {
+      const auto &n = pair.first;
+      const auto &v = pair.second;
       const char *name = "TXXX";
 
       if (n.CmpNoCase(TAG_TITLE) == 0) {

src/export/ExportMP3.cpp

@@ -1970,8 +1970,9 @@ int ExportMP3::AddTags(AudacityProject *WXUNUSED(project), char **buffer, bool *
 #ifdef USE_LIBID3TAG
    struct id3_tag *tp = id3_tag_new();
 
-   wxString n, v;
-   for (bool cont = tags->GetFirst(n, v); cont; cont = tags->GetNext(n, v)) {
+   for (const auto &pair : tags->GetRange()) {
+      const auto &n = pair.first;
+      const auto &v = pair.second;
       const char *name = "TXXX";
 
       if (n.CmpNoCase(TAG_TITLE) == 0) {

src/export/ExportOGG.cpp

@@ -349,8 +349,10 @@ bool ExportOGG::FillComment(AudacityProject *project, vorbis_comment *comment, T
 
    vorbis_comment_init(comment);
 
-   wxString n, v;
-   for (bool cont = metadata->GetFirst(n, v); cont; cont = metadata->GetNext(n, v)) {
+   wxString n;
+   for (const auto &pair : metadata->GetRange()) {
+      n = pair.first;
+      const auto &v = pair.second;
       if (n == TAG_YEAR) {
          n = wxT("DATE");
       }

src/export/ExportPCM.cpp

@@ -746,8 +746,9 @@ void ExportPCM::AddID3Chunk(wxString fName, Tags *tags, int sf_format)
 #ifdef USE_LIBID3TAG
    struct id3_tag *tp = id3_tag_new();
 
-   wxString n, v;
-   for (bool cont = tags->GetFirst(n, v); cont; cont = tags->GetNext(n, v)) {
+   for (const auto &pair : tags->GetRange()) {
+      const auto &n = pair.first;
+      const auto &v = pair.second;
       const char *name = "TXXX";
 
       if (n.CmpNoCase(TAG_TITLE) == 0) {