Keep item ordering as much as possible

The ordering goes first by type and then by uuid.  In the case of
DRAWSEGMENT and EDGE_MODULE, we also sort by shape type before UUID.

Fixes https://gitlab.com/kicad/code/kicad/issues/4068

include/class_board_item.h

@@ -341,6 +341,11 @@ public:
     virtual void TransformShapeWithClearanceToPolygon( SHAPE_POLY_SET& aCornerBuffer,
             int aClearanceValue, int aError = ARC_LOW_DEF, bool ignoreLineWidth = false ) const;
 
+    struct ptr_cmp
+    {
+        bool operator() ( const BOARD_ITEM* a, const BOARD_ITEM* b ) const;
+    };
+
 protected:
     /**
      * Helper function

pcbnew/class_board_item.cpp

@@ -139,6 +139,17 @@ void BOARD_ITEM::TransformShapeWithClearanceToPolygon( SHAPE_POLY_SET& aCornerBu
 };
 
 
+bool BOARD_ITEM::ptr_cmp::operator() ( const BOARD_ITEM* a, const BOARD_ITEM* b ) const
+{
+    if( a->Type() != b->Type() )
+        return a->Type() < b->Type();
+
+    if( a->GetLayer() != b->GetLayer() )
+        return a->GetLayer() < b->GetLayer();
+
+    return a->m_Uuid < b->m_Uuid;
+}
+
 static struct BOARD_ITEM_DESC
 {
     BOARD_ITEM_DESC()

pcbnew/class_drawsegment.cpp

@@ -1178,6 +1178,27 @@ void DRAWSEGMENT::SwapData( BOARD_ITEM* aImage )
 }
 
 
+bool DRAWSEGMENT::cmp_drawings::operator()( const BOARD_ITEM* aFirst, const BOARD_ITEM* aSecond ) const
+{
+    if( aFirst->Type() != aSecond->Type() )
+        return aFirst->Type() < aSecond->Type();
+
+    if( aFirst->GetLayer() != aSecond->GetLayer() )
+        return aFirst->GetLayer() < aSecond->GetLayer();
+
+    if( aFirst->Type() == PCB_LINE_T )
+    {
+        const DRAWSEGMENT* dwgA = static_cast<const DRAWSEGMENT*>( aFirst );
+        const DRAWSEGMENT* dwgB = static_cast<const DRAWSEGMENT*>( aSecond );
+
+        if( dwgA->GetShape() != dwgB->GetShape() )
+            return dwgA->GetShape() < dwgB->GetShape();
+    }
+
+    return aFirst->m_Uuid < aSecond->m_Uuid;
+}
+
+
 static struct DRAWSEGMENT_DESC
 {
     DRAWSEGMENT_DESC()

pcbnew/class_drawsegment.h

@@ -297,6 +297,11 @@ public:
 
     virtual void SwapData( BOARD_ITEM* aImage ) override;
 
+    struct cmp_drawings
+    {
+        bool operator()( const BOARD_ITEM* aFirst, const BOARD_ITEM* aSecond ) const;
+    };
+
 #if defined(DEBUG)
     void Show( int nestLevel, std::ostream& os ) const override { ShowDummy( os ); }
 #endif

pcbnew/class_module.cpp

@@ -1621,6 +1621,36 @@ bool MODULE::HasNonSMDPins() const
 }
 
 
+bool MODULE::cmp_drawings::operator()( const BOARD_ITEM* aFirst, const BOARD_ITEM* aSecond ) const
+{
+    if( aFirst->Type() != aSecond->Type() )
+        return aFirst->Type() < aSecond->Type();
+
+    if( aFirst->GetLayer() != aSecond->GetLayer() )
+        return aFirst->GetLayer() < aSecond->GetLayer();
+
+    if( aFirst->Type() == PCB_MODULE_EDGE_T )
+    {
+        const EDGE_MODULE* dwgA = static_cast<const EDGE_MODULE*>( aFirst );
+        const EDGE_MODULE* dwgB = static_cast<const EDGE_MODULE*>( aSecond );
+
+        if( dwgA->GetShape() != dwgB->GetShape() )
+            return dwgA->GetShape() < dwgB->GetShape();
+    }
+
+    return aFirst->m_Uuid < aSecond->m_Uuid;
+}
+
+
+bool MODULE::cmp_pads::operator()( const D_PAD* aFirst, const D_PAD* aSecond ) const
+{
+    if( aFirst->GetName() != aSecond->GetName() )
+        return StrNumCmp( aFirst->GetName(), aSecond->GetName() ) < 0;
+
+    return aFirst->m_Uuid < aSecond->m_Uuid;
+}
+
+
 static struct MODULE_DESC
 {
     MODULE_DESC()

pcbnew/class_module.h

@@ -680,6 +680,17 @@ public:
 
     virtual void SwapData( BOARD_ITEM* aImage ) override;
 
+    struct cmp_drawings
+    {
+        bool operator()( const BOARD_ITEM* aFirst, const BOARD_ITEM* aSecond ) const;
+    };
+
+    struct cmp_pads
+    {
+        bool operator()( const D_PAD* aFirst, const D_PAD* aSecond ) const;
+    };
+
+
 #if defined(DEBUG)
     virtual void Show( int nestLevel, std::ostream& os ) const override { ShowDummy( os ); }
 #endif

pcbnew/class_track.cpp

@@ -939,6 +939,21 @@ double ARC::GetArcAngleEnd() const
 }
 
 
+bool TRACK::cmp_tracks::operator() ( const TRACK* a, const TRACK* b ) const
+{
+    if( a->GetNetCode() != b->GetNetCode() )
+        return a->GetNetCode() < b->GetNetCode();
+
+    if( a->GetLayer() != b->GetLayer() )
+        return a->GetLayer() < b->GetLayer();
+
+    if( a->Type() != b->Type() )
+        return a->Type() < b->Type();
+
+    return a->m_Uuid < b->m_Uuid;
+}
+
+
 #if defined(DEBUG)
 
 wxString TRACK::ShowState( int stateBits )

pcbnew/class_track.h

@@ -237,6 +237,11 @@ public:
         return true;
     }
 
+    struct cmp_tracks
+    {
+        bool operator()( const TRACK* aFirst, const TRACK* aSecond ) const;
+    };
+
 #if defined (DEBUG)
     virtual void Show( int nestLevel, std::ostream& os ) const override { ShowDummy( os ); }
 

pcbnew/kicad_plugin.cpp

@@ -601,34 +601,44 @@ void PCB_IO::formatHeader( BOARD* aBoard, int aNestLevel ) const
 
 void PCB_IO::format( BOARD* aBoard, int aNestLevel ) const
 {
+
+    std::set<BOARD_ITEM*, BOARD_ITEM::ptr_cmp> sorted_modules( aBoard->Modules().begin(),
+            aBoard->Modules().end() );
+    std::set<BOARD_ITEM*, BOARD_ITEM::ptr_cmp> sorted_drawings( aBoard->Drawings().begin(),
+            aBoard->Drawings().end() );
+    std::set<TRACK*, TRACK::cmp_tracks> sorted_tracks( aBoard->Tracks().begin(),
+            aBoard->Tracks().end() );
+    std::set<BOARD_ITEM*, BOARD_ITEM::ptr_cmp> sorted_zones( aBoard->Zones().begin(),
+            aBoard->Zones().end() );
+
     formatHeader( aBoard, aNestLevel );
 
     // Save the modules.
-    for( auto module : aBoard->Modules() )
+    for( auto module : sorted_modules )
     {
         Format( module, aNestLevel );
         m_out->Print( 0, "\n" );
     }
 
     // Save the graphical items on the board (not owned by a module)
-    for( auto item : aBoard->Drawings() )
+    for( auto item : sorted_drawings )
         Format( item, aNestLevel );
 
-    if( aBoard->Drawings().size() )
+    if( sorted_drawings.size() )
         m_out->Print( 0, "\n" );
 
     // Do not save MARKER_PCBs, they can be regenerated easily.
 
     // Save the tracks and vias.
-    for( auto track : aBoard->Tracks() )
+    for( auto track : sorted_tracks )
         Format( track, aNestLevel );
 
-    if( aBoard->Tracks().size() )
+    if( sorted_tracks.size() )
         m_out->Print( 0, "\n" );
 
     // Save the polygon (which are the newer technology) zones.
-    for( int i = 0; i < aBoard->GetAreaCount();  ++i )
-        Format( aBoard->GetArea( i ), aNestLevel );
+    for( auto zone : sorted_zones )
+        Format( zone, aNestLevel );
 }
 
 
@@ -983,17 +993,25 @@ void PCB_IO::format( MODULE* aModule, int aNestLevel ) const
     Format( (BOARD_ITEM*) &aModule->Reference(), aNestLevel+1 );
     Format( (BOARD_ITEM*) &aModule->Value(), aNestLevel+1 );
 
+    std::set<D_PAD*, MODULE::cmp_pads> sorted_pads( aModule->Pads().begin(),
+            aModule->Pads().end() );
+    std::set<BOARD_ITEM*, MODULE::cmp_drawings> sorted_drawings( aModule->GraphicalItems().begin(),
+            aModule->GraphicalItems().end() );
+    std::set<BOARD_ITEM*, BOARD_ITEM::ptr_cmp> sorted_zones( aModule->Zones().begin(),
+            aModule->Zones().end() );
+
     // Save drawing elements.
-    for( auto gr : aModule->GraphicalItems() )
+
+    for( auto gr : sorted_drawings )
         Format( gr, aNestLevel+1 );
 
     // Save pads.
-    for( auto pad : aModule->Pads() )
-        format( pad, aNestLevel+1 );
+    for( auto pad : sorted_pads )
+        Format( pad, aNestLevel+1 );
 
     // Save zones.
-    for( auto zone : aModule->Zones() )
-        format( zone, aNestLevel + 1 );
+    for( auto zone : sorted_zones )
+        Format( zone, aNestLevel + 1 );
 
     // Save 3D info.
     auto bs3D = aModule->Models().begin();