Add and use List::Last(). NFC.

src/dsc.h

@@ -250,6 +250,10 @@ public:
     const T *First() const {
         return IsEmpty() ? nullptr : &(elem[0]);
     }
+
+    T *Last() { return IsEmpty() ? nullptr : &(elem[n - 1]); }
+    const T *Last() const { return IsEmpty() ? nullptr : &(elem[n - 1]); }
+
     T *NextAfter(T *prev) {
         if(IsEmpty() || !prev) return NULL;
         if(prev - First() == (n - 1)) return NULL;

src/exportstep.cpp

@@ -121,7 +121,7 @@ int StepFileWriter::ExportCurveLoop(SBezierLoop *loop, bool inner) {
 
     List<int> listOfTrims = {};
 
-    SBezier *sb = &(loop->l[loop->l.n - 1]);
+    SBezier *sb = loop->l.Last();
 
     // Generate "exactly closed" contours, with the same vertex id for the
     // finish of a previous edge and the start of the next one. So we need

src/file.cpp

@@ -343,7 +343,7 @@ bool SolveSpaceUI::SaveToFile(const Platform::Path &filename) {
     // A group will have either a mesh or a shell, but not both; but the code
     // to print either of those just does nothing if the mesh/shell is empty.
 
-    Group *g = SK.GetGroup(SK.groupOrder[SK.groupOrder.n - 1]);
+    Group *g = SK.GetGroup(*SK.groupOrder.Last());
     SMesh *m = &g->runningMesh;
     for(i = 0; i < m->l.n; i++) {
         STriangle *tr = &(m->l[i]);

src/graphicswin.cpp

@@ -383,7 +383,7 @@ void GraphicsWindow::Init() {
     // And with the last group active
     ssassert(!SK.groupOrder.IsEmpty(),
              "Group order can't be empty since we will activate the last group.");
-    activeGroup = SK.groupOrder[SK.groupOrder.n - 1];
+    activeGroup = *SK.groupOrder.Last();
     SK.GetGroup(activeGroup)->Activate();
 
     showWorkplanes = false;

src/polygon.cpp

@@ -283,9 +283,7 @@ bool SEdgeList::AssemblePolygon(SPolygon *dest, SEdge *errorAt, bool keepDir) co
         // Create a new empty contour in our polygon, and finish assembling
         // into that contour.
         dest->AddEmptyContour();
-        if(!AssembleContour(first, last, &(dest->l[dest->l.n-1]),
-                errorAt, keepDir))
-        {
+        if(!AssembleContour(first, last, dest->l.Last(), errorAt, keepDir)) {
             allClosed = false;
         }
         // But continue assembling, even if some of the contours are open

src/srf/boolean.cpp

@@ -293,16 +293,16 @@ void SSurface::FindChainAvoiding(SEdgeList *src, SEdgeList *dest,
 {
     ssassert(!src->l.IsEmpty(), "Need at least one edge");
     // Start with an arbitrary edge.
-    dest->l.Add(&(src->l[0]));
+    dest->l.Add(src->l.First());
     src->l.ClearTags();
-    src->l[0].tag = 1;
+    src->l.First()->tag = 1;
 
     bool added;
     do {
         added = false;
         // The start and finish of the current edge chain
-        Vector s = dest->l[0].a,
-               f = dest->l[dest->l.n - 1].b;
+        Vector s = dest->l.First()->a,
+               f = dest->l.Last()->b;
 
         // We can attach a new edge at the start or finish, as long as that
         // start or finish point isn't in the list of points to avoid.

src/srf/curve.cpp

@@ -470,15 +470,15 @@ void SBezierLoop::MakePwlInto(SContour *sc, double chordTol) const {
         }
     }
     // Ensure that it's exactly closed, not just within a numerical tolerance.
-    if((sc->l[sc->l.n - 1].p).Equals(sc->l[0].p)) {
-        sc->l[sc->l.n - 1] = sc->l[0];
+    if((sc->l.Last()->p).Equals(sc->l.First()->p)) {
+        *sc->l.Last() = *sc->l.First();
     }
 }
 
 bool SBezierLoop::IsClosed() const {
     if(l.n < 1) return false;
-    Vector s = l[0].Start(),
-           f = l[l.n-1].Finish();
+    Vector s = l.First()->Start(),
+           f = l.Last()->Finish();
     return s.Equals(f);
 }
 
@@ -512,7 +512,7 @@ SBezierLoopSet SBezierLoopSet::From(SBezierList *sbl, SPolygon *poly,
         } else {
             ret.l.Add(&loop);
             poly->AddEmptyContour();
-            loop.MakePwlInto(&(poly->l[poly->l.n-1]), chordTol);
+            loop.MakePwlInto(poly->l.Last(), chordTol);
         }
     }
 
@@ -553,7 +553,7 @@ double SBezierLoopSet::SignedArea() {
 void SBezierLoopSet::MakePwlInto(SPolygon *sp) const {
     for(const SBezierLoop *sbl = l.First(); sbl; sbl = l.NextAfter(sbl)) {
         sp->AddEmptyContour();
-        sbl->MakePwlInto(&(sp->l[sp->l.n - 1]));
+        sbl->MakePwlInto(sp->l.Last());
     }
 }
 
@@ -618,7 +618,7 @@ void SBezierLoopSetSet::FindOuterFacesFrom(SBezierList *sbl, SPolygon *spxyz,
         for(pt = sc->l.First(); pt; pt = sc->l.NextAfter(pt)) {
             double u, v;
             srfuv->ClosestPointTo(pt->p, &u, &v);
-            spuv.l[spuv.l.n - 1].AddPoint(Vector::From(u, v, 0));
+            spuv.l.Last()->AddPoint(Vector::From(u, v, 0));
         }
     }
     spuv.normal = Vector::From(0, 0, 1); // must be, since it's in xy plane now
@@ -850,11 +850,11 @@ STrimBy STrimBy::EntireCurve(SShell *shell, hSCurve hsc, bool backwards) {
 
     if(backwards) {
         stb.finish = sc->pts[0].p;
-        stb.start = sc->pts[sc->pts.n - 1].p;
+        stb.start = sc->pts.Last()->p;
         stb.backwards = true;
     } else {
         stb.start = sc->pts[0].p;
-        stb.finish = sc->pts[sc->pts.n - 1].p;
+        stb.finish = sc->pts.Last()->p;
         stb.backwards = false;
     }