Fixed crash when using negative array indices

git-svn-id: http://svn.clifford.at/openscad/trunk@433 b57f626f-c46c-0410-a088-ec61d464b74c

4 files changed, 4 insertions, 4 deletions

diff --git a/doc/OpenSCAD-polygons.graffle b/doc/OpenSCAD-polygons.graffle
index c8c1a94..1dae615 100644
--- a/doc/OpenSCAD-polygons.graffle
+++ b/doc/OpenSCAD-polygons.graffle
diff --git a/doc/OpenSCAD-polygons.pdf b/doc/OpenSCAD-polygons.pdf
index bf00397..150024d 100644
--- a/doc/OpenSCAD-polygons.pdf
+++ b/doc/OpenSCAD-polygons.pdf
diff --git a/doc/TODO.txt b/doc/TODO.txt
index c0a25d4..3f62c80 100644
--- a/doc/TODO.txt
+++ b/doc/TODO.txt
@@ -9,7 +9,7 @@ CRASH BUGS
 ----------
 o Broken polyhedron() entities are not correctly detected and cause CGAL segfaults
 o Export STL: Exports existing CGAL model even though the current model is changed, but not CGAL rendered
-o Negative array indices causes crash: v=[0,1,2]; a=v[-1];
+
 
 USER INTERFACE
 --------------
@@ -66,7 +66,7 @@ o Computation
 o Misc
   - Reload and compile: Ask for confirmation if file is locally edited
     (make this configurable in preferences?)
-  - Save: Ask for confirmation if file has been externaly changed
+  - Save: Ask for confirmation if file has been externally changed
   - Rename OpenCSG and CGAL to smth. not specific to the underlying libraries
     (e.g Preview, Render)
 
@@ -127,7 +127,7 @@ o Refactor from MainWindow:
 o C++-ify
   - Use smart pointers where it makes sense (e.g. instead of homegrown refcount,
     and to get memory ownership under control)
-  - Use static_cast instead of C-style casts
+  - Use static_cast/dynamic_cast instead of C-style casts
 o dxflinextrude and dxfrotextrude could share code
 o Consider decoupling DXF-specific functionality from the 2D subsystem
 o Make the interfaces from OpenSCAD and OpenCSG and CGAL cleaner to facilitate
diff --git a/src/expr.cc b/src/expr.cc
index 35fc776..23bcc32 100644
--- a/src/expr.cc
+++ b/src/expr.cc
@@ -81,7 +81,7 @@ Value Expression::evaluate(const Context *context) const
 		Value v2 = children[1]->evaluate(context);
 		if (v1.type == Value::VECTOR && v2.type == Value::NUMBER) {
 			int i = (int)(v2.num);
-			if (i < v1.vec.size())
+			if (i >= 0 && i < v1.vec.size())
 				return *v1.vec[i];
 		}
 		return Value();