allow trivial copyonwrite() on empty vec/mat/...

la_traits.h

@@ -69,7 +69,6 @@ extern "C" {
 
 namespace LA {
 
-extern bool _LA_count_check;
 
 //forward declarations
 template<typename C> class NRVec;

laerror.cc

@@ -44,7 +44,8 @@ namespace LA {
 GPU_START gpu_start_instant;
 #endif
 
-bool _LA_count_check=true;
+const bool _LA_count_check=true;
+const bool _LA_warn_empty_copyonwrite=false;
 
 extern "C" void _findme(void) {}; //for autoconf test we need a function with C linkage
 

laerror.h

@@ -28,6 +28,10 @@ extern int traceback(int flags);
 extern void sigtraceback(int sig,int flags);
 }
 
+extern const bool _LA_warn_empty_copyonwrite;
+extern const bool _LA_count_check;
+
+
 //exception class for laerror
 class LAerror
 	{

mat.h

@@ -1089,7 +1089,13 @@ NRMat<T> & NRMat<T>::operator|=(const NRMat<T> &rhs) {
  ******************************************************************************/
 template <typename T>
 void NRMat<T>::copyonwrite(bool detachonly) {
-	if(!count) laerror("attempt to call copyonwrite() for a matrix with count == 0");
+	if(!count) 
+                { 
+                if(nn||mm) laerror("nonempty matrix without reference count encountered");
+                if(_LA_warn_empty_copyonwrite) std::cout <<"Warning: copyonwrite of empty matrix\n";
+                return;
+                }
+
 	if(*count > 1){
 		(*count)--;
 		count = new int;

smat.h

@@ -957,7 +957,12 @@ NRSMat<T> & NRSMat<T>::operator=(const NRSMat<T> & rhs) {
  ******************************************************************************/
 template <typename T>
 void NRSMat<T>::copyonwrite(bool detachonly) {
-	if(!count) laerror("calling NRSMat<T>::copyonwrite() for undefined NRSMat<T> object");
+	if(!count) 
+                { 
+                if(nn) laerror("nonempty smat without reference count encountered");
+                if(_LA_warn_empty_copyonwrite) std::cout <<"Warning: copyonwrite of empty smat\n";
+                return;
+                }
 	if(*count > 1){
 		(*count)--;
 		count = new int;

sparsemat.cc

@@ -145,7 +145,13 @@ while(l)
 template <class T>
 void SparseMat<T>::copyonwrite(bool detachonly)
 {
-        if(!count) laerror("probably an assignment to undefined sparse matrix");
+	if(!count) 
+                { 
+                if(nn||mm) laerror("nonempty sparsemat without reference count encountered");
+                if(_LA_warn_empty_copyonwrite) std::cout <<"Warning: copyonwrite of empty sparsemat\n";
+                return;
+                }
+
         if(*count > 1)
                 {
                 (*count)--;

vec.h

@@ -1011,7 +1011,12 @@ NRVec<T>::~NRVec() {
  ******************************************************************************/
 template <typename T>
 void NRVec<T>::copyonwrite(bool detachonly) {
-	if(!count) laerror("copyonwrite of an undefined vector");
+	if(!count)
+		{
+		if(nn) laerror("nonempty vector without reference count encountered");
+		if(_LA_warn_empty_copyonwrite) std::cout <<"Warning: copyonwrite of empty vector\n";
+		return;
+		}
 	if(*count > 1) {
 		(*count)--;
 		 count = new int;