clearFilter - release memory avoiding crashes

clearFilter - delete root Leaf
Leaf constructor: initialize left,right and cond to null pointers
Leaf::clear avoid crashes when called with a null pointer parameter,
and release memory in all cases allocated in the parser
TODO: still crashes if called from DataFilter destructor, see #4249

src/Core/DataFilter.cpp

@@ -1642,23 +1642,47 @@ bool Leaf::isNumber(DataFilterRuntime *df, Leaf *leaf)
 
 void Leaf::clear(Leaf *leaf)
 {
-    return; // TODO: fix this function to release memory in all Leaf cases avoiding crashes
+    if (leaf == NULL) return; // critical to avoid crashes
 
     switch(leaf->type) {
+    case Leaf::Script :
     case Leaf::String : delete leaf->lvalue.s; break;
     case Leaf::Symbol : delete leaf->lvalue.n; break;
     case Leaf::Logical  :
     case Leaf::BinaryOperation :
     case Leaf::Operation : clear(leaf->lvalue.l);
                            clear(leaf->rvalue.l);
-                           delete(leaf->lvalue.l);
-                           delete(leaf->rvalue.l);
+                           delete leaf->lvalue.l;
+                           delete leaf->rvalue.l;
+                           break;
+    case Leaf::UnaryOperation : clear(leaf->lvalue.l);
+                           delete leaf->lvalue.l;
                            break;
     case Leaf::Function :  clear(leaf->lvalue.l);
-                           delete(leaf->lvalue.l);
-                            break;
-    default:
-        break;
+                           delete leaf->lvalue.l;
+                           clear(leaf->series);
+                           delete leaf->series;
+                           foreach (Leaf* l, leaf->fparms) clear(l);
+                           leaf->fparms.clear();
+                           break;
+    case Leaf::Compound :  foreach (Leaf* l, *(leaf->lvalue.b)) clear(l);
+                           delete leaf->lvalue.b;
+                           break;
+    case Leaf::Conditional : clear(leaf->lvalue.l);
+                           clear(leaf->rvalue.l);
+                           clear(leaf->cond.l);
+                           delete leaf->lvalue.l;
+                           delete leaf->rvalue.l;
+                           delete leaf->cond.l;
+                           break;
+    case Leaf::Index :
+    case Leaf::Select :    clear(leaf->lvalue.l);
+                           delete leaf->lvalue.l;
+                           foreach (Leaf* l, leaf->fparms) clear(l);
+                           leaf->fparms.clear();
+                           break;
+    case Leaf::Float :
+    case Leaf::Integer :   break;
     }
 
 }
@@ -3323,6 +3347,7 @@ void DataFilter::clearFilter()
 {
     if (treeRoot) {
         treeRoot->clear(treeRoot);
+        delete treeRoot;
         treeRoot = NULL;
     }
     rt.isdynamic = false;

src/Core/DataFilter.h

@@ -114,7 +114,7 @@ class Leaf {
 
     public:
 
-        Leaf(int loc, int leng) : type(none),op(0),series(NULL),dynamic(false),loc(loc),leng(leng),inerror(false) { }
+        Leaf(int loc, int leng) : type(none),lvalue(),rvalue(),cond(),op(0),series(NULL),dynamic(false),loc(loc),leng(leng),inerror(false) { }
 
         // evaluate against a RideItem using its context
         //
@@ -145,6 +145,7 @@ class Leaf {
                Compound, Script } type;
 
         union value {
+            value() { l = NULL; };
             float f;
             int i;
             QString *s;