Add ability to grow/shrink a vector using slicing, also adds Insert/Remove methods for VectorVal

src/Expr.cc

@@ -3201,24 +3201,26 @@ void IndexExpr::Assign(Frame* f, Val* v, Opcode op)
 	case TYPE_VECTOR:
 		{
 		const ListVal *lv = v2->AsListVal();
+		VectorVal* v1_vect = v1->AsVectorVal();
 
 		if ( lv->Length() > 1 )
 			{
-			int len = v1->AsVectorVal()->Size();
+			int len = v1_vect->Size();
 			bro_int_t first = get_slice_index(lv->Index(0)->CoerceToInt(), len);
 			bro_int_t last = get_slice_index(lv->Index(1)->CoerceToInt(), len);
-			int slice_length = last - first;
 
-			const VectorVal *v_vect = v->AsVectorVal();
-			if ( slice_length != v_vect->Size())
-				RuntimeError("vector being assigned to slice does not match size of slice");
-			else if ( slice_length >= 0 )
+			// Remove the elements from the vector within the slice
+			for ( int idx = first; idx < last; idx++ )
+				v1_vect->Remove(first);
+
+			// Insert the new elements starting at the first position
+			VectorVal* v_vect = v->AsVectorVal();
+			for ( int idx = 0; idx < v_vect->Size(); idx++, first++ )
 				{
-				for ( int idx = first; idx < last; idx++ )
-					v1->AsVectorVal()->Assign(idx, v_vect->Lookup(idx - first)->Ref(), op);
+				v1_vect->Insert(first, v_vect->Lookup(idx)->Ref());
 				}
 			}
-		else if ( !v1->AsVectorVal()->Assign(v2, v, op))
+		else if ( !v1_vect->Assign(v2, v, op) )
 			{
 			if ( v )
 				{

src/Val.cc

@@ -3407,6 +3407,44 @@ bool VectorVal::AssignRepeat(unsigned int index, unsigned int how_many,
 	return true;
 	}
 
+bool VectorVal::Insert(unsigned int index, Val* element)
+	{
+	if ( element &&
+	     ! same_type(element->Type(), vector_type->YieldType(), 0) )
+		{
+		Unref(element);
+		return false;
+		}
+
+	vector<Val*>::iterator it;
+	if ( index < val.vector_val->size() )
+		it = std::next(val.vector_val->begin(), index);
+	else
+		it = val.vector_val->end();
+
+	// Note: we do *not* Ref() the element, if any, at this point.
+	// AssignExpr::Eval() already does this; other callers must remember
+	// to do it similarly.
+	val.vector_val->insert(it, element);
+
+	Modified();
+	return true;
+	}
+
+bool VectorVal::Remove(unsigned int index)
+	{
+	if ( index >= val.vector_val->size() )
+		return false;
+
+	Val* val_at_index = (*val.vector_val)[index];
+	auto it = std::next(val.vector_val->begin(), index);
+	val.vector_val->erase(it);
+	Unref(val_at_index);
+
+	Modified();
+	return true;
+	}
+
 int VectorVal::AddTo(Val* val, int /* is_first_init */) const
 	{
 	if ( val->Type()->Tag() != TYPE_VECTOR )

src/Val.h

@@ -1194,6 +1194,12 @@ public:
 	// Won't shrink size.
 	unsigned int ResizeAtLeast(unsigned int new_num_elements);
 
+	// Insert an element at a specific position into the underlying vector.
+	bool Insert(unsigned int index, Val* element);
+
+	// Removes an element or a range of elements from a specific position.
+	bool Remove(unsigned int start_index);
+
 protected:
 	friend class Val;
 	VectorVal()	{ }

testing/btest/Baseline/language.vector/out

@@ -65,3 +65,5 @@ slicing (PASS)
 slicing (PASS)
 slicing assignment (PASS)
 slicing assignment (PASS)
+slicing assignment grow (PASS)
+slicing assignment shrink (PASS)

testing/btest/language/vector.zeek

@@ -179,4 +179,8 @@ event zeek_init()
 	test_case( "slicing assignment", all_set(v17 == vector(6, 2, 3, 4, 5)) );
 	v17[2:4] = vector(7, 8);
 	test_case( "slicing assignment", all_set(v17 == vector(6, 2, 7, 8, 5)) );
+	v17[2:4] = vector(9, 10, 11);
+	test_case( "slicing assignment grow", all_set(v17 == vector(6, 2, 9, 10, 11, 5)) );
+	v17[2:5] = vector(9);
+	test_case( "slicing assignment shrink", all_set(v17 == vector(6, 2, 9, 5)) );
 }