Fixed ArrayForTrees__modify() in C++ backend

Author: Kishan-Ved

pydatastructs/linear_data_structures/_backend/cpp/arrays/ArrayForTrees.hpp

@@ -87,7 +87,70 @@ static PyObject* ArrayForTrees___str__(ArrayForTrees *self) {
 
 static PyObject* ArrayForTrees__modify(ArrayForTrees *self,
                                                     PyObject* args) {
-    // TO DO: Write the new modify function here
+    // This has been tested completely except for the if() statements in the loop mentioned below.
+    // Returning of the dictionary is also tested and it works fine
+
+    if(((double)self->_num/(double)self->_size) < self->_load_factor){
+        PyObject* new_indices = PyDict_New();
+
+        // PyObject* arr_new = OneDimensionalArray___new__(&TreeNodeType, reinterpret_cast<PyObject*>(2*self->_num + 1));
+        // This is how arr_new was made in DynamicOneDimensionalArray__modify() for the previous line :-
+        long new_size = 2 * self->_num + 1;
+        PyObject** arr_new = reinterpret_cast<PyObject**>(std::malloc(new_size * sizeof(PyObject*)));
+        for( int i = 0; i < new_size; i++ ) {
+            Py_INCREF(Py_None);
+            arr_new[i] = Py_None;
+        }
+
+        // For some debugging:
+        // return __str__(arr_new, new_size); // Prints: ['', '', '']
+
+        int j=0;
+        PyObject** _data = self->_one_dimensional_array->_data; // Check this line
+        for(int i=0; i<=self->_last_pos_filled;i++){
+            if(_data[i] != Py_None){ // Check this line. Python code: if self[i] is not None:
+                Py_INCREF(Py_None); // This was put in DynamicOneDimensionalArray line 116
+                arr_new[j] = _data[i];
+                PyObject_SetItem(new_indices, PyLong_FromLong(reinterpret_cast<TreeNode*>(_data[i])->key), PyLong_FromLong(j));
+                j += 1;
+            }
+        }
+
+        // The following loop has if() statements which need to be tested
+
+        for(int i=0;i<j;i++){
+            if(reinterpret_cast<TreeNode*>(arr_new[i])->left != Py_None){
+                reinterpret_cast<TreeNode*>(arr_new[i])->left = PyObject_GetItem(
+                    new_indices,
+                    PyLong_FromLong(
+                        reinterpret_cast<TreeNode*>(_data[PyLong_AsLong(reinterpret_cast<TreeNode*>(arr_new[i])->left)])->key
+                    )
+                );
+            }
+            if(reinterpret_cast<TreeNode*>(arr_new[i])->right != Py_None){
+                reinterpret_cast<TreeNode*>(arr_new[i])->right = PyObject_GetItem(
+                    new_indices,
+                    PyLong_FromLong(
+                        reinterpret_cast<TreeNode*>(_data[PyLong_AsLong(reinterpret_cast<TreeNode*>(arr_new[i])->right)])->key
+                    )
+                );
+            }
+            if(reinterpret_cast<TreeNode*>(arr_new[i])->parent != Py_None){
+                reinterpret_cast<TreeNode*>(arr_new[i])->parent = PyObject_GetItem(
+                    new_indices,
+                    PyLong_FromLong(
+                        reinterpret_cast<TreeNode*>(_data[PyLong_AsLong(reinterpret_cast<TreeNode*>(arr_new[i])->parent)])->key
+                    )
+                );
+            }
+        }
+        self->_last_pos_filled = j - 1;
+        self->_one_dimensional_array->_data = arr_new;
+        self->_size = new_size;
+        self->_size = new_size;
+
+        return new_indices;
+    }
     Py_RETURN_NONE;
 }
 

pydatastructs/linear_data_structures/tests/test_arrays.py

@@ -139,23 +139,20 @@ def test_ArrayForTrees():
     root = TreeNode(1, 100)
     A = AFT(TreeNode, [root])
     assert str(A) == "['(None, 1, 100, None)']"
-    print(str(A))
     node = TreeNode(2, 200)
     A.append(node)
-    print(str(A))
-    A._modify()
+    assert str(A) == "['(None, 1, 100, None)', '(None, 2, 200, None)']"
 
 def test_cpp_ArrayForTrees():
     from pydatastructs.linear_data_structures._backend.cpp import _arrays
     from pydatastructs.utils._backend.cpp import _nodes
     AFT = _arrays.ArrayForTrees
     root = TreeNode(1, 100, backend=Backend.CPP)
     A = AFT(_nodes.TreeNode, [root])
-    # print(str(A))
     assert str(A) == "['(None, 1, 100, None)']"
-
-    # TO DO: Fix _modify()
-    # print(A._modify())
+    node = TreeNode(2, 200, backend=Backend.CPP)
+    A.append(node)
+    assert str(A) == "['(None, 1, 100, None)', '(None, 2, 200, None)']"
 
 # test_ArrayForTrees()
 # test_cpp_ArrayForTrees()