Add path pop to mgp API (#1249)

include/_mgp.hpp

@@ -477,6 +477,8 @@ inline void path_destroy(mgp_path *path) { mgp_path_destroy(path); }
 
 inline void path_expand(mgp_path *path, mgp_edge *edge) { MgInvokeVoid(mgp_path_expand, path, edge); }
 
+inline void path_pop(mgp_path *path) { MgInvokeVoid(mgp_path_pop, path); }
+
 inline size_t path_size(mgp_path *path) { return MgInvoke<size_t>(mgp_path_size, path); }
 
 inline mgp_vertex *path_vertex_at(mgp_path *path, size_t index) {

include/_mgp_mock.py

@@ -333,6 +333,13 @@ class Path:
         self._vertices.append(edge.end_id)
         self._edges.append((edge.start_id, edge.end_id, edge.id))
 
+    def pop(self):
+        if not self._edges:
+            raise IndexError("Path contains no relationships.")
+
+        self._vertices.pop()
+        self._edges.pop()
+
     def vertex_at(self, index: int) -> Vertex:
         return Vertex(self._vertices[index], self._graph)
 

include/mg_procedure.h

@@ -543,6 +543,10 @@ void mgp_path_destroy(struct mgp_path *path);
 /// Return mgp_error::MGP_ERROR_UNABLE_TO_ALLOCATE if unable to allocate memory for path extension.
 enum mgp_error mgp_path_expand(struct mgp_path *path, struct mgp_edge *edge);
 
+/// Remove the last node and the last relationship from the path.
+/// Return mgp_error::MGP_ERROR_OUT_OF_RANGE if the path contains no relationships.
+enum mgp_error mgp_path_pop(struct mgp_path *path);
+
 /// Get the number of edges in a mgp_path.
 /// Current implementation always returns without errors.
 enum mgp_error mgp_path_size(struct mgp_path *path, size_t *result);

include/mgp.hpp

@@ -886,6 +886,8 @@ class Path {
 
   /// @brief Adds a relationship continuing from the last node on the path.
   void Expand(const Relationship &relationship);
+  /// @brief Removes the last node and the last relationship from the path.
+  void Pop();
 
   /// @exception std::runtime_error Path contains element(s) with unknown value.
   bool operator==(const Path &other) const;
@@ -2995,6 +2997,8 @@ inline Relationship Path::GetRelationshipAt(size_t index) const {
 
 inline void Path::Expand(const Relationship &relationship) { mgp::path_expand(ptr_, relationship.ptr_); }
 
+inline void Path::Pop() { mgp::path_pop(ptr_); }
+
 inline bool Path::operator==(const Path &other) const { return util::PathsEqual(ptr_, other.ptr_); }
 
 inline bool Path::operator!=(const Path &other) const { return !(*this == other); }

include/mgp.py

@@ -983,6 +983,24 @@ class Path:
         self._vertices = None
         self._edges = None
 
+    def pop(self):
+        """
+        Remove the last node and the last relationship from the path.
+
+        Raises:
+            InvalidContextError: If using an invalid `Path` instance
+            OutOfRangeError: If the path contains no relationships.
+
+        Examples:
+            ```path.pop()```
+        """
+        if not self.is_valid():
+            raise InvalidContextError()
+        self._path.pop()
+        # Invalidate our cached tuples
+        self._vertices = None
+        self._edges = None
+
     @property
     def vertices(self) -> typing.Tuple[Vertex, ...]:
         """
@@ -1023,6 +1041,10 @@ class Path:
             self._edges = tuple(Edge(self._path.edge_at(i)) for i in range(num_edges))
         return self._edges
 
+    @property
+    def length(self) -> int:
+        return self._path.size()
+
 
 class Record:
     """Represents a record of resulting field values."""

include/mgp_mock.py

@@ -929,6 +929,25 @@ class Path:
         self._vertices = None
         self._edges = None
 
+    def pop(self):
+        """
+        Remove the last node and the last relationship from the path.
+
+        Raises:
+            InvalidContextError: If using an invalid `Path` instance
+            OutOfRangeError: If the path contains no relationships.
+
+        Examples:
+            ```path.pop()```
+        """
+        if not self.is_valid():
+            raise InvalidContextError()
+        self._path.pop()
+
+        # Invalidate cached tuples
+        self._vertices = None
+        self._edges = None
+
     @property
     def vertices(self) -> typing.Tuple[Vertex, ...]:
         """