Refactored code for better clarity

Author: takanotaiga

simulation/behavior_tree_plugin/src/pedestrian/walk_straight_action.cpp

@@ -40,11 +40,7 @@ void WalkStraightAction::getBlackBoardValues() { PedestrianActionNode::getBlackB
 
 bool WalkStraightAction::checkPreconditions()
 {
-  if (request_ != traffic_simulator::behavior::Request::WALK_STRAIGHT) {
-    return false;
-  } else {
-    return true;
-  }
+  return request_ == traffic_simulator::behavior::Request::WALK_STRAIGHT;
 }
 
 BT::NodeStatus WalkStraightAction::doAction()

simulation/behavior_tree_plugin/src/vehicle/follow_lane_sequence/follow_front_entity_action.cpp

@@ -75,7 +75,7 @@ bool FollowFrontEntityAction::checkPreconditions()
     request_ != traffic_simulator::behavior::Request::NONE &&
     request_ != traffic_simulator::behavior::Request::FOLLOW_LANE) {
     return false;
-  } else if (getRightOfWayEntities(route_lanelets_).size() != 0) {
+  } else if (getRightOfWayEntities(route_lanelets_).empty()) {
     return false;
   } else if (!behavior_parameter_.see_around) {
     return false;

simulation/behavior_tree_plugin/src/vehicle/follow_lane_sequence/stop_at_crossing_entity_action.cpp

@@ -92,7 +92,7 @@ bool StopAtCrossingEntityAction::checkPreconditions()
     return false;
   } else if (!behavior_parameter_.see_around) {
     return false;
-  } else if (getRightOfWayEntities(route_lanelets_).size() != 0) {
+  } else if (getRightOfWayEntities(route_lanelets_).empty()) {
     return false;
   } else {
     return true;

simulation/behavior_tree_plugin/src/vehicle/follow_lane_sequence/stop_at_stop_line_action.cpp

@@ -91,7 +91,7 @@ bool StopAtStopLineAction::checkPreconditions()
     return false;
   } else if (!behavior_parameter_.see_around) {
     return false;
-  } else if (getRightOfWayEntities(route_lanelets_).size() != 0) {
+  } else if (getRightOfWayEntities(route_lanelets_).empty()) {
     return false;
   } else if (!canonicalized_entity_status_->isInLanelet()) {
     return false;

simulation/behavior_tree_plugin/src/vehicle/follow_lane_sequence/stop_at_traffic_light_action.cpp

@@ -94,7 +94,7 @@ bool StopAtTrafficLightAction::checkPreconditions()
     return false;
   } else if (!behavior_parameter_.see_around) {
     return false;
-  } else if (getRightOfWayEntities(route_lanelets_).size() != 0) {
+  } else if (getRightOfWayEntities(route_lanelets_).empty()) {
     return false;
   } else {
     return true;