88 lines
3.3 KiB
C++
88 lines
3.3 KiB
C++
#include "engine/guidance/verbosity_reduction.hpp"
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#include "engine/guidance/collapsing_utility.hpp"
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#include <boost/assert.hpp>
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#include <iterator>
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namespace osrm
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{
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namespace engine
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{
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namespace guidance
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{
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std::vector<RouteStep> suppressShortNameSegments(std::vector<RouteStep> steps)
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{
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// guard against empty routes, even though they shouldn't happen
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if (steps.empty())
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return steps;
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// we remove only name changes that don't offer additional information
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const auto name_change_without_lanes = [](const RouteStep &step) {
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return hasTurnType(step, TurnType::NewName) && !hasLanes(step);
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};
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// check if the next step is not important enough to announce
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const auto can_be_extended_to = [](const RouteStep &step) {
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const auto is_not_arrive = !hasWaypointType(step);
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const auto is_silent = !hasTurnType(step) || hasTurnType(step, TurnType::Suppressed);
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return is_not_arrive && is_silent;
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};
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const auto suppress = [](RouteStep &from_step, RouteStep &onto_step) {
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from_step.ElongateBy(onto_step);
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onto_step.Invalidate();
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};
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// suppresses name segments that announce already known names or announce a name that will be
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// only available for a very short time
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const auto reduce_verbosity_if_possible = [suppress, can_be_extended_to](
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RouteStepIterator ¤t_turn_itr, RouteStepIterator &previous_turn_itr) {
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if (haveSameName(*previous_turn_itr, *current_turn_itr))
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suppress(*previous_turn_itr, *current_turn_itr);
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else
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{
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// remember the location of the name change so we can advance the previous turn
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const auto location_of_name_change = current_turn_itr;
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auto distance = current_turn_itr->distance;
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// sum up all distances that can be relevant to the name change
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while (can_be_extended_to(*(current_turn_itr + 1)) &&
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distance < NAME_SEGMENT_CUTOFF_LENGTH)
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{
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++current_turn_itr;
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distance += current_turn_itr->distance;
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}
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if (distance < NAME_SEGMENT_CUTOFF_LENGTH)
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suppress(*previous_turn_itr, *current_turn_itr);
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else
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previous_turn_itr = location_of_name_change;
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}
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};
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BOOST_ASSERT(!hasTurnType(steps.back()) && hasWaypointType(steps.back()));
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for (auto previous_turn_itr = steps.begin(), current_turn_itr = std::next(previous_turn_itr);
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!hasWaypointType(*current_turn_itr);
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++current_turn_itr)
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{
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BOOST_ASSERT(hasTurnType(*current_turn_itr) &&
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!hasTurnType(*current_turn_itr, TurnType::Suppressed));
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if (name_change_without_lanes(*current_turn_itr) &&
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haveSameMode(*previous_turn_itr, *current_turn_itr))
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{
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// check if the name can be reduced, also sets previous_turn_itr if update is necessary
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reduce_verbosity_if_possible(current_turn_itr, previous_turn_itr);
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}
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else
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{
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// remember the current (non-suppressed) item as a new start of a segment
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previous_turn_itr = current_turn_itr;
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}
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}
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return removeNoTurnInstructions(std::move(steps));
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}
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} // namespace guidance
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} // namespace engine
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} // namespace osrm
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