From e46237d8d5d39f77ebfe17fc53911923b5c5d745 Mon Sep 17 00:00:00 2001
From: "Daniel J. Hofmann" <daniel@trvx.org>
Date: Fri, 8 Jan 2016 13:00:24 +0100
Subject: [PATCH] Make PolylineCompresser's encode and decode free standing
 functions

---
 include/engine/polyline_compressor.hpp | 21 ++++-------
 src/engine/polyline_compressor.cpp     | 48 +++++++++++++-------------
 src/engine/polyline_formatter.cpp      |  4 ++-
 src/engine/route_parameters.cpp        |  6 ++--
 unit_tests/engine/geometry_string.cpp  |  3 +-
 5 files changed, 39 insertions(+), 43 deletions(-)

diff --git a/include/engine/polyline_compressor.hpp b/include/engine/polyline_compressor.hpp
index 9a7ba4d02d7..8f7b695bf92 100644
--- a/include/engine/polyline_compressor.hpp
+++ b/include/engine/polyline_compressor.hpp
@@ -2,6 +2,7 @@
 #define POLYLINECOMPRESSOR_H_
 
 #include "osrm/coordinate.hpp"
+#include "engine/segment_information.hpp"
 
 #include <string>
 #include <vector>
@@ -10,21 +11,13 @@ namespace osrm
 {
 namespace engine
 {
+// Encodes geometry into polyline format.
+// See: https://developers.google.com/maps/documentation/utilities/polylinealgorithm
+std::string polylineEncode(const std::vector<SegmentInformation> &geometry);
 
-struct SegmentInformation;
-
-class PolylineCompressor
-{
-  private:
-    std::string encode_vector(std::vector<int> &numbers) const;
-
-    std::string encode_number(const int number_to_encode) const;
-
-  public:
-    std::string get_encoded_string(const std::vector<SegmentInformation> &polyline) const;
-
-    std::vector<util::FixedPointCoordinate> decode_string(const std::string &geometry_string) const;
-};
+// Decodes geometry from polyline format
+// See: https://developers.google.com/maps/documentation/utilities/polylinealgorithm
+std::vector<util::FixedPointCoordinate> polylineDecode(const std::string &polyline);
 }
 }
 
diff --git a/src/engine/polyline_compressor.cpp b/src/engine/polyline_compressor.cpp
index 042653084f7..2af6735a3b9 100644
--- a/src/engine/polyline_compressor.cpp
+++ b/src/engine/polyline_compressor.cpp
@@ -1,14 +1,30 @@
 #include "engine/polyline_compressor.hpp"
-#include "engine/segment_information.hpp"
 
-#include "osrm/coordinate.hpp"
+#include <cstddef>
 
 namespace osrm
 {
 namespace engine
 {
+namespace /*detail*/ // anonymous to keep TU local
+{
+
+std::string encode(int number_to_encode)
+{
+    std::string output;
+    while (number_to_encode >= 0x20)
+    {
+        const int next_value = (0x20 | (number_to_encode & 0x1f)) + 63;
+        output += static_cast<char>(next_value);
+        number_to_encode >>= 5;
+    }
+
+    number_to_encode += 63;
+    output += static_cast<char>(number_to_encode);
+    return output;
+}
 
-std::string PolylineCompressor::encode_vector(std::vector<int> &numbers) const
+std::string encode(std::vector<int> &numbers)
 {
     std::string output;
     const auto end = numbers.size();
@@ -22,28 +38,13 @@ std::string PolylineCompressor::encode_vector(std::vector<int> &numbers) const
     }
     for (const int number : numbers)
     {
-        output += encode_number(number);
+        output += encode(number);
     }
     return output;
 }
+} // anonymous ns
 
-std::string PolylineCompressor::encode_number(int number_to_encode) const
-{
-    std::string output;
-    while (number_to_encode >= 0x20)
-    {
-        const int next_value = (0x20 | (number_to_encode & 0x1f)) + 63;
-        output += static_cast<char>(next_value);
-        number_to_encode >>= 5;
-    }
-
-    number_to_encode += 63;
-    output += static_cast<char>(number_to_encode);
-    return output;
-}
-
-std::string
-PolylineCompressor::get_encoded_string(const std::vector<SegmentInformation> &polyline) const
+std::string polylineEncode(const std::vector<SegmentInformation> &polyline)
 {
     if (polyline.empty())
     {
@@ -64,11 +65,10 @@ PolylineCompressor::get_encoded_string(const std::vector<SegmentInformation> &po
             previous_coordinate = segment.location;
         }
     }
-    return encode_vector(delta_numbers);
+    return encode(delta_numbers);
 }
 
-std::vector<util::FixedPointCoordinate>
-PolylineCompressor::decode_string(const std::string &geometry_string) const
+std::vector<util::FixedPointCoordinate> polylineDecode(const std::string &geometry_string)
 {
     std::vector<util::FixedPointCoordinate> new_coordinates;
     int index = 0, len = geometry_string.size();
diff --git a/src/engine/polyline_formatter.cpp b/src/engine/polyline_formatter.cpp
index 0b22ddb2442..617ef7977ae 100644
--- a/src/engine/polyline_formatter.cpp
+++ b/src/engine/polyline_formatter.cpp
@@ -5,6 +5,8 @@
 
 #include "osrm/coordinate.hpp"
 
+#include <vector>
+
 namespace osrm
 {
 namespace engine
@@ -13,7 +15,7 @@ namespace engine
 util::json::String
 PolylineFormatter::printEncodedString(const std::vector<SegmentInformation> &polyline) const
 {
-    return util::json::String(PolylineCompressor().get_encoded_string(polyline));
+    return util::json::String(polylineEncode(polyline));
 }
 
 util::json::Array
diff --git a/src/engine/route_parameters.cpp b/src/engine/route_parameters.cpp
index 6565896f352..bbcf40def70 100644
--- a/src/engine/route_parameters.cpp
+++ b/src/engine/route_parameters.cpp
@@ -7,6 +7,9 @@
 
 #include "engine/polyline_compressor.hpp"
 
+#include <string>
+#include <utility>
+
 namespace osrm
 {
 namespace engine
@@ -153,8 +156,7 @@ void RouteParameters::AddSource(const boost::fusion::vector<double, double> &rec
 
 void RouteParameters::SetCoordinatesFromGeometry(const std::string &geometry_string)
 {
-    PolylineCompressor pc;
-    coordinates = pc.decode_string(geometry_string);
+    coordinates = polylineDecode(geometry_string);
 }
 }
 }
diff --git a/unit_tests/engine/geometry_string.cpp b/unit_tests/engine/geometry_string.cpp
index 182cabda887..235df9b6b1a 100644
--- a/unit_tests/engine/geometry_string.cpp
+++ b/unit_tests/engine/geometry_string.cpp
@@ -18,8 +18,7 @@ BOOST_AUTO_TEST_CASE(decode)
 {
     // Polyline string for the 5 coordinates
     const std::string polyline = "_gjaR_gjaR_pR_ibE_pR_ibE_pR_ibE_pR_ibE";
-    PolylineCompressor pc;
-    std::vector<util::FixedPointCoordinate> coords = pc.decode_string(polyline);
+    const auto coords = polylineDecode(polyline);
 
     // Test coordinates; these would be the coordinates we give the loc parameter,
     // e.g. loc=10.00,10.0&loc=10.01,10.1...