correctly detect loss of prefix/suffix

CHANGELOG.md

@@ -12,6 +12,7 @@
       - Fixed an issue that would result in segfaults for viaroutes with an invalid intermediate segment when u-turns were allowed at the via-location
       - Invalid only_* restrictions could result in loss of connectivity. As a fallback, we assume all turns allowed when the restriction is not valid
       - Fixed a bug that could result in an infinite loop when finding information about an upcoming intersection
+      - Fixed a bug that led to not discovering if a road simply looses a considered prefix
 
 # 5.3.0
   Changes from 5.3.0-rc.3

features/guidance/suffix-changes.feature

@@ -3,7 +3,7 @@ Feature: Suppress New Names on dedicated Suffices
 
     Background:
         Given the profile "car"
-        Given a grid size of 10 meters
+        Given a grid size of 2000 meters
 
     Scenario: Suffix To Suffix
         Given the node map
@@ -44,6 +44,19 @@ Feature: Suppress New Names on dedicated Suffices
             | waypoints | route           | turns         |
             | a,c       | West 42,East 42 | depart,arrive |
 
+    Scenario: Prefix Change ref
+        Given the node map
+            | a |   | b |   | c |
+
+        And the ways
+            | nodes  | name    |
+            | ab     | West 42 |
+            | bc     | 42      |
+
+       When I route I should get
+            | waypoints | route      | turns         |
+            | a,c       | West 42,42 | depart,arrive |
+
     Scenario: Prefix Change and Reference
         Given the node map
             | a |   | b |   | c |

include/extractor/guidance/toolkit.hpp

@@ -205,38 +205,45 @@ inline bool requiresNameAnnounced(const std::string &from,
     const auto name_is_contained =
         boost::starts_with(from_name, to_name) || boost::starts_with(to_name, from_name);
 
-    const auto checkForPrefixOrSuffixChange =
+    const auto checkForPrefixOrSuffixChange = [](
-        [](const std::string &first, const std::string &second, const SuffixTable &suffix_table) {
+        const std::string &first, const std::string &second, const SuffixTable &suffix_table) {
 
         const auto first_prefix_and_suffixes = getPrefixAndSuffix(first);
         const auto second_prefix_and_suffixes = getPrefixAndSuffix(second);
         // reverse strings, get suffices and reverse them to get prefixes
-            const auto checkTable = [&](const std::string str) {
+        const auto checkTable = [&](const std::string& str) {
             return str.empty() || suffix_table.isSuffix(str);
         };
 
+        const auto getOffset = [](const std::string &str) -> std::size_t {
+            if (str.empty())
+                return 0;
+            else
+                return str.length() + 1;
+        };
+
         const bool is_prefix_change = [&]() -> bool {
             if (!checkTable(first_prefix_and_suffixes.first))
                 return false;
-                if (!checkTable(first_prefix_and_suffixes.first))
+            if (!checkTable(second_prefix_and_suffixes.first))
                 return false;
-                return !first.compare(first_prefix_and_suffixes.first.length(),
+            return !first.compare(getOffset(first_prefix_and_suffixes.first),
                                   std::string::npos,
                                   second,
-                                      second_prefix_and_suffixes.first.length(),
+                                  getOffset(second_prefix_and_suffixes.first),
                                   std::string::npos);
         }();
 
         const bool is_suffix_change = [&]() -> bool {
             if (!checkTable(first_prefix_and_suffixes.second))
                 return false;
-                if (!checkTable(first_prefix_and_suffixes.second))
+            if (!checkTable(second_prefix_and_suffixes.second))
                 return false;
             return !first.compare(0,
-                                      first.length() - first_prefix_and_suffixes.second.length(),
+                                  first.length() - getOffset(first_prefix_and_suffixes.second),
                                   second,
                                   0,
-                                      second.length() - second_prefix_and_suffixes.second.length());
+                                  second.length() - getOffset(second_prefix_and_suffixes.second));
         }();
 
         return is_prefix_change || is_suffix_change;