Added numeric string compare

[supertux.git] / src / util / string_util.cpp

diff --git a/src/util/string_util.cpp b/src/util/string_util.cpp
index b681930..d3cb8ab 100644 (file)
--- a/src/util/string_util.cpp
+++ b/src/util/string_util.cpp
@@ -14,6 +14,8 @@
 //  You should have received a copy of the GNU General Public License
 //  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#include <algorithm>
+
 #include "string_util.hpp"
 
 bool
@@ -29,4 +31,62 @@ StringUtil::has_suffix(const std::string& data, const std::string& suffix)
   }
 }
 
+bool
+StringUtil::numeric_less(const std::string& lhs, const std::string& rhs)
+{
+  std::string::size_type i = 0;
+  std::string::size_type min_len = std::min(lhs.size(), rhs.size());
+
+  while(i < min_len)
+  {
+    if (isdigit(lhs[i]) && isdigit(rhs[i]))
+    {
+      // have two digits, so check which number is smaller
+      std::string::size_type li = i+1;
+      std::string::size_type ri = i+1;
+
+      // find the end of the number in both strings
+      while(li < lhs.size() && isdigit(lhs[li])) { li += 1; }
+      while(ri < rhs.size() && isdigit(rhs[ri])) { ri += 1; }
+
+      if (li == ri)
+      {
+        // end is at the same point in both strings, so do a detaile
+        // comparism of the numbers
+        for(std::string::size_type j = i; j < li; ++j)
+        {
+          if (lhs[j] != rhs[j])
+          {
+            return lhs[j] < rhs[j];
+          }
+        }
+
+        // numbers are the same, so jump to the end of the number and compare
+        i = li;
+      }
+      else
+      {
+        // numbers have different numbers of digits, so the number
+        // with the least digits wins
+        return li < ri;
+      }
+    }
+    else
+    {
+      // do normal character comparism
+      if (lhs[i] != rhs[i])
+      {
+        return lhs[i] < rhs[i];
+      }
+      else
+      {
+        // strings are the same so far, so continue
+        i += 1;
+      }
+    }
+  }
+
+  return lhs.size() < rhs.size();
+}
+
 /* EOF */