From 61c02fdd7a55f42b621f419fd5bda24dba877b1e Mon Sep 17 00:00:00 2001
From: Beman <bdawes@acm.org>
Date: Sun, 12 Jul 2015 17:01:57 -0400
Subject: [PATCH] rfind working.

---
 include/boost/utility/string_view.hpp | 18 +++++++---
 test/string_view_test3.cpp            | 52 ++++++++++++++++++++++++++-
 2 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/include/boost/utility/string_view.hpp b/include/boost/utility/string_view.hpp
index 9944641..0ac0c5b 100644
--- a/include/boost/utility/string_view.hpp
+++ b/include/boost/utility/string_view.hpp
@@ -227,11 +227,19 @@ namespace boost {
             { return find(basic_string_view(s), pos); }
 
         //  rfind
-        size_type rfind(basic_string_view s, size_type pos = npos)
-          const BOOST_NOEXCEPT {
-            const_reverse_iterator iter = std::search ( this->crbegin (), this->crend (),
-                                                s.crbegin (), s.crend (), traits::eq );
-            return iter == this->crend () ? npos : reverse_distance ( this->crbegin (), iter );
+        size_type rfind(basic_string_view s, size_type pos = npos) const BOOST_NOEXCEPT {
+            if (len_ < s.len_)
+              return npos;
+            if (pos > len_ - s.len_) 
+              pos = len_ - s.len_;
+            if (s.len_ == 0u)     // an empty string is always found
+              return pos;
+            for (const charT* cur = ptr_ + pos;; --cur) {
+                if (traits::compare(cur, s.ptr_, s.len_) == 0)
+                  return cur - ptr_;
+                if (cur == ptr_)
+                  return npos;
+                };
             }
         size_type rfind(charT c, size_type pos = npos) const BOOST_NOEXCEPT
             { return rfind(basic_string_view(&c, 1), pos); }
diff --git a/test/string_view_test3.cpp b/test/string_view_test3.cpp
index ea6b510..679cf0f 100644
--- a/test/string_view_test3.cpp
+++ b/test/string_view_test3.cpp
@@ -35,7 +35,6 @@ namespace
     BOOST_TEST_EQ(sv3.find(sv2), s3.find(s2));
     BOOST_TEST_EQ(sv1.find(sv3, 7), s1.find(s3, 7));
     BOOST_TEST_EQ(sv1.find(sv3, 5), s1.find(s3, 5));
-    //std::cout << s1.find(s3, 5) << std::endl;
 
     BOOST_TEST_EQ(sv1.find(sv2), s1.find(s2));
     for (std::string::size_type i = 0; i <= 8; ++i)
@@ -70,6 +69,56 @@ namespace
       BOOST_TEST_EQ(sv1.find("abc", i), s1.find("abc", i));
   }
 
+  void rfind_test()
+  {
+    //  rfind - test two modified and two new signatures
+    std::string s1("ababcab");
+    boost::string_view sv1(s1);
+    std::string s2("ab");
+    boost::string_view sv2(s2);
+    std::string s3;
+    boost::string_view sv3(s3);
+
+     //  first signature
+    BOOST_TEST_EQ(sv3.rfind(sv3), s3.rfind(s3));
+    BOOST_TEST_EQ(sv2.rfind(sv3), s2.rfind(s3));
+    BOOST_TEST_EQ(sv3.rfind(sv2), s3.rfind(s2));
+    BOOST_TEST_EQ(sv1.rfind(sv3, 7), s1.rfind(s3, 7));
+    BOOST_TEST_EQ(sv1.rfind(sv3, 5), s1.rfind(s3, 5));
+
+    BOOST_TEST_EQ(sv1.rfind(sv2), s1.rfind(s2));
+    for (std::string::size_type i = s1.size(); i <= s1.size(); --i)
+    {
+      // std::cout << i << ": " << sv1.rfind(sv2, i) << " " << s1.rfind(s2, i) << std::endl;
+      BOOST_TEST_EQ(sv1.rfind(sv2, i), s1.rfind(s2, i));
+    }
+    for (std::string::size_type i = 0; i <= 8; ++i)
+    {
+      //std::cout << i << std::endl;
+      BOOST_TEST_EQ(sv1.rfind(sv3, i), s1.rfind(s3, i));
+    }
+
+    //  second signature
+    for (std::string::size_type i = 0; i <= 8; ++i)
+    {
+      //std::cout << i << std::endl;
+      BOOST_TEST_EQ(sv1.rfind('b', i), s1.rfind('b', i));
+    }
+
+    //  third signature
+    for (std::string::size_type i = 0; i <= 8; ++i)
+      for (std::string::size_type j = 0; j <= 4; ++j)
+      {
+        //std::cout << i << " " << j << std::endl;
+        BOOST_TEST_EQ(sv1.rfind("abc", i, j), s1.rfind("abc", i, j));
+      }
+
+    //  fourth signature
+    BOOST_TEST_EQ(sv1.rfind("abc"), s1.rfind("abc"));
+    for (std::string::size_type i = 0; i <= 8; ++i)
+      BOOST_TEST_EQ(sv1.rfind("abc", i), s1.rfind("abc", i));
+  }
+
 }  // unnamed namespace
 
 int cpp_main(int argc, char* argv[])
@@ -82,6 +131,7 @@ int cpp_main(int argc, char* argv[])
   //  compare, five new signatures
 
   find_test();
+  rfind_test();
   
   return boost::report_errors();
 }