add safe_unique()

lib/kyut/Reordering-inl.hpp

@@ -6,6 +6,7 @@
 #include <algorithm>
 #include "BitStreamWriter.hpp"
 #include "CircularBitStreamReader.hpp"
+#include "SafeUnique.hpp"
 
 namespace kyut {
     namespace detail {

lib/kyut/SafeUnique.hpp

+#ifndef INCLUDE_kyut_SafeUnique_cpp
+#define INCLUDE_kyut_SafeUnique_cpp
+
+#include <cassert>
+#include <vector>
+
+namespace kyut {
+    template <typename Iterator, typename Pred>
+    Iterator safe_unique(Iterator begin, Iterator end, Pred pred) {
+        if (begin == end) {
+            return begin;
+        }
+
+        // This implementation is inefficient
+        std::vector<typename std::iterator_traits<Iterator>::value_type> a, b;
+
+        auto it = begin;
+        a.emplace_back(std::move(*it++));
+
+        while (it != end) {
+            if (pred(a.back(), *it)) {
+                b.emplace_back(std::move(*it));
+            } else {
+                a.emplace_back(std::move(*it));
+            }
+            ++it;
+        }
+
+        it = begin;
+        for (std::size_t i = 0; i < a.size(); i++) {
+            *it++ = std::move(a[i]);
+        }
+
+        const auto result = it;
+
+        for (std::size_t i = 0; i < b.size(); i++) {
+            *it++ = std::move(b[i]);
+        }
+
+        assert(it == end);
+        return result;
+    }
+} // namespace kyut
+
+#endif // INCLUDE_kyut_SafeUnique_cpp

test/CMakeLists.txt

@@ -4,6 +4,7 @@ add_executable(test_kyut
     test_BitStreamWriter.cpp
     test_CircularBitStreamReader.cpp
     test_Reordering.cpp
+    test_SafeUnique.cpp
 )
 
 target_link_libraries(test_kyut

test/test_SafeUnique.cpp

+#include "kyut/SafeUnique.hpp"
+
+#include <string>
+#include <gtest/gtest.h>
+
+TEST(kyut, safe_unique) {
+    std::string x = "01122233458889";
+
+    const auto result = kyut::safe_unique(std::begin(x), std::end(x), [](char a, char b) { return a == b; });
+
+    EXPECT_EQ(result, std::begin(x) + 8);
+    EXPECT_EQ(x, "01234589122388");
+}