diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 0077748..9a3125e 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -6,6 +6,7 @@ set(TEST_NAMES
     test_get
     test_value_operator
     test_datetime
+    test_acceptor
     )
 
 add_definitions("-Wall -Wpedantic")
diff --git a/tests/test_acceptor.cpp b/tests/test_acceptor.cpp
new file mode 100644
index 0000000..a16d83c
--- /dev/null
+++ b/tests/test_acceptor.cpp
@@ -0,0 +1,65 @@
+#define BOOST_TEST_MODULE "test_acceptor"
+#ifdef UNITTEST_FRAMEWORK_LIBRARY_EXIST
+#include <boost/test/unit_test.hpp>
+#else
+#define BOOST_TEST_NO_LIB
+#include <boost/test/included/unit_test.hpp>
+#endif
+#include <toml/acceptor.hpp>
+#include <iostream>
+
+template<typename T>
+struct wrapping_iterator
+{
+    typedef T value_type;
+    typedef std::size_t difference_type;
+    typedef value_type* pointer;
+    typedef value_type& reference;
+    typedef std::forward_iterator_tag iterator_category;
+
+    wrapping_iterator(value_type v) : value_(v){}
+
+    value_type operator*(){return value_;}
+
+    wrapping_iterator operator++()   {advanced = true;return *this;}
+    wrapping_iterator operator++(int){advanced = true;return *this;}
+
+    operator bool() const {return advanced;}
+
+  private:
+
+    bool advanced = false;
+    value_type value_;
+};
+
+template<typename T>
+inline wrapping_iterator<T> wrap(T v) {return wrapping_iterator<T>(v);}
+
+BOOST_AUTO_TEST_CASE(test_conditions)
+{
+    BOOST_CHECK( toml::is_space::invoke(wrap(' ')));
+    BOOST_CHECK(!toml::is_space::invoke(wrap('a')));
+
+    BOOST_CHECK( toml::is_tab::invoke(wrap('\t')));
+    BOOST_CHECK(!toml::is_tab::invoke(wrap('a')));
+
+    for(char c = '0'; c <= '9'; ++c)
+        BOOST_CHECK(toml::is_number::invoke(wrap(c)));
+    BOOST_CHECK(!toml::is_number::invoke(wrap('a')));
+
+    for(char c = 'a'; c <= 'z'; ++c)
+        BOOST_CHECK(toml::is_lowercase::invoke(wrap(c)));
+    BOOST_CHECK(!toml::is_lowercase::invoke(wrap('A')));
+
+    for(char c = 'A'; c <= 'Z'; ++c)
+        BOOST_CHECK(toml::is_uppercase::invoke(wrap(c)));
+    BOOST_CHECK(!toml::is_uppercase::invoke(wrap('a')));
+
+    BOOST_CHECK(toml::is_whitespace::invoke(wrap(' ')));
+    BOOST_CHECK(toml::is_whitespace::invoke(wrap('\t')));
+
+    std::string barekey("hoge1-piyo2_fuga3");
+    BOOST_CHECK(toml::is_barekey::invoke(barekey.cbegin()) == barekey.cend());
+    std::string partial("hoge1.piyo2_fuga3");
+    BOOST_CHECK(toml::is_barekey::invoke(partial.cbegin()) == partial.cbegin()+5);
+}
diff --git a/toml/acceptor.hpp b/toml/acceptor.hpp
new file mode 100644
index 0000000..d3409c4
--- /dev/null
+++ b/toml/acceptor.hpp
@@ -0,0 +1,172 @@
+#ifndef TOML11_ACCEPTOR
+#define TOML11_ACCEPTOR
+#include <type_traits>
+#include <iterator>
+
+namespace toml
+{
+
+template<typename charT, charT c>
+struct is_charactor
+{
+    typedef charT value_type;
+    constexpr static value_type target = c;
+ 
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    constexpr static Iterator invoke(Iterator iter)
+    {
+        return *iter == c ? std::next(iter) : iter;
+    }
+};
+
+template<typename charT, charT head, charT ... tail>
+struct is_none_of
+{
+    typedef charT value_type;
+ 
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    constexpr static Iterator invoke(Iterator iter)
+    {
+        return *iter == head ? iter : is_not_a<tail...>::invoke(iter);
+    }
+};
+
+template<typename charT, charT tail>
+struct is_none_of<charT, tail>
+{
+    typedef charT value_type;
+ 
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    constexpr static Iterator invoke(Iterator iter)
+    {
+        return *iter == tail ? iter : std::next(iter);
+    }
+};
+
+template<typename charT, charT lw, charT up>
+struct is_in_range
+{
+    typedef charT value_type;
+    constexpr static value_type upper = up;
+    constexpr static value_type lower = lw;
+    static_assert(lower <= upper, "lower <= upper");
+ 
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    constexpr static Iterator invoke(Iterator iter)
+    {
+        return (lower <= *iter && *iter <= upper) ? std::next(iter) : iter;
+    }
+};
+
+template<typename ... condT>
+struct is_one_of;
+template<typename headT, typename ... condT>
+struct is_one_of<headT, condT...>
+{
+    typedef typename headT::value_type value_type;
+    static_assert(
+        std::is_same<value_type, typename is_one_of<condT...>::value_type>::value,
+        "different value_type");
+
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    static Iterator invoke(Iterator iter)
+    {
+        const Iterator tmp = headT::invoke(iter);
+        return (tmp != iter) ? tmp : is_one_of<condT...>::invoke(iter);
+    }
+};
+template<typename tailT>
+struct is_one_of<tailT>
+{
+    typedef typename tailT::value_type value_type;
+
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    static Iterator invoke(Iterator iter)
+    {
+        const Iterator tmp = tailT::invoke(iter);
+        return (tmp != iter) ? tmp : iter;
+    }
+};
+
+template<typename ...condT>
+struct is_chain_of;
+template<typename headT, typename ...condT>
+struct is_chain_of<headT, condT ... >
+{
+    typedef typename headT::value_type value_type;
+    static_assert(
+        std::is_same<value_type, typename is_one_of<condT...>::value_type>::value,
+        "different value_type");
+
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    static Iterator invoke(Iterator iter)
+    {
+        const Iterator tmp = headT::invoke(iter);
+        return (tmp != iter) ? is_chain_of<condT...>::invoke(tmp) : iter;
+    }
+};
+template<typename tailT>
+struct is_chain_of<tailT>
+{
+    typedef typename tailT::value_type value_type;
+
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    static Iterator invoke(Iterator iter)
+    {
+        const Iterator tmp = tailT::invoke(iter);
+        return (tmp != iter) ? tmp : iter;
+    }
+};
+
+template<typename condT>
+struct is_repeat_of
+{
+    typedef typename condT::value_type value_type;
+
+    template<typename Iterator, class = typename std::enable_if<
+        std::is_same<typename std::iterator_traits<Iterator>::value_type,
+                     value_type>::value>::type>
+    static Iterator invoke(Iterator iter)
+    {
+        Iterator tmp = condT::invoke(iter);
+        while(tmp != iter)
+        {
+            iter = tmp;
+            tmp = condT::invoke(iter);
+        }
+        return iter;
+    }
+};
+
+using is_space      = is_charactor<char, ' '>;
+using is_tab        = is_charactor<char, '\t'>;
+using is_number     = is_in_range<char, '0', '9'>;
+using is_lowercase  = is_in_range<char, 'a', 'z'>;
+using is_uppercase  = is_in_range<char, 'A', 'Z'>;
+using is_alphabet   = is_one_of<is_lowercase, is_uppercase>;
+using is_whitespace = is_one_of<is_space, is_tab>;
+using is_newline    = is_one_of<is_charactor<char, '\n'>,
+    is_chain_of<is_charactor<char, '\r'>, is_charactor<char, '\n'>>>;
+using is_barekey_component = is_one_of<is_alphabet, is_number,
+    is_charactor<char, '_'>, is_charactor<char, '-'>>;
+using is_barekey = is_repeat_of<is_barekey_component>;
+
+
+}//toml
+#endif// TOML11_ACCEPTOR