diff --git a/3party/nonstd/iconv.h b/3party/nonstd/iconv.h
new file mode 100644
index 0000000..f0b6602
--- /dev/null
+++ b/3party/nonstd/iconv.h
@@ -0,0 +1,114 @@
+/*
+Copyright (c) 2011, Yuya Unno
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the Yuya Unno nor the
+      names of its contributors may be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#pragma once
+
+#include <errno.h>
+#include <iconv.h>
+
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+namespace iconvpp {
+
+class converter {
+public:
+    converter(const std::string &out_encode,
+              const std::string &in_encode,
+              bool ignore_error = false,
+              size_t buf_size = 1024)
+        : ignore_error_(ignore_error),
+          buf_size_(buf_size)
+    {
+        if (buf_size == 0) {
+            throw std::runtime_error("buffer size must be greater than zero");
+        }
+
+        iconv_t conv = ::iconv_open(out_encode.c_str(), in_encode.c_str());
+        if (conv == (iconv_t) -1) {
+            if (errno == EINVAL)
+                throw std::runtime_error("not supported from " + in_encode
+                                         + " to " + out_encode);
+            else
+                throw std::runtime_error("unknown error");
+        }
+        iconv_ = conv;
+    }
+
+    ~converter() { iconv_close(iconv_); }
+
+    void convert(const std::string &input, std::string &output) const
+    {
+        // copy the string to a buffer as iconv function requires a non-const char
+        // pointer.
+        std::vector<char> in_buf(input.begin(), input.end());
+        char *src_ptr = &in_buf[0];
+        size_t src_size = input.size();
+
+        std::vector<char> buf(buf_size_);
+        std::string dst;
+        while (0 < src_size) {
+            char *dst_ptr = &buf[0];
+            size_t dst_size = buf.size();
+            size_t res =
+                ::iconv(iconv_, &src_ptr, &src_size, &dst_ptr, &dst_size);
+            if (res == (size_t) -1) {
+                if (errno == E2BIG) {
+                    // ignore this error
+                } else if (ignore_error_) {
+                    // skip character
+                    ++src_ptr;
+                    --src_size;
+                } else {
+                    check_convert_error();
+                }
+            }
+            dst.append(&buf[0], buf.size() - dst_size);
+        }
+        dst.swap(output);
+    }
+
+private:
+    void check_convert_error() const
+    {
+        switch (errno) {
+        case EILSEQ:
+        case EINVAL:
+            throw std::runtime_error("invalid multibyte chars");
+        default:
+            throw std::runtime_error("unknown error");
+        }
+    }
+
+    iconv_t iconv_;
+    bool ignore_error_;
+    const size_t buf_size_;
+};
+
+}// namespace iconvpp