Preliminary header for ozlibstream

1 files changed, 111 insertions, 0 deletions

diff --git a/include/io/ozlibstream.h b/include/io/ozlibstream.h
new file mode 100644
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--- /dev/null
+++ b/include/io/ozlibstream.h
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+/*
+ * libnbt++ - A library for the Minecraft Named Binary Tag format.
+ * Copyright (C) 2013, 2015  ljfa-ag
+ *
+ * This file is part of libnbt++.
+ *
+ * libnbt++ is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * libnbt++ is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with libnbt++.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef OZLIBSTREAM_H_INCLUDED
+#define OZLIBSTREAM_H_INCLUDED
+
+#include <ostream>
+#include <vector>
+#include <zlib.h>
+
+namespace zlib
+{
+
+///Exception thrown in case zlib encounters a problem
+class zlib_error : public std::runtime_error
+{
+public:
+    const int errcode;
+
+    explicit zlib_error(const char* what_arg, int errcode = Z_ERRNO):
+        std::runtime_error(what_arg), errcode(errcode)
+    {}
+};
+
+/**
+ * @brief Stream buffer used by zlib::ozlibstream
+ * @see ozlibstream
+ */
+class deflate_streambuf : public std::streambuf
+{
+public:
+    explicit deflate_streambuf(std::ostream& output, int level = -1, int window_bits = 15, int mem_level = 8, int strategy = Z_DEFAULT_STRATEGY);
+    ~deflate_streambuf() noexcept;
+
+    //Moving
+    deflate_streambuf(deflate_streambuf&&) noexcept = default;
+    deflate_streambuf& operator=(deflate_streambuf&&) noexcept = default;
+
+    //No copying
+    deflate_streambuf(const deflate_streambuf&) = delete;
+    deflate_streambuf& operator=(const deflate_streambuf&) = delete;
+
+    std::ostream& get_ostr() const { return os; }
+
+private:
+    std::ostream& os;
+    std::vector<char> in;
+    std::vector<char> out;
+    z_stream zstr;
+
+    void deflate_chunk(int flush = Z_NO_FLUSH);
+
+    int_type overflow(int_type ch) override;
+    int sync() override;
+};
+
+/**
+ * @brief An ostream adapter that compresses data using zlib
+ *
+ * This ostream wraps another ostream. Data written to an ozlibstream will be
+ * deflated (compressed) with zlib and written to the wrapped ostream.
+ */
+class ozlibstream : public std::ostream
+{
+public:
+    /**
+     * @param output the ostream to wrap
+     * @param level the compression level. Ranges from 0 to 9, or -1 for the default
+     * @param gzip_header whether to write a gzip header rather than a zlib header
+     */
+    explicit ozlibstream(std::ostream& output, int level, bool gzip):
+        ozlibstream(output, level, 15 + (gzip ? 16 : 0))
+    {}
+
+    /**
+     * @param output the ostream to wrap
+     * @param level the compression level. Ranges from 0 to 9, or -1 for the default
+     *
+     * Refer to the zlib documentation of deflateInit2 for a detailed explanation of the arguments.
+     */
+    explicit ozlibstream(std::ostream& output, int level = -1, int window_bits = 15, int mem_level = 8, int strategy = Z_DEFAULT_STRATEGY):
+        buf(output, level, window_bits, mem_level, strategy)
+    {
+        init(&buf);
+    }
+    ///@return the wrapped ostream
+    std::ostream& get_ostr() const { return buf.get_ostr(); }
+
+private:
+    deflate_streambuf buf;
+};
+
+}
+
+#endif // OZLIBSTREAM_H_INCLUDED