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authorprep <prep@lindenlab.com>2012-11-28 16:36:34 -0500
committerprep <prep@lindenlab.com>2012-11-28 16:36:34 -0500
commite0432f98ee515f9777604aa784d28b63d2abfe40 (patch)
tree398fcae43d9904bde2112a7085c7ef7c1a926100 /indra/llcorehttp/bufferstream.h
parentbf87920fc91e2ca2b8d9f6f2656ad632c3005164 (diff)
parentf5a47417fde70f78b99744386c6da0bcf78e60d5 (diff)
SH-3563. Pull and merge from viewer-development. Modest code changes to fix alignment issue in llAppearance.
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+/**
+ * @file bufferstream.h
+ * @brief Public-facing declaration for the BufferStream adapter class
+ *
+ * $LicenseInfo:firstyear=2012&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2012, Linden Research, Inc.
+ *
+ * This library 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;
+ * version 2.1 of the License only.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
+ * $/LicenseInfo$
+ */
+
+#ifndef _LLCORE_BUFFER_STREAM_H_
+#define _LLCORE_BUFFER_STREAM_H_
+
+
+#include <sstream>
+#include <cstdlib>
+
+#include "bufferarray.h"
+
+
+/// @file bufferstream.h
+///
+/// std::streambuf and std::iostream adapters for BufferArray
+/// objects.
+///
+/// BufferArrayStreamBuf inherits std::streambuf and implements
+/// an unbuffered interface for streambuf. This may or may not
+/// be the most time efficient implementation and it is a little
+/// challenging.
+///
+/// BufferArrayStream inherits std::iostream and will be the
+/// adapter object most callers will be interested in (though
+/// it uses BufferArrayStreamBuf internally). Instances allow
+/// for the usual streaming operators ('<<', '>>') and serialization
+/// methods.
+///
+/// Example of LLSD serialization to a BufferArray:
+///
+/// BufferArray * ba = new BufferArray;
+/// BufferArrayStream bas(ba);
+/// LLSDSerialize::toXML(llsd, bas);
+/// operationOnBufferArray(ba);
+/// ba->release();
+/// ba = NULL;
+/// // operationOnBufferArray and bas are each holding
+/// // references to the ba instance at this point.
+///
+
+namespace LLCore
+{
+
+
+// =====================================================
+// BufferArrayStreamBuf
+// =====================================================
+
+/// Adapter class to put a std::streambuf interface on a BufferArray
+///
+/// Application developers will rarely be interested in anything
+/// other than the constructor and even that will rarely be used
+/// except indirectly via the @BufferArrayStream class. The
+/// choice of interfaces implemented yields a bufferless adapter
+/// that doesn't used either the input or output pointer triplets
+/// of the more common buffered implementations. This may or may
+/// not be faster and that question could stand to be looked at
+/// sometime.
+///
+
+class BufferArrayStreamBuf : public std::streambuf
+{
+public:
+ /// Constructor increments the reference count on the
+ /// BufferArray argument and calls release() on destruction.
+ BufferArrayStreamBuf(BufferArray * array);
+ virtual ~BufferArrayStreamBuf();
+
+private:
+ BufferArrayStreamBuf(const BufferArrayStreamBuf &); // Not defined
+ void operator=(const BufferArrayStreamBuf &); // Not defined
+
+public:
+ // Input interfaces from std::streambuf
+ int_type underflow();
+ int_type uflow();
+ int_type pbackfail(int_type ch);
+ std::streamsize showmanyc();
+
+ // Output interfaces from std::streambuf
+ int_type overflow(int c);
+ std::streamsize xsputn(const char * src, std::streamsize count);
+
+ // Common/misc interfaces from std::streambuf
+ std::streampos seekoff(std::streamoff off, std::ios_base::seekdir way, std::ios_base::openmode which);
+
+protected:
+ BufferArray * mBufferArray; // Ref counted
+ size_t mReadCurPos;
+ int mReadCurBlock;
+ const char * mReadBegin;
+ const char * mReadCur;
+ const char * mReadEnd;
+ size_t mWriteCurPos;
+
+}; // end class BufferArrayStreamBuf
+
+
+// =====================================================
+// BufferArrayStream
+// =====================================================
+
+/// Adapter class that supplies streaming operators to BufferArray
+///
+/// Provides a streaming adapter to an existing BufferArray
+/// instance so that the convenient '<<' and '>>' conversions
+/// can be applied to a BufferArray. Very convenient for LLSD
+/// serialization and parsing as well.
+
+class BufferArrayStream : public std::iostream
+{
+public:
+ /// Constructor increments the reference count on the
+ /// BufferArray argument and calls release() on destruction.
+ BufferArrayStream(BufferArray * ba);
+ ~BufferArrayStream();
+
+protected:
+ BufferArrayStream(const BufferArrayStream &);
+ void operator=(const BufferArrayStream &);
+
+protected:
+ BufferArrayStreamBuf mStreamBuf;
+}; // end class BufferArrayStream
+
+
+} // end namespace LLCore
+
+#endif // _LLCORE_BUFFER_STREAM_H_