SH-3177 Add streambuf/iostream adapters to BufferArray object.

Initial version that should have enough of the plumbing to produce
a working adapter.  Memory test is showing 8 bytes held after one
of the tests so I'm going to revisit that later.  But basic
functionality is there going by the unit tests.

1 files changed, 285 insertions, 0 deletions

diff --git a/indra/llcorehttp/bufferstream.cpp b/indra/llcorehttp/bufferstream.cpp
new file mode 100644
index 0000000000..6553900eef
--- /dev/null
+++ b/indra/llcorehttp/bufferstream.cpp
@@ -0,0 +1,285 @@
+/**
+ * @file bufferstream.cpp
+ * @brief Implements 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
+ * $/LicenseInfo$
+ */
+
+#include "bufferstream.h"
+
+#include "bufferarray.h"
+
+
+namespace LLCore
+{
+
+BufferArrayStreamBuf::BufferArrayStreamBuf(BufferArray * array)
+	: mBufferArray(array),
+	  mReadCurPos(0),
+	  mReadCurBlock(-1),
+	  mReadBegin(NULL),
+	  mReadCur(NULL),
+	  mReadEnd(NULL),
+	  mWriteCurPos(0)
+{
+	if (array)
+	{
+		array->addRef();
+		mWriteCurPos = array->mLen;
+	}
+}
+
+
+BufferArrayStreamBuf::~BufferArrayStreamBuf()
+{
+	if (mBufferArray)
+	{
+		mBufferArray->release();
+		mBufferArray = NULL;
+	}
+}
+
+	
+BufferArrayStreamBuf::int_type BufferArrayStreamBuf::underflow()
+{
+	if (! mBufferArray)
+	{
+		return traits_type::eof();
+	}
+
+	if (mReadCur == mReadEnd)
+	{
+		// Find the next block with actual data or leave
+		// mCurBlock/mCur/mEnd unchanged if we're at the end
+		// of any block chain.
+		const char * new_begin(NULL), * new_end(NULL);
+		int new_cur_block(mReadCurBlock + 1);
+
+		while (mBufferArray->getBlockStartEnd(new_cur_block, &new_begin, &new_end))
+		{
+			if (new_begin != new_end)
+			{
+				break;
+			}
+			++new_cur_block;
+		}
+		if (new_begin == new_end)
+		{
+			return traits_type::eof();
+		}
+
+		mReadCurBlock = new_cur_block;
+		mReadBegin = mReadCur = new_begin;
+		mReadEnd = new_end;
+	}
+
+	return traits_type::to_int_type(*mReadCur);
+}
+
+
+BufferArrayStreamBuf::int_type BufferArrayStreamBuf::uflow()
+{
+	const int_type ret(underflow());
+
+	if (traits_type::eof() != ret)
+	{
+		++mReadCur;
+		++mReadCurPos;
+	}
+	return ret;
+}
+
+
+BufferArrayStreamBuf::int_type BufferArrayStreamBuf::pbackfail(int_type ch)
+{
+	if (! mBufferArray)
+	{
+		return traits_type::eof();
+	}
+
+	if (mReadCur == mReadBegin)
+	{
+		// Find the previous block with actual data or leave
+		// mCurBlock/mBegin/mCur/mEnd unchanged if we're at the
+		// beginning of any block chain.
+		const char * new_begin(NULL), * new_end(NULL);
+		int new_cur_block(mReadCurBlock - 1);
+
+		while (mBufferArray->getBlockStartEnd(new_cur_block, &new_begin, &new_end))
+		{
+			if (new_begin != new_end)
+			{
+				break;
+			}
+			--new_cur_block;
+		}
+		if (new_begin == new_end)
+		{
+			return traits_type::eof();
+		}
+
+		mReadCurBlock = new_cur_block;
+		mReadBegin = new_begin;
+		mReadEnd = mReadCur = new_end;
+	}
+
+	if (traits_type::eof() != ch && mReadCur[-1] != ch)
+	{
+		return traits_type::eof();
+	}
+	--mReadCurPos;
+	return traits_type::to_int_type(*--mReadCur);
+}
+
+
+std::streamsize BufferArrayStreamBuf::showmanyc()
+{
+	if (! mBufferArray)
+	{
+		return -1;
+	}
+	return mBufferArray->mLen - mReadCurPos;
+}
+
+
+BufferArrayStreamBuf::int_type BufferArrayStreamBuf::overflow(int c)
+{
+	if (! mBufferArray || mWriteCurPos > mBufferArray->mLen)
+	{
+		return traits_type::eof();
+	}
+	const size_t wrote(mBufferArray->write(mWriteCurPos, &c, 1));
+	mWriteCurPos += wrote;
+	return wrote ? c : traits_type::eof();
+}
+
+
+std::streamsize BufferArrayStreamBuf::xsputn(const char * src, std::streamsize count)
+{
+	if (! mBufferArray || mWriteCurPos > mBufferArray->mLen)
+	{
+		return 0;
+	}
+	const size_t wrote(mBufferArray->write(mWriteCurPos, src, count));
+	mWriteCurPos += wrote;
+	return wrote;
+}
+
+
+std::streampos BufferArrayStreamBuf::seekoff(std::streamoff off,
+											 std::ios_base::seekdir way,
+											 std::ios_base::openmode which)
+{
+	std::streampos ret(-1);
+
+	if (! mBufferArray)
+	{
+		return ret;
+	}
+	
+	if (std::ios_base::in == which)
+	{
+		size_t pos(0);
+
+		switch (way)
+		{
+		case std::ios_base::beg:
+			pos = off;
+			break;
+			
+		case std::ios_base::cur:
+			pos = mReadCurPos += off;
+			break;
+			
+		case std::ios_base::end:
+			pos = mBufferArray->mLen - off;
+			break;
+
+		default:
+			return ret;
+		}
+
+		if (pos >= mBufferArray->size())
+		{
+			pos = (std::max)(size_t(0), mBufferArray->size() - 1);
+		}
+		size_t ba_offset(0);
+		int block(mBufferArray->findBlock(pos, &ba_offset));
+		if (block < 0)
+			return ret;
+		const char * start(NULL), * end(NULL);
+		if (! mBufferArray->getBlockStartEnd(block, &start, &end))
+			return ret;
+		mReadCurBlock = block;
+		mReadBegin = start;
+		mReadCur = start + ba_offset;
+		mReadEnd = end;
+		ret = mReadCurPos = pos;
+	}
+	else if (std::ios_base::out == which)
+	{
+		size_t pos(0);
+
+		switch (way)
+		{
+		case std::ios_base::beg:
+			pos = off;
+			break;
+			
+		case std::ios_base::cur:
+			pos = mWriteCurPos += off;
+			break;
+			
+		case std::ios_base::end:
+			pos = mBufferArray->mLen - off;
+			break;
+
+		default:
+			return ret;
+		}
+
+		if (pos < 0)
+			return ret;
+		if (pos > mBufferArray->size())
+		{
+			pos = mBufferArray->size();
+		}
+		ret = mWriteCurPos = pos;
+	}
+
+	return ret;
+}
+
+
+BufferArrayStream::BufferArrayStream(BufferArray * ba)
+	: std::iostream(&mStreamBuf),
+	  mStreamBuf(ba)
+{}
+	
+			
+BufferArrayStream::~BufferArrayStream()
+{}
+	
+
+}  // end namespace LLCore
+
+