From eacbcb3f3acc2ab63fb3942cd452b698133bc097 Mon Sep 17 00:00:00 2001
From: Richard Heck <rgheck@comcast.net>
Date: Fri, 3 Aug 2007 14:07:39 +0000
Subject: [PATCH] Fix bug 4096. Don't disconnect the buffer until we're ready
 to connect again. Also, clean up the code a little.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@19287 a592a061-630c-0410-9148-cb99ea01b6c8
---
 src/BufferView.cpp        |  7 ++++---
 src/BufferView.h          |  3 ++-
 src/frontends/LyXView.cpp | 31 ++++++++++++++++---------------
 src/frontends/LyXView.h   |  6 ++++++
 4 files changed, 28 insertions(+), 19 deletions(-)

diff --git a/src/BufferView.cpp b/src/BufferView.cpp
index ba9be957aa..390b62e01d 100644
--- a/src/BufferView.cpp
+++ b/src/BufferView.cpp
@@ -143,7 +143,7 @@ Buffer * BufferView::buffer() const
 }
 
 
-void BufferView::setBuffer(Buffer * b)
+Buffer * BufferView::setBuffer(Buffer * b)
 {
 	LYXERR(Debug::INFO) << BOOST_CURRENT_FUNCTION
 			    << "[ b = " << b << "]" << endl;
@@ -182,7 +182,7 @@ void BufferView::setBuffer(Buffer * b)
 	// If we're quitting lyx, don't bother updating stuff
 	if (quitting) {
 		buffer_ = 0;
-		return;
+		return 0;
 	}
 
 	//FIXME Fix for bug 3440 is here.
@@ -209,7 +209,7 @@ void BufferView::setBuffer(Buffer * b)
 	offset_ref_ = 0;
 
 	if (!buffer_)
-		return;
+		return 0;
 
 	LYXERR(Debug::INFO) << BOOST_CURRENT_FUNCTION
 					<< "Buffer addr: " << buffer_ << endl;
@@ -243,6 +243,7 @@ void BufferView::setBuffer(Buffer * b)
 
 	if (graphics::Previews::status() != LyXRC::PREVIEW_OFF)
 		graphics::Previews::get().generateBufferPreviews(*buffer_);
+	return buffer_;
 }
 
 
diff --git a/src/BufferView.h b/src/BufferView.h
index da21627964..93a4ae9be4 100644
--- a/src/BufferView.h
+++ b/src/BufferView.h
@@ -86,7 +86,8 @@ public:
 	/// set the buffer we are viewing.
 	/// \todo FIXME: eventually, we will create a new BufferView
 	/// when switching Buffers, so this method should go.
-	void setBuffer(Buffer * b);
+	/// returns the buffer currently set
+	Buffer * setBuffer(Buffer * b);
 	/// return the buffer being viewed.
 	Buffer * buffer() const;
 
diff --git a/src/frontends/LyXView.cpp b/src/frontends/LyXView.cpp
index 2f8898a6fb..773231394d 100644
--- a/src/frontends/LyXView.cpp
+++ b/src/frontends/LyXView.cpp
@@ -133,20 +133,21 @@ void LyXView::setBuffer(Buffer * b, bool child_document)
 	// parentfilename will be used in case when we switch to a child
 	// document (hence when child_document is true)
 	string parentfilename;
-	if (oldBuffer) {
+	if (oldBuffer)
 		parentfilename = oldBuffer->fileName();
-		disconnectBuffer();
-	}
 
 	if (!b && theBufferList().empty())
 		getDialogs().hideBufferDependent();
 
-	work_area_->bufferView().setBuffer(b);
+	Buffer * newBuffer = work_area_->bufferView().setBuffer(b);
 
-	//FIXME This would be a little simpler if setBuffer returned the buffer.
-	Buffer * newBuffer = work_area_->bufferView().buffer();
 	if (newBuffer) {
-		if (child_document && newBuffer->getMasterBuffer() != oldBuffer) {
+		//Are we closing an oldBuffer which was a child document?
+		if (!b && oldBuffer && oldBuffer->getMasterBuffer() != oldBuffer)
+			// Update the labels and section numbering of its master Buffer.
+			updateLabels(*oldBuffer->getMasterBuffer());
+		//Are we opening a new child document?
+		else if (child_document && newBuffer->getMasterBuffer() != oldBuffer) {
 			// Set the parent name of the child document.
 			// This makes insertion of citations and references in the child work,
 			// when the target is in the parent or another child document.
@@ -154,13 +155,11 @@ void LyXView::setBuffer(Buffer * b, bool child_document)
 			// Update the labels and section numbering to the new master Buffer.
 			updateLabels(*newBuffer->getMasterBuffer());
 		}
-
-		if (!b && oldBuffer && oldBuffer->getMasterBuffer() != oldBuffer)
-			// We are closing oldBuffer which was a child document so we
-			// must update the labels and section numbering of its master
-			// Buffer.
-			updateLabels(*oldBuffer->getMasterBuffer());
-
+		//Now that all the updating of the old buffer has been done, we can
+		//connect the new buffer. Note that this will also disconnect the old 
+		//buffer, if such there is.
+		//FIXME Is it clear that this should go right here? Or should it go
+		//earlier before the previous if (in which case we'd remove the "else")?
 		connectBuffer(*newBuffer);
 
 		/* FIXME: We need to rebuild the Toc dialog before the others even
@@ -178,7 +177,9 @@ void LyXView::setBuffer(Buffer * b, bool child_document)
 		// hidden. This should go here because some dialogs (eg ToC)
 		// require bv_->text.
 		getDialogs().updateBufferDependent(true);
-	}
+	} else
+		//Disconnect the old buffer...there's no new one.
+		disconnectBuffer();
 
 	if (quitting)
 		return;
diff --git a/src/frontends/LyXView.h b/src/frontends/LyXView.h
index f2def70078..adf88d0ec3 100644
--- a/src/frontends/LyXView.h
+++ b/src/frontends/LyXView.h
@@ -254,6 +254,12 @@ private:
 	/// connect to signals in the given buffer
 	void connectBuffer(Buffer & buf);
 	/// disconnect from signals in the given buffer
+	/// NOTE: Do not call this unless you really want no buffer
+	/// to be connected---for example, when closing the last open
+	/// buffer. If you are switching buffers, just call 
+	/// connectBuffer(), and the old buffer will be disconnected
+	/// automatically. This ensures that we do not leave LyX in a
+	/// state in which no buffer is connected.
 	void disconnectBuffer();
 
 	/// BufferView messages signal connection