There is a significant Editline rewrite, adding a bunch of
improvements. It has been well tested on OSx, but not yet upstreamed.
I have spent some time reviewing the proposed patch and working through
issues to get it running on linux. To see the patch and accompanying
discussion, refer to: http://reviews.llvm.org/D5835 The main issues
that came up are related to handling wide characters and differences
between platforms.
Internally, lldb uses std::string which is an array of 8 bit chars, that
can either be 7 bit ascii, or utf8 encoded wide characters. Libedit uses
either char, or wchar_t which is a 32 bit char on linux.
<codecvt> : the patch uses a c++ 11 class std::codecvt_utf8, this is a
facet implementation that will do utf8 to wchar convervsion. It is part
of c++ 11 standard, but not yet supported in gcc. I can use #ifdef to
temporarily write equivalent functionality in that case while we wait
for gcc to catch up.
libedit : libedit is a prerequisite that a new linux/lldb user installs
( sudo apt-get install libedit-dev ). A few years ago, libedit added
versions of its functions that work on wchar_t. Unfortunately, this
option is not built by default, and not present in the Ubuntu
distribution. To get around this, I see a few options:
- take libedit source files (or subset) and add to the lldb project. We
could either build a .so file, or just statically link the .cpp files.
- rework the Editline rewrite, so it either uses standard 8 bit chars,
or wchar_t/utf8 depending on the platform. This would be conditionally
built depending on the platform.
- modify Ubuntu, so 'sudo apt-get install dev-libedit' installs a
version that has been built with wide character support enabled.
- introduce custom step for new linux lldb users, where they download
libedit source and build and install a wchar version
The last 2 options don't seem that great.
I expect there will be problems on Windows, which I think uses utf16
coding. The file EditLineWin.cpp, contains prototypes for most of the
structures and functions needed, but they look stubbed out.
Any thoughts?
Shawn.
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