[cfe-dev] Incremental parsing/compilation question

[Vassil Vassilev]

Hi,

In cling we have line-by-line input that comes from a terminal-like prompt.
We do incremental compilation of the input.  The input lines come as 
llvm::MemoryBuffers
We compile each memory buffer by passing them to clang.  However, when clang
parses a buffer it sees EOF in the end and destroys it's current lexer 
and what not.

For example cling can have:
[cling$] extern "C" int printf(const char* fmt, ...);
[cling$] int i = 12;
[cling$] printf("%d\n", i);

Every line comes in memory buffer containing \0 in the end.  Clang 
considers that as
an EOF.  Ideally I want to tell the parser that the parsing of the 
translation unit is not
yet done, but that it should be suspended until next user's input.

Correct me if I am wrong, but the best way of doing that would be to 
implement a
'suspend' token.  When the lexer and parser see that 'suspend' token 
they would stop
as if it was EOF token but without deleting/cleaning anything, so that 
the parsing could
be restarted later with the same state.

If this is the right approach what would be the best way to represent 
the 'suspend'
token?  i.e. which ascii char that would trigger the suspension?   (I'd 
really like to have
"$" but it is already part of an extension).

Vassil