Re: Design of a TextBuffer and support of istream
On 12.01.2013 00:41, Vincent R wrote:
To design this TextBuffer class I have 2 options :
1) Store the source code buffer inside a std::string and maintain
information between the index of lines and the corresponding position
inside the std::string.
2) Store the source code buffer as a vector<std::string>, it simplifies
a bit the problem because in this case we have a direct mapping between
a line index and the representation inside TextBuffer.
I think I will try to implement the second choice (except if you tell me
that it's a bad idea)
I would strongly recommend to use the second choice. Simply because the
update frequency could be rather high. E.g. if every time the user
presses a key a large file needs to be updated in memory, including your
line index, then this could significantly degrade performance. Some
people like code files with 100kB and more. Generated code from OR
mappers could also get quite large.
but I have a problem because this buffer will be
parsed by a lexer that requires the TextBuffer object to implement
istream :
You do not need to implement an istream. std::istream will do well.
What you need to do is implement a custom streambuf. This is needed for
the istream constructor.
And I don't know how I can implement this std::istream & open() method.
Should TextBuffer inherits from public std::streambuf ?
There is no need to /inherit/ from streambuf. Composition is sufficient.
While I am it, if someone has already implemnted a textbuffer class that
allow to insert/remove lines and that allow to access buffer easily
either by line or by position please let me know.
Probably someone has done so. But whether the license and the interface
matches are other questions.
Marcel