BufWriter has more capacity (8k vs 1k) and doesn't flush the stream after '\n'.
That change helps to reduce the number of syscalls, especially when dealing with text files.
Since BufWriter has a different way of getting number of pending elements than LineWriter -
Pending trait was introduced to deal with that.
When a byte-oriented stream function touches a stream, that stream
should be set to byte-oriented mode if it hasn't been set yet. If
it has been set, the opertion should only succeed if the stream is
already in byte-oriented mode.
Signed-off-by: Wren Turkal <wt@penguintechs.org>
This function is used to set the orientation of a stream to either
byte-oriented or wchar-oriented.
More info on this function is here:
https://man7.org/linux/man-pages/man3/fwide.3p.html
This implementation only impmlemnts the manual switching and does
not yet guard against using a byte-oriented stream with wchar
functions and vice versa. Those step will come in additional
commits.
Signed-off-by: Wren Turkal <wt@penguintechs.org>
The LookAheadReader api works similar to read but it has 2 methods,
lookahead: it will read 1 byte (with internal ftell) without modifying
the file's own ftell() and commit() which saves the current file ftell
LookAheadReader can wrap both buffers and files
Scanf function requires look ahead to function properly, In case of
scanning from a buffer that will not be an issue, but in our case we are
reading from file, so lookaheads needs to be undone (via lseek) in our
case. The only problem here is that if we opened a file that doesn't
support lseek such as many of the file /dev/*
At least in relibc, each call to ungetc should decrement ftell() by one
also allowing negative ftell() this is not possible on relibc thus gcc
failing to compile (gcc compiles tools that is later used to compile gcc
itself and these tools are the ones that fail)
According to the standards, only one ungetc may be guaranteed however
glibc allows more than one of those, and to be glibc compatiable, one
needs to be able to do the same, allowing only 1 ungetc may trigger bug
while compiling gcc as ungetc is used there alot
Arthur Paulino