No includes.
Buffer holds the memory on top of which a parse tree / syntax tree is constructed.
Return the origin of the given pointer (filename and line number)
read a line directive starting at position pos, and return the line number found.
replace the text between from and to by the text between begin and begin + length
reset the current position to position c
return the size of the buffer
Write the buffer into the given output stream The first line contains a line directive issuing the input file name; if filename is non-empty, use this to fake another one.