From: "B. K. Oxley (binkley)" <binkley@...>
Date: 2005-04-28T00:52:19+09:00
Subject: node.h and nd_line

I'm interested in adding more precise source location information to 
NODE structs.  I see:

typedef struct RNode {
     /* ... */
     char *nd_file;
     int nd_line;
     /* ... */
} NODE;

But the accessor macros for nd_line look like this (spaces added for 
email clarity):

#define nd_line(n) ((unsigned int) (((RNODE(n))->flags >> NODE_LSHIFT) & 
NODE_LMASK))
#define nd_set_line(n,l) \
RNODE(n)->flags=((RNODE(n)->flags & ~(-1 << NODE_LSHIFT)) | (((l) & 
NODE_LMASK) << NODE_LSHIFT))

What is going on?  :)

What I'd like to do is add an int nd_pos member to RNode to record the 
precise byte position in nd_file for the node, but I'm somewhat baffled 
by the utter lack of ".nd_line" or "->nd_line" in the sources.  Looking 
at parse.y, frequently assign the nd_line(node) macro to 
ruby_sourceline, but I do not grasp how that macro uses nd_line.


Thanks,
--binkley