While working on a tcl implementation of a cpp (i.e. C preprocessor) I found it necessary to splice together 
lines with escaped new lines while preserving the line number where the splice began.

Given a file of source lines that look like the following.

======
line(1)
line(2)\
line(3) with space after excape\    
line(4)\
line(5)
line(6)\
line(7)
line(8)
======

This code ...

======
set fid [open [file normalize "./filename"] r]
set text [read ${fid}]
close $fid
regsub -all -- {[\\][ \t]*[\n]} ${text} "\\\n" text
while { [regsub -all -- {[\\][\n](.*?[^\\])[\n]} ${text} "\\1\n\n" text] } {}
======

produces the following results (line number were added).

%|no.|output|%
|'''1'''| line(1)|
|'''2'''|line(2)line(3) with space after excapeline(4)line(5)
|'''3'''|| 
|'''4'''||
|'''5'''||
|'''6'''|line(6)line(7)|
|'''7'''||
|'''8'''|line(8)|

Notice that the lines have been spliced together and the spliced lines 
occur on the correct line in the output.

[Tom Krehbiel]

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[Category File]