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|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]