Find Dot Separated Words in a String - regex

Question

I need to parse a log file to pick out strings that match the following case-insensitive pattern:
libname.data <--- Okay
libname.* <--- Not okay
For those with SAS experience, I'm trying to get SAS dataset names out of a large log.
All strings are space-separated. Some examples of lines:
NOTE: The data set LIBNAME.DATA has 428 observations and 15 variables.
MPRINT(MYMACRO): data libname.data;
MPRINT(MYMACRO): create table libname.data(rename=(var1 = var2)) as select distinct var1, var2 as
MPRINT(MYMACRO): format=date. from libname.data where ^missing(var1) and ^missing(var2) and
What I've tried
This PERL regular expression:
/^(?!.*[.*]{2})[a-z0-9*_:-]+(?:\.[a-z0-9;_:-]+)+$/mi
https://regex101.com/r/jYkXn5/1
In SAS code:
data test;
line = 'words and stuff libname.data';
test = prxmatch('/^(?!.*[.*]{2})[a-z0-9*_:-]+(?:\.[a-z0-9;_:-]+)+$/mi', line);
run;
Problem
This will work when the line only contains this exact string, but it will not work if the line contains other strings.
Solution
Thanks, Blindy!
The regex that worked for me to parse SAS datasets from a log is:
/(?!.*[.*]{3})[a-z_]+[a-z0-9_]+(?:\.[a-z0-9_]+)/mi
data test;
line = 'NOTE: COMPRESSING DATA SET LIBNAME.DATA DECREASED SIZE BY 46.44 PERCENT';
prxID = prxparse('/(?!.*[.*]{3})[a-z]+[a-z0-9_]+(?:\.[a-z0-9_]+)/mi');
call prxsubstr(prxID, line, position, length);
dataset = substr(line, position, length);
run;
This will still pick up some SQL select statements but that is easily solvable through post-processing.

Answer 1

You anchored your expression at the beginning, simply remove the first ^ and you're set.
/(?!.*[.*]{2})[a-z0-9*_:-]+(?:\.[a-z0-9;_:-]+)+$/mi

Answer 2

You can get by just locating the following landmark text in a log file line.
... data set <LIBNAME>.<MEMNAME> ...
If the data set name is in the log you can presume it was correctly formed.
data want;
length line $1000;
infile LOG_FILE lrecl=1000 length=L;
input line $VARYING. L;
* literally "data set <name>" followed by space or period;
rx = prxparse('/data set (.*?)\.(.*?)[. ]/');
if prxmatch(rx,line) then do;
length libname $8 memname $32;
libname = prxposn(rx,1,line);
memname = prxposn(rx,2,line);
line_number = _n_;
output;
end;
keep libname memname line_number;
run;
Some adjustment would be needed if the data set names are name literals of the form '<anything>'N
There are also a plethora of existing SAS Log file parsers and analyzers out on the web that you can utilize.

Answer 3

The lookahead at the start prevents matching .. but the pattern by itself will not match that, as the character classes are repeated 1 or more times and do not contain a dot.
If you don't want to match ** as well, and the string should not start with *, you can add that to a character class [*.] together with the dot, and take it out of the first character class.
In that case, you could omit the positive lookahead and the anchor:
/[a-z0-9_:-]+(?:[.*][a-z0-9_:-]+)+/i
Regex demo
As the pattern does not contain any anchors, you could omit the m flag.