Delimiters in a variable matching not properly tracked.

[LinZhihao-723]

Bug

The current implementation doesn't correctly track the delimiters in a variable matching when simulating DFAs. Instead of backtracking to the last one, we should backtrack to the first one seen in the simulation.

log-surgeon version

bf3cf2b

Environment

Any

Reproduction steps

• Add a schema variable that contains multiple delimiters, n
• Parse a log that contains a substring (surrounded by delimiters) that matches until the last delimiter
• The lexer will not backtrack to the first delimiter in the substring