Regex search pattern in very large file

Question

I\'d like to search pattern in very large file (f.e above 1 GB) that consists of single line. It is not possible to load it into memory. Currently, I use BufferedRead

Answer 1

I think the solution for you would be to implement CharSequence as a wrapper over very large text files.

Why? Because building a Matcher from a Pattern takes a CharSequence as an argument.

Of course, easier said than done... But then you only have three methods to implement, so that shouldn't be too hard...

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EDIT I took the plunge and I ate my own dog's food. The "worst part" is that it actually works!

Answer 2

It seems like you may need to break that search-pattern down into pieces, since, given your restrictions, searching for it in its entirety is failing.

Can you determine that a buffer contains the beginning of a match? If so, save that state and then search the next portion for the next part of the match. Continue until the entire search-term is found.