Regex over multiple strings

Question

I need to use a regex to start matching in one string and end matching in another string. For example, given a regex:

[A-Z]+[0-9]+

and two strings:

String s1 = "aaaABC";
String s2 = "1245aaa";

It should be possible to do as follows:

regex.feed(s1);  // returns the start of the match at 3 and end at 5
regex.feed(s2);  // returns continuation of the match at 0 and end at 4

Concatenation of the two strings can't be done.

Any ready-made libraries to do that? Any ideas on how to make one myself?

Questions requesting library recommendations are off topic. As for doing it yourself, you are expected to at least attempt it yourself first. Show us you've put effort into this. What problems are you having implementing this yourself? — Vince
– Vince, Commented Nov 9, 2015 at 13:03
Because they're scattered over a large XML file. I need to visit every node and treat the text in every node as a piece of one string. I don't know in which node the match will start and how much nodes will it take to complete the match. But I need to remember the nodes where the match happened and the positions of start/end in the node's text. — Anatoliy Kmetyuk
– Anatoliy Kmetyuk, Commented Nov 9, 2015 at 13:03
What you're asking doesn't really make sense. You're treating regular expressions as something you can calculate over a stream, but you require backtracking to handle them. — Phylogenesis
– Phylogenesis, Commented Nov 9, 2015 at 13:06

Stephen C · Accepted Answer · 2015-11-09 13:05:48Z

2

Any ready-made libraries to do that?

AFAIK, No. This is a very unusual requirement.

Any ideas on how to make one myself?

Well the obvious solution is to concatenate the strings.

But another solution might be to create a custom CharSequence class that delivers the the characters of one string followed by the second string. Then pass an instance of that class as the parameter for the Pattern.matcher(...).

Based on your comment, you actually want to search a sequence of strings extracted from an XML DOM. Implementing a CharSequence that supports this efficiently could be a bit of a challenge.

answered Nov 9, 2015 at 13:05

Stephen C

723k95 gold badges849 silver badges1.3k bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Regex over multiple strings

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related