Data analysts should be able to use Text.location_of to find indexes within string using various matchers

[radeusgd]

Pull Request Description

Implements https://www.pivotaltracker.com/n/projects/2539304/stories/181266029

Important Notes

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• The documentation has been updated if necessary.
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  • Unit tests have been written where possible.
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[jdunkerley]

LGTM - not sure whether we need the IntArrayBuilder over just using a Java List but no harm having it.

[radeusgd]

LGTM - not sure whether we need the IntArrayBuilder over just using a Java List but no harm having it.

Fair, but I wanted to avoid the cost of boxing which is incurred by the ArrayList.

I did a very rudimentary benchmark (should use JMH to measure this properly, but just to get a general feeling) and over multiple runs the IntArrayBuilder seems to be more than twice as fast as the ArrayList (sometimes even ~30x faster). So I think it is worth it - while the cost of boxing is low, for such a low level operation it is still visible. Honestly I'm surprised that the standard library does not provide such a helper data structure - seems that such a structure is included in 'extensions' like Guava.