Add "BoostQueryParser"

[takanuva15]

Hi, the apache docs reference the Boost Query Parser that can be used, but it seems there is no API for that currently within this library. Can we add that in?

(I can help with this if you are fine with me adding this feature in a PR)

[stevenferrer]

Hi @takanuva15, I can work on this a little later, could you please provide some details of your use-case for this parser? thanks!

[takanuva15]

Hi, our company uses this parser for their recommendations logic when determining what "related items" to show a user when they click on a specific item. Items that match the same general topic/tag get a boost using this parser over other possible criteria, like popularity.

Here's a sample query that we would build with this parser: {!boost b=recip(ms(NOW/HOUR,myDate),3.16e-11,1,1)) v=myTopic defType=dismax}