Initial patch:

• add extension points to ContextQuery and ContextSuggestField
• add dedicated addAllContexts() method to ContextQuery to account for all context values
• simplify ContextQuery logic for extracting contexts

Thanks Areek Zillur, patch looks good ... can you give some example use cases
to motivate opening things up via subclassing?

I saw some minor things:

+import java.util.*;

Could you fix your IDE to do keep each import separate? Thanks.

I think toString is now not-so-friendly vs before, since we cutover to
IntsRef contexts key? (IntsRef.toString vs CharSequence.toString).

Thanks Michael McCandless for the review!

can you give some example use cases
to motivate opening things up via subclassing?

An use-case for opening up ContextSuggestField#contexts() is to
get context values from another field in a document. The
field in question might not be present at context field creation time
(e.g. due to the field not being added yet) but can be accessed from the
document when it is being indexed. Opening up contexts() will allow
sub-classes to steal the context values from the document at index-time.

After more thought, I have reverted opening up ContextQuery#convertAutomaton
via sub-classing, it has proven to be difficult to use. Originally, it was meant
such that sub-classes can modify the context automaton without having to
worry about all the implementation details.

saw some minor things:
+import java.util.*;
Could you fix your IDE to do keep each import separate? Thanks.

Fixed the imports.

I think toString is now not-so-friendly vs before, since we cutover to
IntsRef contexts key? (IntsRef.toString vs CharSequence.toString)

Thanks for catching this, now it uses BytesRef.utf8ToString

Updated Patch:

• make toString friendly, fix up imports
• revert opening up ContextQuery#convertAutomaton

Thanks for the explanation Areek Zillur, it seems very expert, and thanks for the new patch ... +1 to commit.

Commit 1693493 from Areek Zillur in branch 'dev/trunk'
[ https://svn.apache.org/r1693493 ]

LUCENE-6702: Add a method to inject context values at index time in ContextSuggestField and simplify ContextQuery and add dedicated method to consider all contexts at query time

Commit 1693494 from Areek Zillur in branch 'dev/branches/branch_5x'
[ https://svn.apache.org/r1693494 ]

LUCENE-6702: Add a method to inject context values at index time in ContextSuggestField and simplify ContextQuery and add dedicated method to consider all contexts at query time

Thanks Michael McCandless for the review!

Bulk close for 5.3.0 release