Extend array_position function with instance number

Currently array_position only returns the first occurrence of the given element. We want to extend array_position to take an additional parameter instance similar to strpos.

array_position(x, element, instance) -> bigint

For example, for array x: [1, 3, 2, 1, 4, 3, 2, 5, 4, 1]:

array_position(x, 1) = 1 -- existing function
array_position(x, 1, 1) = 1 -- same as existing function with 2 input parameters
array_position(x, 1, 2) = 4 -- returns index of the second occurrence of 1
array_position(x, 5, 2) = 0 -- returns 0 because there is no second occurrence of 5
array_position(x, 1, -1) = 10 -- returns index of the first occurrence of 1 from the back
array_posision(x, 1, -2) = 4 -- returns index of the second occurrence of 1 from the back

[adaco]

@rongrong thanks! That does the trick.

[rongrong]

I use java 1.8. Try export JAVA_HOME=$(/usr/libexec/java_home -v 1.8) and see whether it works.