[GROOVY-4665] incorrect behavior of array subscript operator with reverse ranges

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.7.7, 1.8-beta-4
• Fix Version/s: 2.2.0-rc-1
• Component/s: groovy-jdk
• Environment: any
• Assignee: Unassigned
• Reporter: Pertino Juan
• Created: 06/Feb/11 20:53
• Updated: 14/Oct/13 16:53
• Resolved: 22/Sep/13 02:08

Description

reverse ranges like X..-Y are used in lists to represent forward ranges of the form X..list.size()-Y.
this is not the case with arrays, as these special cases return a list that match the reverse range.

this can easily be tested with this snippet

def list = [1,2,3,4]
int[] array = list
assert list[2..-1] == [3,4]
assert array[2..-1] == [3,4]

which currently yields

Assertion failed: 

assert array[2..-1] == [3,4]
       |    |       |
       |    |       false
       |    [3, 2, 1, 4]
       [1, 2, 3, 4]

we can track this to the protected DGM.primitiveArrayGet(Object,Range) that is called from DGM.getAt(int[],Range) and its siblings.

this method just iterates the range to generate the returned list, whereas the list equivalent DGM.getAt(List,Range) makes use of DGMS.subListBorders(int,Range) to detect the reverse ranges.