Describe the bug
Subscripting a deque with indices < -n does not raise an index error. Instead, the indices wrap around twice, and only start throwing index errors when idx < -2n.
This behavior is only present in the deque container from my testing.
Operating system
macOS
CPU architecture
x86_64
GraalPy version
25.0.2 Native Standalone and JVM standalone
JDK version
No response
Context configuration
No response
Steps to reproduce
Subscript a deque container with an index < -n where n is the size of the deque.
Expected behavior
An index error should be thrown if the idx < -n.
Stack trace
Additional context
example
"""Access a deque with gradually decreasing negative indices and report
whether each access raises an IndexError."""
from collections import deque
def main():
d = deque([10, 20, 30, 40, 50])
print(f"deque: {list(d)}")
print(f"length: {len(d)}\n")
# Start at -1 and gradually decrease (more negative) past the valid range.
# Valid negative indices for a length-N deque are -1 .. -N; anything
# beyond -N should raise IndexError.
for index in range(-1, -12, -1):
try:
value = d[index]
print(f"d[{index}] = {value}")
except IndexError as exc:
print(f"d[{index}] -> IndexError: {exc}")
if __name__ == "__main__":
main()This script produces these results:
ztawfick@MacBook-Q2KK9 graalpy % python3 deque_negative_index.py
deque: [10, 20, 30, 40, 50]
length: 5
d[-1] = 50
d[-2] = 40
d[-3] = 30
d[-4] = 20
d[-5] = 10
d[-6] -> IndexError: deque index out of range
d[-7] -> IndexError: deque index out of range
d[-8] -> IndexError: deque index out of range
d[-9] -> IndexError: deque index out of range
d[-10] -> IndexError: deque index out of range
d[-11] -> IndexError: deque index out of range
ztawfick@MacBook-Q2KK9 graalpy % graalpy deque_negative_index.py
deque: [10, 20, 30, 40, 50]
length: 5
d[-1] = 50
d[-2] = 40
d[-3] = 30
d[-4] = 20
d[-5] = 10
d[-6] = 50
d[-7] = 40
d[-8] = 30
d[-9] = 20
d[-10] = 10
d[-11] -> IndexError: deque index out of range
Describe the bug
Subscripting a deque with indices < -n does not raise an index error. Instead, the indices wrap around twice, and only start throwing index errors when idx < -2n.
This behavior is only present in the deque container from my testing.
Operating system
macOS
CPU architecture
x86_64
GraalPy version
25.0.2 Native Standalone and JVM standalone
JDK version
No response
Context configuration
No response
Steps to reproduce
Subscript a deque container with an index < -n where n is the size of the deque.
Expected behavior
An index error should be thrown if the idx < -n.
Stack trace
Additional context
example
This script produces these results: