Cyclic List Neighbor Pair Tool

Description

Require a nonempty values list, normalize signed index modulo its length, and return that item and its cyclic successor.

Token lists preserve element boundaries that raw character matching can lose. Prefix-suffix overlap and separator placement depend on exact element and empty-list conventions.

Require a nonempty values list, normalize signed index modulo its length, and return that item and its cyclic successor.

When to use this tool

Use Cyclic List Neighbor Pair when you need a token-boundary overlap or separator-count calculation.

How to use the tool and how it works

Enter values, index. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read current, next. Use the output convention below.

Require a nonempty values list, normalize signed index modulo its length, and return that item and its cyclic successor.^[1]

Input field	Meaning and units	Accepted input
values	Values	Required. Array of text; maximum UTF-16 length 8192; maximum items 256.
index	Zero-based position or diagnostic index under the calculation above; inspect any sentinel policy.	Required. Safe integer.

Output field	Interpretation	Returned shape
current	Current	Required. Text; maximum UTF-16 length 8192.
next	Next	Required. Text; maximum UTF-16 length 8192.

json

{
  "input": {
    "values": [
      "A",
      "B",
      "C"
    ],
    "index": 2
  },
  "output": {
    "current": "C",
    "next": "A"
  }
}

Limitations and assumptions

A singleton returns the same value twice; no list mutation or neighbor search is performed.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Choose token normalization and escaping rules before joining or merging the actual list contents.

References

Calculation and input contract: list/cyclic-list-neighbor-pair — tool.io

Similar or alternative tools

List Cycle One Step Predecessor
Subtract one from a valid index and reduce modulo positive length for predecessor.
List Neighbor Gap Cyclic Endpoint
Return period minus the last position plus the first for wrapGap.