String Prefix Border Length Table

Bounded UTF-16 string string prefix border length table; exact code-unit matching, no Unicode normalization or grapheme inference.

Description

Bounded UTF-16 string string prefix border length table; exact code-unit matching, no Unicode normalization or grapheme inference.

A prefix-border table records the longest proper border of each progressively longer prefix. It exposes recurring prefix structure.

When to use this tool

Bounded UTF-16 string string prefix border length table; exact code-unit matching, no Unicode normalization or grapheme inference.

Prepare the supplied text fields for this operation.
Compare the complete example with the representation used by your own input before carrying the result into another step.

How to use the tool and how it works

Enter text. Use the exact text syntax, units and index conventions explained below.
Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
Read result.lengths. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

For each prefix ending at position j, enumerate its proper border lengths and return the longest or zero. The result list aligns with original code-unit positions.^[1]

Input field	Meaning and representation	Accepted input
text	text.	Text; at most 8,192 UTF-16 code units, subject to the grammar above

Output field	Interpretation
result	Object containing the named outputs below.
result.lengths	The lengths list in the ordering and representation described above.

json

{
  "input": {
    "text": "ababa"
  },
  "output": {
    "result": {
      "lengths": [
        0,
        0,
        1,
        2,
        3
      ]
    }
  }
}

Limitations and assumptions

This bounded implementation checks borders directly rather than promising a linear-time algorithm. Input is at most 128 UTF-16 code units.
The string-analysis source text is bounded to 128 UTF-16 code units; offsets and lengths use those code units.
All declared input fields are required and unexpected top-level fields are rejected. Numbers must be finite; lists are limited to 128 entries and ordinary text fields to 8,192 UTF-16 code units, with tighter limits where stated.
JSON text inputs must parse within bounded nesting and size limits. Numeric outputs outside the safe finite range are rejected; large exact integer results use decimal strings. Indexes and half-open spans are zero-based unless a rank is explicitly described as one-based.

Alternative or Complementary methods

Use a code-point or grapheme-aware text method when the task concerns user-perceived characters. These bounded literal operations retain case and code-unit structure rather than normalizing linguistic text.

References

Tool behavior and example: String Prefix Border Length Table — tool.io

Similar or alternative tools

Palindromic Prefix Lengths
Bounded UTF-16 string palindromic prefix lengths; exact code-unit matching, no Unicode normalization or grapheme inference.
Whole String Border List
Bounded UTF-16 string whole string border list; exact code-unit matching, no Unicode normalization or grapheme inference.