Sequence index map

sequence-index-map · version 1.0.0 · Sequences & diffs · free, no key needed

Map each left-sequence index to a kept right index, or null if deleted, and list inserted right indices.

Use when you need to: sequence index map · map left indices onto a right sequence · sequence keep index map.

Supported

• sequence index map
• map left indices onto a right sequence
• sequence keep index map

Not supported

• fuzzy matching
• patience diff
• histogram diff
• unicode normalization
• locale compare
• longest common substring

Behavior

• left and right are sequences of JSON null, boolean, string, or IEEE-754 safe integer items.
• Item equality is JavaScript === after validation; there is no case folding, locale compare, or Unicode normalization.
• The map is built from the Myers shortest edit script: keep stores the right index, delete stores null.
• When two Myers D-paths tie, the library prefers a delete from the left sequence.
• inserted lists right indices that came from insert ops, in script order.
• For left ["A","B","C"] and right ["A","X","C"] the map is [0, null, 2] and inserted is [1].
• Empty left yields map [] . The string "__proto__" is an ordinary item. Unknown input fields are rejected.

Input

• left (array of null or boolean or string or integer, required): max items 1024
• right (array of null or boolean or string or integer, required): max items 1024

Output

• map (array of integer or null, required): max items 1024; each min 0
• inserted (array of integer, required): each min 0

Limits

• max sequence items: 1024
• max item string bytes: 4096
• max text bytes: 262144
• max output bytes: 1048576

Example

Request input:

{
  "left": [
    "A",
    "B",
    "C"
  ],
  "right": [
    "A",
    "X",
    "C"
  ]
}

Response:

{
  "result": {
    "map": [
      0,
      null,
      2
    ],
    "inserted": [
      1
    ]
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "sequence-index-map",
  "version": "1.0.0",
  "input": {
    "left": [
      "A",
      "B",
      "C"
    ],
    "right": [
      "A",
      "X",
      "C"
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/sequence-index-map/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"left":["A","B","C"],"right":["A","X","C"]}'

The machine-readable contract is at /v1/tools/sequence-index-map/versions/1.0.0.

CLI

node cli.mjs run sequence-index-map 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Sequence apply edit script: Apply a keep/delete/insert edit script to a bounded sequence with exact value matching and no fuzz.
• Sequence compose edit scripts: Compose two sequence edit scripts into one per-item keep/delete/insert script.
• Sequence three way merge: Three-way merge two sequence descendants against a shared base into clean or conflict regions.
• Sequence apply hunks: Apply disjoint original-address sequence hunks with exact context and no fuzz.
• Sequence diff hunks: Group a Myers sequence edit script into context hunks with 0-based original addresses.
• Sequence edit script: Compute the Myers shortest edit script between two bounded sequences, with keep/delete/insert counts.