Offset Through Edit Transform
Transform an original offset through nonoverlapping edits; offsets at or inside replaced spans map to start or end by explicit affinity.
Description
Transform an original offset through nonoverlapping edits; offsets at or inside replaced spans map to start or end by explicit affinity.
An offset map tracks a cursor through insertions, deletions and replacements. Affinity resolves which side of inserted or replaced text receives a boundary position.
When to use this tool
Transform an original offset through nonoverlapping edits; offsets at or inside replaced spans map to start or end by explicit affinity.
- Prepare the supplied sourceLength, offset, editsJson, rightAffinity 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 sourceLength, offset, editsJson, rightAffinity. 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.transformedOffset. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
Validate offset against sourceLength and validate edits in original coordinates. Accumulate length changes before the position; for positions belonging to an edit boundary or replaced span, choose its left or right replacement edge according to rightAffinity.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| sourceLength | source length. | Integer from 0 to 8192 inclusive |
| offset | offset. | Integer from 0 to sourceLength inclusive |
| editsJson | JSON text, entered as one text field. The decoded structure is illustrated below; it is not a separate file. | Text |
| rightAffinity | Explicit choice for right affinity; supply a boolean rather than a text label. | true or false |
For the JSON text fields, the following decoded structures show the example records before they are serialized into input strings. Keep field names, list nesting and value types as shown.
[
{
"field": "editsJson",
"decoded": [
{
"start": 1,
"end": 2,
"text": "XY"
}
]
}
]| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.transformedOffset | The transformed offset value under the stated formula or text convention. |
{
"input": {
"sourceLength": 3,
"offset": 1,
"editsJson": "[{\"start\":1,\"end\":2,\"text\":\"XY\"}]",
"rightAffinity": true
},
"output": {
"result": {
"transformedOffset": 3
}
}
}Limitations and assumptions
- The map is based on supplied edit spans and replacement lengths rather than actual source text. Edits are sorted internally and must be nonoverlapping with distinct starts; surrogate and grapheme boundaries are not repaired.
- Text offsets and lengths use UTF-16 code units unless explicitly described as bytes or code points. CRLF, CR and LF are recognized as line endings; a terminal newline creates a final empty line in the shared line model.
- Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
- Ordinary string lists have at most 128 entries of at most 128 code units each; numeric lists and matrices have separate bounded size checks. Nonfinite results and excessively large serialized outputs are rejected.
- Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.
Alternative or Complementary methods
Use a parser or language-aware editor when quoting, syntax or nested constructs matter. For plain text transforms, keep UTF-16 offsets, Unicode code points, grapheme clusters and UTF-8 byte offsets distinct; apply changes to the same source version used to calculate spans.
References
Similar or alternative tools
- Selection Through Edit Transform
Transform each selection endpoint with its stated affinity; preserve any resulting reversed orientation rather than silently swap endpoints.
- Code Point Index to UTF-8 Byte Offset
Convert zero-based Unicode scalar index to UTF-8 byte offset; reject unpaired surrogates and count scalars rather than grapheme clusters.