Selection Outdent Transform

Transform full lines intersecting a half-open UTF-16 selection, preserving line endings. Outdent only an exact supplied prefix, without guessing tab widths.

Description

Transform full lines intersecting a half-open UTF-16 selection, preserving line endings.

Outdenting a selected block removes one exact indentation unit from affected lines. Lines without that literal prefix can remain unchanged.

When to use this tool

Transform full lines intersecting a half-open UTF-16 selection, preserving line endings.

Prepare the supplied text, start, end, indent 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, start, end, indent. 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.text, result.changedLines. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

Validate a selection and a nonempty space/tab indent. Select intersected lines, or the cursor's content line for an empty selection, and remove indent only where it is the exact leading prefix. Return changedLines and rebuilt text.^[1]

Input field	Meaning and representation	Accepted input
text	text.	Text; at most 8,192 UTF-16 code units, subject to the grammar above
start	start.	Finite number
end	end.	Finite number
indent	indent.	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.text	The text value under the stated formula or text convention.
result.changedLines	The changed lines list in the ordering and representation described above.

json

{
  "input": {
    "text": "  a\nb",
    "start": 0,
    "end": 4,
    "indent": "  "
  },
  "output": {
    "result": {
      "text": "a\nb",
      "changedLines": [
        1
      ]
    }
  }
}

Limitations and assumptions

A selection ending at the next line's start excludes that next line. Original newline spellings are preserved; selection coordinates themselves are not transformed and mixed indentation is not normalized.
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

Tool behavior and example: Selection Outdent Transform — tool.io

Similar or alternative tools

Selection Indent Transform
Transform full lines intersecting a half-open UTF-16 selection, preserving line endings.
Selection Through Edit Transform
Transform each selection endpoint with its stated affinity; preserve any resulting reversed orientation rather than silently swap endpoints.