Consecutive Duplicate Line Collapser
Collapse only consecutive identical line contents, retaining each kept line separator; nonadjacent duplicates remain.
Description
Collapse only consecutive identical line contents, retaining each kept line separator; nonadjacent duplicates remain.
Collapsing adjacent duplicate lines removes repeated neighbors without globally deduplicating a document. Keeping the first occurrence also determines which newline is retained.
When to use this tool
Collapse only consecutive identical line contents, retaining each kept line separator; nonadjacent duplicates remain.
- 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.text, result.removedLineCount. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
Parse lines, retain the first line and each later line whose content differs from its immediate predecessor, then join retained contents with their own original line endings. Return removedLineCount.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.text | The text value under the stated formula or text convention. |
| result.removedLineCount | The removed line count value under the stated formula or text convention. |
{
"input": {
"text": "a\na\nb"
},
"output": {
"result": {
"text": "a\nb",
"removedLineCount": 1
}
}
}Limitations and assumptions
- Newline style is ignored when deciding duplication but retained from kept records. Blank lines and a terminal empty line follow the same rule; nonadjacent duplicates are preserved.
- 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
- duplicate word checker
Check whether any whitespace-delimited word appears more than once, ignoring case.
- Line and Column to UTF-16 Offset
Map one-based logical line/UTF-16 content column to offset; columns inside separators are intentionally not accepted.