HTML Table Cell Span Occupancy Map
Build an occurrence-preserving HTML cell-span owner map at explicitly supplied source coordinates for one row group; rowspan zero reaches that group’s end, no automatic browser table placement.
Description
Build an occurrence-preserving HTML cell-span owner map at explicitly supplied source coordinates for one row group; rowspan zero reaches that group’s end, no automatic browser table placement.
A spanning table cell can own several grid positions. This map exposes overlaps among explicitly positioned cells within one supplied row group.
When to use this tool
Build an occurrence-preserving HTML cell-span owner map at explicitly supplied source coordinates for one row group; rowspan zero reaches that group’s end, no automatic browser table placement.
- Prepare the supplied cellsJson, rows, columns 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 cellsJson, rows, columns. 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.occupancy, result.overlaps. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
Parse cellsJson as objects with row, column, rowspan and colspan. rows and columns range from 0 to 128; coordinates are zero-based, rowspan from 0 to 65,534 and colspan from 1 to 1,000. A zero rowspan reaches the group's final row. Append each source-cell index to every covered position and report positions with multiple owners; reject spans outside the grid.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| cellsJson | JSON text, entered as one text field. The decoded structure is illustrated below; it is not a separate file. | Text |
| rows | rows. | Integer from 0 to 128 inclusive |
| columns | columns. | Integer from 0 to 128 inclusive |
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": "cellsJson",
"decoded": [
{
"row": 0,
"column": 0,
"rowspan": 0,
"colspan": 1
},
{
"row": 1,
"column": 0,
"rowspan": 1,
"colspan": 2
}
]
}
]| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.occupancy | The occupancy list in the ordering and representation described above. |
| result.overlaps | The overlaps list in the ordering and representation described above. |
{
"input": {
"cellsJson": "[{\"row\":0,\"column\":0,\"rowspan\":0,\"colspan\":1},{\"row\":1,\"column\":0,\"rowspan\":1,\"colspan\":2}]",
"rows": 2,
"columns": 2
},
"output": {
"result": {
"occupancy": [
[
[
0
],
[]
],
[
[
0,
1
],
[
1
]
]
],
"overlaps": [
{
"row": 1,
"column": 0,
"owners": [
0,
1
]
}
]
}
}
}Limitations and assumptions
- No HTML is parsed and no browser placement algorithm is run. Coordinates and row-group boundaries must already be established; an empty owner list denotes an uncovered position.
- 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
For actual document behavior, inspect a parsed DOM and the relevant HTML algorithm. These tools transform supplied tokens, observations or coordinates; compare the browser result when parsing or layout matters.
References
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