Order of items in the array of changes after removeColumns() operation depends on the address mapping policy

[sequba]

Description

This unit test fails:

it('removeColumns() returns the same array of changes regardless of the address mapping policy', () => {
  const data = [
    [1, 2, '=A2'],
    [3, 4, '=B1'],
  ]

  const alwaysDenseEngine = HyperFormula.buildFromArray(data, { chooseAddressMappingPolicy: new AlwaysDense() })
  const alwaysDenseChanges = alwaysDenseEngine.removeColumns(0, [0, 2])
  const alwaysSparseEngine = HyperFormula.buildFromArray(data, { chooseAddressMappingPolicy: new AlwaysSparse() })
  const alwaysSparseChanges = alwaysSparseEngine.removeColumns(0, [0, 2])

  expect(alwaysDenseChanges).toEqual(alwaysSparseChanges)
})

The root cause of it is the difference in the implementations of entriesFromColumnsSpan method in SparseStrategy and DenseStrategy.

As described by @thilgen in #1196:

AddressMapping is an abstract class that internally can use either SparseStrategy or DenseStrategy

AddressMapping.entriesFromColumnsSpan() allows the caller to request a range of cells based on a specified ColumnsSpan

Items returned from AddressMapping.entriesFromColumnsSpan() should be in the same order regardless of which strategy is in use

Unfortunately SparseStrategy returns the results by iterating first across the columns and then across the rows

  public* entriesFromColumnsSpan(columnsSpan: ColumnsSpan): IterableIterator<[SimpleCellAddress, CellVertex]> {
    for (const col of columnsSpan.columns()) {
      const colMapping = this.mapping.get(col)
      if (colMapping !== undefined) {
        for (const [row, vertex] of colMapping.entries()) {
          yield [simpleCellAddress(columnsSpan.sheet, col, row), vertex]
        }
      }
    }
  }

and DenseStrategy returns the results by iterating first across the rows and then across the columns

  public* entriesFromColumnsSpan(columnsSpan: ColumnsSpan): IterableIterator<[SimpleCellAddress, CellVertex]> {
    for (let y = 0; y < this.height; ++y) {
      for (let x = columnsSpan.columnStart; x <= columnsSpan.columnEnd; ++x) {
        const vertex = this.getCellVertex(x, y)
        if (vertex) {
          yield [simpleCellAddress(columnsSpan.sheet, x, y), vertex]
        }
      }
    }

[AMBudnik]

Closed as done and released in HyperFormula 2.4.0