GridPadScopeImpl.kt

internal class GridPadScopeImpl(private val cells: GridPadCells) : GridPadScope {

    // list of composables to future measurement and placement
    internal val data: MutableList<GridPadContent> = mutableListOf()

    override fun item(
        row: Int?, column: Int?, rowSpan: Int, columnSpan: Int,
        itemContent: @Composable GridPadItemScope.() -> Unit
    ) {        
        findPlaceForContent(
            row = row, column = column, rowSpan = rowSpan, columnSpan = columnSpan
        ) { cellRow, cellColumn ->
            this.data.add(
                GridPadContent(
                    row = cellRow,
                    column = cellColumn,
                    rowSpan = rowSpan,
                    columnSpan = columnSpan,
                    item = { itemContent() }
                )
            )
        }
    }

    private fun findPlaceForContent(
        row: Int?, column: Int?, rowSpan: Int, columnSpan: Int,
        callback: (row: Int, column: Int) -> Unit
    ): Boolean {
        // some logic for locating in the grid in cases where no row or column is specified
    }
}

internal class GridPadContent(
    val row: Int, val column: Int, val rowSpan: Int, val columnSpan: Int,
    val item: @Composable GridPadItemScope.() -> Unit
)