Address translation helpers

[wojciechczerniak]

Description

This was already committed to the master branch on Friday.

public simpleCellAddressToString(address: SimpleCellAddress, sheet: number): string
public simpleCellAddressFromString(stringAddress: string, sheet: number): SimpleCellAddress

I'm just wondering if it's necessary to validate the sheet number? Shouldn't this be a static that just parses the address both ways? Why do we need a fallback?

If the sheet number is missing we can add it later. Moreover, the missing sheet property might be the information of its own.

Also, we don't always know the sheet id (number) might be necessary to have a helper to translate sheet name to sheet id. Done in #32

[wojciechczerniak]

Ok, I think I get it now.

hyperformula/src/parser/addressRepresentationConverters.ts

Lines 103 to 107 in 62dbd20

	if (sheetIndex !== address.sheet) {
	return `\$${sheetName}.${column}${address.row + 1}`
	} else {
	return `${column}${address.row + 1}`
	}

Basically sheet param is necessary to indicate where is the cell/sheet that requests the address so the returned address is either absolute or relative to that sheet. IMO this would be clearer with includeSheetName: boolean = false or absoluteSheetName: boolean = false.

Another question is how do we indicate that row or column should be absolute or relative?

[swistak35]

Close, but not exactly. If we give engine to interpret C64, we don't know, whether this is in context of Sheet1 (the result would be: {sheet: 0, col: 2, row: 63}), or Sheet2 (the result would be: {sheet: 1, col: 2, row: 63}). So we need context, in which sheet we ask for that address. Of course, sheet is sometimes obvious -- when someone give us sheet explicit, like Sheet42!A1, but it's not always the case.

We can think of many different "formats" for addresses. But when we've worked on the engine, only two were really needed:

• totally absolute address (SimpleCellAddress type) -- this one has only numerical values, all always absolute.
• R0C0 format (CellAddress class). This one come up always with additional information, whether column/row is relative/absolute. The sheet is always absolute, because we didn't consider 3D references.

My suggestion is to wait, until we will really need some other formats than these two, because we can discuss many formats fora a long time, but that probably won't be productive :)

[bardek8]

@wojciechczerniak Is there anything crucial left in this issue to be done in Dec19?

[wojciechczerniak]

@bardek8 No. I think I understood it now correctly.

It would be helpful to extend the JSDoc to explain it better and override might not be the best name. I will ask if @scarletfog could take a look, having the context from @swistak35 should be easy to fill the gap if any.

hyperformula/src/HyperFormula.ts

Lines 472 to 494 in 62dbd20

	/**
	* Computes simple (absolute) address of a cell address based on it's string representation.
	* If sheet name is present in string representation but is not present in engine, returns undefined.
	* If sheet name is not present in string representation, returns {@param sheet} as sheet number
	*
	* @param stringAddress - string representation of cell address, e.g. 'C64'
	* @param sheet - override sheet index regardless of sheet mapping
	* @returns absolute representation of address, e.g. { sheet: 0, col: 1, row: 1 }
	*/
	public simpleCellAddressFromString(stringAddress: string, sheet: number) {
	return simpleCellAddressFromString(this.sheetMapping.get, stringAddress, sheet)
	}
	/**
	* Returns string representation of absolute address
	* If sheet index is not present in engine, returns undefined
	*
	* @param address - object representation of absolute address
	* @param sheet - if is not equal with address sheet index, string representation will contain sheet name
	* */
	public simpleCellAddressToString(address: SimpleCellAddress, sheet: number): string | undefined {
	return simpleCellAddressToString(this.sheetMapping.name, address, sheet)
	}