Make `Cell::setContent` use `unique_ptr` and
`make_unique` for expressions to avoid potential memory
leaks.
Also renames `expo` to `newExpr` to avoid mixup with the
member variable `expression`.
Both changes was made at the request of @chennes.
This commit only changes the user interaction with spreadsheet and does
not affect backwards compatibility (as valid cell expressions are
prefixed with '=' when serialized).
This fixes [#4156](https://tracker.freecadweb.org/view.php?id=4156),
which is discussed in the forum thread:
https://forum.freecadweb.org/viewtopic.php?f=3&t=39665
There has been additional logic added to handle numbers and simple
fractions without using '='.
The behaviour is what is expected by the spreadsheet test cases
and in line with how other spreadsheet software works.
The '-prefix can still be used to force the input to be handled as
as string instead.
Example of numbers and fractions handled are:
3
2mm
1/8
1mm/2
1/2mm
2/m
1mm/2s
More complex expressions are not handled without '=' and will be stored
as strings instead, for example:
2 / 3 / 2
1 + 1/3
for Drawing, Image, Inspection, Mesh, MeshPart, Part, Path, Points, Raytracing, ReverseEngineering, Spreadsheet, Start, Surface, Web
TODO: fix several -Woverflow in area
PropertySheet is changed to derive from PropertyExpressionContainer,
which makes it a link type property that is capable of external linking.
It now relies on the unified link property API to manage object
depenency, and tracking of object life time, relabeling, etc.
This patch also includes various fix and improvement of Spreadsheet,
such as improved recompute efficiency, correct handling of document
label change, etc.
- Refactoring/clean-up of code
- Dependency tracking of aliased cells
- Various resolution errors
- Rewriting of ranges when columns/rows are inserted/removed
- References to aliases keep their units.
