Add String.number_format() method for more readable large numbers

[Calinou]

This is used in the editor to display large numbers such as in the View Information panel.

TextServer.format_number() automatically uses this method with the current language (if no language is specified), which benefits many locations in the editor such as the inspector, performance monitors and the 3D editor View Information panel.

Unit tests have been added for both String.number_format() and TextServer.number_format().

• This closes Add a String method to format numbers with a delimiter separator and custom decimal separator godot-proposals#9289.

Preview

English

French

[KoBeWi]

Does not work well in the inspector:

oVhfcccVSz.mp4

Double click will select parts separately and the commas are treated as decimal separators, so if you add an actual separator, the result is invalid.

In space-separated locales, the decimal part is simply rejected.

F0tKHTQ5DY.mp4

[AThousandShips]

Somewhat related on the editor side I think:

• Allow functions with multiple arguments inside EditorSpinSlider #80541

[Calinou]

Does not work well in the inspector:

I recall it working correctly in my testing (the displayed number during editing didn't have any separators). I think it should work this way preferably, but we should make it so EditorSpinSlider and SpinBox accept numbers with various separators nonetheless for better usability.

To handle situations where we have both , and . separators in the same string, the decimal separator is the one that comes last in the string.

[bruvzg]

TextServerAdvanced::_format_number isn't doing anything like this (adding separators), it's only converting western Arabic numerals to the language specific numeral system. So it should be either modified to do so or not use it as fallback.

For the reference: ICU have full number formatting methods, but we do not build ICU internationalization part and do not include relevant databases (nor sure if it's possible to include only part relevant to the number formatting, full database is ~36 MB).

Edit: decimal format strings are part of main locale files, so not counting extra code that should be added it will add at least 8MB if data if used directly. So it probably should be a custom implementation, similar to the one used for numeral system conversion.