Master ticket tracking expression API completeness

[anandthakker]

This ticket is intended to define what set of operators would constitute a "complete" expression API and track its implementation.

• Math Add some missing math expressions #5853
  • All the Math.* functions from Javascript
  • All the relevant functions from NSExpression
  • is-nan Add is-nan expression #5494
• Geo
  • Haversine distance Distance expression operator #6062
• Color
  • All the color-modifying functions from CSS4 Add color modifying expressions #5676
• Arrays
  • Construction Allow expressions as elements in array output values #6155
  • Search An expression to check if an array contains a given value #4698
  • Slicing
  • Join
• Strings
  • Search Add expression operator testing whether a string contains a substring #4113 (but see also Regular Expressions)
  • Replace Add find-and-replace expression operator #4100 (but see also Regular Expressions)
  • Slicing
• Regular Expressions Implement "regex" expression that returns an array of match groups or… #6228
• Locale and language
  • Test for script support Add an expressions string lookup operator that returns the script of the string? #5807
  • Case and diacritic folding Case and diacritic folding for expression operators #4136
• Date and time
• Reflection into style state
  • Style image availability Add expression operator to determine style image availability #5261

[1ec5]

All the relevant functions from NSExpression

Inspired by this issue, I attempted to compile a similar issue to track feature parity with NSPredicate and NSExpression: mapbox/mapbox-gl-native#11786.

[gorshkov-leonid]

Hi, I have not found

1. toHex(or toString(16))
2. substrig to save to variable
3. modification operation: variable(set) / object(set) / array(splice)
4. how about supporting #FFFFFFFF(8 bytes) from css4 - number->to-color?
   So. all ideas from https://gist.github.com/gorshkov-leonid/bd4d603fd049f4419983cfb80e221688, I think it is verry complicated solution and new features can make it better

[stevage]

Oh, I didn't know about this ticket!

Me, I would love more string-handling functions:

• left
• right
• split
• titlecase (yes I know it's difficult to do in a locale-independent way)

[lbutler]

Oh, I didn't know about this ticket!

Me, I would love more string-handling functions:

• left
• right
• split
• titlecase (yes I know it's difficult to do in a locale-independent way)

@stevage, just letting you know that my PR #9450 was merged in and soon you will have slice which you can use on strings to do left/right/mid. Check out #9443 to see some examples.

It's not perfect but if you had just a single word you could always slice the first letter and uppercase it and concat with the remainder of the string, something like the below (untested!)

['concat', ['upcase', ['slice', ['get','attributeToTitleCase'], 0 ,1]], ['downcase', ['slice', ['get','attributeToTitleCase'], 1]]]

[FinnRG]

@mourner We extended mapbox-gl with a few basic date functions (new datetype, epoch: int -> date, hour and minute to get those values from a date value). Those are obviously pretty specific for our use case, but I could dedicate time to implement a more general date API.

My questions would be:

• Is such an extension desired by the mapbox team?
• What should the API surface look like? (Timezone handling, date formats, etc.)
• Is a port of these APIs to the react native SDK a minimum requirement?