Add find-and-replace expression operator

[lucaswoj]

From @nickidlugash on August 3, 2015 23:46

Currently we can't make use of the way duplex shields in the mapbox streets data are designed to be styled, because we can't use regex as part of values, and we also don't accept \n as a space for line wrapping. Is it feasible to implement the ability to use find/replace and \n?

Copied from original issue: mapbox/mapbox-gl-style-spec#321

[lucaswoj]

From @1ec5 on August 3, 2015 23:48

The regex half of this is covered by #233.

[lucaswoj]

From @jfirebaugh on August 4, 2015 0:53

#233 is for the use of regexes in filters, which is a different use case.

I seem to recall an issue for wrapping on newlines, but I can't find it at the moment.

[lucaswoj]

We have a separate issue for regex support and have already implemented newline support.

[lucaswoj]

From @jfirebaugh on December 22, 2016 18:25

As noted above: the other issue is for regex support in filters. This is about regex support in functions.

[1ec5]

As of #5434, expressions (the successor to functions) can be used as filters. #4089 tracks adding an expression operator for testing whether a string matches a regular expression, but we can leave this issue open to track adding an expression operator for finding and replacing occurrences of a substring or regular expression match within a given string.

[stevage]

Currently you can kind of workaround find-and-replace without regex, but it's pretty clunky:

["match", ["index-of", "Mount", ["to-string", ["get", "name"]]], 0, ["concat", "Mt", ["slice", ["to-string", ["get", "name"]],5]],  ["to-string", ["get", "name"]]]

This would certainly improve the ergonomics of that.