VS Code snippet transform syntax supports converting capture groups to a variety of formats, including lowercase, camelCase, and PascalCase. Support for snake_case would be awesome.

See https://code.visualstudio.com/docs/editor/userdefinedsnippets#_grammar

This feature would be helpful when trying to define a snippet that automatically adds a json struct tag to Go fields, for example:

type Person struct {
    FirstName `json:"first_name"`
}

This is the snippet definition I'm using right now, though it's buggy:

"property with JSON and YAML": {
	"prefix": "prop",
	"body": [
		"${1:name} ${2:string} `yaml:\"${1/([A-Z]?[a-z]+)([A-Z])/${1:/downcase}_${2:/downcase}/g}\" json:\"${1/([A-Z]?[a-z]+)([A-Z])/${1:/downcase}_${2:/downcase}/g}\"`"
	],
},