Validate implicit getters

[jpsim]

Read-only properties and subscripts should avoid using the get keyword.

[delebedev]

cat file.swift

struct Thing {

    var foo: Int {
      get { return 3 }
      set { _abc = newValue }
    }

    var bar: Int { return 42 }

    var baz: Int {
      get { return 42 }
    }
}

sourcekitten structure --file file.swift:

{
  "key.substructure" : [
    {
      "key.kind" : "source.lang.swift.decl.struct",
      "key.offset" : 1,
      "key.nameoffset" : 8,
      "key.namelength" : 5,
      "key.bodyoffset" : 15,
      "key.bodylength" : 162,
      "key.accessibility" : "source.lang.swift.accessibility.internal",
      "key.substructure" : [
        {
          "key.kind" : "source.lang.swift.decl.var.instance",
          "key.offset" : 21,
          "key.nameoffset" : 25,
          "key.namelength" : 3,
          "key.bodyoffset" : 35,
          "key.bodylength" : 58,
          "key.accessibility" : "source.lang.swift.accessibility.internal",
          "key.setter_accessibility" : "source.lang.swift.accessibility.internal",
          "key.typename" : "Int",
          "key.name" : "foo",
          "key.length" : 12
        },
        {
          "key.kind" : "source.lang.swift.decl.var.instance",
          "key.offset" : 100,
          "key.nameoffset" : 104,
          "key.namelength" : 3,
          "key.bodyoffset" : 114,
          "key.bodylength" : 11,
          "key.accessibility" : "source.lang.swift.accessibility.internal",
          "key.length" : 12,
          "key.typename" : "Int",
          "key.name" : "bar"
        },
        {
          "key.kind" : "source.lang.swift.decl.var.instance",
          "key.offset" : 132,
          "key.nameoffset" : 136,
          "key.namelength" : 3,
          "key.bodyoffset" : 146,
          "key.bodylength" : 29,
          "key.accessibility" : "source.lang.swift.accessibility.internal",
          "key.length" : 12,
          "key.typename" : "Int",
          "key.name" : "baz"
        }
      ],
      "key.name" : "Thing",
      "key.length" : 177
    }
  ],
  "key.offset" : 0,
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.length" : 179
}

As you can notice there is no structural difference between variable, variable with implicit and explicit getter.

I can start with ASTRule and check every source.lang.swift.decl.var.instance, but what is reliable way to check for get and set keywords? Matching string directly does not look like a good idea (it can be getVar inside a scope or one can omit space and have valid get{ piece.

Is there any way to check for syntax tokens in range? I've found SyntaxMap.tokensIn but I am not sure how to use it outside of the File