Common Niva Patterns

// main.niva // 2) Represent all possible states as tagged unions union JsonObj = | JsonArray arr: MutableList::JsonObj | JsonNumber num: Double | JsonString str: String | JsonFields fld: MutableMap(String, JsonObj) // 3) Add method for union root what to do in every branch JsonObj toJson -> String = | this | JsonArray => this arrToJson | JsonNumber => num toString | JsonString => str packForJson | JsonFields => this fieldToJson //Creating specific methods for generation of JsonArray and JsonFields JsonArray arrToJson -> String = [ createArr = [ b = StringBuilder new arr forEachIndexed: [ i, it -> b append: it toJson i + 1 != arr count => b append: ", " ] b toString ] ^createArr do surroundWith: "[ " and: " ]" ] JsonFields fieldToJson -> String = [ createObj = [ b = StringBuilder new mut i = 0 fld forEach: [ k, v -> b append: k packForJson |> append: ": " |> append: v toJson i + 1 != fld count => b append: ", " i <- i inc ] b toString ] ^createObj do surroundWith: "{ " and: " }" ] jsonNum = JsonNumber num: 5.0 jsonStr = JsonString str: "t'e'x't" jsonFields = JsonFields fld: #{"a\ng'e" jsonNum} arr = JsonArray arr: {jsonNum jsonNum jsonStr jsonFields} arr toJson echo

String surroundWith::String and::String = surroundWith + this + and String surroundWith: x::String = x + this + x String packForJson -> String = this escape surroundWith: "\"" String escape = this replace: "\\" with: "\\\\" |> replace: "\"" with: "\\\"" |> replace: "\n" with: "\\n" |> replace: "\r" with: "\\r" |> replace: "\t" with: "\\t" |> replace: "\'" with: "\\'"