A function for string templating

replace_param.kt

fun replaceParams(string: String, params: Map<String, Any>) = buildString {
    var i = 0
    var j: Int
    while (i < string.length) {
        while (string[i] != '{') {
            append(string[i])
            i++
            if (i > string.length)
                return@buildString
        }
        if (i == string.lastIndex)
            return@buildString
        j = i + 1
        while (string[j] != '}') {
            j++
            if (i > string.length)
                return@buildString
        }
        val paramName = string.substring((i + 1), j)
        val paramValue = params[paramName]
        if (paramValue != null) {
            append(paramValue)
        } else {
            while (i <= j) {
                append(string[i])
                i++
            }
        }
        i = j + 1
    }
}

fun String.withParams(vararg params: Pair<String, Any>) = replaceParams(this, mapOf(*params))

fun main() {
    val template = "{greeting}, {name}, you are {property}"
    println(template.withParams("greeting" to "Hello", "name" to "Mark", "property" to "tall"))
    println(template.withParams("name" to "Manó"))
}