com.phasmidsoftware.parse.ColumnHelper.scala Maven / Gradle / Ivy

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This project is a Scala library for facilitate comparisons in a functional style.

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/*
 * Copyright (c) 2019. Phasmid Software
 */

package com.phasmidsoftware.parse

import scala.annotation.implicitNotFound

/**
  * Type class representing a mapping from a case class parameter to the corresponding column header.
  *
  * @tparam T the type of the object being helped.
  */
@implicitNotFound(msg = "Cannot find an implicit instance of ColumnHelper[${T}]. If ${T} is a case class, you will normally need to provide some help translating column names.")
trait ColumnHelper[T] {
  /**
    * This is the format for the prefix of a name, where "x" represents the value, if any, of the optional string.
    */
  val maybePrefix_ : Option[String]

  /**
    * These are the alias mappings
    */
  val aliases_ : Seq[(String, String)]

  /**
    * This defines the default mapping between parameter names and column names.
    * It is only used if there is no mapping defined in aliases.
    *
    * @return the mapper function.
    */
  val columnNameMapper_ : String => String

  /**
    * This is the lookup function
    *
    * @param so is an optional string to be inserted into the prefix
    * @param w  is the name of column, as determined from the Product which we are trying to fill.
    * @return a String which may include a prefix.
    */
  def lookup(so: Option[String], w: String): String = {
    val column = aliases_.toMap.getOrElse(w, columnNameMapper_(w))
    (for (p <- maybePrefix_; s <- so) yield p.replace("$x", s).replace("$c", column)).getOrElse(column)
  }
}

object ColumnHelper {
  def camelCaseColumnNameMapper(w: String): String = w.replaceAll("([A-Z0-9])", "_$1")

  def camelCaseColumnNameMapperSpace(w: String): String = w.replaceAll("([A-Z0-9])", " $1")
}