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package org.perl8.router
import scala.collection.mutable.ListBuffer
import scala.util.matching.Regex
class Router[T] {
def addRoute (
path: String,
target: T,
defaults: Map[String, String] = Map.empty,
validations: Map[String, Regex] = Map.empty
) {
routes += new Route(path, defaults, validations, target)
}
def route (path: String): Option[Match[T]] = {
val components = path.split("/").filter {
case "" => false
case "." => false // XXX do we want to keep this?
case _ => true
}
routes.view.flatMap(r => r.route(components)).headOption
}
def uriFor (mapping: Map[String, String]): Option[String] = {
// first remove all routes that can't possibly match
// - if the route requires a variable component that doesn't exist in the
// mapping, then it can't match
// - if the route contains a value for a variable component that doesn't
// pass the validation for that component, it can't match
// - if the route contains a default value, and that component also exists
// in the mapping, then the values must match
val possible = routes.toList.flatMap { r =>
r.pathWithMapping(mapping).map(p => r -> p)
}
possible match {
case Nil => None
case (r, path) :: Nil => Some(path)
case _ => {
// then try to disambiguate the remaining possibilities
// - we want the route with the fewest number of "extra" items in the
// mapping, after removing defaults and variable path components
val possibleByRemainder = possible.groupBy { case (r, path) => {
(mapping.keys.toSet -- r.defaults.keys.toSet -- r.variables).size
} }
val found = possibleByRemainder(possibleByRemainder.keys.min)
found match {
case Nil => None
case (r, path) :: Nil => Some(path)
case rs =>
throw new AmbiguousRouteMapping(mapping, rs.map(_._1.path))
}
}
}
}
private val routes = new ListBuffer[Route]
private class Route (
val path: String,
val defaults: Map[String, String],
val validations: Map[String, Regex],
val target: T
) {
lazy val variables = components.flatMap(getVariableName)
def route (
parts: Seq[String],
components: Seq[String] = components,
mapping: Map[String, String] = defaults
): Option[Match[T]] = {
if (components.filter(!isOptional(_)).length == 0 && parts.length == 0) {
Some(new Match[T](path, mapping, target))
}
else if (components.length == 0 || parts.length == 0) {
None
}
else {
components.head match {
case Optional(name) => {
if (validate(name, parts.head)) {
route(parts.tail, components.tail, mapping + (name -> parts.head))
}
else {
route(parts, components.tail, mapping)
}
}
case Variable(name) => {
if (validate(name, parts.head)) {
route(parts.tail, components.tail, mapping + (name -> parts.head))
}
else {
None
}
}
case literal => parts.head match {
case `literal` => route(parts.tail, components.tail, mapping)
case _ => None
}
}
}
}
override def toString = path
def pathWithMapping (mapping: Map[String, String]): Option[String] = {
val requiredDefaults = defaults.keys.filter { k =>
mapping.isDefinedAt(k) && !variables.contains(k)
}
if (requiredDefaults.forall(k => defaults(k) == mapping(k)) &&
requiredVariables.forall(mapping.isDefinedAt)) {
val boundComponents = components.flatMap {
case Optional(v) => {
val component = (mapping get v).flatMap(validComponentValue(v, _))
defaults.get(v).map { default =>
component.flatMap {
case `default` => None
case c => Some(c)
}
}.getOrElse(component)
}
case Variable(v) => validComponentValue(v, (mapping(v)))
case literal => Some(literal)
}
Some(boundComponents.mkString("/"))
}
else {
None
}
}
private lazy val components =
path.split("/").filter(_.length > 0)
private lazy val requiredVariables =
components.filter(!isOptional(_)).flatMap(getVariableName)
private lazy val hasVariable = variables.toSet
private def isOptional (component: String) =
Optional.findFirstIn(component).nonEmpty
private def isVariable (component: String) =
Variable.findFirstIn(component).nonEmpty
private def getVariableName (component: String) = component match {
case Variable(name) => Some(name)
case _ => None
}
private def validate (name: String, component: String) =
validations.get(name).forall(_.findFirstIn(component).nonEmpty)
private def validComponentValue (name: String, component: String) =
if (validate(name, component)) Some(component) else None
private val Optional = """^\?:(.*)$""".r
private val Variable = """^\??:(.*)$""".r
}
private class AmbiguousRouteMapping (
mapping: Map[String, String],
paths: Seq[String]
) extends RuntimeException(
"Ambiguous path descriptor (specified keys " +
mapping.keys.mkString(", ") +
"): could match paths " +
paths.mkString(", ")
)
}
class Match[T] (
val path: String,
val mapping: Map[String, String],
val target: T
)
|
