com.twitter.finatra.http.internal.routing.PathPattern.scala Maven / Gradle / Ivy

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package com.twitter.finatra.http.internal.routing

import com.twitter.inject.Logging
import java.util.regex.Matcher
import scala.collection.immutable
import scala.util.matching.Regex

object PathPattern extends Logging {

  /* Matches and captures route param names */
  private val NamedRouteParamRegex = """:\w+""".r

  /* Matches and captures wildcard route param */
  private val NamedAsteriskRegex = """:\*$""".r

  def apply(uriPattern: String): PathPattern = {
    PathPattern(
      regex = regex(uriPattern),
      captureNames = captureNames(uriPattern))
  }

  /* Private */

  private def regex(uriPattern: String): Regex = {
    val asterisksReplaced = NamedAsteriskRegex.replaceAllIn(uriPattern, """\\E(.*)\\Q""") // The special token :* captures everything after the prefix string
    val colonNameReplaced = NamedRouteParamRegex.replaceAllIn(asterisksReplaced, """\\E([^/]+)\\Q""") // Replace "colon word (e.g. :id) with a capture group that stops at the next forward slash
    val regexStr = """^\Q""" + colonNameReplaced ++ """\E$"""
    new Regex(regexStr)
  }

  private def captureNames(uriPattern: String): Seq[String] = {
    findNames(uriPattern, NamedRouteParamRegex) ++
      findNames(uriPattern, NamedAsteriskRegex)
  }

  /* We drop to remove the leading ':' */
  private def findNames(uriPattern: String, pattern: Regex): Seq[String] = {
    pattern.findAllIn(uriPattern).toSeq map { _.drop(1) }
  }
}

case class PathPattern(
  regex: Regex,
  captureNames: Seq[String] = Seq()) {

  def extract(requestPath: String): Option[Map[String, String]] = {
    val matcher = regex.pattern.matcher(requestPath)
    if (!matcher.matches)
      None
    else
      Some(extractMatches(matcher))
  }

  //Optimized
  private def extractMatches(matcher: Matcher): Map[String, String] = {
    var idx = 0
    val builder = immutable.Map.newBuilder[String, String]

    for (captureName <- captureNames) {
      idx += 1
      builder += captureName -> matcher.group(idx)
    }
    builder.result()
  }
}