monadic tsv

[task-reporter.git] / src / main / scala / jp / ymir / taskReporter / core / TSV.scala

diff --git a/src/main/scala/jp/ymir/taskReporter/core/TSV.scala b/src/main/scala/jp/ymir/taskReporter/core/TSV.scala
index 28d9833ad828817d390ac2dacff1eae45edde8ea..fc4947d766cecc33a2601d4cebd6a2b6cb97056c 100644 (file)
--- a/src/main/scala/jp/ymir/taskReporter/core/TSV.scala
+++ b/src/main/scala/jp/ymir/taskReporter/core/TSV.scala
@@ -1,12 +1,66 @@
 package jp.ymir.taskReporter.core
 import scala.collection._
 import scala.collection.immutable.StringLike
+import scala.language.higherKinds
+import scalaz._
 
 object TSV {
   type Header = Seq[Symbol]
   type Field  = String
   type Record = Map[Symbol, Field]
 
+  // ---
+  type Failure[   F[_], R] = String => F[R]
+  type Success[A, F[_], R] = A      => F[R]
+
+  trait Parser[A] {
+    def runParser[F[_], R](kf: Failure[F, R], ks: Success[A, F, R]): F[R]
+  }
+
+  implicit def ParserFunctor = new Functor[Parser] {
+    def map[A, B](m: Parser[A])(f: A => B) = new Parser[B] {
+      def runParser[F[_], R](kf: Failure[F, R], ks: Success[B, F, R]): F[R] = {
+        def ks_(a: A) = ks(f(a))
+        return m.runParser(kf, ks_)
+      }
+    }
+  }
+
+  implicit def ParserApplicative = new Applicative[Parser] {
+    def point[A](a: => A) = new Parser[A] {
+      def runParser[F[_], R](kf: Failure[F, R], ks: Success[A, F, R]): F[R] = ks(a)
+    }
+
+    def ap[A, B](m: => Parser[A])(fm: => Parser[A => B]) = new Parser[B] {
+      def runParser[F[_], R](kf: Failure[F, R], ks: Success[B, F, R]): F[R] = {
+        def ks_(f: A => B): F[R] = {
+          def ks__(a: A) = ks(f(a))
+          return m.runParser(kf, ks__)
+        }
+        return fm.runParser(kf, ks_)
+      }
+    }
+  }
+
+  implicit def ParserMonad = new Monad[Parser] {
+    def point[A](a: => A) = implicitly[Applicative[Parser]].point(a)
+
+    def bind[A, B](m: Parser[A])(f: A => Parser[B]) = new Parser[B] {
+      def runParser[F[_], R](kf: Failure[F, R], ks: Success[B, F, R]): F[R] = {
+        def ks_(a: A) = f(a).runParser(kf, ks)
+        return m.runParser(kf, ks_)
+      }
+    }
+  }
+
+  def runParser[A](p: Parser[A]): Either[String, A] = {
+    type F[A] = Either[String, A]
+    def left (errMsg: String): F[A] = Left(errMsg)
+    def right(x     : A     ): F[A] = Right(x)
+    return p.runParser(left, right)
+  }
+  // ---
+
   def decode[A: FromRecord](tsv: StringLike[_]): Seq[A] = {
     val lines  = tsv.split('\n').filter(!_.isEmpty)
     val header = lines.head.split('\t').map(Symbol(_))