The TSV parser is now monadic.

[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 5b2d261f5cec1bf49e97a0a303d95b69efcb7301..817d950376ab7a3779ff2aa75e7881a373c9dc3b 100644 (file)
--- a/src/main/scala/jp/ymir/taskReporter/core/TSV.scala
+++ b/src/main/scala/jp/ymir/taskReporter/core/TSV.scala
@@ -8,19 +8,8 @@ import scalaz._
 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] {
+  implicit val 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))
@@ -29,7 +18,7 @@ object TSV {
     }
   }
 
-  implicit def ParserApplicative = new Applicative[Parser] {
+  implicit val 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)
@@ -45,7 +34,7 @@ object TSV {
     }
   }
 
-  implicit def ParserMonad = new Monad[Parser] {
+  implicit val ParserMonad = new Monad[Parser] {
     def point[A](a: => A) = a.point[Parser]
 
     def bind[A, B](m: Parser[A])(f: A => Parser[B]) = new Parser[B] {
@@ -56,7 +45,7 @@ object TSV {
     }
   }
 
-  implicit def ParserMonadError = new MonadError[({type λ[String, α] = Parser[α]})#λ, String] {
+  implicit val ParserMonadError = new MonadError[({type λ[String, α] = Parser[α]})#λ, String] {
     def point[A](a: => A) = a.point[Parser]
     def bind[A, B](m: Parser[A])(f: A => Parser[B]) = m.flatMap(f)
 
@@ -72,37 +61,53 @@ object TSV {
         = kf(e)
     }
   }
+
+  implicit def ToMonadErrorOps[A](m: Parser[A]) = new {
+    def handleError(f: String => Parser[A]): Parser[A]
+      = implicitly[MonadError[({type λ[String, α] = Parser[α]})#λ, String]].handleError(m)(f)
+  }
+
   implicit def ToMonadErrorIdOps(e: String) = new {
     def raiseError[A]: Parser[A]
       = implicitly[MonadError[({type λ[String, α] = Parser[α]})#λ, String]].raiseError(e)
   }
 
+  type Header = Seq[Symbol]
+
+  case class Field(value: String) {
+    def parseField[A: FromField]
+      = implicitly[FromField[A]].parseField(Field(value))
+  }
+
+  case class Record(value: Map[Symbol, Field]) {
+    def parseRecord[A: FromRecord]
+      = implicitly[FromRecord[A]].parseRecord(Record(value))
+
+    def lookup[A: FromField](name: Symbol): Parser[A]
+      = value.get(name).fold(("no field named " + name.name).raiseError[A])(_.parseField[A])
+  }
+
+  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]
+  }
+
   def runParser[A](p: Parser[A]): Either[String, A] = {
     type F[R] = Either[String, R]
     def left (e: String): F[A] = Left(e)
     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(_))
-    val body   = lines.tail.map(line => (header zip line.split('\t')).toMap)
-    return body.map(implicitly[FromRecord[A]].parseRecord)
-  }
 
   trait FromRecord[A] {
-    def parseRecord(r: Record): A
+    def parseRecord(r: Record): Parser[A]
   }
 
   trait FromField[A] {
     def parseField(f: Field): Parser[A]
   }
-  implicit def toFromFieldOps(f: Field) = new {
-    def parseField[A: FromField]
-      = implicitly[FromField[A]].parseField(f)
-  }
 
   trait ToRecord[A] {
     def toRecord(a: A): Record
@@ -112,11 +117,28 @@ object TSV {
     def toField(a: A): Field
   }
 
+  class DecodeFailedException private(e: RuntimeException) extends RuntimeException(e) {
+    def this(msg: String) = this(new RuntimeException(msg))
+    def this(msg: String, cause: Throwable) = this(new RuntimeException(msg, cause))
+  }
+
+  def decode[A: FromRecord](tsv: StringLike[_]): Seq[A] = {
+    val lines  = tsv.split('\n').filter(!_.isEmpty)
+    val header = lines.head.split('\t').map(Symbol(_))
+    val body   = lines.tail.map(line => Record((header zip line.split('\t').map { Field(_) }).toMap))
+    return body.map { r =>
+      runParser(r.parseRecord[A]) match {
+        case Right(a) => a
+        case Left(e)  => throw new DecodeFailedException(e)
+      }
+    }
+  }
+
   // Option[A]
   implicit def OptionFromField[A: FromField] = new FromField[Option[A]] {
     def parseField(f: Field): Parser[Option[A]] = {
-      if (f.isEmpty) {
-        return (None : Option[A]).point[Parser]
+      if (f.value.isEmpty) {
+        return None.point[Parser]
       }
       else {
         f.parseField[A].map { Some(_) }
@@ -125,15 +147,15 @@ object TSV {
   }
 
   // String
-  implicit def StringFromField = new FromField[String] {
-    def parseField(f: Field): Parser[String] = f.point[Parser]
+  implicit val StringFromField = new FromField[String] {
+    def parseField(f: Field): Parser[String] = f.value.point[Parser]
   }
 
   // Int
-  implicit def IntFromField = new FromField[Int] {
+  implicit val IntFromField = new FromField[Int] {
     def parseField(f: Field): Parser[Int] = {
       try {
-        f.toInt.point[Parser]
+        f.value.toInt.point[Parser]
       }
       catch {
         case e: NumberFormatException =>