Add BSONReader.collect combinator (#424)

Author: cchantep

api/src/main/scala/BSONReader.scala

@@ -74,6 +74,22 @@ trait BSONReader[T] { self =>
   def afterRead[U](f: T => U): BSONReader[U] =
     new BSONReader.MappedReader[T, U](self, f)
 
+  /**
+   * '''EXPERIMENTAL:''' (API may change without notice)
+   */
+  def collect[U](read: PartialFunction[T, U]): BSONReader[U] =
+    BSONReader.from[U] { bson =>
+      self.readTry(bson).flatMap { v =>
+        read.lift(v) match {
+          case Some(result) =>
+            Success(result)
+
+          case None =>
+            Failure(exceptions.ValueDoesNotMatchException(s"${v}"))
+        }
+      }
+    }
+
   /**
    * $beforeReadDescription
    *
@@ -250,7 +266,7 @@ object BSONReader extends BSONReaderCompat with BSONReaderInstances {
     iterable[T, Seq](read)
 
   /**
-   * '''EXPERIMENTAL:''' Creates a [[BSONDocumentReader]] that reads
+   * '''EXPERIMENTAL:''' Creates a [[BSONReader]] that reads
    * the [[BSONArray]] elements.
    *
    * {{{
@@ -276,7 +292,7 @@ object BSONReader extends BSONReaderCompat with BSONReaderInstances {
     }
 
   /**
-   * '''EXPERIMENTAL:''' Creates a [[BSONDocumentReader]] that reads
+   * '''EXPERIMENTAL:''' Creates a [[BSONReader]] that reads
    * the [[BSONArray]] elements.
    *
    * @see [[tuple2]]
@@ -295,7 +311,7 @@ object BSONReader extends BSONReaderCompat with BSONReaderInstances {
     }
 
   /**
-   * '''EXPERIMENTAL:''' Creates a [[BSONDocumentReader]] that reads
+   * '''EXPERIMENTAL:''' Creates a [[BSONReader]] that reads
    * the [[BSONArray]] elements.
    *
    * @see [[tuple2]]
@@ -319,7 +335,7 @@ object BSONReader extends BSONReaderCompat with BSONReaderInstances {
   }
 
   /**
-   * '''EXPERIMENTAL:''' Creates a [[BSONDocumentReader]] that reads
+   * '''EXPERIMENTAL:''' Creates a [[BSONReader]] that reads
    * the [[BSONArray]] elements.
    *
    * @see [[tuple2]]

api/src/test/scala/HandlerSpec.scala

@@ -243,11 +243,33 @@ final class HandlerSpec
     }
   }
 
-  "Complex Array" should {
+  "Complex array" should {
     "be of size = 6" in {
       array.size must_=== 6
     }
 
+    "be collect'ed" in {
+      val reader =
+        implicitly[BSONReader[Seq[BSONValue]]].collect[::[BSONValue]] {
+          case head :: tail => ::(head, tail)
+        }
+
+      reader.readTry(array) must beSuccessfulTry(
+        ::(
+          BSONString("elem0"),
+          List(
+            BSONInteger(1),
+            BSONDouble(2.222),
+            BSONDocument("name" -> "Joe"),
+            BSONArray(0L),
+            BSONString("pp[4]")
+          )
+        )
+      ) and {
+        reader.readTry(BSONArray.empty) must beFailedTry[Seq[BSONValue]]
+      }
+    }
+
     "have a an int = 2 at index 2" in {
       array.get(1) must beSome(BSONInteger(1)) and (array.getAsOpt[Int](
         1
@@ -399,8 +421,10 @@ final class HandlerSpec
     "fails from array" in {
       BSONDocument("foo" -> BSONArray.empty).getAsTry[BSONDocument](
         "foo"
-      ) must_=== Failure(TypeDoesNotMatchException("BSONDocument", "[]"))
-    }
+      ) must_=== Failure(
+        TypeDoesNotMatchException("BSONDocument", "Array ([])")
+      )
+    } tag "wip"
   }
 
   "BSONDateTime" should {