Provide JGit-based implementation for File trait.

JGitFile uses lazy vals as mechanism to avoid computing values that might
not be needed at all.

For every JGitFile created there's check performed to make sure that given
object exists.

Signed-off-by: Grzegorz Kossakowski <grek@google.com>

3 files changed, 128 insertions, 0 deletions

diff --git a/src/main/scala/com/google/gimd/jgit/JGitDatabaseException.scala b/src/main/scala/com/google/gimd/jgit/JGitDatabaseException.scala
new file mode 100644
index 0000000..c7fd49a
--- /dev/null
+++ b/src/main/scala/com/google/gimd/jgit/JGitDatabaseException.scala
@@ -0,0 +1,22 @@
+// Copyright (C) 2009 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gimd.jgit
+
+class JGitDatabaseException(message: String, cause: Throwable)
+        extends DatabaseException(message, cause) {
+
+  def this(message: String) = this(message, null)
+
+}
diff --git a/src/main/scala/com/google/gimd/jgit/JGitFile.scala b/src/main/scala/com/google/gimd/jgit/JGitFile.scala
new file mode 100644
index 0000000..6c6c13c
--- /dev/null
+++ b/src/main/scala/com/google/gimd/jgit/JGitFile.scala
@@ -0,0 +1,36 @@
+// Copyright (C) 2009 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gimd.jgit
+
+import file.{FileType, File}
+import java.io.{InputStreamReader, ByteArrayInputStream}
+import org.spearce.jgit.lib.{ObjectId, Repository}
+import text.Parser
+
+final class JGitFile[T](val path: String, val blobId: ObjectId, val fileType: FileType[T],
+                        val jgitRepository: Repository) extends File[T] {
+
+  lazy val message = Parser.parse(new InputStreamReader(blobInputStream, "UTF-8"))
+  lazy val userObject = fileType.userType.toUserType(message)
+
+  private lazy val blobInputStream = {
+    val objectLoader = jgitRepository.openBlob(blobId)
+    if (objectLoader == null)
+      throw new JGitDatabaseException("Blob '" + blobId.name + "' does not exist.")
+
+    new ByteArrayInputStream(objectLoader.getCachedBytes)
+  }
+
+}
diff --git a/src/test/scala/com/google/gimd/jgit/JGitFileTestCase.scala b/src/test/scala/com/google/gimd/jgit/JGitFileTestCase.scala
new file mode 100644
index 0000000..2f0da79
--- /dev/null
+++ b/src/test/scala/com/google/gimd/jgit/JGitFileTestCase.scala
@@ -0,0 +1,70 @@
+// Copyright (C) 2009 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gimd.jgit
+
+
+import file.FileType
+import junit.framework.Assert._
+import org.junit.Test
+import org.spearce.jgit.lib.ObjectId
+
+class JGitFileTestCase extends AbstractJGitTestCase {
+
+  case class SimpleMessage(name: String, value: Int)
+
+  object SimpleMessageType extends UserType[SimpleMessage] {
+    def toMessageBuffer(sm: SimpleMessage) = (new MessageBuffer()) ++
+      List(Field("name", sm.name), Field("value", sm.value))
+    def toUserType(m: Message): SimpleMessage = {
+      val name = m.one("name").stringField.value
+      val value = m.one("value").intField.value
+      SimpleMessage(name, value)
+    }
+  }
+
+  object SimpleMessageFileType extends FileType[SimpleMessage] {
+    val pathPrefix = None
+    val pathSuffix = None
+    val userType = SimpleMessageType
+  }
+
+  @Test
+  def testMessage {
+    val simpleMessage = SimpleMessage("Test", 10)
+    val expected: Message = SimpleMessageType.toMessageBuffer(simpleMessage).readOnly
+
+    val blobId = writeTextContent(expected.toString)
+
+    val jGitFile = new JGitFile("test", blobId, SimpleMessageFileType, repository)
+    assertEquals(expected, jGitFile.message)
+  }
+
+  @Test
+  def testUserObject {
+    val expected = SimpleMessage("Test", 10)
+    val message: Message = SimpleMessageType.toMessageBuffer(expected).readOnly
+
+    val blobId = writeTextContent(message.toString)
+
+    val jGitFile = new JGitFile("test", blobId, SimpleMessageFileType, repository)
+    assertEquals(expected, jGitFile.userObject)
+  }
+
+  @Test{val expected = classOf[JGitDatabaseException]}
+  def testMessageOfNonExistingObject {
+    val jGitFile = new JGitFile("test", ObjectId.zeroId, SimpleMessageFileType, repository)
+    jGitFile.message
+  }
+}