Can I relative-copy files in sbt? - scala

Question

I have a directory structure like this:
a
/one
hey.class
hey.tasty
you.class
you.tasty
/two
foo.class
foo.tasty
/three
bar.class
bar.tasty
b
/one
/two
/three
I need a way to copy all the .tasty files from their respective places in /a to their corresponding places in /b in a sbt task.

Answer 1

You can create the sbt task and pass the original and destination folders in the following manner:
val copyTasties = inputKey[Unit]("Copy .tasty files")
copyTasties := {
val userInput = Def.spaceDelimited().parsed
if (userInput.size != 2) {
throw new IllegalArgumentException("Original and target directories should be define!")
}
val from = Paths.get(userInput.head)
val to = Paths.get(userInput.last)
Files
.walk(from)
.filter(Files.isRegularFile(_))
.filter(path => path.toString.endsWith("tasty"))
.forEach { original =>
val relative = from.relativize(original)
val destination = to.resolve(relative)
IO.copyFile(original.toFile, destination.toFile)
}
}
Then you can invoke it like this:
copyTasties C:\\Dev\\sandbox\\a C:\\Dev\\sandbox\\b
If the original and destination are stable(for example they are directories inside the project) you can rewrite the task:
import java.nio.file.{Files, Paths}
import sbt._
val copyTastiesHardcoded = taskKey[Unit]("Copy .tasty files")
copyTastiesHardcoded := {
val baseDir = baseDirectory.value.toPath
val from = baseDir.resolve("a")
val to = baseDir.resolve("b")
Files
.walk(from)
.filter(Files.isRegularFile(_))
.filter(path => path.toString.endsWith("tasty"))
.forEach { original =>
val relative = from.relativize(original)
val destination = to.resolve(relative)
IO.copyFile(original.toFile, destination.toFile)
}
}
and invoke it without arguments
copyTastiesHardcoded

Answer 2

There are some useful utility methods in sbt that will help you find files and copy them around. Unfortunately the use a wild mixture of the traditional java.io.File and the more modern java.nio.file.Path, so you need to do conversions between them:
val copyFiles = taskKey[Unit]("copy files")
copyFiles := {
val inputDir = baseDirectory.value.toPath / "a"
val files: Seq[(Path, FileAttributes)] =
FileTreeView.default.list(inputDir.toGlob / RecursiveGlob / "*.tasty")
val outputDir = baseDirectory.value.toPath / "b"
IO.copy {
files.map { case (p, _) =>
p.toFile -> outputDir.resolve(inputDir.relativize(p)).toFile
}
}
}
Note that I'm using a glob here to find the files:
https://www.scala-sbt.org/1.x/docs/Globs.html