Add copy-option to merge the source into the target (#65)

Commits:

* Add option to copy to merge source with target
* Added mergeFolders param to other copy methods
* Added missing import
* Wrapped lines and improved test name
* Added a test case for a merge copy
* Documented new mergeFolders option

Pull request: #65

Author: lefou

os/src/FileOps.scala

@@ -6,6 +6,7 @@
  */
 package os
 
+import java.nio.file
 import java.nio.file.{Path => _, _}
 import java.nio.file.attribute.{FileAttribute, PosixFilePermission, PosixFilePermissions}
 
@@ -134,28 +135,34 @@ object copy {
   def matching(followLinks: Boolean = true,
                replaceExisting: Boolean = false,
                copyAttributes: Boolean = false,
-               createFolders: Boolean = false)
+               createFolders: Boolean = false,
+               mergeFolders: Boolean = false)
               (partialFunction: PartialFunction[Path, Path]): PartialFunction[Path, Unit] = {
     new PartialFunction[Path, Unit] {
       def isDefinedAt(x: Path) = partialFunction.isDefinedAt(x)
       def apply(from: Path) = {
         val dest = partialFunction(from)
         makeDir.all(dest/up)
-        os.copy(from, dest, followLinks, replaceExisting, copyAttributes, createFolders)
+        os.copy(
+          from, dest, followLinks, replaceExisting, copyAttributes, createFolders, mergeFolders
+        )
       }
     }
 
   }
   def matching(partialFunction: PartialFunction[Path, Path]): PartialFunction[Path, Unit] = {
     matching()(partialFunction)
   }
-  def apply(from: Path,
-            to: Path,
-            followLinks: Boolean = true,
-            replaceExisting: Boolean = false,
-            copyAttributes: Boolean = false,
-            createFolders: Boolean = false): Unit = {
-    if (createFolders) makeDir.all(to/up)
+  def apply(
+             from: Path,
+             to: Path,
+             followLinks: Boolean = true,
+             replaceExisting: Boolean = false,
+             copyAttributes: Boolean = false,
+             createFolders: Boolean = false,
+             mergeFolders: Boolean = false
+           ): Unit = {
+    if (createFolders) makeDir.all(to / up)
     val opts1 =
       if (followLinks) Array[CopyOption]()
       else Array[CopyOption](LinkOption.NOFOLLOW_LINKS)
@@ -169,8 +176,15 @@ object copy {
       !to.startsWith(from),
       s"Can't copy a directory into itself: $to is inside $from"
     )
-    def copyOne(p: Path) = {
-      Files.copy(p.wrapped, (to/(p relativeTo from)).wrapped, opts1 ++ opts2 ++ opts3:_*)
+
+    def copyOne(p: Path): file.Path = {
+      val target = to / p.relativeTo(from)
+      if (mergeFolders && isDir(p, followLinks) && isDir(target, followLinks)) {
+        // nothing to do
+        target.wrapped
+      } else {
+        Files.copy(p.wrapped, target.wrapped, opts1 ++ opts2 ++ opts3: _*)
+      }
     }
 
     copyOne(from)
@@ -187,8 +201,12 @@ object copy {
               followLinks: Boolean = true,
               replaceExisting: Boolean = false,
               copyAttributes: Boolean = false,
-              createFolders: Boolean = false): Unit = {
-      os.copy(from, to/from.last, followLinks, replaceExisting, copyAttributes, createFolders)
+              createFolders: Boolean = false,
+              mergeFolders: Boolean = false): Unit = {
+      os.copy(
+        from, to/from.last,
+        followLinks, replaceExisting, copyAttributes, createFolders, mergeFolders
+      )
     }
   }
 

os/test/src-jvm/ExampleTests.scala

@@ -254,7 +254,7 @@ object ExampleTests extends TestSuite{
       assert(lines == 9)
     }
 
-    test("noLongLines"){
+    test("Source code line length does not exceed 100"){
 
       // Ensure that we don't have any Scala files in the current working directory
       // which have lines more than 100 characters long, excluding generated sources

os/test/src-jvm/OpTestsJvmOnly.scala

@@ -102,6 +102,14 @@ object OpTestsJvmOnly extends TestSuite{
           os.copy(d/"folderA", d/"folderC")
           assert(os.read(d/"folderC"/"folderB"/"file") == "Cow")
         }
+        test("merging"){
+          val mergeDir = d/"merge"
+          os.write(mergeDir/"folderA"/"folderB"/"file", "Cow", createFolders = true)
+          os.write(mergeDir/"folderC"/"file", "moo", createFolders = true)
+          os.copy(mergeDir/"folderA", mergeDir/"folderC", mergeFolders = true)
+          assert(os.read(mergeDir/"folderC"/"folderB"/"file") == "Cow")
+          assert(os.read(mergeDir/"folderC"/"file") == "moo")
+        }
       }
       test("mv"){
         test("basic"){

readme.md

@@ -924,6 +924,20 @@ os.list(wd / "folder2") ==> Seq(wd / "folder2" / "nestedA", wd / "folder2" / "ne
 os.copy.over(wd / "folder1", wd / "folder2")
 os.list(wd / "folder2") ==> Seq(wd / "folder2" / "one.txt")
 ```
+
+#### os.copy with `mergeFolders`
+
+If you want to copy a directory over another but don't want to overwrite the whole destination directory (and loose it's content),
+you can use the `mergeFolders` option of [os.copy](#oscopy).
+
+```scala
+os.list(wd / "folder1") ==> Seq(wd / "folder1" / "one.txt")
+os.list(wd / "folder2") ==> Seq(wd / "folder2" / "nestedA", wd / "folder2" / "nestedB")
+os.copy(wd / "folder1", wd / "folder2", mergeFolders = true)
+os.list(wd / "folder2") ==> Seq(wd / "folder2" / "one.txt", wd / "folder2" / "nestedA", wd / "folder2" / "nestedB")
+```
+
+
 #### os.makeDir
 
 ```scala