[POC] Support the literal "." path

Fix #381

Author: lefou

os/src/Path.scala

@@ -35,15 +35,18 @@ object PathChunk extends PathChunkMacros {
       }
     }.reverse
   private[os] def segmentsFromStringLiteralValidation(literal: String): Array[String] = {
-    val stringSegments = segmentsFromString(literal)
-    val validSegmnts = reduceUps(validLiteralSegments(stringSegments))
-    val sanitizedLiteral = validSegmnts.mkString("/")
-    if (validSegmnts.isEmpty) throw InvalidSegment(
-      literal,
-      s"Literal path sequence [$literal] doesn't affect path being formed, please remove it"
-    )
-    if (literal != sanitizedLiteral) throw NonCanonicalLiteral(literal, sanitizedLiteral)
-    stringSegments
+    if (literal == ".") Array.empty
+    else {
+      val stringSegments = segmentsFromString(literal)
+      val validSegments = reduceUps(validLiteralSegments(stringSegments))
+      val sanitizedLiteral = validSegments.mkString("/")
+      if (validSegments.isEmpty) throw InvalidSegment(
+        literal,
+        s"Literal path sequence [$literal] doesn't affect path being formed, please remove it"
+      )
+      if (literal != sanitizedLiteral) throw NonCanonicalLiteral(literal, sanitizedLiteral)
+      stringSegments
+    }
   }
   private def validLiteralSegments(segments: Array[String]): Array[String] = {
     val AllowedLiteralSegment = ".."

os/test/src/PathTests.scala

@@ -60,6 +60,9 @@ object PathTests extends TestSuite {
         assert(root / "hello" / ".." / "world" == root / "hello" / os.up / "world")
         assert(root / "hello" / "../world" == root / "hello" / os.up / "world")
       }
+      test("literal [.]") {
+        assert(root / "." == root)
+      }
 
       test("Compile errors") {
 
@@ -122,13 +125,11 @@ object PathTests extends TestSuite {
         compileError("""root / "//foo/" """).check("", nonCanonicalLiteral("//foo/", "foo"))
 
         compileError(""" rel / "src" / "" """).check("", removeLiteralErr(""))
-        compileError(""" rel / "src" / "." """).check("", removeLiteralErr("."))
 
         compileError(""" root / "src/"  """).check("", nonCanonicalLiteral("src/", "src"))
         compileError(""" root / "src/." """).check("", nonCanonicalLiteral("src/.", "src"))
 
         compileError(""" root / "" """).check("", removeLiteralErr(""))
-        compileError(""" root / "." """).check("", removeLiteralErr("."))
 
       }
     }