BUG: IOstream::compressionEnum() used Switch::switchType incorrectly

- use enhanced Switch constructor and the new valid() method to
  avoid potential pitfalls of using Switch::switchType directly.

src/OpenFOAM/db/IOstreams/IOstreams/IOstream.C

@@ -61,9 +61,9 @@ Foam::IOstream::compressionType
 Foam::IOstream::compressionEnum(const word& compression)
 {
     // get Switch (bool) value, but allow it to fail
-    Switch::switchType sw = Switch::asEnum(compression, true);
+    Switch sw(compression, true);
 
-    if (sw != Switch::INVALID)
+    if (sw.valid())
     {
         return sw ? IOstream::COMPRESSED : IOstream::UNCOMPRESSED;
     }

src/OpenFOAM/primitives/bools/Switch/Switch.C

@@ -83,7 +83,7 @@ Foam::Switch::switchType Foam::Switch::asEnum
             << abort(FatalError);
     }
 
-    return INVALID;
+    return Switch::INVALID;
 }
 
 
@@ -115,7 +115,6 @@ bool Foam::Switch::asBool
         return false;
     }
 
-
     return (sw & 0x1);
 }
 

src/OpenFOAM/primitives/bools/Switch/SwitchIO.C

@@ -53,9 +53,13 @@ Foam::Istream& Foam::operator>>(Istream& is, Switch& s)
     else if (t.isWord())
     {
         // allow invalid values, but catch after for correct error message
-        Switch::switchType sw = Switch::asEnum(t.wordToken(), true);
+        Switch sw(t.wordToken(), true);
 
-        if (sw == Switch::INVALID)
+        if (sw.valid())
+        {
+            s.switch_ = sw.switch_;
+        }
+        else
         {
             is.setBad();
             FatalIOErrorIn("operator>>(Istream&, Switch&)", is)
@@ -64,10 +68,6 @@ Foam::Istream& Foam::operator>>(Istream& is, Switch& s)
 
             return is;
         }
-        else
-        {
-            s.switch_ = sw;
-        }
     }
     else
     {