[svsim] Add type classes for modifying settings

Add two new type classes that describe modifications of
`CommonCompilationSettings` or `Backend.Settings`.  Default
implementations are provided which make no modifications.

Signed-off-by: Schuyler Eldridge <[email protected]>

Author: seldridge

svsim/src/main/scala/Backend.scala

@@ -3,6 +3,14 @@ package svsim
 import java.io.File
 import scala.util.matching.Regex
 
+trait CommonSettingsModifications extends (CommonCompilationSettings => CommonCompilationSettings)
+
+object CommonSettingsModifications {
+
+  implicit def unmodified: CommonSettingsModifications = identity(_)
+
+}
+
 // -- Compilation Settings
 
 /** Settings supported by all svsim backends.
@@ -92,6 +100,15 @@ trait Backend {
 
 }
 
+/** Type class to modify backend comopilation settings */
+trait BackendSettingsModifications extends (Backend.Settings => Backend.Settings)
+
+object BackendSettingsModifications {
+
+  implicit def unmodified: BackendSettingsModifications = identity(_)
+
+}
+
 final object Backend {
 
   /** The super type of all backend-specific settings. */