compiler, runtime: Begin Runtime Refactor

Ultimately, the goal is to completely separate the compilation from
the runtime to make it possible to have the interpreter/evaluator
be "just another" entity that can perform meaningful work when
given a parsed GP4 program.

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

Sources/Macros/Macros.swift

@@ -439,11 +439,36 @@ public struct CliTestDeclarationMacro: PeerMacro, Sendable {
   }
 }
 
+public struct DeriveCompilableStatement: PeerMacro, Sendable {
+  public static func expansion(
+    of node: AttributeSyntax,
+    providingPeersOf declaration: some DeclSyntaxProtocol,
+    in context: some MacroExpansionContext
+  ) throws -> [DeclSyntax] {
+
+    let type_name = declaration.cast(ExtensionDeclSyntax.self).extendedType
+    let implementation = DeclSyntax(
+      """
+        extension VariableDeclarationStatement: CompilableStatement {
+          public static func CompileStatement(
+            node: Node, withContext context: CompilerContext
+          ) -> Result<P4Statement> {
+            return switch Compile(node: node, withContext: context) {
+              case .Ok(let res): .Ok(res)
+              case .Error(let e): .Error(e)
+            }
+          }
+        }
+      """)
+    return [implementation]
+  }
+}
+
 @main
 struct P4Macros: CompilerPlugin {
   var providingMacros: [Macro.Type] = [
     RequireResult.self, RequireErrorResult.self, UseOkResult.self, UseErrorResult.self,
     RequireNodeType.self, SkipUnlessNodeType.self, SkipUnlessNodesTypes.self, RequireNodesType.self,
-    MustOr.self, CliTestDeclarationMacro.self,
+    MustOr.self, CliTestDeclarationMacro.self, DeriveCompilableStatement.self,
   ]
 }