compiler, language, runtime: Separate Parser Type From Instances

In P4, parsers are considered types. Those parsers are instantiated.
The instantiated parsers are values. Previously, gp4 treated a parser
type and a parser value as identical. This PR makes that difference
clear _and_ sets the stage for the future.

TODO: Make the same distinction between control and action types and
values.

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

Sources/P4Compiler/Compiler.swift

@@ -46,7 +46,7 @@ public func ConfigureP4Parser() -> Result<SwiftTreeSitter.Parser> {
 /// knowledge of an expected type. For instance, when compiling a return statement, the
 /// compiler must know the return type of the function to type check.
 public struct CompilerContext {
-  let instances: VarTypeScopes
+  let instances: StaticVarValueScopes
   let types: TypeTypeScopes
   let externs: TypeTypeScopes
   let ffis: [P4FFI]
@@ -54,7 +54,7 @@ public struct CompilerContext {
   let extern_context: Bool
 
   public init() {
-    instances = VarTypeScopes().enter()
+    instances = StaticVarValueScopes().enter()
     types = TypeTypeScopes().enter()
     externs = TypeTypeScopes().enter()
     expected_type = .none
@@ -62,7 +62,7 @@ public struct CompilerContext {
     ffis = Array()
   }
 
-  public init(withInstances _instances: VarTypeScopes, withTypes _types: TypeTypeScopes) {
+  public init(withInstances _instances: StaticVarValueScopes, withTypes _types: TypeTypeScopes) {
     instances = _instances
     types = _types
     externs = TypeTypeScopes().enter()
@@ -72,7 +72,7 @@ public struct CompilerContext {
   }
 
   public init(
-    withInstances _instances: VarTypeScopes, withTypes _types: TypeTypeScopes,
+    withInstances _instances: StaticVarValueScopes, withTypes _types: TypeTypeScopes,
     withExpectation expectation: P4QualifiedType?, withExtern extern: Bool,
     withExterns externs: TypeTypeScopes, withFFIs foreigns: [P4FFI]
   ) {
@@ -90,7 +90,7 @@ public struct CompilerContext {
   ///
   /// - Parameter instances: a ``VarTypeScopes`` with the updated instances for the newly created compiler context.
   /// - Returns: A new compiler context based on the current but new instances.
-  public func update(newInstances instances: VarTypeScopes) -> CompilerContext {
+  public func update(newInstances instances: StaticVarValueScopes) -> CompilerContext {
     return CompilerContext(
       withInstances: instances, withTypes: self.types, withExpectation: self.expected_type,
       withExtern: self.extern_context, withExterns: self.externs, withFFIs: self.ffis)