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/P4Lang/Parser.swift

@@ -22,11 +22,11 @@ public struct LocalElements {}
 public struct LocalElement {}
 
 public struct ParserAssignmentStatement {
-  public let lvalue: EvaluatableLValueExpression
-  public let value: EvaluatableExpression
+  public let lvalue: P4LValueExpression
+  public let value: P4Expression
 
   public init(
-    withLValue lvalue: EvaluatableLValueExpression, withValue value: EvaluatableExpression
+    withLValue lvalue: P4LValueExpression, withValue value: P4Expression
   ) {
     self.lvalue = lvalue
     self.value = value
@@ -34,12 +34,9 @@ public struct ParserAssignmentStatement {
 }
 
 /// A P4 Parser State
-///
-/// Note: A P4 Parser State is both a type and a value.
-/// This "bare" parser state represents the state more as a type than a value.
 public class ParserState: P4Type, Equatable, CustomStringConvertible {
   let name: Identifier
-  public let statements: [EvaluatableStatement]
+  public let statements: [P4Statement]
 
   public static func == (lhs: ParserState, rhs: ParserState) -> Bool {
     return lhs.eq(rhs: rhs)
@@ -60,12 +57,12 @@ public class ParserState: P4Type, Equatable, CustomStringConvertible {
     return self.name
   }
 
-  public func getStatements() -> [EvaluatableStatement] {
+  public func getStatements() -> [P4Statement] {
     return self.statements
   }
 
   /// Construct a ParserState
-  public init(_ name: Identifier, _ statements: [EvaluatableStatement] = Array()) {
+  public init(_ name: Identifier, _ statements: [P4Statement] = Array()) {
     self.name = name
     self.statements = statements
   }
@@ -100,7 +97,7 @@ public class ParserStateDirectTransition: ParserState {
   /// Construct a ParserState
   public init(
     name: Identifier, withNextState next_state: InstantiatedParserState,
-    withStatements stmts: [EvaluatableStatement] = Array(),
+    withStatements stmts: [P4Statement] = Array(),
   ) {
     self.next_state = next_state
     self.next_state_identifier = .none
@@ -109,7 +106,7 @@ public class ParserStateDirectTransition: ParserState {
 
   public init(
     name: Identifier, withNextStateIdentifier next_state_id: Identifier,
-    withStatements stmts: [EvaluatableStatement] = Array(),
+    withStatements stmts: [P4Statement] = Array(),
   ) {
     self.next_state = .none
     self.next_state_identifier = next_state_id
@@ -129,7 +126,7 @@ public class ParserStateDirectTransition: ParserState {
 public class ParserStateNoTransition: ParserState {
   /// Construct a ParserState
   public init(
-    name: Identifier, withStatements stmts: [EvaluatableStatement] = Array(),
+    name: Identifier, withStatements stmts: [P4Statement] = Array(),
   ) {
     super.init(name, stmts)
   }
@@ -145,7 +142,7 @@ public class ParserStateSelectTransition: ParserState {
 
   public init(
     name: Identifier, withTransitionExpression te: SelectExpression,
-    withStatements stmts: [EvaluatableStatement] = Array()
+    withStatements stmts: [P4Statement] = Array()
   ) {
     self.te = te
     super.init(name, stmts)