Refactor Parsing/Runtime

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

Sources/P4Runtime/Runtime.swift

@@ -0,0 +1,64 @@
+// p4rse, Copyright 2026, Will Hawkins
+//
+// This file is part of p4rse.
+//
+// This file is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+import Common
+import P4Lang
+
+/// The runtime for a parser
+public class ParserRuntime: CustomStringConvertible {
+  public var parser: ParserInstance
+
+  init(execution: ParserInstance) {
+    self.parser = execution
+  }
+
+  /// Create a parser runtime from a P4 program
+  public static func create(program: P4Lang.Program) -> Result<ParserRuntime> {
+
+    return switch program.starting_parser() {
+    case .Ok(let parser):
+      switch ParserInstance.compile(parser) {
+      case .Ok(let execution): .Ok(P4Runtime.ParserRuntime(execution: execution))
+      case .Error(let error): .Error(error)
+      }
+    case .Error(let error): .Error(error)
+    }
+  }
+
+  /// Run the P4 parser on a given packet
+  public func run() -> Result<(ParserState, ProgramExecution)> {
+    return .Ok(parser.execute())
+  }
+
+  public var description: String {
+    return "Runtime:\nExecution: \(parser)"
+  }
+}
+
+/// Instances of parsers are executable
+extension ParserInstance: ParserExecution {
+  public func execute() -> (ParserState, ProgramExecution) {
+    var execution = self as ProgramExecution
+    var c = self.start_state
+
+    // Evaluate until the state is either accept or reject.
+    while !c.done() && !execution.hasError() {
+      (c, execution) = c.execute(program: execution)
+    }
+    return (c.current(), execution)
+  }
+}