Refactor

Refactor into four major components:

1. Common: Things shared among all other components.
2. Lang: P4-language-related components.
3. Runtime: Components required to run a P4 program.
4. Parser: Components for parsing a P4 program from source.

Other components:

1. Macros
2. Tests
3. TreeSitterExtensions: Extra tree sitter functionality

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

Sources/Common/Support.swift

@@ -0,0 +1,85 @@
+// 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/>.
+
+public struct Error: Equatable {
+    public private(set) var msg: String
+
+    public init(withMessage msg: String) {
+        self.msg = msg
+    }
+}
+
+public struct Nothing: CustomStringConvertible {
+    public var description: String {
+        return "Nothing"
+    }
+
+    public init() {}
+}
+
+
+public enum Result<OKT>: Equatable {
+    case Ok(OKT)
+    case Error(Error)
+
+    public static func == (lhs: Result, rhs: Result) -> Bool {
+        switch (lhs, rhs) {
+        case (Ok, Ok):
+            return true
+        case (Error(let le), Error(let re)):
+            return le.msg == re.msg
+        default:
+            return false
+        }
+    }
+
+    public func error() -> Error? {
+        if case Result.Error(let e) = self {
+            return e
+        }
+        return nil
+    }
+}
+
+extension Result where OKT: CustomStringConvertible {
+    public var description: String {
+        switch self {
+            case Result.Error(let e):
+                return e.msg
+            case Result.Ok(let o):
+                return "\(o)"
+        }
+    }
+}
+
+extension Result {
+    public var description: String {
+        switch self {
+            case Result.Error(let e):
+                return e.msg
+            case Result.Ok(_):
+                return "Ok"
+        }
+    }
+}
+
+@freestanding(expression) public macro RequireOkResult<T>(_: Result<T>) -> Bool =
+    #externalMacro(module: "Macros", type: "RequireResult")
+@freestanding(expression) public macro RequireErrorResult<T>(_: Error, _: Result<T>) -> Bool =
+    #externalMacro(module: "Macros", type: "RequireErrorResult")
+@freestanding(expression) public macro UseOkResult<T>(_: Result<T>) -> T =
+    #externalMacro(module: "Macros", type: "UseOkResult")