gp4/Sources/P4Compiler/Declarations.swift

// 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
import P4Runtime
import SwiftTreeSitter
import TreeSitterExtensions
import TreeSitterP4

extension Declaration: 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)
    }
  }
}

extension Declaration: Compilable {
  public typealias C = Declaration
  public static func Compile(
    node: Node, withContext context: CompilerContext
  ) -> Result<Declaration> {

    // Be kind to our user -- if we are at a declaration node, dive into it!
    let declaration_node =
      if node.nodeType == "declaration" {
        node.child(at: 0)!
      } else {
        node
      }

    let declaration_compilers: [String: any Compilable<Declaration>.Type] = [
      "function_declaration": FunctionDeclaration.self,
      "control_declaration": Control.self,
      "type_declaration": P4Struct.self,
      "parserDeclaration": Parser.self,
      /// ASSUME: Type declarations are struct declarations.
      "extern_declaration": ExternDeclaration.self,
    ]

    guard let declaration_compiler = declaration_compilers[declaration_node.nodeType!] else {
      return .Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Could not find parser for declaration \(declaration_node.nodeType!)"))
    }

    return declaration_compiler.Compile(node: declaration_node, withContext: context).map {
      result in
      .Ok(result)
    }
  }
}

extension FunctionDeclaration: Compilable {
  public typealias C = Declaration
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Common.Result<Declaration> {
    let function_declaration_node = node
    #RequireNodeType<Node, ParameterList>(
      node: function_declaration_node, type: "function_declaration",
      nice_type_name: "Function Declaration")

    var walker = Walker(node: function_declaration_node)
    var context = context

    var current_node: Node? = .none

    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: function_declaration_node.toSourceLocation(),
          withError: "Missing function declaration component")))

    let maybe_function_type = Types.CompileType(type: current_node!, withContext: context)
    guard case .Ok(let function_type) = maybe_function_type else {
      return .Error(maybe_function_type.error()!)
    }

    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: function_declaration_node.toSourceLocation(),
          withError: "Missing function declaration component")))

    let maybe_function_name = Identifier.Compile(node: current_node!, withContext: context)
    guard case .Ok(let function_name) = maybe_function_name else {
      return .Error(maybe_function_name.error()!)
    }

    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: function_declaration_node.toSourceLocation(),
          withError: "Missing function declaration component")))

    let maybe_function_parameters = ParameterList.Compile(node: current_node!, withContext: context)
    guard case .Ok(let function_parameters) = maybe_function_parameters
    else {
      return .Error(maybe_function_parameters.error()!)
    }

    var function_body: BlockStatement? = .none

    walker.next()
    if let body = walker.getNext() {
      // Add the parameters into scope.
      var function_scope = context.instances.enter()
      for parameter in function_parameters.parameters {
        function_scope = function_scope.declare(
          identifier: parameter.name, withValue: (parameter.type, .none))
      }

      let maybe_function_body = BlockStatement.Compile(
        node: body,
        withContext: context.update(newInstances: function_scope).update(
          newExpectation: function_type))

      guard case .Ok(let parsed_function_body) = maybe_function_body else {
        return .Error(maybe_function_body.error()!)
      }
      function_body = parsed_function_body
    } else {

      // If we are in an extern context, no body is okay!

      if !context.extern_context {
        return Result.Error(
          ErrorWithLocation(
            sourceLocation: function_declaration_node.toSourceLocation(),
            withError: "Missing function declaration component"))
      }
    }

    let function_declaration = Declaration(
      TypedIdentifier(
        id: function_name,
        withType: P4QualifiedType(
          FunctionDeclaration(
            named: function_name, ofType: function_type, withParameters: function_parameters,
            withBody: function_body))))

    // Do not use the updated context returned by parsing the body
    // and do not use the function_scope, either.
    // And, do not update the context if we are compiling in an
    // extern context -- the wrapping extern declaration will take care of that.
    return .Ok(
      function_declaration,
    )
  }
}

extension P4Struct: Compilable {
  public typealias C = Declaration
  static public func Compile(
    node: Node, withContext context: CompilerContext
  ) -> Result<Declaration> {
    let struct_declaration_node = node.child(at: 0)!
    var walker = Walker(node: struct_declaration_node)
    var currentNode: Node? = .none

    #RequireNodeType<Node, Result<Declaration>>(
      node: struct_declaration_node, type: "struct_declaration",
      nice_type_name: "struct declaration")

    // Skip the keyword struct
    walker.next()
    #MustOr(
      result: currentNode, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: struct_declaration_node.toSourceLocation(),
          withError: "Missing function declaration component")))

    // The name of the struct type.
    let maybe_struct_identifier = Identifier.Compile(
      node: currentNode!, withContext: context)
    guard case Result.Ok(let struct_identifier) = maybe_struct_identifier else {
      return Result.Error(maybe_struct_identifier.error()!)
    }
    walker.next()

    // Skip the '{'
    walker.next()
    #MustOr(
      result: currentNode, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: struct_declaration_node.toSourceLocation(),
          withError: "Missing function declaration component")))

    // If there are no fields, it will be a "}"
    if currentNode!.nodeType == "}" {
      let struc = Declaration(
        TypedIdentifier(
          id: struct_identifier,
          withType: P4QualifiedType(
            P4Struct(withName: struct_identifier, andFields: P4StructFields([])))))
      return Result.Ok(struc)
    }

    var parse_errs: (any Errorable)? = .none
    var current_context = context
    var parsed_fields: [P4StructFieldIdentifier] = Array()

    if currentNode!.nodeType == "struct_declaration_fields" {
      currentNode!.enumerateNamedChildren { declaration_field in
        switch VariableDeclarationStatement.Compile(
          node: declaration_field, withContext: current_context)
        {
        case .Ok(let declaration):
          let variable_declaration = declaration as! VariableDeclarationStatement
          parsed_fields.append(
            P4StructFieldIdentifier(
              id: variable_declaration.identifier, withType: variable_declaration.initializer.type()
            ))
        case .Error(let e):
          parse_errs =
            if let e = parse_errs {
              parse_errs?.append(error: e)
            } else {
              e
            }
        }
      }
    }

    if let parse_errs = parse_errs {
      return .Error(ErrorWithLabel("Error(s) parsing select cases", parse_errs))
    }

    let declared_struct = Declaration(
      TypedIdentifier(
        id: struct_identifier,
        withType: P4QualifiedType(
          P4Struct(
            withName: struct_identifier, andFields: P4StructFields(parsed_fields)))))
    return .Ok(declared_struct)
  }
}

extension P4Lang.Parser: Compilable {
  public typealias C = Declaration

  public static func Compile(
    node: Node, withContext context: CompilerContext
  ) -> Result<Declaration> {
    let parser_node = node
    #RequireNodeType<Node, Result<Declaration>>(
      node: parser_node, type: "parserDeclaration", nice_type_name: "parser declaration")
    var current_context = context

    var walker = Walker(node: parser_node)
    var current_node: Node? = .none

    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: parser_node.toSourceLocation(),
          withError: "Missing elements of parser declaration")))

    if current_node!.nodeType != "parserType" {
      return .Error(
        ErrorWithLocation(
          sourceLocation: current_node!.toSourceLocation(),
          withError: "Missing type for parser declaration"))
    }

    let type_node = current_node
    var parser_name: Common.Identifier? = .none

    /// TODO: Handle parser parameter lists.
    var parameter_list = ParameterList()

    do {
      var type_node_walker = Walker(node: type_node!)
      var type_node_child: Node? = .none

      #MustOr(
        result: type_node_child, thing: type_node_walker.getNext(),
        or: Result<Declaration>.Error(
          ErrorWithLocation(
            sourceLocation: parser_node.toSourceLocation(),
            withError: "Missing elements of parser type in parser declaration")))

      if type_node_child!.nodeType == "annotations" {
        return .Error(
          ErrorWithLocation(
            sourceLocation: type_node_child!.toSourceLocation(),
            withError: "Annotations in parser type are not yet handled."))
        // Will increment indexes here.
      }

      type_node_walker.next()
      #MustOr(
        result: type_node_child, thing: type_node_walker.getNext(),
        or: Result<Declaration>.Error(
          ErrorWithLocation(
            sourceLocation: type_node_child!.toSourceLocation(),
            withError: "Missing name in parser type declaration")))

      switch Identifier.Compile(node: type_node_child!, withContext: current_context) {
      case .Ok(let id): parser_name = id
      case .Error(let e):
        return .Error(e)
      }

      type_node_walker.next()
      #MustOr(
        result: type_node_child, thing: type_node_walker.getNext(),
        or: Result<Declaration>.Error(
          ErrorWithLocation(
            sourceLocation: type_node_child!.toSourceLocation(),
            withError: "Missing parser parameters")))

      switch ParameterList.Compile(node: type_node_child!, withContext: current_context) {
      case .Ok(let parsed_parameter_list):
        parameter_list = parsed_parameter_list
      case .Error(let e):
        return .Error(e)
      }
    }

    // Now, let's put the parameters into scope.
    for parameter in parameter_list.parameters {
      current_context = current_context.update(
        newInstances: current_context.instances.declare(
          identifier: parameter.name, withValue: (parameter.type, .none)))
    }

    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: parser_node.toSourceLocation(),
          withError: "Missing parser declaration component")))

    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: parser_node.toSourceLocation(),
          withError: "Missing elements of parser declaration")))

    if current_node!.nodeType == "parserLocalElements" {
      return .Error(
        ErrorWithLocation(
          sourceLocation: current_node!.toSourceLocation(),
          withError: "Parser Local Elements are not yet handled."))
      // Will increment indexes here.
    }

    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: parser_node.toSourceLocation(),
          withError: "Missing body of parser declaration")))

    if current_node!.nodeType != "parserStates" {
      return .Error(Error(withMessage: "Missing parser states in parser declaration"))
    }

    /// TODO: Handle extern parsers.
    switch SpecialCompilers.CompileParserBody(
      withName: parser_name!, withParameters: parameter_list, node: current_node!,
      withContext: current_context)
    {
    case Result.Ok((let parser, let updated_context)):
      let parser_declaration = Declaration(
        TypedIdentifier(id: parser.name, withType: P4QualifiedType(parser)))
      // Create a new context with the name of the parser that was just compiled in scope.
      return .Ok(
        parser_declaration,
      )
    case Result.Error(let error): return .Error(error)
    }
  }
}

extension Control: Compilable {
  public typealias C = Declaration
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Common.Result<Declaration> {

    #RequireNodeType<Node, Result<Declaration>>(
      node: node, type: "control_declaration", nice_type_name: "control declaration")

    var walker = Walker(node: node)
    var current_node: Node? = .none

    var local_context = context

    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Missing control declaration component")))

    guard
      case .Ok(let control_name) = Identifier.Compile(
        node: current_node!, withContext: local_context)
    else {
      return Result.Error(
        Error(withMessage: "Could not parse a parameter name from \(current_node!.text!)"))
    }

    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Missing control declaration component")))

    let maybe_control_parameters = ParameterList.Compile(
      node: current_node!, withContext: local_context)
    guard case .Ok(let control_parameters) = maybe_control_parameters
    else {
      return .Error(maybe_control_parameters.error()!)
    }

    // Before continuing, make sure to put the parameters into context.
    var control_scope = local_context.instances.enter()
    for parameter in control_parameters.parameters {
      control_scope = control_scope.declare(
        identifier: parameter.name, withValue: (parameter.type, .none))
    }
    local_context = local_context.update(newInstances: control_scope)

    walker.next()
    // Skip the '{'
    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Declaration>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Missing control declaration component")))

    var actions: [Action] = Array()
    var tables: [Table] = Array()
    var apply: ApplyStatement? = .none

    //                                                         Because the final child
    //                                                         is the '}'.
    //                                                          \/\/
    let body_parse_results = walker.overUntil(n: node.childCount - 1) { current_node in
      if current_node.nodeType == "action_declaration" {
        let maybe_action_declaration = Action.Compile(
          node: current_node, withContext: local_context)
        guard
          case .Ok(let action_declaration) = maybe_action_declaration
        else {
          return .Error(maybe_action_declaration.error()!)
        }
        actions.append(action_declaration)
        // Now, add the declaration into the context.
        local_context = local_context.update(
          newTypes: local_context.types.declare(
            identifier: action_declaration.name, withValue: action_declaration))
      } else if current_node.nodeType == "table_declaration" {
        let maybe_table_declaration = Table.Compile(
          node: current_node, withContext: local_context)
        guard
          case .Ok(let table_declaration) = maybe_table_declaration
        else {
          return .Error(maybe_table_declaration.error()!)
        }
        tables.append(table_declaration)
      } else if current_node.nodeType == "apply_statement" {
        // When we see an apply, that is it for the actions and the tables.
        let maybe_apply_statement = ApplyStatement.Compile(
          node: current_node, withContext: local_context)
        guard
          case .Ok(let apply_statement) = maybe_apply_statement
        else {
          return .Error(maybe_apply_statement.error()!)
        }
        apply = (apply_statement as! ApplyStatement)

        // The apply is the last thing in a control declaration.
        // But, that is handled by the compiler.
      } else {
        return .Error(
          ErrorWithLocation(
            sourceLocation: current_node.toSourceLocation(),
            withError: "Uknown node type in control declaration"))
      }
      return .Ok(())
    }

    if case .Error(let e) = body_parse_results {
      return .Error(e)
    }

    // There should only be a single table!
    /// TODO: Check the semantics here.
    if tables.count > 1 {
      /// TODO: Make this error message better.
      /// IDEA: Add a "compilation context" for the error message into the `CompilationContext`
      // that can be retrieved to make the error messages nicer.
      return .Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "More than one table in control declaration"))
    }

    // Check to make sure that there is an apply.
    guard let apply = apply else {
      return .Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(), withError: "Missing apply in control declaration"
        ))
    }

    let control = Control(
      named: control_name, withParameters: control_parameters, withTable: tables[0],
      withActions: Actions(withActions: actions), withApply: apply)

    let declared_control =
      Declaration(
        TypedIdentifier(
          id: control_name,
          withType: P4QualifiedType(control)))

    // Don't forget to add the newly declared Control to the instance that we were given
    // (and not the one that we entered to do the parsing of this Control).
    return .Ok(declared_control)
  }
}

extension Action: Compilable {
  public typealias C = Action
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Result<Action> {
    #RequireNodeType<Node, P4Type>(
      node: node, type: "action_declaration", nice_type_name: "Action Declaration")

    var walker = Walker(node: node)
    var current_node: Node? = .none
    var current_context = context

    // Skip action keyword
    walker.next()

    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Action>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(), withError: "Missing action declaration component"
        ))
    )

    guard
      case .Ok(let action_name) = Identifier.Compile(
        node: current_node!, withContext: current_context)
    else {
      return Result.Error(
        Error(withMessage: "Could not parse an action name from \(current_node!.text!)"))
    }

    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Action>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(), withError: "Missing action declaration component"
        ))
    )

    let maybe_action_parameters = ParameterList.Compile(
      node: current_node!, withContext: current_context)
    guard case .Ok(let action_parameters) = maybe_action_parameters
    else {
      return .Error(maybe_action_parameters.error()!)
    }

    // Check whether the parameters are in the proper order.
    let remaining_parameters = action_parameters.parameters.drop(while: {
      $0.type.direction() != .none
    })
    if remaining_parameters.contains(where: { $0.type.direction() != .none }) {
      return .Error(
        ErrorWithLocation(
          sourceLocation: current_node!.toSourceLocation(),
          withError: "All parameters with direction must precede directionless parameters"))
    }

    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Action>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(), withError: "Missing action declaration component"
        ))
    )

    // Add the parameters into scope.
    var function_scope = context.instances.enter()
    for parameter in action_parameters.parameters {
      function_scope = function_scope.declare(
        identifier: parameter.name, withValue: (parameter.type, .none))
    }

    let maybe_action_body = BlockStatement.Compile(
      node: current_node!, withContext: context.update(newInstances: function_scope))
    guard case .Ok(let action_body) = maybe_action_body else {
      return .Error(maybe_action_body.error()!)
    }

    /// TODO: Actions cannot contain switches!

    return .Ok(
      Action(
        named: action_name, withParameters: action_parameters,
        withBody: (action_body as! BlockStatement)))
  }
}

extension TableKeyEntry: Compilable {
  public typealias C = TableKeyEntry
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Result<TableKeyEntry> {

    #RequireNodeType<Node, TableKeyEntry>(
      node: node, type: "table_key_entry", nice_type_name: "Table Key Entry")

    var walker = Walker(node: node)

    var current_node: Node? = .none

    let current_context = context

    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<TableKeyEntry>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Missing table key entry declaration component")))

    let maybe_keyset_expression = KeysetExpression.compile(
      node: current_node!, withContext: current_context)
    guard case .Ok(let keyset_expression) = maybe_keyset_expression else {
      return Result.Error(maybe_keyset_expression.error()!)
    }

    walker.next()
    // Skip the ':'
    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<TableKeyEntry>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Missing table key entry declaration component")))

    let maybe_match_type = TableKeyMatchType.Compile(
      node: current_node!, withContext: current_context)
    guard case .Ok(let match_type) = maybe_match_type else {
      return .Error(maybe_match_type.error()!)
    }

    return .Ok(TableKeyEntry(keyset_expression as! KeysetExpression, match_type))
  }
}

extension TableKeyMatchType: Compilable {
  public typealias C = TableKeyMatchType
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Result<TableKeyMatchType> {
    #RequireNodeType<Node, TableKeyMatchType>(
      node: node, type: "table_key_match_type", nice_type_name: "Table Key Match Type")

    if node.text! == "exact" {
      return .Ok(TableKeyMatchType.Exact)
    }
    return .Error(
      ErrorWithLocation(
        sourceLocation: node.toSourceLocation(),
        withError: "\(node.text!) is not a valid match type)"))
  }
}

extension TableKeys: Compilable {
  public typealias C = TableKeys
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Result<TableKeys> {
    #RequireNodeType<Node, TableKeyMatchType>(
      node: node, type: "table_keys", nice_type_name: "Table Keys")

    var walker = Walker(node: node)
    // Skip the
    // keys = {
    // 1    2 3
    walker.next()  // 1
    walker.next()  // 2
    walker.next()  // 3

    var current_node: Node? = .none

    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<TableKeys>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Missing table keys declaration component in control declaration"))
    )

    let (keys, errors) = walker.try_map(n: node.childCount - 1, onlyNamed: true) { current_node in
      return switch TableKeyEntry.Compile(node: current_node, withContext: context) {
      case .Ok(let keyset_expression): .Ok(keyset_expression)
      case .Error(let e): .Error(e)
      }
    }

    if !errors.isEmpty {
      return .Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Error(s) parsing table key: "
            + (errors.map { error in
              return "\(error.msg())"
            }.joined(separator: ";"))))
    }

    return .Ok(TableKeys(withEntries: keys))
  }
}

extension TableActionsProperty: Compilable {
  public typealias C = TableActionsProperty
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Result<TableActionsProperty> {
    #RequireNodeType<Node, TableActionsProperty>(
      node: node, type: "table_actions", nice_type_name: "Table Actions")

    var walker = Walker(node: node)
    // Skip the
    // actions = {
    // 1    2 3
    walker.next()  // 1
    walker.next()  // 2
    walker.next()  // 3

    var current_node: Node? = .none

    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<TableActionsProperty>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Missing table actions declaration component in control declaration"))
    )

    let (actions, errors) = walker.try_map(n: node.childCount - 1, onlyNamed: true) {
      current_node in
      switch Identifier.Compile(node: current_node, withContext: context) {
      case .Ok(let listed_action):
        switch context.types.lookup(identifier: listed_action) {
        case .Ok(let maybe_action):
          if maybe_action.eq(rhs: Action()) {
            return .Ok(TypedIdentifier(id: listed_action, withType: P4QualifiedType(maybe_action)))
          }
          return .Error(
            ErrorWithLocation(
              sourceLocation: node.toSourceLocation(),
              withError: "\(listed_action) does not name an action"))
        case .Error(let e): return .Error(e)
        }
      case .Error(let e): return .Error(e)
      }
    }

    if !errors.isEmpty {
      return .Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Error(s) parsing table actions: "
            + (errors.map { error in
              return "\(error.msg())"
            }.joined(separator: ";"))))
    }

    return .Ok(TableActionsProperty(actions))
  }
}
extension TablePropertyList: Compilable {
  public typealias C = TablePropertyList
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Result<TablePropertyList> {

    #RequireNodeType<Node, TablePropertyList>(
      node: node, type: "table_property_list", nice_type_name: "Table Property List")

    var current_context = context

    var keys: [TableKeys] = Array()
    var actions: [TableActionsProperty] = Array()
    var errors: [any Errorable] = Array()

    node.enumerateNamedChildren { child in
      if child.nodeType == "table_keys" {
        switch TableKeys.Compile(node: child, withContext: current_context) {
        case .Ok(let table_key):
          keys.append(table_key)
        case .Error(let e): errors.append(e)
        }
      } else if child.nodeType == "table_actions" {
        switch TableActionsProperty.Compile(node: child, withContext: current_context) {
        case .Ok(let table_action_property):
          actions.append(table_action_property)
        case .Error(let e): errors.append(e)
        }
      } else {
        errors.append(
          ErrorWithLocation(
            sourceLocation: child.toSourceLocation(),
            withError: "Uknown node type in control declaration"))
      }
    }

    if !errors.isEmpty {
      return .Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "Error(s) parsing property list: "
            + (errors.map { error in
              return "\(error.msg())"
            }.joined(separator: ";"))))
    }

    // There should be only one table keys!
    if keys.count > 1 {
      // Todo: Make this error message better.
      return .Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "More than one key set in table property list"))
    }

    // There should be only one table actions!
    if actions.count > 1 {
      // Todo: Make this error message better.
      return .Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(),
          withError: "More than one actions in table property list"))
    }
    if actions.isEmpty {
      actions.append(TableActionsProperty())
    }

    return .Ok(TablePropertyList(withActions: actions[0], withKeys: keys[0]))

  }
}

extension Table: Compilable {
  public typealias C = Table
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Result<Table> {

    let table_declaration_node = node
    #RequireNodeType<Node, Table>(
      node: table_declaration_node, type: "table_declaration", nice_type_name: "Table Declaration")

    var walker = Walker(node: table_declaration_node)

    var current_node: Node? = .none

    let current_context = context

    walker.next()  // Skip the XXX?
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Table>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(), withError: "Missing table declaration component")
      ))

    guard
      case .Ok(let table_name) = Identifier.Compile(
        node: current_node!, withContext: current_context)
    else {
      return Result.Error(
        Error(withMessage: "Could not parse a table name from \(current_node!.text!)"))
    }

    walker.next()
    // Skip the '{'
    walker.next()
    #MustOr(
      result: current_node, thing: walker.getNext(),
      or: Result<Table>.Error(
        ErrorWithLocation(
          sourceLocation: node.toSourceLocation(), withError: "Missing table declaration component")
      ))

    let maybe_table_property_list = TablePropertyList.Compile(
      node: current_node!, withContext: current_context)
    guard case .Ok(let table_property_list) = maybe_table_property_list else {
      return Result.Error(maybe_table_property_list.error()!)
    }

    return .Ok(Table(withName: table_name, withPropertyList: table_property_list))
  }
}

extension ExternDeclaration: Compilable {
  public typealias C = Declaration
  public static func Compile(
    node: SwiftTreeSitter.Node, withContext context: CompilerContext
  ) -> Result<Declaration> {
    let extern_declaration_node = node
    #RequireNodeType<Node, Declaration>(
      node: extern_declaration_node, type: "extern_declaration",
      nice_type_name: "Extern Declaration")

    let declaration_node = extern_declaration_node.child(at: 1)!
    #RequireNodeType<Node, Declaration>(
      node: declaration_node, type: "declaration", nice_type_name: "Declaration")
    let declarationed_node = declaration_node.child(at: 0)!

    let maybe_declared = Declaration.Compile(
      node: declarationed_node, withContext: context.update(newExtern: true))

    guard case .Ok(let declared) = maybe_declared else {
      return .Error(maybe_declared.error()!)
    }

    // Before we are okay with this declaration, it must already be registered as an extern
    // with the matching "stuff".

    let found_ffi = context.ffis.first { ffi in
      ffi.type().baseType().eq(rhs: declared.identifier.type.baseType())
    }

    guard let found_ffi = found_ffi else {
      return .Error(
        ErrorWithLocation(
          sourceLocation: declarationed_node.toSourceLocation(),
          withError:
            "Could not find a foreign function that matches the extern declaration (\(declared))"))
    }

    let extern_declaration = Declaration(extern: declared, ffi: found_ffi)

    return .Ok(
      extern_declaration,
    )
  }
}