compiler, runtime: Initial Support For Calling Controls

Support calling (invoking) a Control. There is still plenty more to
do here, but we are off to a good start.

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

Sources/P4Compiler/Declarations.swift

@@ -691,7 +691,6 @@ extension TableKeys: Compilable {
     walker.next()  // 3
 
     var current_node: Node? = .none
-    var current_context = context
 
     #MustOr(
       result: current_node, thing: walker.getNext(),
@@ -700,28 +699,22 @@ extension TableKeys: Compilable {
           node: node, withError: "Missing table keys declaration component in control declaration"))
     )
 
-    var entries: [TableKeyEntry] = Array()
-    var errors: [Error] = Array()
-
-    current_node!.enumerateNamedChildren { entry in
-      switch TableKeyEntry.Compile(node: current_node!, withContext: current_context) {
-      case .Ok((let keyset_expression, let updated_context)):
-        entries.append(keyset_expression)
-        current_context = updated_context
-      case .Error(let e): errors.append(e)
+    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(
-        Error(
-          withMessage: "Error(s) parsing table key: "
+        ErrorOnNode(node: node, withError: "Error(s) parsing table key: "
             + (errors.map { error in
               return "\(error.msg)"
             }.joined(separator: ";"))))
     }
 
-    return .Ok((TableKeys(withEntries: entries), current_context))
+    return .Ok((TableKeys(withEntries: keys), context))
   }
 }
 
@@ -828,7 +821,7 @@ extension TablePropertyList: Compilable {
         ErrorOnNode(node: node, withError: "More than one key set in table property list"))
     }
 
-    // There should be only one table keys!
+    // There should be only one table actions!
     if actions.count > 1 {
       // Todo: Make this error message better.
       return .Error(

Sources/P4Lang/Control.swift

@@ -89,7 +89,7 @@ public struct Action: CustomStringConvertible, P4DataType, P4DataValue {
 }
 
 public struct Actions: CustomStringConvertible {
-  let actions: [Action]
+  public let actions: [Action]
   public init(withActions actions: [Action]) {
     self.actions = actions
   }
@@ -107,8 +107,8 @@ public enum TableKeyMatchType {
 }
 
 public struct TableKeyEntry: CustomStringConvertible {
-  let key: KeysetExpression
-  let match_type: TableKeyMatchType
+  public let key: KeysetExpression
+  public let match_type: TableKeyMatchType
 
   public init(_ key: KeysetExpression, _ match: TableKeyMatchType) {
     self.key = key
@@ -121,19 +121,19 @@ public struct TableKeyEntry: CustomStringConvertible {
 }
 
 public struct TableKeys: CustomStringConvertible {
-  let entries: [TableKeyEntry]
+  public let keys: [TableKeyEntry]
 
   public init(withEntries entries: [TableKeyEntry]) {
-    self.entries = entries
+    self.keys = entries
   }
   public init() {
-    self.entries = []
+    self.keys = []
   }
 
   public var description: String {
     return "Table Keys: "
-      + self.entries.map { entry in
-        return "\(entry)"
+      + self.keys.map { key in
+        return "\(key)"
       }.joined(separator: ";")
   }
 }
@@ -153,8 +153,8 @@ public struct TableActionsProperty: CustomStringConvertible {
 }
 
 public struct TablePropertyList: CustomStringConvertible {
-  let actions: TableActionsProperty
-  let keys: TableKeys
+  public let actions: TableActionsProperty
+  public let keys: TableKeys
   public init(withActions actions: TableActionsProperty, withKeys keys: TableKeys) {
     self.actions = actions
     self.keys = keys
@@ -166,17 +166,30 @@ public struct TablePropertyList: CustomStringConvertible {
 }
 
 public struct Table: CustomStringConvertible {
-  let properties: TablePropertyList
+  public let properties: TablePropertyList
   let name: Identifier
+  public let entries: [(P4Value, TypedIdentifier)]
 
-  public init(withName name: Identifier, withPropertyList property_list: TablePropertyList) {
+  public init(
+    withName name: Identifier, withPropertyList property_list: TablePropertyList,
+    withEntries entries: [(P4Value, TypedIdentifier)] = []
+  ) {
     self.name = name
     self.properties = property_list
+    self.entries = entries
   }
 
   public var description: String {
     return "Table named: \(self.name) \(self.properties)"
   }
+
+  /// When the control is evaluated, the value of the x in the table is
+  /// compared to the entries and the match is assocated with an action
+  /// that is invoked when the match occurs!
+
+  public func update(addEntry entry: (P4Value, TypedIdentifier)) -> Table{
+    return Table(withName: self.name, withPropertyList: self.properties, withEntries: self.entries + [entry])
+  }
 }
 
 public struct Control: P4DataType, P4DataValue, Equatable, CustomStringConvertible {
@@ -236,8 +249,8 @@ public struct Control: P4DataType, P4DataValue, Equatable, CustomStringConvertib
     return "Control named \(self._name) \(self.parameters) \(self.actions) \(self.table)"
   }
 
-  let actions: Actions
-  let table: Table
+  public let actions: Actions
+  public let table: Table
   let _parameters: ParameterList
   let _name: Identifier
   let apply: ApplyStatement
@@ -261,6 +274,12 @@ public struct Control: P4DataType, P4DataValue, Equatable, CustomStringConvertib
     self.apply = apply
   }
 
+  public func updateTable(addEntry entry: (P4Value, TypedIdentifier)) -> Control {
+    let table = self.table.update(addEntry: entry)
+
+    return Control(named: self.name, withParameters: self.parameters, withTable: table, withActions: self.actions, withApply: self.apply)
+  }
+
   public func def() -> any P4DataValue {
     return Control(
       named: Identifier(name: ""),

Sources/P4Runtime/Control.swift

@@ -0,0 +1,100 @@
+// 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
+
+extension Control: LibraryCallable {
+  public typealias T = P4TableHitMissValue
+  public func call(
+    execution: Common.ProgramExecution, arguments: ArgumentList
+  ) -> (P4TableHitMissValue, Common.ProgramExecution) {
+
+    var control_execution = execution.enter_scope()
+
+    // Add initial values to the global scope
+    for (name, value) in execution.getGlobalValues() {
+      control_execution = control_execution.declare(identifier: name, withValue: value)
+    }
+
+    let call_body: (ProgramExecution) -> (Result<P4TableHitMissValue>, ProgramExecution) = {
+      execution in
+      var control_execution = execution
+
+      for action in self.actions.actions {
+        control_execution = control_execution.declare(
+          identifier: action.name, withValue: P4Value(action))
+      }
+
+      for key in self.table.properties.keys.keys {
+        // Every evaluation of the key starts from an unchanged execution context.
+        let (key_eval, updated_execution) = key.key.evaluate(execution: control_execution)
+
+        guard case .Ok(let key_val) = key_eval else {
+          return (.Error(key_eval.error()!), updated_execution)
+        }
+
+        /// ASSUME: The first matching entry is the one to do.
+        /// TODO: Check whether this matches architecture.
+        for (val, action) in self.table.entries {
+
+          // Skip those with mismatching types.
+
+          if !val.type().eq(key_val.type()) {
+            continue;
+          }
+
+          /// ASSUME: All matches are exact.
+          if val.eq(key_val) {
+            // Lookup action!
+
+            let maybe_action = updated_execution.scopes.lookup(identifier: action)
+            guard case .Ok(let action) = maybe_action else {
+              return (.Error(maybe_action.error()!), updated_execution)
+            }
+
+            let aaction = (action.dataValue() as! Action)
+
+            return switch aaction.evaluate(execution: updated_execution) {
+            case (ControlFlow.Error, let updated_execution):
+              (.Error(updated_execution.getError()!), updated_execution)
+            case (_, let updated_execution): (.Ok(P4TableHitMissValue.Hit), updated_execution)
+            }
+          }
+        }
+      }
+      return (.Ok(P4TableHitMissValue.Miss), control_execution)
+    }
+
+    switch Call(body: call_body, withArguments: arguments, withParameters: self.parameters, inExecution: control_execution) {
+      case (.Ok(let r), let updated_execution): return (r, updated_execution)
+      case (.Error(let e), let updated_execution): return (P4TableHitMissValue.Miss, updated_execution.setError(error: e))
+    }
+  }
+}
+
+extension Action: EvaluatableStatement {
+  public func evaluate(
+    execution: Common.ProgramExecution
+  ) -> (Common.ControlFlow, Common.ProgramExecution) {
+    if let body = self.body {
+      return body.evaluate(execution: execution)
+    }
+
+    return (ControlFlow.Next, execution)
+  }
+}