Support Calling Parsers With Parameters

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

Sources/P4Lang/Declarations.swift

@@ -38,6 +38,10 @@ public struct Parameter: CustomStringConvertible {
 public struct ParameterList: CustomStringConvertible {
   public var parameters: [Parameter]
 
+  public init() {
+    self.parameters = Array()
+  }
+
   public init(_ parameters: [Parameter]) {
     self.parameters = parameters
   }

Sources/P4Lang/Expressions.swift

@@ -200,3 +200,34 @@ public struct FieldAccessExpression {
     self.field = field
   }
 }
+
+public struct ArgumentList {
+  public let arguments: [(Int, EvaluatableExpression)]
+  public init(_ arguments: [EvaluatableExpression]) {
+    self.arguments = zip(1..., arguments).map { (idx, argument) in
+      (idx, argument)
+    }
+  }
+
+  public func compatible(_ parameters: ParameterList) -> Result<()> {
+    if self.arguments.count != parameters.parameters.count {
+      return .Error(
+        Error(
+          withMessage:
+            "\(self.arguments.count) arguments found but \(parameters.parameters.count) required"))
+    }
+
+    for (arg, param) in zip(self.arguments, parameters.parameters) {
+      let arg_index = arg.0
+      let arg_type = arg.1.type()
+      if !arg_type.eq(rhs: param.type) {
+        return .Error(
+          Error(
+            withMessage:
+              "Argument \(arg_index)'s type (\(arg_type)) is incompatible with the parameter type (\(param.type))"
+          ))
+      }
+    }
+    return .Ok(())
+  }
+}

Sources/P4Lang/Parser.swift

@@ -319,10 +319,11 @@ public struct Parser: P4Type, P4Value {
   public var states: ParserStates
 
   public var name: Identifier
-  public var parameters: ParameterList?
+  public var parameters: ParameterList
 
   public init(withName name: Identifier) {
     self.states = ParserStates()
+    self.parameters = ParameterList()
     self.name = name
   }
 
@@ -349,7 +350,6 @@ public struct Parser: P4Type, P4Value {
   }
 
   public var description: String {
-    let parameters = self.parameters?.description ?? "N/A"
     return "Parser \(self.name) with parameters: \(parameters) and states: \(self.states)"
   }