SwiftExtract: Include a few general purpose is... checks

Author: ktoso

Sources/SwiftExtract/SwiftTypes/SwiftFunctionSignature.swift

@@ -38,6 +38,11 @@ public struct SwiftFunctionSignature: Equatable {
     effectSpecifiers.contains(.throws)
   }
 
+  /// Whether any parameter is variadic (`T...`).
+  public var hasVariadicParams: Bool {
+    parameters.contains(where: \.isVariadic)
+  }
+
   public init(
     selfParameter: SwiftSelfParameter? = nil,
     parameters: [SwiftParameter],

Sources/SwiftExtract/SwiftTypes/SwiftParameter.swift

@@ -20,16 +20,44 @@ public struct SwiftParameter: Equatable {
   public var parameterName: String?
   public var type: SwiftType
 
+  /// Whether this is a variadic parameter (`T...`).
+  public var isVariadic: Bool
+  /// Whether the parameter declares a default value.
+  public var hasDefaultValue: Bool
+  /// The default-value expression source, if any (e.g. `42`, `[]`).
+  public var defaultValueExpression: String?
+
   public init(
     convention: SwiftParameterConvention,
     argumentLabel: String? = nil,
     parameterName: String? = nil,
-    type: SwiftType
+    type: SwiftType,
+    isVariadic: Bool = false,
+    hasDefaultValue: Bool = false,
+    defaultValueExpression: String? = nil
   ) {
     self.convention = convention
     self.argumentLabel = argumentLabel
     self.parameterName = parameterName
     self.type = type
+    self.isVariadic = isVariadic
+    self.hasDefaultValue = hasDefaultValue
+    self.defaultValueExpression = defaultValueExpression
+  }
+
+  /// The simple parameter name, falling back to the argument label.
+  public var name: String {
+    parameterName ?? argumentLabel ?? "_"
+  }
+
+  /// The external argument label, falling back to the parameter name.
+  public var effectiveLabel: String {
+    argumentLabel ?? name
+  }
+
+  /// Whether this parameter is passed `inout`.
+  public var isInout: Bool {
+    convention == .inout
   }
 }
 
@@ -75,6 +103,9 @@ extension SwiftParameter {
     self.argumentLabel = nil
     self.parameterName = node.firstName?.identifier?.name
     self.argumentLabel = node.firstName?.identifier?.name
+    self.isVariadic = false
+    self.hasDefaultValue = node.defaultValue != nil
+    self.defaultValueExpression = node.defaultValue?.value.trimmedDescription
   }
 }
 
@@ -113,6 +144,11 @@ extension SwiftParameter {
     // Determine the type.
     self.type = try SwiftType(type, lookupContext: lookupContext)
 
+    // Variadic / default-value information.
+    self.isVariadic = node.ellipsis != nil
+    self.hasDefaultValue = node.defaultValue != nil
+    self.defaultValueExpression = node.defaultValue?.value.trimmedDescription
+
     // FIXME: swift-syntax itself should have these utilities based on identifiers.
     if let secondName = node.secondName {
       self.argumentLabel = node.firstName.identifier?.name