Add async/await support to Meta.

Author: StephaneMagne

Sources/Meta/Function.swift

@@ -199,7 +199,9 @@ public struct Function: Hashable, Node {
     public var body = FunctionBody()
 
     public var resultType: TypeIdentifier?
-    
+
+    public var `async` = false
+
     public var `throws` = false
 
     public var `static` = false
@@ -295,7 +297,13 @@ public struct Function: Hashable, Node {
         _self.resultType = resultType
         return _self
     }
-    
+
+    public func with(async: Bool) -> Function {
+        var _self = self
+        _self.async = `async`
+        return _self
+    }
+
     public func with(throws: Bool) -> Function {
         var _self = self
         _self.throws = `throws`
@@ -492,7 +500,9 @@ extension Function {
             .map { $0.swiftString }
             .joined(separator: ", ")
             .wrapped("<", ">")
-        
+
+        let `async` = self.async ? " async" : .empty
+
         let `throws` = self.throws ? " throws" : .empty
 
         let resultType = self.resultType?.swiftString.prefixed(" -> ") ?? .empty
@@ -510,7 +520,7 @@ extension Function {
             .joined(separator: ", ")
 
         let build = {
-            return "\(beforeParameters)\(parameters))\(`throws`)\(resultType)\(constraints) \(self.body.swiftString)"
+            return "\(beforeParameters)\(parameters))\(`async`)\(`throws`)\(resultType)\(constraints) \(self.body.swiftString)"
         }
 
         if self.parameters.count > 4 || build().count > 80 {

Sources/Meta/Reference.swift

@@ -35,6 +35,7 @@ public enum Reference: Hashable, MetaSwiftConvertible, Node {
     case name(ReferenceName)
     case tuple(Tuple)
     case unwrap
+    case `await`
     case `try`
     case optionalTry
     case `throw`
@@ -62,6 +63,7 @@ public enum Reference: Hashable, MetaSwiftConvertible, Node {
              .name,
              .tuple,
              .unwrap,
+             .await,
              .try,
              .optionalTry,
              .throw,
@@ -153,6 +155,8 @@ extension Reference {
             return tuple.swiftString
         case .unwrap:
             return "?"
+        case .await:
+            return "await "
         case .try:
             return "try "
         case .optionalTry:

Tests/MetaTests/FileTests.swift

@@ -90,7 +90,21 @@ final class FileTests: XCTestCase {
                     .adding(member: Return(value: Value.bool(true))
                 )
             )
-        
+            .adding(member: EmptyLine())
+            .adding(member:
+                Function(kind: .named("printError"))
+                    .with(async: true)
+                    .with(throws: true)
+                    .with(resultType: TypeIdentifier.bool)
+                    .adding(member: .await | .type(TypeIdentifier(name: "Logger")) + .named("error") | .call(Tuple()
+                        .adding(parameter: TupleParameter(value: +.named("error")))
+                        .adding(parameter: TupleParameter(value: Reference.named("lowercasedMessage")))
+                        .adding(parameter: TupleParameter(name: "assert", value: Value.bool(true))))
+                    )
+                    .adding(member: Return(value: Value.bool(true))
+                )
+            )
+
         let barID = TypeIdentifier(name: "Bar")
         let bar = Type(identifier: barID)
             .adding(inheritedType: .string)
@@ -171,6 +185,11 @@ final class FileTests: XCTestCase {
                 Logger.error(.error, lowercasedMessage, assert: true)
                 return true
             }
+
+            func printError() async throws -> Bool {
+                await Logger.error(.error, lowercasedMessage, assert: true)
+                return true
+            }
         }
         
         public enum Bar: String {