Move ContentType.identifier logic into the translator (#141)

Move ContentType.identifier logic into the translator

### Motivation

In preparation for changing the mapping of content type names onto enum case names, we need to have the `ContentType.identifier` logic on a translator, which has access to the feature flags, so that we can later conditionalize the logic.

### Modifications

Takes the first step - moves the existing logic onto the translator.

### Result

NFC

### Test Plan

Added unit tests both for the existing logic, and also for the stubbed out logic behind the feature flag.


Reviewed by: simonjbeaumont

Builds:
     ✔︎ pull request validation (5.8) - Build finished. 
     ✔︎ pull request validation (5.9) - Build finished. 
     ✔︎ pull request validation (docc test) - Build finished. 
     ✔︎ pull request validation (integration test) - Build finished. 
     ✔︎ pull request validation (nightly) - Build finished. 
     ✔︎ pull request validation (soundness) - Build finished. 

#141

Author: czechboy0

Sources/_OpenAPIGeneratorCore/Translator/Content/ContentInspector.swift

@@ -52,7 +52,7 @@ extension FileTranslator {
         else {
             return nil
         }
-        let identifier = content.contentType.identifier
+        let identifier = contentSwiftName(content.contentType)
         let associatedType = try TypeAssigner.typeUsage(
             usingNamingHint: identifier,
             withSchema: content.schema,

Sources/_OpenAPIGeneratorCore/Translator/Content/ContentSwiftName.swift

@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftOpenAPIGenerator open source project
+//
+// Copyright (c) 2023 Apple Inc. and the SwiftOpenAPIGenerator project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftOpenAPIGenerator project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+import OpenAPIKit30
+
+extension FileTranslator {
+
+    /// Returns a Swift-safe identifier used as the name of the content
+    /// enum case.
+    ///
+    /// - Parameter contentType: The content type for which to compute the name.
+    func contentSwiftName(_ contentType: ContentType) -> String {
+        if config.featureFlags.contains(.multipleContentTypes) {
+            return "unsupported"
+        } else {
+            switch contentType {
+            case .json:
+                return "json"
+            case .text:
+                return "text"
+            case .binary:
+                return "binary"
+            }
+        }
+    }
+}

Sources/_OpenAPIGeneratorCore/Translator/Content/ContentType.swift

@@ -69,19 +69,6 @@ enum ContentType: Hashable {
         }
     }
 
-    /// An identifier used as the Payload.Content enum case name
-    /// in generated code.
-    var identifier: String {
-        switch self {
-        case .json:
-            return "json"
-        case .text:
-            return "text"
-        case .binary:
-            return "binary"
-        }
-    }
-
     /// The coding strategy appropriate for this content type.
     var codingStrategy: CodingStrategy {
         switch self {

Sources/_OpenAPIGeneratorCore/Translator/RequestBody/translateRequestBody.swift

@@ -56,7 +56,7 @@ extension TypesFileTranslator {
             )
             bodyMembers.append(contentsOf: inlineTypeDecls)
         }
-        let identifier = content.content.contentType.identifier
+        let identifier = contentSwiftName(content.content.contentType)
         let associatedType = content.resolvedTypeUsage
         let contentCase: Declaration = .enumCase(
             .init(
@@ -178,7 +178,7 @@ extension ClientFileTranslator {
         let typedContent = requestBody.content
         let content = typedContent.content
         let contentType = content.contentType
-        let contentTypeIdentifier = contentType.identifier
+        let contentTypeIdentifier = contentSwiftName(contentType)
         let contentTypeHeaderValue = contentType.headerValueForSending
 
         let transformReturnExpr: Expression = .return(
@@ -270,7 +270,7 @@ extension ServerFileTranslator {
         let contentTypeUsage = typedContent.resolvedTypeUsage
         let content = typedContent.content
         let contentType = content.contentType
-        let contentTypeIdentifier = contentType.identifier
+        let contentTypeIdentifier = contentSwiftName(contentType)
         let codingStrategyName = contentType.codingStrategy.runtimeName
         let isOptional = !requestBody.request.required
 

Sources/_OpenAPIGeneratorCore/Translator/Responses/translateResponse.swift

@@ -63,7 +63,7 @@ extension TypesFileTranslator {
             response.content,
             inParent: bodyTypeName
         ) {
-            let identifier = typedContent.content.contentType.identifier
+            let identifier = contentSwiftName(typedContent.content.contentType)
             let associatedType = typedContent.resolvedTypeUsage
             if TypeMatcher.isInlinable(typedContent.content.schema), let inlineType = typedContent.typeUsage {
                 let inlineTypeDecls = try translateSchema(

Sources/_OpenAPIGeneratorCore/Translator/Responses/translateResponseOutcome.swift

@@ -169,7 +169,7 @@ extension ClientFileTranslator {
                 argumentNames: ["value"],
                 body: [
                     .expression(
-                        .dot(typedContent.content.contentType.identifier)
+                        .dot(contentSwiftName(typedContent.content.contentType))
                             .call([
                                 .init(label: nil, expression: .identifier("value"))
                             ])
@@ -323,7 +323,7 @@ extension ServerFileTranslator {
             let contentType = typedContent.content.contentType
             let switchContentCases: [SwitchCaseDescription] = [
                 .init(
-                    kind: .case(.dot(contentType.identifier), ["value"]),
+                    kind: .case(.dot(contentSwiftName(contentType)), ["value"]),
                     body: [
                         .expression(
                             .return(

Tests/OpenAPIGeneratorCoreTests/TestUtilities.swift

@@ -25,20 +25,26 @@ class Test_Core: XCTestCase {
 
     func makeTranslator(
         components: OpenAPI.Components = .noComponents,
-        diagnostics: any DiagnosticCollector = PrintingDiagnosticCollector()
+        diagnostics: any DiagnosticCollector = PrintingDiagnosticCollector(),
+        featureFlags: FeatureFlags = []
     ) -> any FileTranslator {
         makeTypesTranslator(
             components: components,
-            diagnostics: diagnostics
+            diagnostics: diagnostics,
+            featureFlags: featureFlags
         )
     }
 
     func makeTypesTranslator(
         components: OpenAPI.Components = .noComponents,
-        diagnostics: any DiagnosticCollector = PrintingDiagnosticCollector()
+        diagnostics: any DiagnosticCollector = PrintingDiagnosticCollector(),
+        featureFlags: FeatureFlags = []
     ) -> TypesFileTranslator {
         TypesFileTranslator(
-            config: .init(mode: .types),
+            config: .init(
+                mode: .types,
+                featureFlags: featureFlags
+            ),
             diagnostics: diagnostics,
             components: components
         )

Tests/OpenAPIGeneratorCoreTests/Translator/Content/Test_ContentSwiftName.swift

@@ -0,0 +1,58 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftOpenAPIGenerator open source project
+//
+// Copyright (c) 2023 Apple Inc. and the SwiftOpenAPIGenerator project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftOpenAPIGenerator project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+import XCTest
+import OpenAPIKit30
+@testable import _OpenAPIGeneratorCore
+
+final class Test_ContentSwiftName: Test_Core {
+
+    func testExisting() throws {
+        let nameMaker = makeTranslator(featureFlags: []).contentSwiftName
+        let cases: [(String, String)] = [
+            ("application/json", "json"),
+            ("application/x-www-form-urlencoded", "binary"),
+            ("multipart/form-data", "binary"),
+            ("text/plain", "text"),
+            ("*/*", "binary"),
+            ("application/xml", "binary"),
+            ("application/octet-stream", "binary"),
+            ("application/myformat+json", "json"),
+            ("foo/bar", "binary"),
+        ]
+        try _testIdentifiers(cases: cases, nameMaker: nameMaker)
+    }
+
+    func testProposed() throws {
+        let nameMaker = makeTranslator(featureFlags: [.multipleContentTypes]).contentSwiftName
+        let cases: [(String, String)] = [
+            ("application/json", "unsupported"),
+            ("application/x-www-form-urlencoded", "unsupported"),
+            ("multipart/form-data", "unsupported"),
+            ("text/plain", "unsupported"),
+            ("*/*", "unsupported"),
+            ("application/xml", "unsupported"),
+            ("application/octet-stream", "unsupported"),
+            ("application/myformat+json", "unsupported"),
+            ("foo/bar", "unsupported"),
+        ]
+        try _testIdentifiers(cases: cases, nameMaker: nameMaker)
+    }
+
+    func _testIdentifiers(cases: [(String, String)], nameMaker: (ContentType) -> String) throws {
+        for item in cases {
+            let contentType = try XCTUnwrap(ContentType(item.0))
+            XCTAssertEqual(nameMaker(contentType), item.1, "Case \(item.0) failed")
+        }
+    }
+}