[Refactor] Introduce TranslatorContext (1/2) (#638)

### Motivation

To make upcoming PRs less noisy, we need a way to propagate
configuration all the way deep to types like TypeAssigner/TypeMatcher,
which historically didn't have that need.

### Modifications

Introduced a new wrapper type called TranslatorContext, which wraps the
existing closure that converts arbitrary strings into safe Swift names
(which might in the future also need to be further customized).

The idea is that this new struct is what we'd attach more config to
shortly.

There'll be a few more smaller PRs like this, I'm breaking them up for
easier review.

### Result

Generalized the way to propagate config into low level translator
utilities.

### Test Plan

All tests still pass.

Author: czechboy0

Sources/_OpenAPIGeneratorCore/Translator/ClientTranslator/ClientTranslator.swift

@@ -37,8 +37,7 @@ struct ClientFileTranslator: FileTranslator {
         let imports =
             Constants.File.clientServerImports + config.additionalImports.map { ImportDescription(moduleName: $0) }
 
-        let clientMethodDecls =
-            try OperationDescription.all(from: doc.paths, in: components, asSwiftSafeName: swiftSafeName)
+        let clientMethodDecls = try OperationDescription.all(from: doc.paths, in: components, context: context)
             .map(translateClientMethod(_:))
 
         let clientStructPropertyDecl: Declaration = .commentable(

Sources/_OpenAPIGeneratorCore/Translator/CommonTranslations/SwiftSafeNames.swift

@@ -13,16 +13,7 @@
 //===----------------------------------------------------------------------===//
 import Foundation
 
-extension FileTranslator {
-
-    /// Returns a copy of the string modified to be a valid Swift identifier.
-    ///
-    /// - Parameter string: The string to convert to be safe for Swift.
-    /// - Returns: A Swift-safe version of the input string.
-    func swiftSafeName(for string: String) -> String { string.safeForSwiftCode }
-}
-
-fileprivate extension String {
+extension String {
 
     /// Returns a string sanitized to be usable as a Swift identifier.
     ///

Sources/_OpenAPIGeneratorCore/Translator/CommonTranslations/translateAllAnyOneOf.swift

@@ -78,7 +78,7 @@ extension TypesFileTranslator {
                     originalName: key,
                     typeUsage: propertyType,
                     associatedDeclarations: associatedDeclarations,
-                    asSwiftSafeName: swiftSafeName
+                    context: context
                 )
                 var referenceStack = ReferenceStack.empty
                 let isKeyValuePairSchema = try TypeMatcher.isKeyValuePair(
@@ -209,7 +209,7 @@ extension TypesFileTranslator {
         let decoder: Declaration
         if let discriminator {
             let originalName = discriminator.propertyName
-            let swiftName = swiftSafeName(for: originalName)
+            let swiftName = context.asSwiftSafeName(originalName)
             codingKeysDecls = [
                 .enum(
                     accessModifier: config.access,

Sources/_OpenAPIGeneratorCore/Translator/CommonTranslations/translateObjectStruct.swift

@@ -100,7 +100,7 @@ extension TypesFileTranslator {
                     originalName: key,
                     typeUsage: propertyType,
                     associatedDeclarations: associatedDeclarations,
-                    asSwiftSafeName: swiftSafeName
+                    context: context
                 )
             }
 
@@ -175,7 +175,7 @@ extension TypesFileTranslator {
             default: .emptyInit,
             isSerializedInTopLevelDictionary: false,
             associatedDeclarations: associatedDeclarations,
-            asSwiftSafeName: swiftSafeName
+            context: context
         )
         return (.allowingAdditionalProperties, extraProperty)
     }

Sources/_OpenAPIGeneratorCore/Translator/CommonTranslations/translateStringEnum.swift

@@ -49,11 +49,11 @@ extension FileTranslator {
                     // In nullable enum schemas, empty strings are parsed as Void.
                     // This is unlikely to be fixed, so handling that case here.
                     // https://github.com/apple/swift-openapi-generator/issues/118
-                    if isNullable && anyValue is Void { return (swiftSafeName(for: ""), .string("")) }
+                    if isNullable && anyValue is Void { return (context.asSwiftSafeName(""), .string("")) }
                     guard let rawValue = anyValue as? String else {
                         throw GenericError(message: "Disallowed value for a string enum '\(typeName)': \(anyValue)")
                     }
-                    let caseName = swiftSafeName(for: rawValue)
+                    let caseName = context.asSwiftSafeName(rawValue)
                     return (caseName, .string(rawValue))
                 case .integer:
                     let rawValue: Int

Sources/_OpenAPIGeneratorCore/Translator/CommonTypes/DiscriminatorExtensions.swift

@@ -79,7 +79,9 @@ extension FileTranslator {
     /// component.
     /// - Parameter type: The `OneOfMappedType` for which to determine the case name.
     /// - Returns: A string representing the safe Swift name for the specified `OneOfMappedType`.
-    func safeSwiftNameForOneOfMappedType(_ type: OneOfMappedType) -> String { swiftSafeName(for: type.rawNames[0]) }
+    func safeSwiftNameForOneOfMappedType(_ type: OneOfMappedType) -> String {
+        context.asSwiftSafeName(type.rawNames[0])
+    }
 }
 
 extension OpenAPI.Discriminator {

Sources/_OpenAPIGeneratorCore/Translator/CommonTypes/StructBlueprint.swift

@@ -146,15 +146,14 @@ struct PropertyBlueprint {
     /// referring to them in the property.
     var associatedDeclarations: [Declaration] = []
 
-    /// A converted function from user-provided strings to strings
-    /// safe to be used as a Swift identifier.
-    var asSwiftSafeName: (String) -> String
+    /// A set of configuration values that inform translation.
+    var context: TranslatorContext
 }
 
 extension PropertyBlueprint {
 
     /// A name that is verified to be a valid Swift identifier.
-    var swiftSafeName: String { asSwiftSafeName(originalName) }
+    var swiftSafeName: String { context.asSwiftSafeName(originalName) }
 
     /// The JSON path to the property.
     ///

Sources/_OpenAPIGeneratorCore/Translator/FileTranslator.swift

@@ -43,3 +43,19 @@ protocol FileTranslator {
     /// - Throws: An error if translation encounters issues or errors during the process.
     func translateFile(parsedOpenAPI: ParsedOpenAPIRepresentation) throws -> StructuredSwiftRepresentation
 }
+
+extension FileTranslator {
+
+    /// A new context from the file translator.
+    var context: TranslatorContext { TranslatorContext(asSwiftSafeName: { $0.safeForSwiftCode }) }
+}
+
+/// A set of configuration values for concrete file translators.
+struct TranslatorContext {
+
+    /// A closure that returns a copy of the string modified to be a valid Swift identifier.
+    ///
+    /// - Parameter string: The string to convert to be safe for Swift.
+    /// - Returns: A Swift-safe version of the input string.
+    var asSwiftSafeName: (String) -> String
+}

Sources/_OpenAPIGeneratorCore/Translator/Multipart/MultipartContentInspector.swift

@@ -120,7 +120,7 @@ extension FileTranslator {
         }
         var parts: [MultipartSchemaTypedContent] = try topLevelObject.properties.compactMap {
             (key, value) -> MultipartSchemaTypedContent? in
-            let swiftSafeName = swiftSafeName(for: key)
+            let swiftSafeName = context.asSwiftSafeName(key)
             let typeName = typeName.appending(
                 swiftComponent: swiftSafeName + Constants.Global.inlineTypeSuffix,
                 jsonComponent: key

Sources/_OpenAPIGeneratorCore/Translator/Multipart/translateMultipart.swift

@@ -64,7 +64,7 @@ extension TypesFileTranslator {
                 typeUsage: headersTypeName.asUsage,
                 default: headersStructBlueprint.hasEmptyInit ? .emptyInit : nil,
                 associatedDeclarations: [headersStructDecl],
-                asSwiftSafeName: swiftSafeName
+                context: context
             )
         } else {
             headersProperty = nil
@@ -90,7 +90,7 @@ extension TypesFileTranslator {
             originalName: Constants.Operation.Body.variableName,
             typeUsage: bodyTypeUsage,
             associatedDeclarations: associatedDeclarations,
-            asSwiftSafeName: swiftSafeName
+            context: context
         )
         let structDecl = translateStructBlueprint(
             .init(
@@ -137,7 +137,7 @@ extension TypesFileTranslator {
             switch part {
             case .documentedTyped(let documentedPart):
                 let caseDecl: Declaration = .enumCase(
-                    name: swiftSafeName(for: documentedPart.originalName),
+                    name: context.asSwiftSafeName(documentedPart.originalName),
                     kind: .nameWithAssociatedValues([.init(type: .init(part.wrapperTypeUsage))])
                 )
                 let decl = try translateMultipartPartContent(
@@ -404,7 +404,7 @@ extension FileTranslator {
             switch part {
             case .documentedTyped(let part):
                 let originalName = part.originalName
-                let identifier = swiftSafeName(for: originalName)
+                let identifier = context.asSwiftSafeName(originalName)
                 let contentType = part.partInfo.contentType
                 let partTypeName = part.typeName
                 let schema = part.schema
@@ -613,7 +613,7 @@ extension FileTranslator {
             switch part {
             case .documentedTyped(let part):
                 let originalName = part.originalName
-                let identifier = swiftSafeName(for: originalName)
+                let identifier = context.asSwiftSafeName(originalName)
                 let contentType = part.partInfo.contentType
                 let headersTypeName = part.typeName.appending(
                     swiftComponent: Constants.Operation.Output.Payload.Headers.typeName,