feat: Read JSON AST models into memory

Package.swift

@@ -303,9 +303,13 @@ let package = Package(
         .executableTarget(
             name: "SmithyCodegenCLI",
             dependencies: [
+                "SmithyCodegenCore",
                 .product(name: "ArgumentParser", package: "swift-argument-parser"),
             ]
         ),
+        .target(
+            name: "SmithyCodegenCore"
+        ),
         .testTarget(
             name: "ClientRuntimeTests",
             dependencies: [

Sources/SmithyCodegenCLI/SmithyCodegenCLI.swift

@@ -7,6 +7,7 @@
 
 import ArgumentParser
 import Foundation
+import struct SmithyCodegenCore.CodeGenerator
 
 @main
 struct SmithyCodegenCLI: AsyncParsableCommand {
@@ -17,6 +18,9 @@ struct SmithyCodegenCLI: AsyncParsableCommand {
     @Option(help: "The full or relative path to write the schemas output file.")
     var schemasPath: String?
 
+    @Option(help: "The full or relative path to write the struct consumers output file.")
+    var structConsumersPath: String?
+
     func run() async throws {
         let currentWorkingDirectoryFileURL = currentWorkingDirectoryFileURL()
         print("Current working directory: \(currentWorkingDirectoryFileURL.path)")
@@ -31,12 +35,11 @@ struct SmithyCodegenCLI: AsyncParsableCommand {
         // If --schemas-path was supplied, create the schema file URL
         let schemasFileURL = resolve(paramName: "--schemas-path", path: schemasPath)
 
-        // All file URLs needed for code generation have now been resolved.
-        // Implement code generation here.
-        if let schemasFileURL {
-            print("Schemas file path: \(schemasFileURL)")
-            FileManager.default.createFile(atPath: schemasFileURL.path, contents: Data())
-        }
+        // Use resolved file URLs to run code generator
+        try CodeGenerator(
+            modelFileURL: modelFileURL,
+            schemasFileURL: schemasFileURL
+        ).run()
     }
 
     private func currentWorkingDirectoryFileURL() -> URL {

Sources/SmithyCodegenCore/AST/ASTError.swift

@@ -0,0 +1,14 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+public struct ASTError: Error {
+    public let localizedDescription: String
+
+    init(_ localizedDescription: String) {
+        self.localizedDescription = localizedDescription
+    }
+}

Sources/SmithyCodegenCore/AST/ASTMember.swift

@@ -0,0 +1,12 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+// See https://smithy.io/2.0/spec/json-ast.html#ast-member
+struct ASTMember: Decodable {
+    let target: String
+    let traits: [String: ASTNode]?
+}

Sources/SmithyCodegenCore/AST/ASTModel.swift

@@ -0,0 +1,13 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+// See https://smithy.io/2.0/spec/json-ast.html#top-level-properties
+struct ASTModel: Decodable {
+    let smithy: String
+    let metadata: ASTNode?
+    let shapes: [String: ASTShape]
+}

Sources/SmithyCodegenCore/AST/ASTNode.swift

@@ -0,0 +1,45 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+/// Contains the value of a Smithy Node, as used in a JSON AST.
+///
+/// Smithy node data is basically the same as the data that can be stored in JSON.
+/// The root of a Smithy node may be of any type, i.e. unlike JSON, the root element is not limited to object or list.
+///
+/// See the definition of node value in the Smithy spec: https://smithy.io/2.0/spec/model.html#node-values
+enum ASTNode {
+    case object([String: ASTNode])
+    case list([ASTNode])
+    case string(String)
+    case number(Double)
+    case boolean(Bool)
+    case null
+}
+
+extension ASTNode: Decodable {
+
+    init(from decoder: any Decoder) throws {
+        let container = try decoder.singleValueContainer()
+        if container.decodeNil() {
+            self = .null
+        } else if let bool = try? container.decode(Bool.self) {
+            self = .boolean(bool)
+        } else if let int = try? container.decode(Int.self) {
+            self = .number(Double(int))
+        } else if let double = try? container.decode(Double.self) {
+            self = .number(double)
+        } else if let string = try? container.decode(String.self) {
+            self = .string(string)
+        } else if let array = try? container.decode([ASTNode].self) {
+            self = .list(array)
+        } else if let dictionary = try? container.decode([String: ASTNode].self) {
+            self = .object(dictionary)
+        } else {
+            throw ASTError("Undecodable value in AST node")
+        }
+    }
+}

Sources/SmithyCodegenCore/AST/ASTReference.swift

@@ -0,0 +1,11 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+// See https://smithy.io/2.0/spec/json-ast.html#ast-shape-reference
+struct ASTReference: Decodable {
+    let target: String
+}

Sources/SmithyCodegenCore/AST/ASTShape.swift

@@ -0,0 +1,33 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+// See https://smithy.io/2.0/spec/json-ast.html#json-ast
+// This Swift type captures fields for all AST shape types
+struct ASTShape: Decodable {
+    let type: ASTType
+    let traits: [String: ASTNode]?
+    let member: ASTMember?
+    let key: ASTMember?
+    let value: ASTMember?
+    let members: [String: ASTMember]?
+    let version: String?
+    let operations: [ASTReference]?
+    let resources: [ASTReference]?
+    let errors: [ASTReference]?
+    let rename: [String: String]?
+    let identifiers: [String: ASTReference]?
+    let properties: [String: ASTReference]?
+    let create: ASTReference?
+    let put: ASTReference?
+    let read: ASTReference?
+    let update: ASTReference?
+    let delete: ASTReference?
+    let list: ASTReference?
+    let collectionOperations: [ASTReference]?
+    let input: ASTReference?
+    let output: ASTReference?
+}

Sources/SmithyCodegenCore/AST/ASTType.swift

@@ -0,0 +1,38 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+// See https://smithy.io/2.0/spec/model.html#shape-types
+enum ASTType: String, Decodable {
+    // These cases are all the standard Smithy shape types
+    case blob
+    case boolean
+    case string
+    case timestamp
+    case byte
+    case short
+    case integer
+    case long
+    case float
+    case document
+    case double
+    case bigDecimal
+    case bigInteger
+    case `enum`
+    case intEnum
+    case list
+    case set
+    case map
+    case structure
+    case union
+    case member
+    case service
+    case resource
+    case operation
+
+    // Special for AST, added 'apply' case
+    case apply
+}

Sources/SmithyCodegenCore/CodeGenerator.swift

@@ -0,0 +1,41 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import struct Foundation.Data
+import class Foundation.FileManager
+import class Foundation.JSONDecoder
+import struct Foundation.URL
+
+public struct CodeGenerator {
+    let modelFileURL: URL
+    let schemasFileURL: URL?
+
+    public init(
+        modelFileURL: URL,
+        schemasFileURL: URL?
+    ) {
+        self.modelFileURL = modelFileURL
+        self.schemasFileURL = schemasFileURL
+    }
+
+    public func run() throws {
+        // Load the AST from the model file
+        let modelData = try Data(contentsOf: modelFileURL)
+        let astModel = try JSONDecoder().decode(ASTModel.self, from: modelData)
+
+        // In the future, AST will be used to create a Model.
+        // Model will be used to generate code.
+
+        // This code simply writes an empty schemas file, since it is expected to exist after the
+        // code generator plugin runs.
+        //
+        // Actual code generation will be implemented here later.
+        if let schemasFileURL {
+            FileManager.default.createFile(atPath: schemasFileURL.path, contents: Data())
+        }
+    }
+}