Add TargetSwiftDebugSettings to PBXProj

tools/generators/lib/PBXProj/src/ReadTargetSwiftDebugSettingsFile.swift

@@ -0,0 +1,33 @@
+import Foundation
+
+public struct ReadTargetSwiftDebugSettingsFile {
+    private let callable: Callable
+
+    /// - Parameters:
+    ///   - callable: The function that will be called in
+    ///     `callAsFunction()`.
+    public init(callable: @escaping Callable = Self.defaultCallable) {
+        self.callable = callable
+    }
+
+    /// Reads the Swift debug settings for a specific target from a file.
+    public  func callAsFunction(
+        from url: URL
+    ) async throws -> TargetSwiftDebugSettings {
+        try await callable(/*url:*/ url)
+    }
+}
+
+// MARK: - ReadTargetSwiftDebugSettingsFile.Callable
+
+extension ReadTargetSwiftDebugSettingsFile {
+    public typealias Callable =
+        (_ url: URL) async throws -> TargetSwiftDebugSettings
+
+    public static func defaultCallable(
+        url: URL
+    ) async throws -> TargetSwiftDebugSettings {
+        return try await .decode(from: url)
+    }
+}
+

tools/generators/lib/PBXProj/src/TargetSwiftDebugSettings.swift

@@ -0,0 +1,56 @@
+import Foundation
+import ToolCommon
+
+public struct TargetSwiftDebugSettings {
+    public let clangArgs: [String]
+    public let frameworkIncludes: [String]
+    public let swiftIncludes: [String]
+}
+
+extension TargetSwiftDebugSettings {
+    static func decode(from url: URL) async throws -> Self {
+        var iterator = url.lines.makeAsyncIterator()
+
+        let clangArgs = try await iterator.consumeArgs("clang args", in: url)
+        let frameworkIncludes =
+            try await iterator.consumeArgs("framework includes", in: url)
+        let swiftIncludes =
+            try await iterator.consumeArgs("swift includes", in: url)
+
+        return Self(
+            clangArgs: clangArgs,
+            frameworkIncludes: frameworkIncludes,
+            swiftIncludes: swiftIncludes
+        )
+    }
+}
+
+private extension AsyncLineSequence.AsyncIterator where Base == URL.AsyncBytes {
+    mutating func consumeArgs(
+        _ name: String,
+        in url: URL
+    ) async throws -> [String] {
+        guard let rawCount = try await next() else {
+            throw PreconditionError(
+                message: url.prefixMessage("Missing \(name) count")
+            )
+        }
+        guard let count = Int(rawCount) else {
+            throw PreconditionError(message: url.prefixMessage("""
+\(name) count "\(rawCount)" was not an integer
+"""))
+        }
+
+        var args: [String] = []
+        for index in (0..<count) {
+            guard let arg = try await next()?.nullsToNewlines else {
+                throw PreconditionError(message: url.prefixMessage("""
+Too few \(name). Found \(index), expected \(count)
+"""))
+            }
+            args.append(arg)
+        }
+
+        return args
+    }
+}

tools/generators/lib/PBXProj/src/WriteTargetSwiftDebugSettings.swift

@@ -0,0 +1,74 @@
+import Foundation
+import OrderedCollections
+
+public struct WriteTargetSwiftDebugSettings {
+    private let callable: Callable
+
+    /// - Parameters:
+    ///   - callable: The function that will be called in
+    ///     `callAsFunction()`.
+    public init(callable: @escaping Callable = Self.defaultCallable) {
+        self.callable = callable
+    }
+
+    /// Writes the Swift debug settings for a certain target to disk.
+    public func callAsFunction(
+        clangArgs: [String],
+        frameworkIncludes: OrderedSet<String>,
+        swiftIncludes: OrderedSet<String>,
+        to url: URL
+    ) throws {
+        try callable(
+            /*clangArgs:*/ clangArgs,
+            /*frameworkIncludes:*/ frameworkIncludes,
+            /*swiftIncludes:*/ swiftIncludes,
+            /*url:*/ url
+        )
+    }
+}
+
+// MARK: - WriteTargetSwiftDebugSettings.Callable
+
+extension WriteTargetSwiftDebugSettings {
+    public typealias Callable = (
+        _ clangArgs: [String],
+        _ frameworkIncludes: OrderedSet<String>,
+        _ swiftIncludes: OrderedSet<String>,
+        _ url: URL
+    ) throws -> Void
+
+    public static func defaultCallable(
+        clangArgs: [String],
+        frameworkIncludes: OrderedSet<String>,
+        swiftIncludes: OrderedSet<String>,
+        to url: URL
+    ) throws {
+
+        var data = Data()
+
+        data.append(Data(String(clangArgs.count).utf8))
+        data.append(separator)
+        for arg in clangArgs {
+            data.append(Data(arg.utf8))
+            data.append(separator)
+        }
+
+        data.append(Data(String(frameworkIncludes.count).utf8))
+        data.append(separator)
+        for include in frameworkIncludes {
+            data.append(Data(include.utf8))
+            data.append(separator)
+        }
+
+        data.append(Data(String(swiftIncludes.count).utf8))
+        data.append(separator)
+        for include in swiftIncludes {
+            data.append(Data(include.utf8))
+            data.append(separator)
+        }
+
+        try data.write(to: url)
+    }
+}
+
+private let separator = Data([0x0a]) // Newline