forked from apple/swift-argument-parser
/
ParsableArguments.swift
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/
ParsableArguments.swift
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//===----------------------------------------------------------*- swift -*-===//
//
// This source file is part of the Swift Argument Parser open source project
//
// Copyright (c) 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
#if canImport(Glibc)
import Glibc
let _exit: (Int32) -> Never = Glibc.exit
#elseif canImport(Darwin)
import Darwin
let _exit: (Int32) -> Never = Darwin.exit
#elseif canImport(CRT)
import CRT
let _exit: (Int32) -> Never = ucrt._exit
#elseif canImport(WASILibc)
import WASILibc
#endif
/// A type that can be parsed from a program's command-line arguments.
///
/// When you implement a `ParsableArguments` type, all properties must be declared with
/// one of the four property wrappers provided by the `ArgumentParser` library.
public protocol ParsableArguments: Decodable {
/// Creates an instance of this parsable type using the definitions
/// given by each property's wrapper.
init()
/// Validates the properties of the instance after parsing.
///
/// Implement this method to perform validation or other processing after
/// creating a new instance from command-line arguments.
mutating func validate() throws
/// The label to use for "Error: ..." messages from this type. (experimental)
static var _errorLabel: String { get }
}
/// A type that provides the `ParsableCommand` interface to a `ParsableArguments` type.
struct _WrappedParsableCommand<P: ParsableArguments>: ParsableCommand {
static var _commandName: String {
let name = String(describing: P.self).convertedToSnakeCase()
// If the type is named something like "TransformOptions", we only want
// to use "transform" as the command name.
if let optionsRange = name.range(of: "_options"),
optionsRange.upperBound == name.endIndex
{
return String(name[..<optionsRange.lowerBound])
} else {
return name
}
}
@OptionGroup var options: P
}
struct StandardError: TextOutputStream {
mutating func write(_ string: String) {
for byte in string.utf8 { putc(numericCast(byte), stderr) }
}
}
var standardError = StandardError()
extension ParsableArguments {
public mutating func validate() throws {}
/// This type as-is if it conforms to `ParsableCommand`, or wrapped in the
/// `ParsableCommand` wrapper if not.
internal static var asCommand: ParsableCommand.Type {
self as? ParsableCommand.Type ?? _WrappedParsableCommand<Self>.self
}
public static var _errorLabel: String {
"Error"
}
}
// MARK: - API
extension ParsableArguments {
/// Parses a new instance of this type from command-line arguments.
///
/// - Parameter arguments: An array of arguments to use for parsing. If
/// `arguments` is `nil`, this uses the program's command-line arguments.
/// - Returns: A new instance of this type.
public static func parse(
_ arguments: [String]? = nil
) throws -> Self {
// Parse the command and unwrap the result if necessary.
switch try self.asCommand.parseAsRoot(arguments) {
case let helpCommand as HelpCommand:
throw ParserError.helpRequested(visibility: helpCommand.visibility)
case let result as _WrappedParsableCommand<Self>:
return result.options
case var result as Self:
do {
try result.validate()
} catch {
throw ParserError.userValidationError(error)
}
return result
default:
// TODO: this should be a "wrong command" message
throw ParserError.invalidState
}
}
/// Returns a brief message for the given error.
///
/// - Parameter error: An error to generate a message for.
/// - Returns: A message that can be displayed to the user.
public static func message(
for error: Error
) -> String {
MessageInfo(error: error, type: self).message
}
/// Returns a full message for the given error, including usage information,
/// if appropriate.
///
/// - Parameter error: An error to generate a message for.
/// - Returns: A message that can be displayed to the user.
public static func fullMessage(
for error: Error
) -> String {
MessageInfo(error: error, type: self).fullText(for: self)
}
/// Returns the text of the help screen for this type.
///
/// - Parameters:
/// - columns: The column width to use when wrapping long line in the
/// help screen. If `columns` is `nil`, uses the current terminal
/// width, or a default value of `80` if the terminal width is not
/// available.
/// - Returns: The full help screen for this type.
@_disfavoredOverload
@available(*, deprecated, message: "Use helpMessage(includeHidden:columns:) instead.")
public static func helpMessage(
columns: Int?
) -> String {
helpMessage(includeHidden: false, columns: columns)
}
/// Returns the text of the help screen for this type.
///
/// - Parameters:
/// - includeHidden: Include hidden help information in the generated
/// message.
/// - columns: The column width to use when wrapping long line in the
/// help screen. If `columns` is `nil`, uses the current terminal
/// width, or a default value of `80` if the terminal width is not
/// available.
/// - Returns: The full help screen for this type.
public static func helpMessage(
includeHidden: Bool = false,
columns: Int? = nil
) -> String {
HelpGenerator(self, visibility: includeHidden ? .hidden : .default)
.rendered(screenWidth: columns)
}
/// Returns the JSON representation of this type.
public static func _dumpHelp() -> String {
DumpHelpGenerator(self).rendered()
}
/// Returns the exit code for the given error.
///
/// The returned code is the same exit code that is used if `error` is passed
/// to `exit(withError:)`.
///
/// - Parameter error: An error to generate an exit code for.
/// - Returns: The exit code for `error`.
public static func exitCode(
for error: Error
) -> ExitCode {
MessageInfo(error: error, type: self).exitCode
}
/// Returns a shell completion script for the specified shell.
///
/// - Parameter shell: The shell to generate a completion script for.
/// - Returns: The completion script for `shell`.
public static func completionScript(for shell: CompletionShell) -> String {
let completionsGenerator = try! CompletionsGenerator(command: self.asCommand, shell: shell)
return completionsGenerator.generateCompletionScript()
}
/// Terminates execution with a message and exit code that is appropriate
/// for the given error.
///
/// If the `error` parameter is `nil`, this method prints nothing and exits
/// with code `EXIT_SUCCESS`. If `error` represents a help request or
/// another `CleanExit` error, this method prints help information and
/// exits with code `EXIT_SUCCESS`. Otherwise, this method prints a relevant
/// error message and exits with code `EX_USAGE` or `EXIT_FAILURE`.
///
/// - Parameter error: The error to use when exiting, if any.
public static func exit(
withError error: Error? = nil
) -> Never {
guard let error = error else {
_exit(ExitCode.success.rawValue)
}
let messageInfo = MessageInfo(error: error, type: self)
let fullText = messageInfo.fullText(for: self)
if !fullText.isEmpty {
if messageInfo.shouldExitCleanly {
print(fullText)
} else {
print(fullText, to: &standardError)
}
}
_exit(messageInfo.exitCode.rawValue)
}
/// Parses a new instance of this type from command-line arguments or exits
/// with a relevant message.
///
/// - Parameter arguments: An array of arguments to use for parsing. If
/// `arguments` is `nil`, this uses the program's command-line arguments.
public static func parseOrExit(
_ arguments: [String]? = nil
) -> Self {
do {
return try parse(arguments)
} catch {
exit(withError: error)
}
}
}
/// Unboxes the given value if it is a `nil` value.
///
/// If the value passed is the `.none` case of any optional type, this function
/// returns `nil`.
///
/// let intAsAny = (1 as Int?) as Any
/// let nilAsAny = (nil as Int?) as Any
/// nilOrValue(intAsAny) // Optional(1) as Any?
/// nilOrValue(nilAsAny) // nil as Any?
func nilOrValue(_ value: Any) -> Any? {
if case Optional<Any>.none = value {
return nil
} else {
return value
}
}
/// Existential protocol for property wrappers, so that they can provide
/// the argument set that they define.
protocol ArgumentSetProvider {
func argumentSet(for key: InputKey) -> ArgumentSet
var _visibility: ArgumentVisibility { get }
}
extension ArgumentSetProvider {
var _visibility: ArgumentVisibility { .default }
}
extension ArgumentSet {
init(_ type: ParsableArguments.Type, visibility: ArgumentVisibility, parent: InputKey.Parent) {
#if DEBUG
do {
try type._validate(parent: parent)
} catch {
assertionFailure("\(error)")
}
#endif
let a: [ArgumentSet] = Mirror(reflecting: type.init())
.children
.compactMap { child -> ArgumentSet? in
guard let codingKey = child.label else { return nil }
if let parsed = child.value as? ArgumentSetProvider {
guard parsed._visibility.isAtLeastAsVisible(as: visibility)
else { return nil }
let key = InputKey(name: codingKey, parent: parent)
return parsed.argumentSet(for: key)
} else {
let arg = ArgumentDefinition(
unparsedKey: codingKey,
default: nilOrValue(child.value), parent: parent)
// Save a non-wrapped property as is
return ArgumentSet(arg)
}
}
self.init(
a.joined().filter { $0.help.visibility.isAtLeastAsVisible(as: visibility) })
}
}
/// The fatal error message to display when someone accesses a
/// `ParsableArguments` type after initializing it directly.
internal let directlyInitializedError = """
--------------------------------------------------------------------
Can't read a value from a parsable argument definition.
This error indicates that a property declared with an `@Argument`,
`@Option`, `@Flag`, or `@OptionGroup` property wrapper was neither
initialized to a value nor decoded from command-line arguments.
To get a valid value, either call one of the static parsing methods
(`parse`, `parseAsRoot`, or `main`) or define an initializer that
initializes _every_ property of your parsable type.
--------------------------------------------------------------------
"""