Add new shouldUseExecutableName configuration property (Issue #295)

.gitignore

@@ -1,5 +1,6 @@
 .DS_Store
 /.build
+/DerivedData
 /Packages
 /*.xcodeproj
 .swiftpm

Sources/ArgumentParser/Documentation.docc/Extensions/CommandConfiguration.md

@@ -4,7 +4,7 @@
 
 ### Creating a Configuration
 
-- ``init(commandName:abstract:usage:discussion:version:shouldDisplay:subcommands:defaultSubcommand:helpNames:)``
+- ``init(commandName:shouldUseExecutableName:abstract:usage:discussion:version:shouldDisplay:subcommands:defaultSubcommand:helpNames:)``
 
 ### Customizing the Help Screen
 
@@ -21,6 +21,7 @@
 ### Defining Command Properties
 
 - ``commandName``
+- ``shouldUseExecutableName``
 - ``version``
 - ``shouldDisplay``
 

Sources/ArgumentParser/Parsable Types/CommandConfiguration.swift

@@ -17,6 +17,13 @@ public struct CommandConfiguration {
   /// the command type to hyphen-separated lowercase words.
   public var commandName: String?
 
+  /// A Boolean value indicating whether to use the executable's file name
+  /// for the command name.
+  ///
+  /// If `commandName` or `_superCommandName` are non-`nil`, this
+  /// value is ignored.
+  public var shouldUseExecutableName: Bool
+
   /// The name of this command's "super-command". (experimental)
   ///
   /// Use this when a command is part of a group of commands that are installed
@@ -61,6 +68,9 @@ public struct CommandConfiguration {
   ///   - commandName: The name of the command to use on the command line. If
   ///     `commandName` is `nil`, the command name is derived by converting
   ///     the name of the command type to hyphen-separated lowercase words.
+  ///   - shouldUseExecutableName: A Boolean value indicating whether to
+  ///     use the executable's file name for the command name. If `commandName`
+  ///     is non-`nil`, this value is ignored.
   ///   - abstract: A one-line description of the command.
   ///   - usage: A custom usage description for the command. When you provide
   ///     a non-`nil` string, the argument parser uses `usage` instead of
@@ -82,6 +92,7 @@ public struct CommandConfiguration {
   ///     are `-h` and `--help`.
   public init(
     commandName: String? = nil,
+    shouldUseExecutableName: Bool = false,
     abstract: String = "",
     usage: String? = nil,
     discussion: String = "",
@@ -92,6 +103,7 @@ public struct CommandConfiguration {
     helpNames: NameSpecification? = nil
   ) {
     self.commandName = commandName
+    self.shouldUseExecutableName = shouldUseExecutableName
     self.abstract = abstract
     self.usage = usage
     self.discussion = discussion
@@ -106,6 +118,7 @@ public struct CommandConfiguration {
   /// (experimental)
   public init(
     commandName: String? = nil,
+    shouldUseExecutableName: Bool = false,
     _superCommandName: String,
     abstract: String = "",
     usage: String? = nil,
@@ -117,6 +130,7 @@ public struct CommandConfiguration {
     helpNames: NameSpecification? = nil
   ) {
     self.commandName = commandName
+    self.shouldUseExecutableName = shouldUseExecutableName
     self._superCommandName = _superCommandName
     self.abstract = abstract
     self.usage = usage

Sources/ArgumentParser/Parsable Types/ParsableCommand.swift

@@ -37,7 +37,9 @@ public protocol ParsableCommand: ParsableArguments {
 extension ParsableCommand {
   public static var _commandName: String {
     configuration.commandName ??
-      String(describing: Self.self).convertedToSnakeCase(separator: "-")
+      (configuration.shouldUseExecutableName && configuration._superCommandName == nil
+        ? UsageGenerator.executableName
+        : String(describing: Self.self).convertedToSnakeCase(separator: "-"))
   }
 
   public static var configuration: CommandConfiguration {

Sources/ArgumentParser/Usage/UsageGenerator.swift

@@ -18,8 +18,7 @@ struct UsageGenerator {
 
 extension UsageGenerator {
   init(definition: ArgumentSet) {
-    let toolName = CommandLine.arguments[0].split(separator: "/").last.map(String.init) ?? "<command>"
-    self.init(toolName: toolName, definition: definition)
+    self.init(toolName: Self.executableName, definition: definition)
   }
 
   init(toolName: String, parsable: ParsableArguments, visibility: ArgumentVisibility, parent: InputKey.Parent) {
@@ -34,6 +33,20 @@ extension UsageGenerator {
 }
 
 extension UsageGenerator {
+  /// Will generate a tool name from the name of the executed file if possible.
+  ///
+  /// If no tool name can be generated, `"<command>"` will be returned.
+  static var executableName: String {
+    if let name = URL(fileURLWithPath: CommandLine.arguments[0]).pathComponents.last {
+      // We quote the name if it contains whitespace to avoid confusion with
+      // subcommands but otherwise leave properly quoting/escaping the command
+      // up to the user running the tool
+      return name.quotedIfContains(.whitespaces)
+    } else {
+      return "<command>"
+    }
+  }
+
   /// The tool synopsis.
   ///
   /// In `roff`.

Sources/ArgumentParser/Utilities/StringExtensions.swift

@@ -9,6 +9,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+@_implementationOnly import Foundation
+
 extension StringProtocol where SubSequence == Substring {
   func wrapped(to columns: Int, wrappingIndent: Int = 0) -> String {
     let columns = columns - wrappingIndent
@@ -120,6 +122,32 @@ extension StringProtocol where SubSequence == Substring {
     return result
   }
 
+  /// Returns a new single-quoted string if this string contains any characters
+  /// from the specified character set. Any existing occurrences of the `'`
+  /// character will be escaped.
+  ///
+  /// Examples:
+  ///
+  ///     "alone".quotedIfContains(.whitespaces)
+  ///     // alone
+  ///     "with space".quotedIfContains(.whitespaces)
+  ///     // 'with space'
+  ///     "with'quote".quotedIfContains(.whitespaces)
+  ///     // with'quote
+  ///     "with'quote and space".quotedIfContains(.whitespaces)
+  ///     // 'with\'quote and space'
+  func quotedIfContains(_ chars: CharacterSet) -> String {
+    guard !isEmpty else { return "" }
+
+    if self.rangeOfCharacter(from: chars) != nil {
+      // Prepend and append a single quote to self, escaping any other occurrences of the character
+      let quote = "'"
+      return quote + self.replacingOccurrences(of: quote, with: "\\\(quote)") + quote
+    }
+
+    return String(self)
+  }
+
   /// Returns the edit distance between this string and the provided target string.
   ///
   /// Uses the Levenshtein distance algorithm internally.

Tests/ArgumentParserUnitTests/CMakeLists.txt

@@ -7,6 +7,7 @@ add_library(UnitTests
   HelpGenerationTests+GroupName.swift
   NameSpecificationTests.swift
   SplitArgumentTests.swift
+  StringQuoteTests.swift
   StringSnakeCaseTests.swift
   StringWrappingTests.swift
   TreeTests.swift

Tests/ArgumentParserUnitTests/StringQuoteTests.swift

@@ -0,0 +1,38 @@
+//===----------------------------------------------------------*- swift -*-===//
+//
+// This source file is part of the Swift Argument Parser open source project
+//
+// Copyright (c) 2022 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
+//
+//===----------------------------------------------------------------------===//
+
+import XCTest
+@testable import ArgumentParser
+
+final class StringQuoteTests: XCTestCase {}
+
+extension StringQuoteTests {
+  func testStringQuoteWithCharacter() {
+    let charactersToQuote = CharacterSet.whitespaces.union(.symbols)
+    let quoteTests = [
+      ("noSpace", "noSpace"),
+      ("a space", "'a space'"),
+      (" startingSpace", "' startingSpace'"),
+      ("endingSpace ", "'endingSpace '"),
+      ("   ", "'   '"),
+      ("\t", "'\t'"),
+      ("with'quote", "with'quote"), // no need to quote, so don't escape quote character either
+      ("with'quote and space", "'with\\'quote and space'"), // quote the string and escape the quote character within
+      ("'\\\\'' '''", "'\\\'\\\\\\\'\\\' \\\'\\\'\\\''"),
+      ("\"\\\\\"\" \"\"\"", "'\"\\\\\"\" \"\"\"'"),
+      ("word+symbol", "'word+symbol'"),
+      ("@£$%'^*(", "'@£$%\\\'^*('")
+    ]
+    for test in quoteTests {
+      XCTAssertEqual(test.0.quotedIfContains(charactersToQuote), test.1)
+    }
+  }
+}