mutating func parse()

in Sources/ArgumentParser/Parsing/CommandParser.swift [201:239]
34 lines of code
10 McCabe index (conditional complexity)

  mutating func parse(arguments: [String]) -> Result<ParsableCommand, CommandError> {
    do {
      try handleCustomCompletion(arguments)
    } catch {
      return .failure(CommandError(commandStack: [commandTree.element], parserError: error as! ParserError))
    }
    
    var split: SplitArguments
    do {
      split = try SplitArguments(arguments: arguments)
    } catch let error as ParserError {
      return .failure(CommandError(commandStack: [commandTree.element], parserError: error))
    } catch {
      return .failure(CommandError(commandStack: [commandTree.element], parserError: .invalidState))
    }
    
    do {
      try checkForCompletionScriptRequest(&split)
      try descendingParse(&split)
      let result = try extractLastParsedValue(split)
      
      // HelpCommand is a valid result, but needs extra information about
      // the tree from the parser to build its stack of commands.
      if var helpResult = result as? HelpCommand {
        try helpResult.buildCommandStack(with: self)
        return .success(helpResult)
      }
      return .success(result)
    } catch let error as CommandError {
      return .failure(error)
    } catch let error as ParserError {
      let error = arguments.isEmpty ? ParserError.noArguments(error) : error
      return .failure(CommandError(commandStack: commandStack, parserError: error))
    } catch is HelpRequested {
      return .success(HelpCommand(commandStack: commandStack))
    } catch {
      return .failure(CommandError(commandStack: commandStack, parserError: .invalidState))
    }
  }