//===--- OptTable.h - Option Table ------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_OPTION_OPTTABLE_H
#define LLVM_OPTION_OPTTABLE_H

#include "llvm/ADT/StringSet.h"
#include "llvm/Option/OptSpecifier.h"

namespace llvm {
class raw_ostream;
namespace opt {
class Arg;
class ArgList;
class InputArgList;
class Option;

/// \brief Provide access to the Option info table.
///
/// The OptTable class provides a layer of indirection which allows Option
/// instance to be created lazily. In the common case, only a few options will
/// be needed at runtime; the OptTable class maintains enough information to
/// parse command lines without instantiating Options, while letting other
/// parts of the driver still use Option instances where convenient.
class OptTable {
public:
  /// \brief Entry for a single option instance in the option data table.
  struct Info {
    /// A null terminated array of prefix strings to apply to name while
    /// matching.
    const char *const *Prefixes;
    const char *Name;
    const char *HelpText;
    const char *MetaVar;
    unsigned ID;
    unsigned char Kind;
    unsigned char Param;
    unsigned short Flags;
    unsigned short GroupID;
    unsigned short AliasID;
  };

private:
  /// \brief The static option information table.
  const Info *OptionInfos;
  unsigned NumOptionInfos;

  unsigned TheInputOptionID;
  unsigned TheUnknownOptionID;

  /// The index of the first option which can be parsed (i.e., is not a
  /// special option like 'input' or 'unknown', and is not an option group).
  unsigned FirstSearchableIndex;

  /// The union of all option prefixes. If an argument does not begin with
  /// one of these, it is an input.
  StringSet<> PrefixesUnion;
  std::string PrefixChars;

private:
  const Info &getInfo(OptSpecifier Opt) const {
    unsigned id = Opt.getID();
    assert(id > 0 && id - 1 < getNumOptions() && "Invalid Option ID.");
    return OptionInfos[id - 1];
  }

protected:
  OptTable(const Info *_OptionInfos, unsigned _NumOptionInfos);
public:
  ~OptTable();

  /// \brief Return the total number of option classes.
  unsigned getNumOptions() const { return NumOptionInfos; }

  /// \brief Get the given Opt's Option instance, lazily creating it
  /// if necessary.
  ///
  /// \return The option, or null for the INVALID option id.
  const Option getOption(OptSpecifier Opt) const;

  /// \brief Lookup the name of the given option.
  const char *getOptionName(OptSpecifier id) const {
    return getInfo(id).Name;
  }

  /// \brief Get the kind of the given option.
  unsigned getOptionKind(OptSpecifier id) const {
    return getInfo(id).Kind;
  }

  /// \brief Get the group id for the given option.
  unsigned getOptionGroupID(OptSpecifier id) const {
    return getInfo(id).GroupID;
  }

  /// \brief Should the help for the given option be hidden by default.
  bool isOptionHelpHidden(OptSpecifier id) const;

  /// \brief Get the help text to use to describe this option.
  const char *getOptionHelpText(OptSpecifier id) const {
    return getInfo(id).HelpText;
  }

  /// \brief Get the meta-variable name to use when describing
  /// this options values in the help text.
  const char *getOptionMetaVar(OptSpecifier id) const {
    return getInfo(id).MetaVar;
  }

  /// \brief Parse a single argument; returning the new argument and
  /// updating Index.
  ///
  /// \param [in,out] Index - The current parsing position in the argument
  /// string list; on return this will be the index of the next argument
  /// string to parse.
  ///
  /// \return The parsed argument, or 0 if the argument is missing values
  /// (in which case Index still points at the conceptual next argument string
  /// to parse).
  Arg *ParseOneArg(const ArgList &Args, unsigned &Index) const;

  /// \brief Parse an list of arguments into an InputArgList.
  ///
  /// The resulting InputArgList will reference the strings in [\p ArgBegin,
  /// \p ArgEnd), and their lifetime should extend past that of the returned
  /// InputArgList.
  ///
  /// The only error that can occur in this routine is if an argument is
  /// missing values; in this case \p MissingArgCount will be non-zero.
  ///
  /// \param ArgBegin - The beginning of the argument vector.
  /// \param ArgEnd - The end of the argument vector.
  /// \param MissingArgIndex - On error, the index of the option which could
  /// not be parsed.
  /// \param MissingArgCount - On error, the number of missing options.
  /// \return An InputArgList; on error this will contain all the options
  /// which could be parsed.
  InputArgList *ParseArgs(const char* const *ArgBegin,
                          const char* const *ArgEnd,
                          unsigned &MissingArgIndex,
                          unsigned &MissingArgCount) const;

  /// \brief Render the help text for an option table.
  ///
  /// \param OS - The stream to write the help text to.
  /// \param Name - The name to use in the usage line.
  /// \param Title - The title to use in the usage line.
  /// \param ShowHidden - Whether help-hidden arguments should be shown.
  void PrintHelp(raw_ostream &OS, const char *Name,
                  const char *Title, bool ShowHidden = false) const;
};
} // end namespace opt
} // end namespace llvm

#endif
