OptTable.h

Go to the documentation of this file.

//===- OptTable.h - Option Table --------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_OPTION_OPTTABLE_H
#define LLVM_OPTION_OPTTABLE_H
 
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Option/OptSpecifier.h"
#include "llvm/Support/StringSaver.h"
#include <cassert>
#include <string>
#include <vector>
 
namespace llvm {
 
class raw_ostream;
template <typename Fn> class function_ref;
 
namespace opt {
 
class Arg;
class ArgList;
class InputArgList;
class Option;
 
/// Helper for overload resolution while transitioning from
/// FlagsToInclude/FlagsToExclude APIs to VisibilityMask APIs.
class Visibility {
  unsigned Mask = ~0U;
 
public:
  explicit Visibility(unsigned Mask) : Mask(Mask) {}
  Visibility() = default;
 
  operator unsigned() const { return Mask; }
};
 
/// 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:
  /// Entry for a single option instance in the option data table.
  struct Info {
    unsigned PrefixesOffset;
    unsigned PrefixedNameOffset;
    const char *HelpText;
    // Help text for specific visibilities. A list of pairs, where each pair
    // is a list of visibilities and a specific help string for those
    // visibilities. If no help text is found in this list for the visibility of
    // the program, HelpText is used instead. This cannot use std::vector
    // because OptTable is used in constexpr contexts. Increase the array sizes
    // here if you need more entries and adjust the constants in
    // OptionParserEmitter::EmitHelpTextsForVariants.
    std::array<std::pair<std::array<unsigned int, 2 /*MaxVisibilityPerHelp*/>,
                         const char *>,
               1 /*MaxVisibilityHelp*/>
        HelpTextsForVariants;
    const char *MetaVar;
    unsigned ID;
    unsigned char Kind;
    unsigned char Param;
    unsigned int Flags;
    unsigned int Visibility;
    unsigned short GroupID;
    unsigned short AliasID;
    const char *AliasArgs;
    const char *Values;
 
    bool hasNoPrefix() const { return PrefixesOffset == 0; }
 
    unsigned getNumPrefixes(ArrayRef<unsigned> PrefixesTable) const {
      return PrefixesTable[PrefixesOffset];
    }
 
    ArrayRef<unsigned>
    getPrefixOffsets(ArrayRef<unsigned> PrefixesTable) const {
      return hasNoPrefix() ? ArrayRef<unsigned>()
                           : PrefixesTable.slice(PrefixesOffset + 1,
                                                 getNumPrefixes(PrefixesTable));
    }
 
    void appendPrefixes(const char *StrTable, ArrayRef<unsigned> PrefixesTable,
                        SmallVectorImpl<StringRef> &Prefixes) const {
      for (unsigned PrefixOffset : getPrefixOffsets(PrefixesTable))
        Prefixes.push_back(&StrTable[PrefixOffset]);
    }
 
    StringRef getPrefix(const char *StrTable, ArrayRef<unsigned> PrefixesTable,
                        unsigned PrefixIndex) const {
      return &StrTable[getPrefixOffsets(PrefixesTable)[PrefixIndex]];
    }
 
    StringRef getPrefixedName(const char *StrTable) const {
      return &StrTable[PrefixedNameOffset];
    }
 
    StringRef getName(const char *StrTable,
                      ArrayRef<unsigned> PrefixesTable) const {
      unsigned PrefixLength =
          hasNoPrefix() ? 0 : getPrefix(StrTable, PrefixesTable, 0).size();
      return getPrefixedName(StrTable).drop_front(PrefixLength);
    }
  };
 
private:
  // A unified string table for these options. Individual strings are stored as
  // null terminated C-strings at offsets within this table.
  const char *StrTable;
 
  // A table of different sets of prefixes. Each set starts with the number of
  // prefixes in that set followed by that many offsets into the string table
  // for each of the prefix strings. This is essentially a Pascal-string style
  // encoding.
  ArrayRef<unsigned> PrefixesTable;
 
  /// The option information table.
  ArrayRef<Info> OptionInfos;
 
  bool IgnoreCase;
  bool GroupedShortOptions = false;
  bool DashDashParsing = false;
  const char *EnvVar = nullptr;
 
  unsigned InputOptionID = 0;
  unsigned UnknownOptionID = 0;
 
protected:
  /// 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 = 0;
 
  /// The union of all option prefixes. If an argument does not begin with
  /// one of these, it is an input.
  SmallVector<StringRef> PrefixesUnion;
 
  /// The union of the first element of all option prefixes.
  SmallString<8> 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];
  }
 
  std::unique_ptr<Arg> parseOneArgGrouped(InputArgList &Args,
                                          unsigned &Index) const;
 
protected:
  /// Initialize OptTable using Tablegen'ed OptionInfos. Child class must
  /// manually call \c buildPrefixChars once they are fully constructed.
  OptTable(const char *StrTable, ArrayRef<unsigned> PrefixesTable,
           ArrayRef<Info> OptionInfos, bool IgnoreCase = false);
 
  /// Build (or rebuild) the PrefixChars member.
  void buildPrefixChars();
 
public:
  virtual ~OptTable();
 
  /// Return the string table used for option names.
  const char *getStrTable() const { return StrTable; }
 
  /// Return the prefixes table used for option names.
  ArrayRef<unsigned> getPrefixesTable() const { return PrefixesTable; }
 
  /// Return the total number of option classes.
  unsigned getNumOptions() const { return OptionInfos.size(); }
 
  /// 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;
 
  /// Lookup the name of the given option.
  StringRef getOptionName(OptSpecifier id) const {
    return getInfo(id).getName(StrTable, PrefixesTable);
  }
 
  /// Lookup the prefix of the given option.
  StringRef getOptionPrefix(OptSpecifier id) const {
    const Info &I = getInfo(id);
    return I.hasNoPrefix() ? StringRef()
                           : I.getPrefix(StrTable, PrefixesTable, 0);
  }
 
  void appendOptionPrefixes(OptSpecifier id,
                            SmallVectorImpl<StringRef> &Prefixes) const {
    const Info &I = getInfo(id);
    I.appendPrefixes(StrTable, PrefixesTable, Prefixes);
  }
 
  /// Lookup the prefixed name of the given option.
  StringRef getOptionPrefixedName(OptSpecifier id) const {
    return getInfo(id).getPrefixedName(StrTable);
  }
 
  /// Get the kind of the given option.
  unsigned getOptionKind(OptSpecifier id) const {
    return getInfo(id).Kind;
  }
 
  /// Get the group id for the given option.
  unsigned getOptionGroupID(OptSpecifier id) const {
    return getInfo(id).GroupID;
  }
 
  /// Get the help text to use to describe this option.
  const char *getOptionHelpText(OptSpecifier id) const {
    return getOptionHelpText(id, Visibility(0));
  }
 
  // Get the help text to use to describe this option.
  // If it has visibility specific help text and that visibility is in the
  // visibility mask, use that text instead of the generic text.
  const char *getOptionHelpText(OptSpecifier id,
                                Visibility VisibilityMask) const {
    auto Info = getInfo(id);
    for (auto [Visibilities, Text] : Info.HelpTextsForVariants)
      for (auto Visibility : Visibilities)
        if (VisibilityMask & Visibility)
          return Text;
    return Info.HelpText;
  }
 
  /// 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;
  }
 
  /// Specify the environment variable where initial options should be read.
  void setInitialOptionsFromEnvironment(const char *E) { EnvVar = E; }
 
  /// Support grouped short options. e.g. -ab represents -a -b.
  void setGroupedShortOptions(bool Value) { GroupedShortOptions = Value; }
 
  /// Set whether "--" stops option parsing and treats all subsequent arguments
  /// as positional. E.g. -- -a -b gives two positional inputs.
  void setDashDashParsing(bool Value) { DashDashParsing = Value; }
 
  /// Find possible value for given flags. This is used for shell
  /// autocompletion.
  ///
  /// \param [in] Option - Key flag like "-stdlib=" when "-stdlib=l"
  /// was passed to clang.
  ///
  /// \param [in] Arg - Value which we want to autocomplete like "l"
  /// when "-stdlib=l" was passed to clang.
  ///
  /// \return The vector of possible values.
  std::vector<std::string> suggestValueCompletions(StringRef Option,
                                                   StringRef Arg) const;
 
  /// Find flags from OptTable which starts with Cur.
  ///
  /// \param [in] Cur - String prefix that all returned flags need
  //  to start with.
  ///
  /// \return The vector of flags which start with Cur.
  std::vector<std::string> findByPrefix(StringRef Cur,
                                        Visibility VisibilityMask,
                                        unsigned int DisableFlags) const;
 
  /// Find the OptTable option that most closely matches the given string.
  ///
  /// \param [in] Option - A string, such as "-stdlibs=l", that represents user
  /// input of an option that may not exist in the OptTable. Note that the
  /// string includes prefix dashes "-" as well as values "=l".
  /// \param [out] NearestString - The nearest option string found in the
  /// OptTable.
  /// \param [in] VisibilityMask - Only include options with any of these
  ///                              visibility flags set.
  /// \param [in] MinimumLength - Don't find options shorter than this length.
  /// For example, a minimum length of 3 prevents "-x" from being considered
  /// near to "-S".
  /// \param [in] MaximumDistance - Don't find options whose distance is greater
  /// than this value.
  ///
  /// \return The edit distance of the nearest string found.
  unsigned findNearest(StringRef Option, std::string &NearestString,
                       Visibility VisibilityMask = Visibility(),
                       unsigned MinimumLength = 4,
                       unsigned MaximumDistance = UINT_MAX) const;
 
  unsigned findNearest(StringRef Option, std::string &NearestString,
                       unsigned FlagsToInclude, unsigned FlagsToExclude = 0,
                       unsigned MinimumLength = 4,
                       unsigned MaximumDistance = UINT_MAX) const;
 
private:
  unsigned
  internalFindNearest(StringRef Option, std::string &NearestString,
                      unsigned MinimumLength, unsigned MaximumDistance,
                      std::function<bool(const Info &)> ExcludeOption) const;
 
public:
  bool findExact(StringRef Option, std::string &ExactString,
                 Visibility VisibilityMask = Visibility()) const {
    return findNearest(Option, ExactString, VisibilityMask, 4, 0) == 0;
  }
 
  bool findExact(StringRef Option, std::string &ExactString,
                 unsigned FlagsToInclude, unsigned FlagsToExclude = 0) const {
    return findNearest(Option, ExactString, FlagsToInclude, FlagsToExclude, 4,
                       0) == 0;
  }
 
  /// 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.
  /// \param [in] VisibilityMask - Only include options with any of these
  /// visibility flags set.
  ///
  /// \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).
  std::unique_ptr<Arg>
  ParseOneArg(const ArgList &Args, unsigned &Index,
              Visibility VisibilityMask = Visibility()) const;
 
  std::unique_ptr<Arg> ParseOneArg(const ArgList &Args, unsigned &Index,
                                   unsigned FlagsToInclude,
                                   unsigned FlagsToExclude) const;
 
private:
  std::unique_ptr<Arg>
  internalParseOneArg(const ArgList &Args, unsigned &Index,
                      std::function<bool(const Option &)> ExcludeOption) const;
 
public:
  /// 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 MissingArgIndex - On error, the index of the option which could
  /// not be parsed.
  /// \param MissingArgCount - On error, the number of missing options.
  /// \param VisibilityMask - Only include options with any of these
  /// visibility flags set.
  /// \return An InputArgList; on error this will contain all the options
  /// which could be parsed.
  InputArgList ParseArgs(ArrayRef<const char *> Args, unsigned &MissingArgIndex,
                         unsigned &MissingArgCount,
                         Visibility VisibilityMask = Visibility()) const;
 
  InputArgList ParseArgs(ArrayRef<const char *> Args, unsigned &MissingArgIndex,
                         unsigned &MissingArgCount, unsigned FlagsToInclude,
                         unsigned FlagsToExclude = 0) const;
 
private:
  InputArgList
  internalParseArgs(ArrayRef<const char *> Args, unsigned &MissingArgIndex,
                    unsigned &MissingArgCount,
                    std::function<bool(const Option &)> ExcludeOption) const;
 
public:
  /// A convenience helper which handles optional initial options populated from
  /// an environment variable, expands response files recursively and parses
  /// options.
  ///
  /// \param ErrorFn - Called on a formatted error message for missing arguments
  /// or unknown options.
  /// \return An InputArgList; on error this will contain all the options which
  /// could be parsed.
  InputArgList parseArgs(int Argc, char *const *Argv, OptSpecifier Unknown,
                         StringSaver &Saver,
                         std::function<void(StringRef)> ErrorFn) const;
 
  /// Render the help text for an option table.
  ///
  /// \param OS - The stream to write the help text to.
  /// \param Usage - USAGE: Usage
  /// \param Title - OVERVIEW: Title
  /// \param VisibilityMask - Only in                 Visibility VisibilityMask,clude options with any of these
  ///                         visibility flags set.
  /// \param ShowHidden     - If true, display options marked as HelpHidden
  /// \param ShowAllAliases - If true, display all options including aliases
  ///                         that don't have help texts. By default, we display
  ///                         only options that are not hidden and have help
  ///                         texts.
  void printHelp(raw_ostream &OS, const char *Usage, const char *Title,
                 bool ShowHidden = false, bool ShowAllAliases = false,
                 Visibility VisibilityMask = Visibility()) const;
 
  void printHelp(raw_ostream &OS, const char *Usage, const char *Title,
                 unsigned FlagsToInclude, unsigned FlagsToExclude,
                 bool ShowAllAliases) const;
 
private:
  void internalPrintHelp(raw_ostream &OS, const char *Usage, const char *Title,
                         bool ShowHidden, bool ShowAllAliases,
                         std::function<bool(const Info &)> ExcludeOption,
                         Visibility VisibilityMask) const;
};
 
/// Specialization of OptTable
class GenericOptTable : public OptTable {
protected:
  GenericOptTable(const char *StrTable, ArrayRef<unsigned> PrefixesTable,
                  ArrayRef<Info> OptionInfos, bool IgnoreCase = false);
};
 
class PrecomputedOptTable : public OptTable {
protected:
  PrecomputedOptTable(const char *StrTable, ArrayRef<unsigned> PrefixesTable,
                      ArrayRef<Info> OptionInfos,
                      ArrayRef<unsigned> PrefixesUnionOffsets,
                      bool IgnoreCase = false)
      : OptTable(StrTable, PrefixesTable, OptionInfos, IgnoreCase) {
    for (unsigned PrefixOffset : PrefixesUnionOffsets)
      PrefixesUnion.push_back(&StrTable[PrefixOffset]);
    buildPrefixChars();
  }
};
 
} // end namespace opt
 
} // end namespace llvm
 
#define LLVM_MAKE_OPT_ID_WITH_ID_PREFIX(                                       \
    ID_PREFIX, PREFIXES_OFFSET, PREFIXED_NAME_OFFSET, ID, KIND, GROUP, ALIAS,  \
    ALIASARGS, FLAGS, VISIBILITY, PARAM, HELPTEXT, HELPTEXTSFORVARIANTS,       \
    METAVAR, VALUES)                                                           \
  ID_PREFIX##ID
 
#define LLVM_MAKE_OPT_ID(PREFIXES_OFFSET, PREFIXED_NAME_OFFSET, ID, KIND,      \
                         GROUP, ALIAS, ALIASARGS, FLAGS, VISIBILITY, PARAM,    \
                         HELPTEXT, HELPTEXTSFORVARIANTS, METAVAR, VALUES)      \
  LLVM_MAKE_OPT_ID_WITH_ID_PREFIX(OPT_, PREFIXES_OFFSET, PREFIXED_NAME_OFFSET, \
                                  ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS,    \
                                  VISIBILITY, PARAM, HELPTEXT,                 \
                                  HELPTEXTSFORVARIANTS, METAVAR, VALUE)
 
#define LLVM_CONSTRUCT_OPT_INFO_WITH_ID_PREFIX(                                \
    ID_PREFIX, PREFIXES_OFFSET, PREFIXED_NAME_OFFSET, ID, KIND, GROUP, ALIAS,  \
    ALIASARGS, FLAGS, VISIBILITY, PARAM, HELPTEXT, HELPTEXTSFORVARIANTS,       \
    METAVAR, VALUES)                                                           \
  llvm::opt::OptTable::Info {                                                  \
    PREFIXES_OFFSET, PREFIXED_NAME_OFFSET, HELPTEXT, HELPTEXTSFORVARIANTS,     \
        METAVAR, ID_PREFIX##ID, llvm::opt::Option::KIND##Class, PARAM, FLAGS,  \
        VISIBILITY, ID_PREFIX##GROUP, ID_PREFIX##ALIAS, ALIASARGS, VALUES      \
  }
 
#define LLVM_CONSTRUCT_OPT_INFO(                                               \
    PREFIXES_OFFSET, PREFIXED_NAME_OFFSET, ID, KIND, GROUP, ALIAS, ALIASARGS,  \
    FLAGS, VISIBILITY, PARAM, HELPTEXT, HELPTEXTSFORVARIANTS, METAVAR, VALUES) \
  LLVM_CONSTRUCT_OPT_INFO_WITH_ID_PREFIX(                                      \
      OPT_, PREFIXES_OFFSET, PREFIXED_NAME_OFFSET, ID, KIND, GROUP, ALIAS,     \
      ALIASARGS, FLAGS, VISIBILITY, PARAM, HELPTEXT, HELPTEXTSFORVARIANTS,     \
      METAVAR, VALUES)
 
#endif // LLVM_OPTION_OPTTABLE_H