OptTable.h

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//===- 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/ADT/StringTable.h"
#include "llvm/Option/OptSpecifier.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/StringSaver.h"
#include <cassert>
#include <cstdint>
#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 LLVM_ABI OptTable {
public:
  /// Represents a subcommand and its options in the option table.
  struct SubCommand {
    const char *Name;
    const char *HelpText;
    const char *Usage;
  };
 
  /// Values of options declared with TableGen `ValuesCode`: only the generated
  /// code knows them, so they cannot go in the string table. The generated
  /// table supplies getOptionValuesCode() for this.
  using ValuesCodeFnTy = StringRef (*)(unsigned);
 
  /// Help text that replaces Info::HelpTextOffset when the visibility mask
  /// being printed intersects Visibility. An option's variants form a run
  /// ended by a zero Visibility.
  struct HelpTextVariant {
    unsigned Visibility;
    StringTable::Offset HelpTextOffset;
  };
 
  /// Fields that are rarely set or take few distinct values, shared by the
  /// options with equal values. Row 0 is all zero.
  struct InfoExtra {
    StringTable::Offset MetaVarOffset;
    StringTable::Offset AliasArgsOffset;
    /// The possible values as a comma separated list, empty for an option whose
    /// values only getOptionValuesCode() knows.
    StringTable::Offset ValuesOffset;
    unsigned Flags;
    uint16_t Visibility;
    // Offset into OptTable's HelpTextVariantsTable; 0 for none.
    uint16_t HelpTextVariantsOffset;
    // Offset into OptTable's SubCommandIDsTable.
    uint16_t SubCommandIDsOffset;
    uint8_t Param;
  };
 
  /// Entry for a single option instance in the option data table. An option's
  /// ID is its 1-based position in the table.
  struct Info {
    StringTable::Offset PrefixedNameOffset;
    /// Offset 0 means the .td supplied no HelpText. A HelpText<""> maps to a
    /// distinct empty string, marking the option deliberately undocumented.
    StringTable::Offset HelpTextOffset;
    uint16_t GroupID;
    uint16_t AliasID;
    // Offset into OptTable's InfoExtrasTable.
    uint16_t ExtraOffset;
    // Offset into OptTable's PrefixesTable.
    uint8_t PrefixesOffset;
    uint8_t Kind;
 
    bool hasNoPrefix() const { return PrefixesOffset == 0; }
 
    unsigned getNumPrefixes(ArrayRef<StringTable::Offset> PrefixesTable) const {
      // We embed the number of prefixes in the value of the first offset.
      return PrefixesTable[PrefixesOffset].value();
    }
 
    ArrayRef<StringTable::Offset>
    getPrefixOffsets(ArrayRef<StringTable::Offset> PrefixesTable) const {
      return hasNoPrefix() ? ArrayRef<StringTable::Offset>()
                           : PrefixesTable.slice(PrefixesOffset + 1,
                                                 getNumPrefixes(PrefixesTable));
    }
 
    bool hasHelpText() const { return HelpTextOffset.value() != 0; }
 
    void appendPrefixes(const StringTable &StrTable,
                        ArrayRef<StringTable::Offset> PrefixesTable,
                        SmallVectorImpl<StringRef> &Prefixes) const {
      for (auto PrefixOffset : getPrefixOffsets(PrefixesTable))
        Prefixes.push_back(StrTable[PrefixOffset]);
    }
 
    StringRef getPrefix(const StringTable &StrTable,
                        ArrayRef<StringTable::Offset> PrefixesTable,
                        unsigned PrefixIndex) const {
      return StrTable[getPrefixOffsets(PrefixesTable)[PrefixIndex]];
    }
 
    StringRef getPrefixedName(const StringTable &StrTable) const {
      return StrTable[PrefixedNameOffset];
    }
 
    StringRef getName(const StringTable &StrTable,
                      ArrayRef<StringTable::Offset> PrefixesTable) const {
      unsigned PrefixLength =
          hasNoPrefix() ? 0 : getPrefix(StrTable, PrefixesTable, 0).size();
      return getPrefixedName(StrTable).drop_front(PrefixLength);
    }
  };
 
  /// The tables TableGen emits for an option set under OPTTABLE_CODE.
  struct Tables {
    StringTable StrTable;
    ArrayRef<StringTable::Offset> PrefixesTable;
    ArrayRef<Info> Infos;
    ArrayRef<InfoExtra> InfoExtras;
    ArrayRef<HelpTextVariant> HelpTextVariants;
    ArrayRef<SubCommand> SubCommands;
    ArrayRef<unsigned> SubCommandIDs;
  };
 
public:
  bool isValidForSubCommand(const Info *CandidateInfo,
                            StringRef SubCommand) const {
    assert(!SubCommand.empty() &&
           "This helper is only for valid registered subcommands.");
    auto SCIT = llvm::find_if(
        SubCommands, [&](const auto &C) { return SubCommand == C.Name; });
    assert(SCIT != SubCommands.end() &&
           "This helper is only for valid registered subcommands.");
    auto SubCommandIDs = getSubCommandIDs(*CandidateInfo);
    unsigned CurrentSubCommandID = SCIT - &SubCommands[0];
    return llvm::is_contained(SubCommandIDs, CurrentSubCommandID);
  }
 
private:
  // A unified string table for these options. Individual strings are stored as
  // null terminated C-strings at offsets within this table.
  StringTable 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<StringTable::Offset> PrefixesTable;
 
  /// The option information table.
  ArrayRef<Info> OptionInfos;
 
  ArrayRef<InfoExtra> InfoExtrasTable;
 
  bool IgnoreCase;
 
  /// The subcommand information table.
  ArrayRef<SubCommand> SubCommands;
 
  /// The subcommand IDs table.
  ArrayRef<unsigned> SubCommandIDsTable;
 
  ArrayRef<HelpTextVariant> HelpTextVariantsTable;
 
  ValuesCodeFnTy ValuesCodeFn = nullptr;
 
  bool GroupedShortOptions = false;
  bool DashDashParsing = false;
  const char *EnvVar = nullptr;
 
  unsigned InputOptionID = 0;
  unsigned UnknownOptionID = 0;
 
  /// 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;
 
  const Info &getInfo(OptSpecifier Opt) const {
    unsigned id = Opt.getID();
    assert(id > 0 && id - 1 < getNumOptions() && "Invalid Option ID.");
    return OptionInfos[id - 1];
  }
 
  StringTable::Offset getHelpTextOffset(const Info &I,
                                        Visibility VisibilityMask) const {
    for (const HelpTextVariant *V =
             &HelpTextVariantsTable[getExtra(I).HelpTextVariantsOffset];
         V->Visibility; ++V)
      if (VisibilityMask & V->Visibility)
        return V->HelpTextOffset;
    return I.HelpTextOffset;
  }
 
  StringRef getOptionValues(const Info &I) const {
    StringRef Values = StrTable[getExtra(I).ValuesOffset];
    if (Values.empty() && ValuesCodeFn)
      Values = ValuesCodeFn(getOptionID(I));
    return Values;
  }
 
  ArrayRef<unsigned> getSubCommandIDs(const Info &I) const {
    // A set starts with its size.
    unsigned Offset = getExtra(I).SubCommandIDsOffset;
    return SubCommandIDsTable.slice(Offset + 1, SubCommandIDsTable[Offset]);
  }
 
  std::unique_ptr<Arg> parseOneArgGrouped(InputArgList &Args,
                                          unsigned &Index) const;
 
protected:
  OptTable(const Tables &Tables, bool IgnoreCase = false);
 
  void setValuesCodeFn(ValuesCodeFnTy Fn) { ValuesCodeFn = Fn; }
 
public:
  virtual ~OptTable();
 
  /// Return the string table used for option names.
  const StringTable &getStrTable() const { return StrTable; }
 
  ArrayRef<SubCommand> getSubCommands() const { return SubCommands; }
 
  /// Return the prefixes table used for option names.
  ArrayRef<StringTable::Offset> getPrefixesTable() const {
    return PrefixesTable;
  }
 
  /// Return the total number of option classes.
  unsigned getNumOptions() const { return OptionInfos.size(); }
 
  unsigned getOptionID(const Info &I) const {
    return &I - OptionInfos.data() + 1;
  }
 
  /// 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);
  }
 
  const InfoExtra &getExtra(const Info &I) const {
    return InfoExtrasTable[I.ExtraOffset];
  }
 
  /// 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.
  StringRef 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.
  StringRef getOptionHelpText(OptSpecifier id,
                              Visibility VisibilityMask) const {
    return StrTable[getHelpTextOffset(getInfo(id), VisibilityMask)];
  }
 
  /// Get the meta-variable name to use when describing
  /// this options values in the help text.
  StringRef getOptionMetaVar(OptSpecifier id) const {
    return StrTable[getExtra(getInfo(id)).MetaVarOffset];
  }
 
  /// Get the alias arguments as a \0 separated list, e.g. "foo\0bar\0".
  const char *getOptionAliasArgs(OptSpecifier id) const {
    return StrTable.getCString(getExtra(getInfo(id)).AliasArgsOffset);
  }
 
  /// 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(),
                 StringRef SubCommand = {}) 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,
                         StringRef SubCommand, bool ShowHidden,
                         bool ShowAllAliases,
                         std::function<bool(const Info &)> ExcludeOption,
                         Visibility VisibilityMask) const;
};
 
} // 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, SUBCOMMANDIDS_OFFSET)                                     \
  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,      \
                         SUBCOMMANDIDS_OFFSET)                                 \
  LLVM_MAKE_OPT_ID_WITH_ID_PREFIX(                                             \
      OPT_, PREFIXES_OFFSET, PREFIXED_NAME_OFFSET, ID, KIND, GROUP, ALIAS,     \
      ALIASARGS, FLAGS, VISIBILITY, PARAM, HELPTEXT, HELPTEXTSFORVARIANTS,     \
      METAVAR, VALUES, SUBCOMMANDIDS_OFFSET)
 
#endif // LLVM_OPTION_OPTTABLE_H