scopestore.hpp

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//==================================================================================================
/// \file
/// This header-file is part of module \alib_alox of the \aliblong.
///
/// Copyright 2013-2026 A-Worx GmbH, Germany.
/// Published under #"mainpage_license".
//==================================================================================================
ALIB_EXPORT namespace alib::lox::detail {
 
// forward declarations
class ScopeInfo;
class PrefixLogable;
 
/// Shortcut to the ScopeStore's hashmap.
template <typename T>   using SSMap = HashMap< PoolAllocator           ,
                                               NString                 ,// key
                                               T                       ,// map
                                               std::hash    <NString>  ,
                                               std::equal_to<NString>  ,
                                               lang::Caching::Enabled  ,
                                               Recycling::None           >;
 
 
// forwards
template<typename T, bool TStackedThreadValues>
class ScopeStore;
 
/// A helper-class that has two specializations to implement different versions of methods
/// #"ScopeStore::Walk" and #"ScopeStore::access" for each boolean value of template argument
/// \p{TStackedThreadValues}.<br>
///
/// @tparam T                    The stored object type.
/// @tparam TStackedThreadValues If true, values stored for thread scopes will be always replaced
///                              instead of appended.
///                              This is, for example, \c false for <em>Log Data</em> and
///                              <em>Log Once</em> and \c true for <em>Scope Domains</em>
///                              and <em>Prefix Logables</em>.
template<typename T, bool TStackedThreadValues>
struct ScopeStoreHelper {
    /// Implements #"ScopeStore::Walk" with two specializations.
    /// @param self The #"%ScopeStore" that invoked us.
    /// @return The result as specified in #"ScopeStore::Walk".
    T   doWalk  ( ScopeStore<T, TStackedThreadValues>& self );
 
    /// Implements #"ScopeStore::access" with two specializations.
    /// @param self  The #"%ScopeStore" that invoked us.
    /// @param cmd   Parameter \p{cmd} of the original method.
    /// @param value Parameter \p{value} of the original method.
    /// @return The result as specified in #"ScopeStore::access".
    T   doAccess( ScopeStore<T, TStackedThreadValues>& self, int cmd, T value );
};
 
#if !DOXYGEN
// specializations for true/false of TStackedThreadValues
template<typename T                           > struct ScopeStoreHelper<T, false> {
    T doWalk  ( ScopeStore<T, false>& self );
    T doAccess( ScopeStore<T, false>& self, int cmd, T value );
};
 
template<typename T                           > struct ScopeStoreHelper<T, true> {
    T doWalk  ( ScopeStore<T, true>& self );
    T doAccess( ScopeStore<T, true>& self, int cmd, T value );
};
#endif
 
//==================================================================================================
/// This class is responsible for scope-related functionality of class Lox.
/// \note This is a pure internal helper-class. Documentation may be limited.
/// @tparam T                    The stored object type.
/// @tparam TStackedThreadValues If true, values stored for thread scopes will be always replaced
///                              instead of appended.
///                              This is, for example, \c false for <em>Log Data</em> and
///                              <em>Log Once</em> and \c true for <em>Scope Domains</em>
///                              and <em>Prefix Logables</em>.
//==================================================================================================
template<typename T, bool TStackedThreadValues>
class ScopeStore {
  #if !DOXYGEN
    friend struct ScopeStoreHelper<T, TStackedThreadValues>;
  #endif
 
  public:
    /// Alias name for the string tree template used for storing language-related data.
    /// The language store uses a \c StringTree with a monotonic allocator.
    /// This does not lead to memory leaks, because during the life-time of a #"%Lox" objects
    /// are only added, but never deleted. If a value is unset, the node is not deleted but
    /// set to a \e nulled value. This makes the language store very memory efficient (and fast).
    using TLanguageStore= containers::StringTree< MonoAllocator,
                                                  T,
                                                  StringTreeNamesAlloc<character> >;
 
    /// The type of object stored for the thread values. This depends on whether multiple
    /// (a stack of) values can be stored, which is not true for log data and log once, as
    /// those operate with hash maps.
    using TThreadMapValue= std::conditional_t<TStackedThreadValues, StdVectorMA<T>, T>;
 
    /// The value of the global scope.
    T                                       globalStore;
 
    /// #"%StringTree" to store data for language-related scopes (path,source,method).
    TLanguageStore                          languageStore;
 
#if !ALIB_SINGLE_THREADED
    /// Key type for the thread store.
    using ThreadMapKey   = std::pair<bool,threads::ThreadID>;
 
    /// Hash functor for <c>std::pair<bool,ThreadID></c>.
    struct BoolThreadIDHash {
        /// Calculates a hash code.
        /// @param src The object to hash.
        /// @return The hash code.
        std::size_t operator()(const std::pair<bool, threads::ThreadID>& src)                const {
            return src.first ? std::size_t( src.second * 282312799l  )
                             : std::size_t( src.second * 573292817l  ) ^ std::size_t(-1);
        }
    };
 
    /// The inner/outer thread map of values. The boolean value of the key is \c true for
    /// the inner store and \c false for the outer.
    HashMap<MonoAllocator,
            ThreadMapKey, TThreadMapValue,
            BoolThreadIDHash              > threadStore;
#endif
 
 
  //################################################################################################
  // Protected fields
  //################################################################################################
  protected:
 
    /// ScopeInfo of 'our' lox.
    ScopeInfo&                              scopeInfo;
 
    /// Flag used to lazily create the key to language-related scope values.
    bool                                    lazyLanguageNode;
 
    /// Indicates if currently a scope walk is active.
    bool                                    walking;
 
    /// The actual scope of a walk.
    Scope                                   actScope;
 
    /// The actual language related scope's map node.
    typename TLanguageStore::Cursor         actStringTreeNode;
 
    /// The path level when using access methods.
    int                                     actPathLevel;
 
#if !ALIB_SINGLE_THREADED
    /// Actual thread ID
    threads::ThreadID                       actThreadID;
#endif
 
    /// The 'local object' returned by a walk after Scope::ThreadInner and before Scope::Method.
    T                                       walkLocalObject;
 
    /// The next value of a walk during \e Scope::ThreadInner/Outer.
    int                                     walkNextThreadIdx;
 
    /// The list of values of \e Scope::ThreadOuter/Inner during a walk.
    TThreadMapValue*                        walkThreadValues;
 
  //################################################################################################
  // Public interface
  //################################################################################################
  public:
 
    /// Constructor
    /// @param scopeInfo      The ScopeInfo singleton of 'our' Lox.
    /// @param monoAllocator  The monotonic allocator used for the
    ///                        #"StringTree" needed by member #"languageStore".
    ALIB_DLL
    ScopeStore( ScopeInfo& scopeInfo, MonoAllocator& monoAllocator  );
 
    /// Destructor
    ALIB_DLL
    ~ScopeStore();
 
    /// Initializes access methods #".Store", #".Get" and #".Remove" and has to be invoked before
    /// using them
    /// @param scope      Scope to use.
    /// @param pathLevel  Used only if parameter \p{scope} equals #"lox Scope::Path;*"
    ///                   to reference parent directories. Optional and defaults to \c 0.
    /// @param threadID   ID of the associated thread (for thread-related scopes only).
    ///                   If #"threads::UNDEFINED" is given, the ID provided in
    ///                   \p{scopeInfo} is used.
    ALIB_DLL
    void InitAccess    ( Scope scope, int pathLevel, threads::ThreadID threadID );
 
    /// Stores a new value.
    /// @param value      The value to set.
    /// @return Returns the previous value stored.
    T Store    ( T value )    { ALIB_ASSERT( value != nullptr, "ALOX" ) return access( 0, value ); }
 
    /// Removes a value.
    /// @param value      The value to remove (must only be given for thread-related \e Scopes).
    /// @return Returns the previous value stored.
    T Remove   ( T value )                                            { return access( 1, value ); }
 
    /// Retrieves the value.
    /// @return Returns the current value stored.
    T Get      ()                                                   { return access( 2, nullptr ); }
 
    /// Initializes a scope 'walk' by storing the given scope information and
    /// setting fields of our walk 'state-machine' to proper start values.
    ///
    /// @param startScope       The \e Scope to start searching for.
    /// @param localObject      The 'local object' returned by a walk after Scope::ThreadInner
    ///                         and before Scope::Method
    ALIB_DLL
    void InitWalk( Scope startScope, const T localObject  );
 
    /// Searches next value in the actual scope. While not found, moves walk state to next outer
    /// state and continues there.
    /// @return The next object found in the current or any next outer scope.
    T   Walk()                 { return ScopeStoreHelper<T, TStackedThreadValues>().doWalk(*this); }
 
   //###############################################################################################
   // Internals
   //###############################################################################################
  protected:
    /// Retrieves and optionally creates an entry in the map that stores language-related
    /// scope information. The result is stored in field #".actStringTreeNode".
    /// @param create     If \c true, a non-existing entry is created.
    void initCursor( bool create );
 
    /// Receives, inserts or removes a value.
    /// @param cmd        0= insert, 1= remove, 2= get.
    /// @param value      The new value or the one to be removed.
    /// @return Returns the previous value stored.
    T access( int cmd, T value )
    { return ScopeStoreHelper<T, TStackedThreadValues>().doAccess( *this, cmd, value ); }
}; // ScopeStore
 
 
#if !DOXYGEN
 
extern template struct ScopeStoreHelper<NString                , true>;
extern template class  ScopeStore      <NString                , true>;
 
extern template struct ScopeStoreHelper<PrefixLogable*         , true>;
extern template class  ScopeStore      <PrefixLogable*         , true>;
 
 
extern template struct ScopeStoreHelper<SSMap<int>*, false>;
extern template class  ScopeStore      <SSMap<int>*, false>;
 
extern template struct ScopeStoreHelper<SSMap<Box>*, false>;
extern template class  ScopeStore      <SSMap<Box>*, false>;
 
#endif
 
} // namespace [alib::lox::detail]