vmap/libs/string/pooledstring.h
2020-11-17 12:16:16 +01:00

93 lines
2.5 KiB
C++

#if !defined( INCLUDED_POOLEDSTRING_H )
#define INCLUDED_POOLEDSTRING_H
#include <map>
#include "generic/static.h"
#include "string/string.h"
#include "container/hashtable.h"
#include "container/hashfunc.h"
/// \brief The string pool class.
class StringPool : public HashTable<char*, std::size_t, RawStringHash, RawStringEqual>
{
};
inline void StringPool_analyse( StringPool& pool ){
typedef std::multimap<std::size_t, const char*> Ordered;
Ordered ordered;
std::size_t total = 0;
std::size_t pooled = 0;
for ( StringPool::iterator i = pool.begin(); i != pool.end(); ++i )
{
std::size_t size = string_length( ( *i ).key ) + 1;
total += size * ( *i ).value;
pooled += size + 20;
ordered.insert( Ordered::value_type( ( *i ).value, ( *i ).key ) );
}
globalOutputStream() << "total: " << Unsigned( total ) << " pooled:" << Unsigned( pooled ) << "\n";
for ( Ordered::iterator i = ordered.begin(); i != ordered.end(); ++i )
{
globalOutputStream() << ( *i ).second << " " << Unsigned( ( *i ).first ) << "\n";
}
}
/// \brief A string which can be copied with zero memory cost and minimal runtime cost.
///
/// \param PoolContext The string pool context to use.
template<typename PoolContext>
class PooledString
{
StringPool::iterator m_i;
static StringPool::iterator increment( StringPool::iterator i ){
++( *i ).value;
return i;
}
static StringPool::iterator insert( const char* string ){
StringPool::iterator i = PoolContext::instance().find( const_cast<char*>( string ) );
if ( i == PoolContext::instance().end() ) {
return PoolContext::instance().insert( string_clone( string ), 1 );
}
return increment( i );
}
static void erase( StringPool::iterator i ){
if ( --( *i ).value == 0 ) {
char* string = ( *i ).key;
PoolContext::instance().erase( i );
string_release( string, string_length( string ) );
}
}
public:
PooledString() : m_i( insert( "" ) ){
}
PooledString( const PooledString& other ) : m_i( increment( other.m_i ) ){
}
PooledString( const char* string ) : m_i( insert( string ) ){
}
~PooledString(){
erase( m_i );
}
PooledString& operator=( const PooledString& other ){
PooledString tmp( other );
tmp.swap( *this );
return *this;
}
PooledString& operator=( const char* string ){
PooledString tmp( string );
tmp.swap( *this );
return *this;
}
void swap( PooledString& other ){
std::swap( m_i, other.m_i );
}
bool operator==( const PooledString& other ) const {
return m_i == other.m_i;
}
const char* c_str() const {
return ( *m_i ).key;
}
};
#endif