Osmium  0.1
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Osmium::StringTable Class Reference

#include <stringtable.hpp>

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List of all members.

Classes

struct  string_info

Public Member Functions

 StringTable ()
string_id_t record_string (const std::string &string)
void store_stringtable (OSMPBF::StringTable *st)
string_id_t map_string_id (const string_id_t interim_id) const
void clear ()

Static Public Member Functions

template<typename A , typename B >
static std::pair< B, A > flip_pair (const std::pair< A, B > &p)

Private Types

typedef uint16_t string_id_t
 type for string IDs (interim and final)
typedef std::map< std::string,
string_info
string2string_info_t
typedef std::vector< string_id_tinterim_id2id_t

Private Attributes

string2string_info_t m_strings
interim_id2id_t m_id2id_map
int m_size

Friends

bool operator< (const string_info &lhs, const string_info &rhs)

Detailed Description

StringTable management for PBF writer

All strings are stored as indexes to rows in a StringTable. The StringTable contains one row for each used string, so strings that are used multiple times need to be stored only once. The StringTable is sorted by usage-count, so the most often used string is stored at index 1.


Member Typedef Documentation

typedef std::vector<string_id_t> Osmium::StringTable::interim_id2id_t [private]

This vector is used to map the interim IDs to real StringTable IDs after writing all strings to the StringTable.

typedef std::map<std::string, string_info> Osmium::StringTable::string2string_info_t [private]

Interim StringTable, storing all strings that should be written to the StringTable once the block is written to disk.

typedef uint16_t Osmium::StringTable::string_id_t [private]

type for string IDs (interim and final)


Constructor & Destructor Documentation


Member Function Documentation

void Osmium::StringTable::clear ( ) [inline]

Clear the stringtable, preparing for the next block.

template<typename A , typename B >
static std::pair<B,A> Osmium::StringTable::flip_pair ( const std::pair< A, B > &  p) [inline, static]
string_id_t Osmium::StringTable::map_string_id ( const string_id_t  interim_id) const [inline]

Map from an interim ID to a real string ID.

string_id_t Osmium::StringTable::record_string ( const std::string &  string) [inline]

record a string in the interim StringTable if it's missing, otherwise just increase its counter, return the interim-id assigned to the string.

void Osmium::StringTable::store_stringtable ( OSMPBF::StringTable *  st) [inline]

Sort the interim StringTable and store it to the real protobuf StringTable. while storing to the real table, this function fills the id2id_map with pairs, mapping the interim-ids to final and real StringTable ids.

Note that the m_strings table is a std::map and as such is sorted lexicographically. When the transformation into the sortedby multimap is done, it gets sorted by the count. The end result (at least with the glibc standard container/algorithm implementation) is that the string table is sorted first by reverse count (ie descending) and then by reverse lexicographic order.


Friends And Related Function Documentation

bool operator< ( const string_info lhs,
const string_info rhs 
) [friend]

Member Data Documentation


The documentation for this class was generated from the following file:
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