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// file : butl/string-table -*- C++ -*-
// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUTL_STRING_TABLE
#define BUTL_STRING_TABLE
#include <vector>
#include <string>
#include <unordered_map>
#include <butl/export>
#include <butl/multi-index>
namespace butl
{
// A pool of strings and, optionally, other accompanying data in which
// each entry is assigned an individual index (or id) of type I (e.g.,
// uint8_t, uint16_t, etc., depending on how many entries are expected).
// Index value 0 is reserved to indicate the "no entry" condition.
//
template <typename I, typename D>
struct string_table_element
{
const I i;
const D d;
};
template <typename I>
struct string_table_element<I, std::string>
{
const I i;
const std::string d;
};
// For custom data the options are to call the data member 'key' or to
// specialize this traits.
//
template <typename D>
struct string_table_traits
{
static const std::string&
key (const D& d) {return d.key;}
};
template <>
struct string_table_traits<std::string>
{
static const std::string&
key (const std::string& d) {return d;}
};
template <typename I, typename D = std::string>
struct string_table
{
// Insert new entry unless one already exists.
//
I
insert (const D&);
// Find existing.
//
I
find (const std::string& k) const
{
auto i (map_.find (key_type (&k)));
return i != map_.end () ? i->second.i : 0;
}
// Reverse lookup.
//
const D&
operator[] (I i) const {assert (i > 0); return vec_[i - 1]->second.d;}
I
size () const {return static_cast<I> (vec_.size ());}
bool
empty () const {return vec_.empty ();}
void
clear () {vec_.clear (); map_.clear ();}
private:
using key_type = butl::map_key<std::string>;
using value_type = string_table_element<I, D>;
using map_type = std::unordered_map<key_type, value_type>;
using traits = string_table_traits<D>;
map_type map_;
std::vector<typename map_type::const_iterator> vec_;
};
}
#include <butl/string-table.txx>
#endif // BUTL_STRING_TABLE
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