The FBB::ReadLineHistory object offers access to the history maintained by FBB::ReadLineBuf and ReadLineStream objects.
The latter two classes use Gnu's readline library to allow editing of input lines. The accumulated history of these objects can be accessed from the ReadLineHistory object.
Since Gnu's readline library maintains global data there can only be one history. The ReadLineHistory class is therefore, like ReadLineBuf a singleton. (Gnu's readline library does, however, offer functions allowing programs to use multiple histories. So it would in principle be possible to design a non-singleton ReadLineHistory class. Since programs normally only interact with a single terminal, there is probably little use for non-singleton ReadLineHistory class).
The ReadLineHistory class encapsulates history access. It offers limited facilities: either forward or backward iterations over the history are offered as well as reading and writing the history from/to streams. When reading the history from a stream it replaces the currently available lines in Gnu's readline history. The content of the history lines and --if defined-- the timestamps of the lines in the history can be obtained using iterators defined by ReadLineHistory.
The class ReadLineHistory defines the following nested types:
HistoryElement
The iterators made available by the ReadLineHistory object provide access to a HistoryElement object. These objects can be copied and assigned to each other, but user programs cannot otherwise construct HistoryElement objects.
The class HistoryElement has but two members:
const_iterator and const_reverse_iterator
The iterators returned by members of the class ReadLineHistory are input iterators, pointing to HistoryElement objects. As they are input iterators modification of the history elements to which they refer is not allowed.
The class const_iterator allows iterations from the first to the last history element, the class const_reverse_iterator allows iterations from the last back to the first history element.
The iterators can be incremented, compared for (in)equality and offer operator* and operator-> members, offering access to, respectively, HistoryElement objects and their addresses.
As the class ReadLineHistory is a singleton class, there are no publicly available constructors, nor are assignment operators available.
cout << history.setTimestamps(true);
#include <iostream>
#include <algorithm>
#include <fstream>
#include <bobcat/datetime>
#include <bobcat/readlinestream>
//#include <bobcat/readlinehistory>
#include "../readlinehistory"
using namespace std;
using namespace FBB;
void showHis(ReadLineHistory::HistoryElement const &element)
{
cout << element.timestamp() << " " << element.line() << '\n';
}
string timestamp()
{
return DateTime().rfc2822();
};
int main(int argc, char **argv)
{
ReadLineStream in("? ", ReadLineBuf::EXPAND_HISTORY);
in.useTimestamps(×tamp);
cout << "Enter some lines, end the input using ctrl-d\n";
string line;
while (getline(in, line))
;
// argument means: write/read
// history timestamps
ReadLineHistory &history = ReadLineHistory::instance(argc > 1);
cout << "All lines, from the first to the last:\n";
for_each(history.begin(), history.end(), showHis);
cout << "\n"
"Again: all lines, from the first to the last:\n";
for_each(history.begin(), history.end(), showHis);
cout << "\n"
"All lines, from the last to the first:\n";
for_each(history.rbegin(), history.rend(), showHis);
cout << "\n"
"History out and in:\n"
"\n";
ofstream hisout("history.out");
hisout << history;
hisout.close();
ifstream hisin("history.out");
hisin >> history;
cout << "All lines, from the first to the last:\n";
for_each(history.begin(), history.end(), showHis);
cout << "\n"
"All lines, from the last to the first:\n";
for_each(history.rbegin(), history.rend(), showHis);
}