zhangyang-zerotierone/ext/librethinkdbxx/src/cursor.cc

#include "cursor.h"
#include "cursor_p.h"
#include "exceptions.h"

namespace RethinkDB {

// for type completion, in order to forward declare with unique_ptr
Cursor::Cursor(Cursor&&) = default;
Cursor& Cursor::operator=(Cursor&&) = default;

CursorPrivate::CursorPrivate(uint64_t token_, Connection *conn_)
    : single(false), no_more(false), index(0),
      token(token_), conn(conn_)
{ }

CursorPrivate::CursorPrivate(uint64_t token_, Connection *conn_, Datum&& datum)
    : single(true), no_more(true), index(0), buffer(Array{std::move(datum)}),
      token(token_), conn(conn_)
{ }

Cursor::Cursor(CursorPrivate *dd) : d(dd) {}

Cursor::~Cursor() {
    try {
        if (d && d->conn) {
            close();
        }
    } catch ( ... ) {}
}

Datum& Cursor::next(double wait) const {
    if (!has_next(wait)) {
        throw Error("next: No more data");
    }

    return d->buffer[d->index++];
}

Datum& Cursor::peek(double wait) const {
    if (!has_next(wait)) {
        throw Error("next: No more data");
    }

    return d->buffer[d->index];
}

void Cursor::each(std::function<void(Datum&&)> f, double wait) const {
    while (has_next(wait)) {
        f(std::move(d->buffer[d->index++]));
    }
}

void CursorPrivate::convert_single() const {
    if (index != 0) {
        throw Error("Cursor: already consumed");
    }

    if (buffer.size() != 1) {
        throw Error("Cursor: invalid response from server");
    }

    if (!buffer[0].is_array()) {
        throw Error("Cursor: not an array");
    }

    buffer.swap(buffer[0].extract_array());
    single = false;
}

void CursorPrivate::clear_and_read_all() const {
    if (single) {
        convert_single();
    }
    if (index != 0) {
        buffer.erase(buffer.begin(), buffer.begin() + index);
        index = 0;
    }
    while (!no_more) {
        add_response(conn->d->wait_for_response(token, FOREVER));
    }
}

Array&& Cursor::to_array() && {
    d->clear_and_read_all();
    return std::move(d->buffer);
}

Array Cursor::to_array() const & {
    d->clear_and_read_all();
    return d->buffer;
}

Datum Cursor::to_datum() const & {
    if (d->single) {
        if (d->index != 0) {
            throw Error("to_datum: already consumed");
        }
        return d->buffer[0];
    }

    d->clear_and_read_all();
    return d->buffer;
}

Datum Cursor::to_datum() && {
    Datum ret((Nil()));
    if (d->single) {
        if (d->index != 0) {
            throw Error("to_datum: already consumed");
        }
        ret = std::move(d->buffer[0]);
    } else {
        d->clear_and_read_all();
        ret = std::move(d->buffer);
    }

    return ret;
}

void Cursor::close() const {
    d->conn->stop_query(d->token);
    d->no_more = true;
}

bool Cursor::has_next(double wait) const {
    if (d->single) {
        d->convert_single();
    }

    while (true) {
        if (d->index >= d->buffer.size()) {
            if (d->no_more) {
                return false;
            }
            d->add_response(d->conn->d->wait_for_response(d->token, wait));
        } else {
            return true;
        }
    }
}

bool Cursor::is_single() const {
    return d->single;
}

void CursorPrivate::add_results(Array&& results) const {
    if (index >= buffer.size()) {
        buffer = std::move(results);
        index = 0;
    } else {
        for (auto& it : results) {
            buffer.emplace_back(std::move(it));
        }
    }
}

void CursorPrivate::add_response(Response&& response) const {
    using RT = Protocol::Response::ResponseType;
    switch (response.type) {
    case RT::SUCCESS_SEQUENCE:
        add_results(std::move(response.result));
        no_more = true;
        break;
    case RT::SUCCESS_PARTIAL:
        conn->continue_query(token);
        add_results(std::move(response.result));
        break;
    case RT::SUCCESS_ATOM:
        add_results(std::move(response.result));
        single = true;
        no_more = true;
        break;
    case RT::SERVER_INFO:
        add_results(std::move(response.result));
        single = true;
        no_more = true;
        break;
    case RT::WAIT_COMPLETE:
    case RT::CLIENT_ERROR:
    case RT::COMPILE_ERROR:
    case RT::RUNTIME_ERROR:
        no_more = true;
        throw response.as_error();
    }
}

Cursor::iterator Cursor::begin() {
    return iterator(this);
}

Cursor::iterator Cursor::end() {
    return iterator(nullptr);
}

Cursor::iterator::iterator(Cursor* cursor_) : cursor(cursor_) {}

Cursor::iterator& Cursor::iterator::operator++ () {
    if (cursor == nullptr) {
        throw Error("incrementing an exhausted Cursor iterator");
    }

    cursor->next();
    return *this;
}

Datum& Cursor::iterator::operator* () {
    if (cursor == nullptr) {
        throw Error("reading from empty Cursor iterator");
    }

    return cursor->peek();
}

bool Cursor::iterator::operator!= (const Cursor::iterator& other) const {
    if (cursor == other.cursor) {
        return false;
    }

    return !((cursor == nullptr && !other.cursor->has_next()) ||
             (other.cursor == nullptr && !cursor->has_next()));
}

}