ConversationExtractor.cpp

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/*
 * This file is part of the DUDS project. It is subject to the BSD-style
 * license terms in the LICENSE file found in the top-level directory of this
 * distribution and at https://github.com/jjackowski/duds/blob/master/LICENSE.
 * No part of DUDS, including this file, may be copied, modified, propagated,
 * or distributed except according to the terms contained in the LICENSE file.
 *
 * Copyright (C) 2017  Jeff Jackowski
 */
#include <duds/hardware/interface/ConversationExtractor.hpp>
#include <cstring>  // for std::memcpy()

namespace duds { namespace hardware { namespace interface {

void ConversationExtractor::set() {
    if (!c) {
        DUDS_THROW_EXCEPTION(ConversationNotSet());
    }
    piter = c->cbegin();
    // first part for extraction
    while ((piter != c->cend() && !(*piter)->extract())) {
        ++piter;
    }
    if (piter == c->cend()) {
        // set conversation end condition
        pos = nullptr;
        remain = 0;
    } else {
        // start at first part to extract
        pos = (*piter)->start();
        remain = (*piter)->length();
    }
}

void ConversationExtractor::advance(std::size_t bytes) {
    // too few bytes?
    if (bytes > remain) {
        DUDS_THROW_EXCEPTION(ConversationReadPastEnd());
    }
    remain -= bytes;
    // no data left in part?
    if (!remain) {
        // if used with a part rather than whole conversation . . .
        if (!c) {
            // set conversation end condition
            pos = nullptr;
            return;
        }
        // find next part for extraction
        do {
            ++piter;
        } while ((piter != c->cend() && !(*piter)->extract()));
        // no more?
        if (piter == c->cend()) {
            // set conversation end condition
            pos = nullptr;
        } else {
            // start at next part
            pos = (*piter)->start();
            remain = (*piter)->length();
        }
    } else {
        // advance within the part
        pos += bytes;
    }
}

void ConversationExtractor::nextPart() {
    if (!c) {
        DUDS_THROW_EXCEPTION(ConversationNotSet());
    }
    if (!pos) {
        DUDS_THROW_EXCEPTION(ConversationReadPastEnd());
    }
    // find next part for extraction
    while ((piter != c->cend() && !(*piter)->extract())) {
        ++piter;
    }
    if (piter == c->cend()) {
        // set conversation end condition
        pos = nullptr;
        remain = 0;
    }
    // start at next part
    pos = (*piter)->start();
    remain = (*piter)->length();
}

void ConversationExtractor::read(char *dest, std::size_t len) {
    if (remain < len) {
        DUDS_THROW_EXCEPTION(ConversationReadPastEnd());
    }
    std::memcpy(dest, pos, len);
    advance(len);
}

} } }