source: tags/arb-7.0.1/PRIMER_DESIGN/PRD_Design.cxx

// =============================================================== //
//                                                                 //
//   File      : PRD_Design.cxx                                    //
//   Purpose   :                                                   //
//                                                                 //
//   Coded by Wolfram Foerster in February 2001                    //
//   Institute of Microbiology (Technical University Munich)       //
//   http://www.arb-home.de/                                       //
//                                                                 //
// =============================================================== //

#include "PRD_Design.hxx"
#include "PRD_SequenceIterator.hxx"
#include "PRD_SearchFIFO.hxx"
#include <arb_progress.h>

#include <iostream>

#include <cmath>

using std::printf;
using std::deque;
using std::cout;
using std::endl;
using std::pair;

//
// Constructor
//
void PrimerDesign::init (const char *sequence_, long int seqLength_,
                         Range       pos1_, Range pos2_, Range length_, Range distance_,
                         Range       ratio_, Range temperature_, int min_dist_to_next_, bool expand_IUPAC_Codes_,
                         int         max_count_primerpairs_, double GC_factor_, double temp_factor_)
{
    error     = NULp;
    sequence  = sequence_;
    seqLength = seqLength_;
    root1     = NULp;
    root2     = NULp;
    list1     = NULp;
    list2     = NULp;
    pairs     = NULp;

    reset_node_counters();

    setPositionalParameters (pos1_, pos2_, length_, distance_);
    setConditionalParameters(ratio_, temperature_, min_dist_to_next_, expand_IUPAC_Codes_, max_count_primerpairs_, GC_factor_, temp_factor_);
}

PrimerDesign::PrimerDesign(const char *sequence_, long int seqLength_,
                            Range pos1_, Range pos2_, Range length_, Range distance_,
                            Range ratio_, Range temperature_, int min_dist_to_next_, bool expand_IUPAC_Codes_,
                            int   max_count_primerpairs_, double GC_factor_, double temp_factor_)
{
    init (sequence_, seqLength_, pos1_, pos2_, length_, distance_, ratio_, temperature_, min_dist_to_next_, expand_IUPAC_Codes_, max_count_primerpairs_, GC_factor_, temp_factor_);
}


PrimerDesign::PrimerDesign(const char *sequence_, long int seqLength_,
                            Range pos1_, Range pos2_, Range length_, Range distance_, int max_count_primerpairs_, double GC_factor_, double temp_factor_)
{
    init (sequence_, seqLength_, pos1_, pos2_, length_, distance_, Range(0, 0), Range(0, 0), -1, false, max_count_primerpairs_, GC_factor_, temp_factor_);
}


PrimerDesign::PrimerDesign(const char *sequence_,   long int seqLength_) {
    init (sequence_, seqLength_, Range(0, 0), Range(0, 0), Range(0, 0), Range(0, 0), Range(0, 0), Range(0, 0), -1, false, 10, 0.5, 0.5);
}


//
// Destructor
//
PrimerDesign::~PrimerDesign () {
    if (root1) delete root1;
    if (root2) delete root2;
    if (list1) delete list1;
    if (list2) delete list2;
    if (pairs) delete [] pairs;
}


void PrimerDesign::setPositionalParameters(Range pos1_, Range pos2_, Range length_, Range distance_) {
    // first take all parameters, then test em
    primer1         = (pos1_.min() < pos2_.min()) ? pos1_ : pos2_;
    primer2         = (pos1_.min() < pos2_.min()) ? pos2_ : pos1_;
    primer_length   = length_;
    primer_distance = distance_;

    // length > 0
    if ((length_.min() <= 0) || (length_.max() <= 0)) {
        error = "invalid primer length (length <= 0)";
        return;
    }

    // determine end of ranges
    SequenceIterator *i = new SequenceIterator(sequence, primer1.min(), SequenceIterator::IGNORE, primer1.max(), SequenceIterator::FORWARD);
    while (i->nextBase() != SequenceIterator::EOS) ;
    primer1.max(i->pos);
    i->restart(primer2.min(), SequenceIterator::IGNORE, primer2.max(), SequenceIterator::FORWARD);
    while (i->nextBase() != SequenceIterator::EOS) ;
    primer2.max(i->pos);

    // primer1.max > primer2_.min =>  distance must be given
    if ((primer2.min() <= primer1.max()) && (distance_.min() <= 0)) {
        error = "using overlapping primer positions you MUST give a primer distance";
        return;
    }

    // use distance-parameter ? (-1 = no)
    if (distance_.min() > 0) {
        // pos2_.max - pos1_.min must be greater than distance_.min
        if (distance_.min() > primer2.max() - primer1.min()) {
            error = "invalid minimal primer distance (more than right.max - left.min)";
            return;
        }
        // pos2_.min - pos1_.max must be less than distance_.max
        if (distance_.max() < primer2.min() - primer1.max()) {
            error = "invalid maximal primer distance (less than right.min - left.max)";
            return;
        }
    }
}


void  PrimerDesign::setConditionalParameters(Range ratio_, Range temperature_, int min_dist_to_next_, bool expand_IUPAC_Codes_, int max_count_primerpairs_, double GC_factor_, double temp_factor_) {
    if ((ratio_.min() < 0) || (ratio_.max() <= 0))
        GC_ratio = Range(-1, -1);
    else
        GC_ratio = ratio_;

    if ((temperature_.min() <= 0) || (temperature_.max() <= 0))
        temperature = Range (-1, -1);
    else
        temperature = temperature_;

    GC_factor                  = GC_factor_;
    temperature_factor         = temp_factor_;
    min_distance_to_next_match = min_dist_to_next_;
    expand_IUPAC_Codes         = expand_IUPAC_Codes_;
    max_count_primerpairs      = max_count_primerpairs_;

    if (pairs) delete [] pairs;
    pairs = new Pair[max_count_primerpairs];
}


//
// run the necessary steps .. abort on error
//
void PrimerDesign::run() {
#if defined(DUMP_PRIMER)
    printf("PrimerDesign : parameters are\n");
    primer1.print("left                    : ", "\n");
    primer2.print("right                   : ", "\n");
    primer_length.print("length                  : ", "\n");
    primer_distance.print("distance                : ", "\n");
    GC_ratio.print("GC ratio                : ", "\n");
    temperature.print("temperature             : ", "\n");
    printf("GC factor               : %f\n", GC_factor);
    printf("temp. factor            : %f\n", temperature_factor);
    printf("min. dist to next match : %i\n", min_distance_to_next_match);
    printf("expand IUPAC            : %s\n", expand_IUPAC_Codes ? "true" : "false");
    printf("error                   : %s\n", error);
#endif

    if (error) {
        printf("not run cause : %s\n", error);
        return;
    }

#if defined(DUMP_PRIMER)
    printf("sizeof(Node) = %zu\n", sizeof(Node));
#endif // DEBUG

    buildPrimerTrees();
    if (error) return;
#if defined(DUMP_PRIMER)
    printPrimerTrees();
#endif

    matchSequenceAgainstPrimerTrees();
    if (error) return;
#if defined(DUMP_PRIMER)
    printPrimerTrees();
#endif

    arb_progress::show_comment("evaluating primer pairs");
    convertTreesToLists();
    if (error) return;
#if defined(DUMP_PRIMER)
    printPrimerLists();
#endif

    evaluatePrimerPairs();
    if (error) return;
#if defined(DUMP_PRIMER)
    printPrimerPairs();
#endif
}

//
// (re)construct raw primer trees
//

// add new child to parent or update existing child
// returns child_index
int PrimerDesign::insertNode (Node *current_, unsigned char base_, PRD_Sequence_Pos pos_, int delivered_, int offset_, int left_, int right_) {
    int  index     = CHAR2CHILD.INDEX[base_];
    bool is_primer = primer_length.includes(delivered_);   // new child is primer if true

    //
    // create new node if necessary or update existing node if its a primer
    //
    if (!current_->child[index]) {
        total_node_counter_left  += left_;
        total_node_counter_right += right_;

        if (is_primer) {
            current_->child[index]     = new Node (current_, base_, pos_, offset_); // primer => new child with positive last_base_index
            primer_node_counter_left  += left_;
            primer_node_counter_right += right_;
        }
        else {
            current_->child[index] = new Node (current_, base_, 0); // no primer => new child with zero position

        }
        current_->child_bits |= CHAR2BIT.FIELD[base_];                              // update child_bits of current node
    }
    else {
        if (is_primer) {
            current_->child[index]->last_base_index = -pos_;                          // primer, but already exists => set pos to negative
            primer_node_counter_left  -= left_;
            primer_node_counter_right -= right_;
        }
    }

    return index;
}

// check if (sub)tree contains a valid primer
bool PrimerDesign::treeContainsPrimer (Node *start) {
    if (start->isValidPrimer()) return true;

    for (int i = 0; i < 4; i++) {
        if (start->child[i]) {
            if (treeContainsPrimer(start->child[i])) return true;
        }
    }

    return false;
}

// remove non-primer-leafs and branches from the tree
void PrimerDesign::clearTree (Node *start, int left_, int right_) {
    // check children
    for (int i = 0; i < 4; i++)
        if (start->child[i]) clearTree(start->child[i], left_, right_);

    // check self
    if (start->isLeaf() && !start->isValidPrimer() && start->parent) {
        total_node_counter_left   -= left_;
        total_node_counter_right  -= right_;

        // remove self from parent
        start->parent->child[CHAR2CHILD.INDEX[start->base]] = NULp;
        start->parent->child_bits &= ~CHAR2BIT.FIELD[start->base];

        // erase node
        delete start;
    }
}

void PrimerDesign::buildPrimerTrees () {
    arb_progress progress("searching possible primers",
                          primer1.max()+primer2.max()-2*primer_length.min());

#if defined(DUMP_PRIMER)
    primer1.print("buildPrimerTrees : pos1\t\t", "\n");
    primer2.print("buildPrimerTrees : pos2\t\t", "\n");
    primer_length.print("buildPrimerTrees : length\t", "\n");
    printf("buildPrimerTrees : (pos,base,delivered,last_base_index)\n");
#endif

    //
    // destroy old trees if exist
    //
    if (root1) delete root1;
    if (root2) delete root2;
    root1 = new Node;
    root2 = new Node;

    reset_node_counters();

    // init iterator with sequence
    SequenceIterator *sequence_iterator = new SequenceIterator(sequence);
    char  base;
    int   child_index;
    Node *current_node;
    int   offset = 0;

    //
    // init. offset-counter
    //
    sequence_iterator->restart(0, primer1.min(), SequenceIterator::IGNORE, SequenceIterator::FORWARD);  // start at 1st absolute pos in aligned seq.
    while (sequence_iterator->nextBase() != SequenceIterator::EOS)                                      // count bases till left range
        offset++;

    //
    // build first tree
    //
    for (PRD_Sequence_Pos start_pos = primer1.min();
          (start_pos < primer1.max()-primer_length.min()) && (sequence[start_pos] != '\x00');
          start_pos++)
    {
        // start iterator at new position
        sequence_iterator->restart(start_pos, primer1.max(), primer_length.max(), SequenceIterator::FORWARD);
        sequence_iterator->nextBase();
        if (sequence_iterator->pos != start_pos) {   // sequence_iterator has skipped spaces = > restart at first valid base
            start_pos                                                                        = sequence_iterator->pos;
        }
        sequence_iterator->restart(start_pos, primer1.max(), primer_length.max(), SequenceIterator::FORWARD);

        // start at top of tree
        current_node = root1;

        // iterate through sequence till end-of-sequence or primer_length.max bases read
        base = sequence_iterator->nextBase();
        while (base != SequenceIterator::EOS) {
            if (! ((base == 'A') || (base == 'T') || (base == 'U') || (base == 'C') || (base == 'G'))) break;  // stop at IUPAC-Codes
            child_index  = insertNode(current_node, base, sequence_iterator->pos, sequence_iterator->delivered, offset, 1, 0);
            current_node = current_node->child[child_index];

            // get next base
            base = sequence_iterator->nextBase();
        }

        offset++;
        progress.inc();
    }

    //
    // clear left tree
    //
#if defined(DUMP_PRIMER)
    printf ("           %li nodes left (%li primers)   %li nodes right (%li primers)\n", total_node_counter_left, primer_node_counter_left, total_node_counter_right, primer_node_counter_right);
    printf ("           clearing left tree\n");
#endif
    clearTree(root1, 1, 0);
#if defined(DUMP_PRIMER)
    printf ("           %li nodes left (%li primers)   %li nodes right (%li primers)\n", total_node_counter_left, primer_node_counter_left, total_node_counter_right, primer_node_counter_right);
#endif

    //
    // count bases till right range
    //
    sequence_iterator->restart(sequence_iterator->pos, primer2.min(), SequenceIterator::IGNORE, SequenceIterator::FORWARD); // run from current pos
    while (sequence_iterator->nextBase() != SequenceIterator::EOS)                                                        // till begin of right range
        offset++;

    if (!treeContainsPrimer(root1)) {
        error = "no primer in left range found .. maybe only spaces in that range ?";
        delete sequence_iterator;
        return;
    }

    //
    // build second tree
    //
    for (PRD_Sequence_Pos start_pos = primer2.min();
          (start_pos < primer2.max()-primer_length.min()) && (sequence[start_pos] != '\x00');
          start_pos++)
    {
        // start iterator at new position
        sequence_iterator->restart(start_pos, primer2.max(), primer_length.max(), SequenceIterator::FORWARD);
        sequence_iterator->nextBase();
        if (sequence_iterator->pos != start_pos) {   // sequence_iterator has skipped spaces = > restart at first valid base
            start_pos                                                                        = sequence_iterator->pos;
        }
        sequence_iterator->restart(start_pos, primer2.max(), primer_length.max(), SequenceIterator::FORWARD);

        // start at top of tree
        current_node = root2;

        // iterate through sequence till end-of-sequence or primer_length.max bases read
        base = sequence_iterator->nextBase();
        while (base != SequenceIterator::EOS) {
            if (! ((base == 'A') || (base == 'T') || (base == 'U') || (base == 'C') || (base == 'G'))) break;  // stop at unsure bases
            child_index = insertNode(current_node, base, sequence_iterator->pos, sequence_iterator->delivered, offset+sequence_iterator->delivered, 0, 1);
            current_node = current_node->child[child_index];

            // get next base
            base = sequence_iterator->nextBase();
        }

        offset++;
        progress.inc();
    }
    progress.done();

    if (!treeContainsPrimer(root2)) {
        error = "no primer in right range found .. maybe only spaces in that range ?";
    }

    delete sequence_iterator;

    //
    // clear left tree
    //
#if defined(DUMP_PRIMER)
    printf ("           %li nodes left (%li primers)   %li nodes right (%li primers)\n", total_node_counter_left, primer_node_counter_left, total_node_counter_right, primer_node_counter_right);
    printf ("           clearing right tree\n");
#endif
    clearTree(root2, 0, 1);
#if defined(DUMP_PRIMER)
    printf ("           %li nodes left (%li primers)   %li nodes right (%li primers)\n", total_node_counter_left, primer_node_counter_left, total_node_counter_right, primer_node_counter_right);
#endif
}


//
// print all primers in trees
//
PRD_Sequence_Pos PrimerDesign::followUp(Node *node_, deque<char> *primer_, int direction_) {
    if (direction_ == FORWARD) primer_->push_front(node_->base);
    else primer_->push_back(node_->base);

    if (!node_->parent) return node_->last_base_index;
    else followUp(node_->parent, primer_, direction_);
    return 0;
}

void PrimerDesign::findNextPrimer(Node *start_at_, int depth_, int *counter_, int direction_) {
    // current node
    printf ("findNextPrimer : start_at_ [ %c,%4li,%2i (%c %c %c %c) ]\n",
              start_at_->base,
              start_at_->last_base_index,
              start_at_->child_bits,
              start_at_->child[1] ? 'G' : ' ',
              start_at_->child[0] ? 'C' : ' ',
              start_at_->child[3] ? 'T' : ' ',
              start_at_->child[3] ? 'X' : ' ');

    if (primer_length.includes(depth_) && start_at_->isValidPrimer())
        depth_++;
    for (int i=0; i < 4; i++)
        if (start_at_->child[i]) findNextPrimer(start_at_->child[i],     depth_, counter_, direction_);
}

#if defined(DUMP_PRIMER)
void PrimerDesign::printPrimerTrees () {
    // start at root1 with zero depth
    int primer_counter;
    primer_counter = 0;
    cout << "findNextPrimer : depth  last_base:index  first_base:index  base" << endl;
    findNextPrimer(root1, 0, &primer_counter, FORWARD);
    cout << "printPrimerTrees : " << primer_counter << " primer found" << endl << endl;

    // start at root2 with zero depth
    primer_counter = 0;
    cout << "findNextPrimer : depth  last_base:index  first_base:index  base" << endl;
    findNextPrimer(root2, 0, &primer_counter, BACKWARD);
    cout << "printPrimerTrees : " << primer_counter << " primer found" << endl;
}
#endif


//
// match the sequence against the primer-trees
//
void PrimerDesign::matchSequenceAgainstPrimerTrees() {
    SearchFIFO       *fifo1             = new SearchFIFO(root1, min_distance_to_next_match, expand_IUPAC_Codes);
    SearchFIFO       *fifo2             = new SearchFIFO(root2, min_distance_to_next_match, expand_IUPAC_Codes);
    SequenceIterator *sequence_iterator = new SequenceIterator(sequence, 0, SequenceIterator::IGNORE, SequenceIterator::IGNORE, SequenceIterator::FORWARD);
    char              base;
    PRD_Sequence_Pos  pos               = sequence_iterator->pos;

#if defined(DUMP_PRIMER)
    printf("root1 : [C %p, G %p, A %p, TU %p]\n", root1->child[0], root1->child[1], root1->child[2], root1->child[3]);
    printf("root2 : [C %p, G %p, A %p, TU %p]\n", root2->child[0], root2->child[1], root2->child[2], root2->child[3]);
#endif

    arb_progress progress(seqLength*2);

    progress.subtitle("match possible primers vs. seq. (forward)");

    base = sequence_iterator->nextBase();
    while (base != SequenceIterator::EOS) {
        pos = sequence_iterator->pos;

        // tree/fifo 1
        if (primer1.includes(pos)) {     // flush fifo1 if in range of Primer 1
            fifo1->flush();
        }
        else {
            // iterate through fifo1
            fifo1->iterateWith(pos, base);

            // append base to fifo1
            fifo1->push(pos);
        }

        // tree/fifo2
        if (primer2.includes(pos)) {     // flush fifo2 if in range of Primer 2
            fifo2->flush();
        }
        else {
            // iterate through fifo2
            fifo2->iterateWith(pos, base);

            // append base to fifo2
            fifo2->push(pos);
        }

        // get next base in sequence
        base = sequence_iterator->nextBase();
        progress.inc();
    }

    sequence_iterator->restart(pos, 0, SequenceIterator::IGNORE, SequenceIterator::BACKWARD);
    fifo1->flush();
    fifo2->flush();

    progress.subtitle("match possible primers vs. seq. (backward)");
    base = INVERT.BASE[sequence_iterator->nextBase()];
    while (base != SequenceIterator::EOS) {
        pos = sequence_iterator->pos;

        // tree/fifo 1
        if (primer1.includes(pos)) {     // flush fifo1 if in range of Primer 1
            fifo1->flush();
        }
        else {
            // iterate through fifo1
            fifo1->iterateWith(pos, base);

            // append base to fifo1
            fifo1->push(pos);
        }

        // tree/fifo2
        if (primer2.includes(pos)) {     // flush fifo2 if in range of Primer 2
            fifo2->flush();
        }
        else {
            // iterate through fifo2
            fifo2->iterateWith(pos, base);

            // append base to fifo2
            fifo2->push(base);
        }

        // get next base in sequence
        base = INVERT.BASE[sequence_iterator->nextBase()];
        progress.inc();
    }
    progress.done();

    delete fifo1;
    delete fifo2;
    delete sequence_iterator;

    if (!treeContainsPrimer(root1)) {
        error = "no primer in left range after match vs. sequence .. maybe some clustered IUPAC-Codes in sequence ?";
        return;
    }

    if (!treeContainsPrimer(root2)) {
        error = "no primer in right range after match vs. sequence .. maybe some clustered IUPAC-Codes in sequence ?";
    }
}


//
// convertTreesToLists
//
// this also checks GC-ratio, temperature and distance
//
void PrimerDesign::calcGCandAT (int &GC_, int &AT_, Node *start_at_) {
    if (!start_at_) return;

    if ((start_at_->base == 'C') || (start_at_->base == 'G'))
        GC_++;
    else
        AT_++;

    calcGCandAT(GC_, AT_, start_at_->parent);
}

void PrimerDesign::convertTreesToLists () {
#if defined(DUMP_PRIMER)
    GC_ratio.print("convertTreesToLists : GC_ratio ", "  ");
    temperature.print("temperature ", "  ");
    primer_distance.print("primer_distance ", "\n");
#endif

    Node             *cur_node;
    Item             *cur_item;
    Item             *new_item;
    int               depth;
    int               AT;
    int               GC;
    bool              GC_and_temperature_matched;
    PRD_Sequence_Pos  min_offset_1 = PRD_MAX_SEQUENCE_POS;
    PRD_Sequence_Pos  max_offset_1 = -1;
    PRD_Sequence_Pos  min_offset_2 = PRD_MAX_SEQUENCE_POS;
    PRD_Sequence_Pos  max_offset_2 = -1;
    pair< Node*, int > new_pair;     // < cur_node->child[i], depth >
    deque< pair<Node*, int> > *stack;

    //
    // list 1
    //
    cur_item = NULp;
    stack = new deque< pair<Node*, int> >;
    // push children of root on stack
    for (int index = 0; index < 4; index++)
        if (root1->child[index]) {
            new_pair = pair<Node*, int>(root1->child[index], 1);
            stack->push_back(new_pair);
        }

    if (!stack->empty()) {
        GC_and_temperature_matched = false;

        while (!stack->empty()) {
            // next node
            cur_node = stack->back().first;
            depth    = stack->back().second;
            stack->pop_back();

            // handle node
            if (primer_length.includes(depth) && cur_node->isValidPrimer()) {
                // calculate conditional parameters
                GC = AT = 0;
                calcGCandAT(GC, AT, cur_node);
                AT = 4*GC + 2*AT;
                GC = (GC * 100) / depth;

                // create new item if conditional parameters are in range
                if (GC_ratio.includes(GC) && temperature.includes(AT)) {
                    GC_and_temperature_matched = true;
                    new_item = new Item(cur_node->last_base_index, cur_node->offset, depth, GC, AT, NULp);

                    // begin list with new item or append to list
                    if (!cur_item) list1 = new_item;
                    else cur_item->next  = new_item;

                    cur_item = new_item;

                    // store position
                    if (cur_node->offset < min_offset_1) min_offset_1 = cur_node->offset;
                    if (cur_node->offset > max_offset_1) max_offset_1 = cur_node->offset;
                }
            }

            // push children on stack
            for (int index = 0; index < 4; index++)
                if (cur_node->child[index]) {
                    new_pair = pair<Node*, int>(cur_node->child[index], depth+1);
                    stack->push_back(new_pair);
                }
        }
        if (!GC_and_temperature_matched) {
            error = "no primer over left range matched the given GC-Ratio/Temperature";
            delete stack;
            return;
        }
    }
    else {
        error = "convertTreesToLists : primertree over left range was empty :( ?";
        delete stack;
        return;
    }

#if defined(DUMP_PRIMER)
    printf("convertTreesToLists : list1 : min_offset %7li  max_offset %7li\n", min_offset_1, max_offset_1);
#endif

    //
    // list 2
    //
    cur_item = NULp;
    stack->clear();
    bool distance_matched = false;
    // push children of root on stack
    for (int index = 0; index < 4; index++)
        if (root2->child[index]) {
            new_pair = pair<Node*, int>(root2->child[index], 1);
            stack->push_back(new_pair);
        }

    if (!stack->empty()) {
        GC_and_temperature_matched = false;

        while (!stack->empty()) {
            // next node
            cur_node = stack->back().first;
            depth    = stack->back().second;
            stack->pop_back();

            // push children on stack
            for (int index = 0; index < 4; index++)
                if (cur_node->child[index]) {
                    new_pair = pair<Node*, int>(cur_node->child[index], depth+1);
                    stack->push_back(new_pair);
                }

            // handle node
            if (primer_length.includes(depth) && cur_node->isValidPrimer()) {
                // check position
                if (primer_distance.min() > 0) {
                    distance_matched = primer_distance.includes(cur_node->offset-max_offset_1, cur_node->offset-min_offset_1);
                    if (!distance_matched) continue;
                }

                // calculate conditional parameters
                GC = AT = 0;
                calcGCandAT(GC, AT, cur_node);
                AT = 4*GC + 2*AT;
                GC = (GC * 100) / depth;

                // create new item if conditional parameters are in range
                if (GC_ratio.includes(GC) && temperature.includes(AT)) {
                    GC_and_temperature_matched = true;
                    new_item = new Item(cur_node->last_base_index, cur_node->offset, depth, GC, AT, NULp);

                    // begin list with new item or append to list
                    if (!cur_item) list2 = new_item;
                    else cur_item->next  = new_item;

                    cur_item = new_item;

                    // store position
                    if (cur_node->offset < min_offset_2) min_offset_2 = cur_node->offset;
                    if (cur_node->offset > max_offset_2) max_offset_2 = cur_node->offset;
                }
            }
        }

        if (primer_distance.min() > 0) {
            if (!distance_matched) {
                error = "no primer over right range was in reach of primers in left range .. check distance parameter";
                delete stack;
                return;
            }
        }

        if (!GC_and_temperature_matched) {
            error = "no primer over right range matched the given GC-Ratio and Temperature";
            delete stack;
            return;
        }
    }
    else {
        error = "convertTreesToLists : primertree over right range was empty :( ?";
        delete stack;
        return;
    }

    delete stack;

#if defined(DUMP_PRIMER)
    printf("convertTreesToLists : list2 : min_offset %7li  max_offset %7li\n", min_offset_2, max_offset_2);
#endif

    //
    // check positions of list1
    //
    if (primer_distance.min() > 0) {    // skip check if primer_distance < 0
        Item *to_remove = NULp;
        cur_item = list1;

        while (cur_item) {
            if (!primer_distance.includes(max_offset_2-cur_item->offset, min_offset_2-cur_item->offset)) {
                // primer in list 1 out of range of primers in list 2 => remove from list 1

                if (cur_item == list1) {
                    // 'to delete'-item is first in list
                    list1 = list1->next;                                // list 1 starts with next item
                    delete cur_item;                            // delete former first item
                    cur_item = list1;                           // new first item is next to be examined
                }
                else {
                    // run through list till 'next' is to delete
                    to_remove = cur_item;                               // remember 'to delete'-item
                    cur_item  = list1;                          // start at first
                    while (cur_item ->next != to_remove)        // run till 'next' is 'to delete'
                        cur_item = cur_item->next;
                    cur_item->next = cur_item->next->next;      // unlink 'next' from list
                    cur_item = cur_item->next;                  // 'next' of 'to delete' is next to be examined
                    delete to_remove;                           // ...
                }
            }
            else
                cur_item = cur_item->next;
        }

        int counter = 0;
        for (cur_item = list1; cur_item; cur_item = cur_item->next)
            counter++;
        if (counter == 0) {
            error = "no primers over left range are in reach of primers over right range .. check distance parameter";
            return;
        }
    }

    int counter = 0;
    for (cur_item = list1; cur_item; cur_item = cur_item->next)
        counter++;
    if (counter == 0) {
        error = "no primers left in left range after GC-ratio/Temperature/Distance - Check";
        return;
    }

    counter = 0;
    for (cur_item = list2; cur_item; cur_item = cur_item->next)
        counter++;
    if (counter == 0) {
        error = "no primers left in right range after GC-ratio/Temperature/Distance - Check";
        return;
    }
}


//
// printPrimerLists
//
#if defined(DUMP_PRIMER)
void PrimerDesign::printPrimerLists () {
    int count = 0;

    printf("printPrimerLists : list 1 : [(start_pos,offset,length), GC_ratio, temperature]\n");
    Item *current = list1;
    while (current) {
        current->print("", "\n");
        current = current->next;
        count++;
    }
    printf(" : %i valid primers\nprintPrimerLists : list 2 : [(start_pos,offset,length), GC_ratio, temperature]\n", count);
    count = 0;
    current = list2;
    while (current) {
        current->print("", "\n");
        current = current->next;
        count++;
    }
    printf(" : %i valid primers\n", count);
}
#endif



//
// evaluatePrimerPairs
//
inline double PrimerDesign::evaluatePair (Item *one_, Item *two_) {
    if ((!one_) || (!two_))
        return -1.0;

    return abs(one_->GC_ratio - two_->GC_ratio)*GC_factor + abs(one_->temperature - two_->temperature)*temperature_factor;
}

void PrimerDesign::insertPair(double rating_, Item *one_, Item *two_) {
    int index = -1;

    // search position
    for (int i = max_count_primerpairs-1; (i >= 0) && (index == -1); i--) {
        // maybe insert new pair ?
        if (pairs[i].rating >= rating_) {
            index = i+1;
        }
    }

    if (index == -1) index = 0;

    // swap till position
    for (int i = max_count_primerpairs-2; i >= index; i--) {
        pairs[i+1].rating = pairs[i].rating;
        pairs[i+1].one    = pairs[i].one;
        pairs[i+1].two    = pairs[i].two;
    }

    // insert new values
    pairs[index].rating = rating_;
    pairs[index].one    = one_;
    pairs[index].two    = two_;

#if defined(DUMP_PRIMER)
    printf("insertPair : [%3i] %6.2f\n", index, rating_);
#endif
}

void PrimerDesign::evaluatePrimerPairs () {
    Item    *one = list1;
    Item    *two;
    double   rating;
    long int counter = 0;

#if defined(DUMP_PRIMER)
    printf ("evaluatePrimerPairs : ...\ninsertPair : [index], rating\n");
#endif

    long list1_elems = 0;
    while (one) {
        list1_elems++;
        one = one->next;
    }
    one = list1;

    arb_progress progress("evaluating primer pairs", list1_elems);
    // outer loop <= > run through list1
    while (one) {
        // inner loop <= > run through list2
        two = list2;
        while (two) {
            // evaluate pair
            rating = evaluatePair(one, two);

            // test if rating is besster that the worst of the best
            if (rating > pairs[max_count_primerpairs-1].rating) {
                // insert in the pairs
                insertPair(rating, one, two);
                counter++;
            }

            // next in inner loop
            two = two->next;
        }

        // next in outer loop
        one = one->next;
        progress.inc();
    }

    if (counter == 0) error = "no primer pair could be found, sorry :(";

#if defined(DUMP_PRIMER)
    printf ("evaluatePrimerPairs : ratings [ %.3f .. %.3f ]\n\n", pairs[max_count_primerpairs-1].rating, pairs[0].rating);
#endif
}

#if defined(DUMP_PRIMER)
void PrimerDesign::printPrimerPairs () {
    printf ("printPairs [index] [rating ( primer1[(start_pos,offset,length),(GC,temp)] , primer2[(pos,offs,len),(GC,temp)])] \n");
    for (int i = 0; i < max_count_primerpairs; i++) {
        printf("printPairs : [%3i]", i);
        pairs[i].print("\t", "\n", sequence);
    }
}
#endif

const char *PrimerDesign::get_result(int num, const char *&primers, int max_primer_length, int max_position_length, int max_length_length) const {
    if ((num < 0) || (num >= max_count_primerpairs)) return NULp; // check for valid index
    if (!pairs[num].one || !pairs[num].two)          return NULp; // check for valid items at given index

    primers = pairs[num].get_primers(sequence);
    return pairs[num].get_result(sequence,   max_primer_length,  max_position_length,  max_length_length);
}