QAbstractItemModel Subclass duplicate entries

[pvdk]

Hello people,

I've successfully subclassed QAbstractItemModel to fit my needs. It acts as a frontend for the ls command. Ls feeds output in the following form to my model:

./parentfolder:
subfolder1/
subfolder2/

./parentfolder/subfolder1:
dir/
dir2/
textfile.txt

./parentfolder/subfolder1/dir:

./parentfolder/subfolder1/dir2:

./parentfolder/subfolder2:
textfile1.txt
textfile2.txt
textfile3.txt


And displays it like in the attached image.
The only thing I can't get fixed is the multiple occurence of parents. I've been struggeling with it the whole day so I hope someone with a fresh mind can see what's wrong with my code:


void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
{
QList<TreeItem*> parents;
QList<int> indentations;
parents << parent;
indentations << 0;

for( int r=0; r<lines.count(); r++ ) {
QString lineData = lines[r].trimmed();

if (!lineData.isEmpty()) {
qDebug() << QString(lineData) << "\n";

// Line is a dir
if (lineData.endsWith(":")) {
// Get rid of the colon
lineData.chop(1);

// Check if the string is a dot from the beginning of the ls output
if (lineData == ".") {
// Get rid of the string
lineData.clear();
}

// Check if the line starts with a dot and get rid of it before we replace the backslashes
if (lineData.startsWith("./")) {
lineData.replace(QString("./"), QString("/"));
}
qDebug() << lineData;

QStringList list = lineData.split("/", QString::SkipEmptyParts);
qDebug() << list << "start appending parent/child shit \n ";

// Reset the parent FIXME: horrible method
parents << parents.first();
for(int p = 0; p < list.size(); p++) {

QList<QVariant> column;
column << list[p];

parents.last()->appendChild(new TreeItem(column, parents.last()));
parents << parents.last()->child(parents.last()->childCount()-1);
}

} else if (lineData.endsWith("/")) {
qDebug() << "is a directory conjo!!!" << lineData << "\n";
} else {
QList<QVariant> column;
column << lineData;

parents.last()->appendChild(new TreeItem(column, parents.last()));
qDebug() << "appended file: " << lineData << "\n";
}
}
}
}

So, in short: I need my QAbstractItemModel to treat items with the same name under the same parent as one item, and not as duplicates.

Thanks in advance,
pvdk

[caduel]

You have to remember the last parent chain.
If the next directory chain (your list in line 31) shares a common prefix with the last line you parsed, then remove only all those parents that do not match.

Example:


path list parents
/a/b/c/d -> [a,b,c,d] [p1, p2, p3, p4]
/a/b/e -> [a,b,e]

Then you reduce parents to [p1, p2] and insert your new item under that chain.
You must not create a new parent chain all over for each line you parse.


Note: this algorithm assumes that the lines are sorted properly, which they should be in your case.

HTH

PS: I did not quite see where you "clear" your parent list.
Line 35 is beyond my understanding, too. Looks strange to me.
(I did not study your code in detail, sorry.)

[pvdk]

Hello caduel,

First of all hanks for your quick reply. I reply now because I was on vacation. Your suggestion put me on the right track but I still can't get it to work right. Could you explain your suggestion with a little more detail, maybe with code examples? As for your PS: that line is in there because it gave me the idea it worked a bit, but it should be replaced/removed with something better.

Thanks alot!

Regards,
pvdk

[caduel]

basically, replace

// Reset the parent FIXME: horrible method
parents << parents.first();
for(int p = 0; p < list.size(); p++) {
QList<QVariant> column;
column << list[p];

parents.last()->appendChild(new TreeItem(column, parents.last()));
parents << parents.last()->child(parents.last()->childCount()-1);
}


by



// store last parent directory chain in a QStringList
// add at top of your function
QStringList lLastDirChain;

...

// and then replace the code above by
QStringList common = common_prefix(lLastDirChain, list);
// remove the un-common dirs from parents
while (parents.count()>common.count()) parents.pop_back();

// now parents should be the common ones:
for(int p=common.count(); p<list.size(); ++p) {
QList<QVariant> column;
column << list[p];
TreeItem * const item = new TreeItem(column, parents.last());
parents.last()->appendChild(item);
parents << item;
}

lLastDirChain = list;


untested, probably does not compile. hopefully still helpful.

PS: use ++p instead of p++ (at least when free standing); faster for iterators.

PPS: common_prefix could be implemented as

static QStringList common_prefix(const QStringList &lhs, const QStringList &rhs)
{
QStringList res;
int minlen = qMin(lhs.count(), rhs.count());
for (int i=0; i<minlen; ++i)
{
if (lhs[i]==rhs[i])
res << lhs[i];
else break;
}
return res;
}