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**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
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** This file is part of Qt Creator.
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** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
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#include "basicproposalitemlistmodel.h"
#include "basicproposalitem.h"
#include "texteditorsettings.h"
#include "completionsettings.h"

#include <QDebug>
#include <QRegExp>
#include <QtAlgorithms>
#include <QHash>

#include <algorithm>

using namespace TextEditor;

uint qHash(const BasicProposalItem &item)
{
    return qHash(item.text());
}

namespace {

const int kMaxSort = 1000;
const int kMaxPrefixFilter = 100;

struct ContentLessThan
{
    bool operator()(const BasicProposalItem *a, const BasicProposalItem *b)
    {
        // If order is different, show higher ones first.
        if (a->order() != b->order())
            return a->order() > b->order();

        // The order is case-insensitive in principle, but case-sensitive when this
        // would otherwise mean equality
        const QString &lowera = a->text().toLower();
        const QString &lowerb = b->text().toLower();
        if (lowera == lowerb)
            return lessThan(a->text(), b->text());
        else
            return lessThan(lowera, lowerb);
    }

    bool lessThan(const QString &a, const QString &b)
    {
        QString::const_iterator pa = a.begin();
        QString::const_iterator pb = b.begin();

        CharLessThan charLessThan;
        enum { Letter, SmallerNumber, BiggerNumber } state = Letter;
        for (; pa != a.end() && pb != b.end(); ++pa, ++pb) {
            if (*pa == *pb)
                continue;
            if (state != Letter) {
                if (!pa->isDigit() || !pb->isDigit())
                    break;
            } else if (pa->isDigit() && pb->isDigit()) {
                if (charLessThan(*pa, *pb))
                    state = SmallerNumber;
                else
                    state = BiggerNumber;
            } else {
                return charLessThan(*pa, *pb);
            }
        }

        if (state == Letter)
            return pa == a.end() && pb != b.end();
        if (pa != a.end() && pa->isDigit())
            return false;                   //more digits
        if (pb != b.end() && pb->isDigit())
            return true;                    //fewer digits
        return state == SmallerNumber;      //same length, compare first different digit in the sequence
    }

    struct CharLessThan
    {
        bool operator()(const QChar &a, const QChar &b)
        {
            if (a == QLatin1Char('_'))
                return false;
            else if (b == QLatin1Char('_'))
                return true;
            else
                return a < b;
        }
    };
};

} // Anonymous

BasicProposalItemListModel::BasicProposalItemListModel()
{}

BasicProposalItemListModel::BasicProposalItemListModel(const QList<BasicProposalItem *> &items)
    : m_originalItems(items)
    , m_currentItems(items)
{
    mapPersistentIds();
}

BasicProposalItemListModel::~BasicProposalItemListModel()
{
    qDeleteAll(m_originalItems);
}

void BasicProposalItemListModel::loadContent(const QList<BasicProposalItem *> &items)
{
    m_originalItems = items;
    m_currentItems = items;
    mapPersistentIds();
}

void BasicProposalItemListModel::mapPersistentIds()
{
    for (int i = 0; i < m_originalItems.size(); ++i)
        m_idByText.insert(m_originalItems.at(i)->text(), i);
}

void BasicProposalItemListModel::reset()
{
    m_currentItems = m_originalItems;
}

int BasicProposalItemListModel::size() const
{
    return m_currentItems.size();
}

QString BasicProposalItemListModel::text(int index) const
{
    return m_currentItems.at(index)->text();
}

QIcon BasicProposalItemListModel::icon(int index) const
{
    return m_currentItems.at(index)->icon();
}

QString BasicProposalItemListModel::detail(int index) const
{
    return m_currentItems.at(index)->detail();
}

void BasicProposalItemListModel::removeDuplicates()
{
    QHash<QString, QVariant> unique;
    QList<BasicProposalItem *>::iterator it = m_originalItems.begin();
    while (it != m_originalItems.end()) {
        const BasicProposalItem *item = *it;
        if (unique.contains(item->text())
                && unique.value(item->text(), QVariant()) == item->data()) {
            it = m_originalItems.erase(it);
        } else {
            unique.insert(item->text(), item->data());
            ++it;
        }
    }
}

void BasicProposalItemListModel::filter(const QString &prefix)
{
    if (prefix.isEmpty())
        return;

    /*
     * This code builds a regular expression in order to more intelligently match
     * camel-case style. This means upper-case characters will be rewritten as follows:
     *
     *   A => [a-z0-9_]*A (for any but the first capital letter)
     *
     * Meaning it allows any sequence of lower-case characters to preceed an
     * upper-case character. So for example gAC matches getActionController.
     *
     * It also implements the first-letter-only case sensitivity.
     */
    const TextEditor::CaseSensitivity caseSensitivity =
        TextEditorSettings::instance()->completionSettings().m_caseSensitivity;

    QString keyRegExp;
    keyRegExp += QLatin1Char('^');
    bool first = true;
    const QLatin1String wordContinuation("[a-z0-9_]*");
    foreach (const QChar &c, prefix) {
        if (caseSensitivity == TextEditor::CaseInsensitive ||
            (caseSensitivity == TextEditor::FirstLetterCaseSensitive && !first)) {

            keyRegExp += QLatin1String("(?:");
            if (c.isUpper() && !first)
                keyRegExp += wordContinuation;
            keyRegExp += QRegExp::escape(c.toUpper());
            keyRegExp += QLatin1Char('|');
            keyRegExp += QRegExp::escape(c.toLower());
            keyRegExp += QLatin1Char(')');
        } else {
            if (c.isUpper() && !first)
                keyRegExp += wordContinuation;
            keyRegExp += QRegExp::escape(c);
        }

        first = false;
    }
    QRegExp regExp(keyRegExp);

    m_currentItems.clear();
    for (QList<BasicProposalItem *>::const_iterator it = m_originalItems.begin();
         it != m_originalItems.end();
         ++it) {
        BasicProposalItem *item = *it;
        if (regExp.indexIn(item->text()) == 0)
            m_currentItems.append(item);
    }
}

bool BasicProposalItemListModel::isSortable(const QString &prefix) const
{
    Q_UNUSED(prefix);

    if (m_currentItems.size() < kMaxSort)
        return true;
    return false;
}

void BasicProposalItemListModel::sort()
{
    qStableSort(m_currentItems.begin(), m_currentItems.end(), ContentLessThan());
}

int BasicProposalItemListModel::persistentId(int index) const
{
    return m_idByText.value(m_currentItems.at(index)->text());
}

bool BasicProposalItemListModel::supportsPrefixExpansion() const
{
    return true;
}

bool BasicProposalItemListModel::keepPerfectMatch(AssistReason reason) const
{
    return reason != IdleEditor;
}

QString BasicProposalItemListModel::proposalPrefix() const
{
    if (m_currentItems.size() >= kMaxPrefixFilter || m_currentItems.isEmpty())
        return QString();

    // Compute common prefix
    QString commonPrefix = m_currentItems.first()->text();
    for (int i = 1, ei = m_currentItems.size(); i < ei; ++i) {
        QString nextItem = m_currentItems.at(i)->text();
        const int length = qMin(commonPrefix.length(), nextItem.length());
        commonPrefix.truncate(length);
        nextItem.truncate(length);

        while (commonPrefix != nextItem) {
            commonPrefix.chop(1);
            nextItem.chop(1);
        }

        if (commonPrefix.isEmpty()) // there is no common prefix, so return.
            return commonPrefix;
    }

    return commonPrefix;
}

IAssistProposalItem *BasicProposalItemListModel::proposalItem(int index) const
{
    return m_currentItems.at(index);
}

QPair<QList<BasicProposalItem *>::iterator,
      QList<BasicProposalItem *>::iterator>
BasicProposalItemListModel::currentItems()
{
    return qMakePair(m_currentItems.begin(), m_currentItems.end());
}
