Long live Qt 4.5!

1 files changed, 508 insertions, 0 deletions

diff --git a/util/lexgen/nfa.cpp b/util/lexgen/nfa.cpp
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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the utils of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** 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
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#include "nfa.h"
+#include <QSet>
+#include <limits.h>
+
+NFA NFA::createSingleInputNFA(InputType input)
+{
+    NFA result;
+    result.initialize(2);
+    result.addTransition(result.initialState, input, result.finalState);
+    return result;
+}
+
+NFA NFA::createSymbolNFA(const QString &symbol)
+{
+    NFA result = NFA::createSingleInputNFA(Epsilon);
+    result.states[result.finalState].symbol = symbol;
+    return result;
+}
+
+void NFA::initialize(int size)
+{
+    states.resize(size);
+    states.fill(State());
+    initialState = 0;
+    finalState = size - 1;
+}
+
+void NFA::addTransition(int from, InputType input, int to)
+{
+    assertValidState(from);
+    assertValidState(to);
+
+    states[from].transitions.insertMulti(input, to);
+}
+
+void NFA::copyFrom(const NFA &other, int baseState)
+{
+    assertValidState(baseState);
+    assertValidState(baseState + other.states.count() - 1);
+
+    for (int i = 0; i < other.states.count(); ++i) {
+        State s = other.states.at(i);
+
+        for (TransitionMap::Iterator it = s.transitions.begin(),
+             end = s.transitions.end(); it != end; ++it)
+            *it += baseState;
+
+        states[baseState + i] = s;
+    }
+}
+
+void NFA::initializeFromPair(const NFA &a, const NFA &b,
+                             int *initialA, int *finalA,
+                             int *initialB, int *finalB)
+{
+    initialize(a.states.count() + b.states.count() + 2);
+
+    int baseIdxA = 1;
+    int baseIdxB = 1 + a.states.count();
+
+    *initialA = a.initialState + baseIdxA;
+    *finalA = a.finalState + baseIdxA;
+
+    *initialB = b.initialState + baseIdxB;
+    *finalB = b.finalState + baseIdxB;
+
+    copyFrom(a, baseIdxA);
+    copyFrom(b, baseIdxB);
+}
+
+NFA NFA::createAlternatingNFA(const NFA &a, const NFA &b)
+{
+    NFA result;
+
+    int newInitialA, newFinalA,
+        newInitialB, newFinalB;
+
+    result.initializeFromPair(a, b, &newInitialA, &newFinalA,
+                              &newInitialB, &newFinalB);
+
+    result.addTransition(result.initialState, Epsilon, newInitialA);
+    result.addTransition(result.initialState, Epsilon, newInitialB);
+
+    result.addTransition(newFinalA, Epsilon, result.finalState);
+    result.addTransition(newFinalB, Epsilon, result.finalState);
+
+    return result;
+}
+
+NFA NFA::createConcatenatingNFA(const NFA &a, const NFA &b)
+{
+    NFA result;
+
+    int initialA, finalA,
+        initialB, finalB;
+
+    result.initializeFromPair(a, b, &initialA, &finalA, &initialB, &finalB);
+
+    result.addTransition(result.initialState, Epsilon, initialA);
+    result.addTransition(finalA, Epsilon, initialB);
+    result.addTransition(finalB, Epsilon, result.finalState);
+    return result;
+}
+
+NFA NFA::createOptionalNFA(const NFA &a)
+{
+    NFA result;
+
+    result.initialize(a.states.count() + 2);
+
+    int baseIdxA = 1;
+    int initialA = a.initialState + baseIdxA;
+    int finalA = a.finalState + baseIdxA;
+
+    result.copyFrom(a, baseIdxA);
+
+    result.addTransition(result.initialState, Epsilon, initialA);
+    result.addTransition(result.initialState, Epsilon, result.finalState);
+
+    result.addTransition(finalA, Epsilon, initialA);
+    result.addTransition(finalA, Epsilon, result.finalState);
+
+    return result;
+}
+
+NFA NFA::createStringNFA(const QByteArray &str)
+{
+    NFA result;
+    foreach (char c, str) {
+        NFA ch = NFA::createSingleInputNFA(c);
+        if (result.isEmpty())
+            result = ch;
+        else
+            result = NFA::createConcatenatingNFA(result, ch);
+    }
+    return result;
+}
+
+NFA NFA::createSetNFA(const QSet<InputType> &set)
+{
+    NFA result;
+    result.initialize(set.count() + 2);
+
+    int state = 1;
+    for (QSet<InputType>::ConstIterator it = set.constBegin(), end = set.constEnd();
+         it != end; ++it, ++state) {
+        result.addTransition(result.initialState, Epsilon, state);
+        result.addTransition(state, *it, result.finalState);
+    }
+
+    /*
+    foreach (InputType input, set) {
+        NFA ch = NFA::createSingleInputNFA(input);
+        if (result.isEmpty())
+            result = ch;
+        else
+            result = NFA::createAlternatingNFA(result, ch);
+    }
+    */
+    return result;
+}
+
+NFA NFA::createZeroOrOneNFA(const NFA &a)
+{
+    NFA epsilonNFA = createSingleInputNFA(Epsilon);
+    return NFA::createAlternatingNFA(a, epsilonNFA);
+}
+
+NFA NFA::applyQuantity(const NFA &a, int minOccurrences, int maxOccurrences)
+{
+    NFA result = a;
+    NFA epsilonNFA = createSingleInputNFA(Epsilon);
+
+    if (minOccurrences == 0) {
+        result = NFA::createAlternatingNFA(result, epsilonNFA);
+    } else {
+        minOccurrences--;
+    }
+    maxOccurrences--;
+
+    for (int i = 0; i < minOccurrences; ++i)
+        result = NFA::createConcatenatingNFA(result, a);
+
+    for (int i = minOccurrences; i < maxOccurrences; ++i)
+        result = NFA::createConcatenatingNFA(result, NFA::createAlternatingNFA(a, epsilonNFA));
+
+    return result;
+}
+
+void NFA::debug()
+{
+    qDebug() << "NFA has" << states.count() << "states";
+    qDebug() << "initial state is" << initialState;
+    qDebug() << "final state is" << finalState;
+
+    for (int i = 0; i < states.count(); ++i) {
+        const State &s = states.at(i);
+        for (TransitionMap::ConstIterator it = s.transitions.constBegin(),
+             end = s.transitions.constEnd(); it != end; ++it)
+            qDebug() << "transition from state" << i << "to" << it.value() << "through"
+                     << (it.key() == Epsilon ? QString("Epsilon") : QString(char(it.key())));
+        if (!s.symbol.isEmpty())
+            qDebug() << "State" << i << "leads to symbol" << s.symbol;
+    }
+}
+
+// helper
+typedef QSet<int> DFAState;
+
+// that's a bad hash, but it's good enough for us
+// and it allows us to use the nice QHash API :)
+inline uint qHash(const DFAState &state)
+{
+    uint val = 0;
+    foreach (int s, state)
+        val |= qHash(s);
+    return val;
+}
+
+DFA NFA::toDFA() const
+{
+    DFA result;
+    result.reserve(states.count());
+
+    QHash<QString, int> symbolReferenceCounts;
+    {
+        QSet<int> symbolStates;
+        for (int i = 0; i < states.count(); ++i)
+            if (!states.at(i).symbol.isEmpty())
+                symbolStates.insert(i);
+
+        QHash<int, QString> epsilonStates;
+        for (int i = 0; i < states.count(); ++i) {
+            const State &s = states.at(i);
+            for (TransitionMap::ConstIterator transition = s.transitions.constBegin(), end = s.transitions.constEnd();
+                 transition != end; ++transition)
+                if (transition.key() == Epsilon && symbolStates.contains(transition.value()))
+                    epsilonStates.insert(i, states.at(transition.value()).symbol);
+        }
+
+        int lastCount;
+        do {
+            lastCount = epsilonStates.count();
+            for (int i = 0; i < states.count(); ++i) {
+                const State &s = states.at(i);
+                for (TransitionMap::ConstIterator transition = s.transitions.constBegin(), end = s.transitions.constEnd();
+                     transition != end; ++transition)
+                    if (transition.key() == Epsilon && epsilonStates.contains(transition.value()))
+                        epsilonStates.insert(i, epsilonStates.value(transition.value()));
+            }
+
+        } while (lastCount != epsilonStates.count());
+
+        for (int i = 0; i < states.count(); ++i) {
+            const State &s = states.at(i);
+            for (TransitionMap::ConstIterator transition = s.transitions.constBegin(), end = s.transitions.constEnd();
+                 transition != end; ++transition) {
+                if (transition.key() == Epsilon)
+                    continue;
+                if (symbolStates.contains(transition.value())) {
+                    const QString symbol = states.at(transition.value()).symbol;
+                    symbolReferenceCounts[symbol]++;
+                } else if (epsilonStates.contains(transition.value())) {
+                    const QString symbol = epsilonStates.value(transition.value());
+                    symbolReferenceCounts[symbol]++;
+                }
+            }
+        }
+        /*
+        for (QHash<QString, int>::ConstIterator symIt = symbolReferenceCounts.constBegin(), symEnd = symbolReferenceCounts.constEnd();
+             symIt != symEnd; ++symIt)
+            qDebug() << "symbol" << symIt.key() << "is reached" << symIt.value() << "times";
+            */
+    }
+
+    
+    QSet<InputType> validInput;
+    foreach (const State &s, states)
+        for (TransitionMap::ConstIterator it = s.transitions.constBegin(),
+             end = s.transitions.constEnd(); it != end; ++it)
+            if (it.key() != Epsilon)
+                validInput.insert(it.key());
+
+    // A DFA state can consist of multiple NFA states.
+    // the dfaStateMap maps from these to the actual
+    // state index within the resulting DFA vector
+    QHash<DFAState, int> dfaStateMap;
+    QStack<DFAState> pendingDFAStates;
+
+    DFAState startState = epsilonClosure(QSet<int>() << initialState);
+
+    result.resize(1);
+    dfaStateMap.insert(startState, 0);
+
+    pendingDFAStates.push(startState);
+
+    while (!pendingDFAStates.isEmpty()) {
+        DFAState state = pendingDFAStates.pop();
+//        qDebug() << "processing" << state << "from the stack of pending states";
+
+        foreach (InputType input, validInput) {
+
+            QSet<int> reachableStates;
+
+            foreach (int nfaState, state) {
+                const TransitionMap &transitions = states.at(nfaState).transitions;
+                TransitionMap::ConstIterator it = transitions.find(input);
+                while (it != transitions.constEnd() && it.key() == input) {
+                    reachableStates.insert(it.value());
+                    ++it;
+                }
+            }
+
+            if (reachableStates.isEmpty())
+                continue;
+
+//            qDebug() << "can reach" << reachableStates << "from input" << char(input);
+
+            QSet<int> closure = epsilonClosure(reachableStates);
+
+//            qDebug() << "closure is" << closure;
+
+            if (!dfaStateMap.contains(closure)) {
+                int dfaState = result.count();
+                result.append(State());
+
+                QString symbol;
+                int refCount = INT_MAX;
+                foreach (int nfaState, closure)
+                    if (!states.at(nfaState).symbol.isEmpty()) {
+//                        qDebug() << "closure also contains symbol" << states.at(nfaState).symbol;
+                        QString candidate = states.at(nfaState).symbol;
+                        int candidateRefCount =symbolReferenceCounts.value(candidate, INT_MAX);
+                        if (candidateRefCount < refCount) {
+                            refCount = candidateRefCount;
+                            symbol = candidate;
+                        }
+                    }
+                if (!symbol.isEmpty())
+                    result.last().symbol = symbol;
+
+                dfaStateMap.insert(closure, dfaState);
+
+                Q_ASSERT(!pendingDFAStates.contains(closure));
+                pendingDFAStates.prepend(closure);
+            }
+
+            result[dfaStateMap.value(state)].transitions.insert(input, dfaStateMap.value(closure));
+        }
+    }
+
+    return result;
+}
+
+QSet<int> NFA::epsilonClosure(const QSet<int> &initialClosure) const
+{
+    QSet<int> closure = initialClosure;
+    closure.reserve(closure.count() * 4);
+
+    QStack<int> stateStack;
+    stateStack.resize(closure.count());
+    qCopy(closure.constBegin(), closure.constEnd(), stateStack.begin());
+
+    while (!stateStack.isEmpty()) {
+        int t = stateStack.pop();
+        const TransitionMap &transitions = states.at(t).transitions;
+        TransitionMap::ConstIterator it = transitions.find(Epsilon);
+        while (it != transitions.constEnd() && it.key() == Epsilon) {
+            const int u = it.value();
+            if (!closure.contains(u)) {
+                closure.insert(u);
+                stateStack.push(u);
+            }
+            ++it;
+        }
+    }
+
+    return closure;
+}
+
+void NFA::setTerminationSymbol(const QString &symbol)
+{
+    states[finalState].symbol = symbol;
+}
+
+void DFA::debug() const
+{
+    qDebug() << "DFA has" << count() << "states";
+
+    for (int i = 0; i < count(); ++i) {
+        const State &s = at(i);
+        if (s.transitions.isEmpty()) {
+            qDebug() << "State" << i << "has no transitions";
+        } else {
+            for (TransitionMap::ConstIterator it = s.transitions.constBegin(),
+                 end = s.transitions.constEnd(); it != end; ++it)
+                qDebug() << "transition from state" << i << "to" << it.value() << "through"
+                         << (it.key() == Epsilon ? QString("Epsilon") : QString(char(it.key())));
+        }
+        if (!s.symbol.isEmpty())
+            qDebug() << "State" << i << "leads to symbol" << s.symbol;
+    }
+
+}
+
+DFA DFA::minimize() const
+{
+    QVector<bool> inequivalentStates(count() * count());
+    inequivalentStates.fill(false);
+
+    for (int i = 0; i < count(); ++i)
+        for (int j = 0; j < i; ++j) {
+            if (i != j && at(i).symbol != at(j).symbol)
+                inequivalentStates[i * count() + j] = true;
+        }
+
+    bool done;
+    do {
+        done = true;
+        for (int i = 0; i < count(); ++i)
+            for (int j = 0; j < count(); ++j) {
+                if (i == j)
+                    continue;
+
+                if (inequivalentStates[i * count() + j])
+                    continue;
+
+                if (at(i).transitions.keys() != at(j).transitions.keys()) {
+                    inequivalentStates[i * count() + j] = true;
+                    done = false;
+                    continue;
+                }
+
+                foreach (InputType a, at(i).transitions.keys()) {
+                    int r = at(i).transitions.value(a, -1);
+                    if (r == -1)
+                        continue;
+                    int s = at(j).transitions.value(a, -1);
+                    if (s == -1)
+                        continue;
+
+                    if (inequivalentStates[r * count() + s]
+                        || r == s) {
+                        inequivalentStates[i * count() + j] = true;
+                        done = false;
+                        break;
+                    }
+                }
+            }
+    } while (!done);
+
+    QHash<int, int> statesToEliminate;
+    for (int i = 0; i < count(); ++i)
+        for (int j = 0; j < i; ++j)
+            if (!inequivalentStates[i * count() + j]) {
+                statesToEliminate.insertMulti(i, j);
+            }
+
+    /*
+    qDebug() << "states to eliminiate:" << statesToEliminate.count();;
+    qDebug() << "merging" << statesToEliminate;
+    debug();
+    */
+
+    return *this;
+}
+
+