/****************************************************************************

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** This file is part of the utils of the Qt Toolkit.

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** contained in the Technology Preview License Agreement accompanying

** this package.

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** 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

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****************************************************************************/

#include "re2nfa.h"

#include "tokenizer.cpp"

RE2NFA::RE2NFA(const QMap<QString, NFA> &macros, const QSet<InputType> &maxInputSet, Qt::CaseSensitivity cs)

    : macros(macros), index(0), errorColumn(-1), maxInputSet(maxInputSet), caseSensitivity(cs)

{

}

NFA RE2NFA::parse(const QString &expression, int *errCol)

{

    tokenize(expression);

    if (symbols.isEmpty())

        return NFA();

    index = 0;

    NFA result = parseExpr();

    if (result.isEmpty()) {

        if (errCol)

            *errCol = errorColumn;

    }

    return result;

}

NFA RE2NFA::parseExpr()

{

    NFA value = parseBranch();

    while (test(TOK_OR)) {

        NFA rhs = parseBranch();

        value = NFA::createAlternatingNFA(value, rhs);

    }

    return value;

}

NFA RE2NFA::parseBranch()

{

    NFA value = parsePiece();

    if (!hasNext())

        return value;

    NFA next;

    do {

        next = parsePiece();

        if (!next.isEmpty())

            value = NFA::createConcatenatingNFA(value, next);

    } while (!next.isEmpty() && hasNext());

    return value;

}

NFA RE2NFA::parsePiece()

{

    NFA atom = parseAtom();

    if (atom.isEmpty() || !hasNext())

        return atom;

    return parseMaybeQuantifier(atom);

}

NFA RE2NFA::parseAtom()

{

    // ####

    switch (next()) {

        case TOK_STRING:

            return createCharNFA();

        case TOK_LPAREN: {

            NFA subExpr = parseExpr();

            next(TOK_RPAREN);

            return subExpr;

        }

        case TOK_LBRACE: {

            QString macroName = lexemUntil(TOK_RBRACE);

            QMap<QString, NFA>::ConstIterator macro = macros.find(macroName);

            if (macro == macros.end()) {

                qWarning("Unknown macro '%s' - probably used before defined", qPrintable(macroName));

                return NFA();

            }

            return *macro;

        }

        case TOK_LBRACKET: {

            NFA set = parseSet();

            next(TOK_RBRACKET);

            return set;

        }

        case TOK_SEQUENCE:

            return parseSet2();

        case TOK_DOT:

            return NFA::createSetNFA(maxInputSet);

        default:

            prev();

            return NFA();

    }

}

NFA RE2NFA::parseMaybeQuantifier(const NFA &nfa)

{

    // ####

    switch (next()) {

        case TOK_STAR:

            return NFA::createOptionalNFA(nfa);

        case TOK_QUESTION:

            return NFA::createZeroOrOneNFA(nfa);

        case TOK_PLUS:

            return NFA::createConcatenatingNFA(nfa, NFA::createOptionalNFA(nfa));

        case TOK_LBRACE: {

              const int rewind = index - 1;

              QString lexemBeforeComma;

              QString lexemAfterComma;

              bool seenComma = false;

              forever {

                  if (test(TOK_COMMA)) {

                      if (seenComma) {

                          errorColumn = symbol().column;

                          return NFA();

                      }

                      seenComma = true;

                  } else if (test(TOK_RBRACE)) {

                      break;

                  } else {

                      next(TOK_STRING);

                      if (seenComma)

                          lexemAfterComma += symbol().lexem;

                      else

                          lexemBeforeComma += symbol().lexem;

                  }

              }

              bool isNumber = false;

              int min = lexemBeforeComma.toInt(&isNumber);

              if (!isNumber) {

                  index = rewind;

                  return nfa;

              }

              int max = min;

              if (seenComma) {

                  max = lexemAfterComma.toInt(&isNumber);

                  if (!isNumber) {

                      errorColumn = symbol().column;

                      return NFA();

                  }

              }

              return NFA::applyQuantity(nfa, min, max);

        }

        default:

            prev();

            return nfa;

    }

}

NFA RE2NFA::parseSet()

{

    QSet<InputType> set;

    bool negate = false;

    next(TOK_STRING);

    do {

        Q_ASSERT(symbol().lexem.length() == 1);

        // ###

        QChar ch = symbol().lexem.at(0);

        if (set.isEmpty() && ch == QLatin1Char('^')) {

            negate = true;

            continue;

        }

        // look ahead for ranges like a-z

        bool rangeFound = false;

        if (test(TOK_STRING)) {

            if (symbol().lexem.length() == 1

                && symbol().lexem.at(0) == QLatin1Char('-')) {

                next(TOK_STRING);

                Q_ASSERT(symbol().lexem.length() == 1);

                QChar last = symbol().lexem.at(0);

                if (ch.unicode() > last.unicode())

                    qSwap(ch, last);

                for (ushort i = ch.unicode(); i <= last.unicode(); ++i) {

                    if (caseSensitivity == Qt::CaseInsensitive) {

                        set.insert(QChar(i).toLower().unicode());

                    } else {

                        set.insert(i);

                    }

                }

                rangeFound = true;

            } else {

                prev();

            }

        }

        if (!rangeFound) {

            if (caseSensitivity == Qt::CaseInsensitive) {

                set.insert(ch.toLower().unicode());

            } else {

                set.insert(ch.unicode());

            }

        }

    } while (test(TOK_STRING));

    if (negate) {

        QSet<InputType> negatedSet = maxInputSet;

        negatedSet.subtract(set);

        set = negatedSet;

    }

    return NFA::createSetNFA(set);

}

NFA RE2NFA::parseSet2()

{

    QSet<InputType> set;

    bool negate = false;

    QString str = symbol().lexem;

    // strip off brackets

    str.chop(1);

    str.remove(0, 1);

    int i = 0;

    while (i < str.length()) {

        // ###

        QChar ch = str.at(i++);

        if (set.isEmpty() && ch == QLatin1Char('^')) {

            negate = true;

            continue;

        }

        // look ahead for ranges like a-z

        bool rangeFound = false;

        if (i < str.length() - 1 && str.at(i) == QLatin1Char('-')) {

            ++i;

            QChar last = str.at(i++);

            if (ch.unicode() > last.unicode())

                qSwap(ch, last);

            for (ushort i = ch.unicode(); i <= last.unicode(); ++i) {

                if (caseSensitivity == Qt::CaseInsensitive) {

                    set.insert(QChar(i).toLower().unicode());

                } else {

                    set.insert(i);

                }

            }

            rangeFound = true;

        }

        if (!rangeFound) {

            if (caseSensitivity == Qt::CaseInsensitive) {

                set.insert(ch.toLower().unicode());

            } else {

                set.insert(ch.unicode());

            }

        }

    }

    if (negate) {

        QSet<InputType> negatedSet = maxInputSet;

        negatedSet.subtract(set);

        set = negatedSet;

    }

    return NFA::createSetNFA(set);

}

NFA RE2NFA::createCharNFA()

{

    NFA nfa;

    // ####

    if (caseSensitivity == Qt::CaseInsensitive) {

        nfa = NFA::createStringNFA(symbol().lexem.toLower().toLatin1());

    } else {

        nfa = NFA::createStringNFA(symbol().lexem.toLatin1());

    }

    return nfa;

}

static inline int skipQuote(const QString &str, int pos)

{

    while (pos < str.length()

           && str.at(pos) != QLatin1Char('"')) {

        if (str.at(pos) == QLatin1Char('\\')) {

            ++pos;

            if (pos >= str.length())

                break;

        }

        ++pos;

    }

    if (pos < str.length())

        ++pos;

    return pos;

}

#if 0

static const char*tokStr(Token t)

{

    switch (t) {

        case TOK_INVALID: return "TOK_INVALID";

        case TOK_STRING: return "TOK_STRING";

        case TOK_LBRACE: return "TOK_LBRACE";

        case TOK_RBRACE: return "TOK_RBRACE";

        case TOK_LBRACKET: return "TOK_LBRACKET";

        case TOK_RBRACKET: return "TOK_RBRACKET";

        case TOK_LPAREN: return "TOK_LPAREN";

        case TOK_RPAREN: return "TOK_RPAREN";

        case TOK_COMMA: return "TOK_COMMA";

        case TOK_STAR: return "TOK_STAR";

        case TOK_OR: return "TOK_OR";

        case TOK_QUESTION: return "TOK_QUESTION";

        case TOK_DOT: return "TOK_DOT";

        case TOK_PLUS: return "TOK_PLUS";

        case TOK_SEQUENCE: return "TOK_SEQUENCE";

        case TOK_QUOTED_STRING: return "TOK_QUOTED_STRING";

    }

    return "";

}

#endif

void RE2NFA::tokenize(const QString &input)

{

    symbols.clear();

#if 1

    RegExpTokenizer tokenizer(input);

    Symbol sym;

    int tok = tokenizer.lex();

    while (tok != -1) {

        Symbol sym;

        sym.token = static_cast<Token>(tok);

        sym.lexem = input.mid(tokenizer.lexemStart, tokenizer.lexemLength);

        if (sym.token == TOK_QUOTED_STRING) {

            sym.lexem.chop(1);

            sym.lexem.remove(0, 1);

            sym.token = TOK_STRING;

        }

        if (sym.token == TOK_STRING || sym.token == TOK_SEQUENCE) {

            for (int i = 0; i < sym.lexem.length(); ++i) {

                if (sym.lexem.at(i) == '\\') {

                    if (i >= sym.lexem.length() - 1)

                        break;

                    QChar ch = sym.lexem.at(i + 1);

                    if (ch == QLatin1Char('n')) {

                        ch = '\n';

                    } else if (ch == QLatin1Char('r')) {

                        ch = '\r';

                    } else if (ch == QLatin1Char('t')) {

                        ch = '\t';

                    } else if (ch == QLatin1Char('f')) {

                        ch = '\f';

                    }

                    sym.lexem.replace(i, 2, ch);

                }

            }

        }

        /*

        if (sym.token == TOK_SEQUENCE) {

            Symbol s;

            s.token = TOK_LBRACKET;

            s.lexem = "[";

            symbols.append(s);

            for (int i = 1; i < sym.lexem.length() - 1; ++i) {

                s.token = TOK_STRING;

                s.lexem = sym.lexem.at(i);

                symbols.append(s);

            }

            s.token = TOK_RBRACKET;

            s.lexem = "]";

            symbols.append(s);

            tok = tokenizer.lex();

            continue;

        }

        */

        symbols.append(sym);

        tok = tokenizer.lex();

    }

#else

    int pos = 0;

    bool insideSet = false;

    while (pos < input.length()) {

        QChar ch = input.at(pos);

        Symbol sym;

        sym.column = pos;

        sym.token = TOK_INVALID;

        sym.lexem = QString(ch);

        switch (ch.toLatin1()) {

            case '"': {

                if (insideSet) {

                    sym.token = TOK_STRING;

                    sym.lexem = QString(ch);

                    symbols += sym;

                    ++pos;

                    continue;

                }

                if (pos + 1 >= input.length())

                    return;

                int quoteEnd = skipQuote(input, pos + 1);

                sym.token = TOK_STRING;

                sym.lexem = input.mid(pos + 1, quoteEnd - pos - 2);

                symbols += sym;

                pos = quoteEnd;

                continue;

            }

            case '{':

                sym.token = (insideSet ? TOK_STRING : TOK_LBRACE);

                break;

            case '}':

                sym.token = (insideSet ? TOK_STRING : TOK_RBRACE);

                break;

            case '[':

                insideSet = true;

                sym.token = TOK_LBRACKET;

                break;

            case ']':

                insideSet = false;

                sym.token = TOK_RBRACKET;

                break;

            case '(':

                sym.token = (insideSet ? TOK_STRING : TOK_LPAREN);

                break;

            case ')':

                sym.token = (insideSet ? TOK_STRING : TOK_RPAREN);

                break;

            case ',':

                sym.token = (insideSet ? TOK_STRING : TOK_COMMA);

                break;

            case '*':

                sym.token = (insideSet ? TOK_STRING : TOK_STAR);

                break;

            case '|':

                sym.token = (insideSet ? TOK_STRING : TOK_OR);

                break;

            case '?':

                sym.token = (insideSet ? TOK_STRING : TOK_QUESTION);

                break;

            case '.':

                sym.token = (insideSet ? TOK_STRING : TOK_DOT);

                break;

            case '+':

                sym.token = (insideSet ? TOK_STRING : TOK_PLUS);

                break;

            case '\\':

                ++pos;

                if (pos >= input.length())

                    return;

                ch = input.at(pos);

                if (ch == QLatin1Char('n')) {

                    ch = '\n';

                } else if (ch == QLatin1Char('r')) {

                    ch = '\r';

                } else if (ch == QLatin1Char('t')) {

                    ch = '\t';

                } else if (ch == QLatin1Char('f')) {

                    ch = '\f';

                }

                // fall through

            default:

                sym.token = TOK_STRING;

                sym.lexem = QString(ch);

                symbols += sym;

                ++pos;

                continue;

        }

        symbols += sym;

        ++pos;

    }

#endif

#if 0

    foreach (Symbol s, symbols) {

        qDebug() << "Tok" << tokStr(s.token) << "lexem" << s.lexem;

    }

#endif

}

bool RE2NFA::next(Token t)

{

    if (hasNext() && next() == t)

        return true;

    errorColumn = symbol().column;

    Q_ASSERT(false);

    return false;

}