preprocessor.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// Copyright (C) 2014 Olivier Goffart <ogoffart@woboq.org>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
 
#include "preprocessor.h"
#include "utils.h"
#include <qstringlist.h>
#include <qfile.h>
#include <qdir.h>
#include <qfileinfo.h>
#include <qvarlengtharray.h>
 
QT_BEGIN_NAMESPACE
 
using namespace QtMiscUtils;
 
#include "ppkeywords.cpp"
#include "keywords.cpp"
 
// transform \r\n into \n
// \r into \n (os9 style)
// backslash-newlines into newlines
static QByteArray cleaned(const QByteArray &input)
{
    QByteArray result;
    result.resize(input.size());
    const char *data = input.constData();
    const char *end = input.constData() + input.size();
    char *output = result.data();
 
    int newlines = 0;
    while (data != end) {
        while (data != end && is_space(*data))
            ++data;
        bool takeLine = (*data == '#');
        if (*data == '%' && *(data+1) == ':') {
            takeLine = true;
            ++data;
        }
        if (takeLine) {
            *output = '#';
            ++output;
            do ++data; while (data != end && is_space(*data));
        }
        while (data != end) {
            // handle \\\n, \\\r\n and \\\r
            if (*data == '\\') {
                if (*(data + 1) == '\r') {
                    ++data;
                }
                if (data != end && (*(data + 1) == '\n' || (*data) == '\r')) {
                    ++newlines;
                    data += 1;
                    if (data != end && *data != '\r')
                        data += 1;
                    continue;
                }
            } else if (*data == '\r' && *(data + 1) == '\n') { // reduce \r\n to \n
                ++data;
            }
            if (data == end)
                break;
 
            char ch = *data;
            if (ch == '\r') // os9: replace \r with \n
                ch = '\n';
            *output = ch;
            ++output;
 
            if (*data == '\n') {
                // output additional newlines to keep the correct line-numbering
                // for the lines following the backslash-newline sequence(s)
                while (newlines) {
                    *output = '\n';
                    ++output;
                    --newlines;
                }
                ++data;
                break;
            }
            ++data;
        }
    }
    result.resize(output - result.constData());
    return result;
}
 
bool Preprocessor::preprocessOnly = false;
void Preprocessor::skipUntilEndif()
{
    while(index < symbols.size() - 1 && symbols.at(index).token != PP_ENDIF){
        switch (symbols.at(index).token) {
        case PP_IF:
        case PP_IFDEF:
        case PP_IFNDEF:
            ++index;
            skipUntilEndif();
            break;
        default:
            ;
        }
        ++index;
    }
}
 
bool Preprocessor::skipBranch()
{
    while (index < symbols.size() - 1
          && (symbols.at(index).token != PP_ENDIF
               && symbols.at(index).token != PP_ELIF
               && symbols.at(index).token != PP_ELSE)
       ){
        switch (symbols.at(index).token) {
        case PP_IF:
        case PP_IFDEF:
        case PP_IFNDEF:
            ++index;
            skipUntilEndif();
            break;
        default:
            ;
        }
        ++index;
    }
    return (index < symbols.size() - 1);
}
 
 
Symbols Preprocessor::tokenize(const QByteArray& input, int lineNum, Preprocessor::TokenizeMode mode)
{
    Symbols symbols;
    // Preallocate some space to speed up the code below.
    // The magic divisor value was found by calculating the average ratio between
    // input size and the final size of symbols.
    // This yielded a value of 16.x when compiling Qt Base.
    symbols.reserve(input.size() / 16);
    const char *begin = input.constData();
    const char *data = begin;
    while (*data) {
        if (mode == TokenizeCpp || mode == TokenizeDefine) {
            int column = 0;
 
            const char *lexem = data;
            int state = 0;
            Token token = NOTOKEN;
            for (;;) {
                if (static_cast<signed char>(*data) < 0) {
                    ++data;
                    continue;
                }
                int nextindex = keywords[state].next;
                int next = 0;
                if (*data == keywords[state].defchar)
                    next = keywords[state].defnext;
                else if (!state || nextindex)
                    next = keyword_trans[nextindex][(int)*data];
                if (!next)
                    break;
                state = next;
                token = keywords[state].token;
                ++data;
            }
 
            // suboptimal, is_ident_char  should use a table
            if (keywords[state].ident && is_ident_char(*data))
                token = keywords[state].ident;
 
            if (token == NOTOKEN) {
                if (*data)
                    ++data;
                // an error really, but let's ignore this input
                // to not confuse moc later. However in pre-processor
                // only mode let's continue.
                if (!Preprocessor::preprocessOnly)
                    continue;
            }
 
            ++column;
 
            if (token > SPECIAL_TREATMENT_MARK) {
                switch (token) {
                case QUOTE:
                    data = skipQuote(data);
                    token = STRING_LITERAL;
                    // concatenate multi-line strings for easier
                    // STRING_LITERAL handling in moc
                    if (!Preprocessor::preprocessOnly
                        && !symbols.isEmpty()
                        && symbols.constLast().token == STRING_LITERAL) {
 
                        const QByteArray newString
                                = '\"'
                                + symbols.constLast().unquotedLexemView()
                                + input.mid(lexem - begin + 1, data - lexem - 2)
                                + '\"';
                        symbols.last() = Symbol(symbols.constLast().lineNum,
                                                STRING_LITERAL,
                                                newString);
                        continue;
                    }
                    break;
                case SINGLEQUOTE:
                    while (*data && (*data != '\''
                                     || (*(data-1)=='\\'
                                         && *(data-2)!='\\')))
                        ++data;
                    if (*data)
                        ++data;
                    token = CHARACTER_LITERAL;
                    break;
                case LANGLE_SCOPE:
                    // split <:: into two tokens, < and ::
                    token = LANGLE;
                    data -= 2;
                    break;
                case DIGIT:
                    {
                    bool hasSeenTokenSeparator = false;;
                    while (isAsciiDigit(*data) || (hasSeenTokenSeparator = *data == '\''))
                        ++data;
                    if (!*data || *data != '.') {
                        token = INTEGER_LITERAL;
                        if (data - lexem == 1 &&
                            (*data == 'x' || *data == 'X'
                             || *data == 'b' || *data == 'B')
                            && *lexem == '0') {
                            ++data;
                            while (isHexDigit(*data) || (hasSeenTokenSeparator = *data == '\''))
                                ++data;
                        } else if (*data == 'L') // TODO: handle other suffixes
                            ++data;
                        if (!hasSeenTokenSeparator) {
                            while (is_ident_char(*data)) {
                                ++data;
                                token = IDENTIFIER;
                            }
                        }
                        break;
                    }
                    token = FLOATING_LITERAL;
                    ++data;
                    Q_FALLTHROUGH();
                    }
                case FLOATING_LITERAL:
                    while (isAsciiDigit(*data) || *data == '\'')
                        ++data;
                    if (*data == '+' || *data == '-')
                        ++data;
                    if (*data == 'e' || *data == 'E') {
                        ++data;
                        while (isAsciiDigit(*data) || *data == '\'')
                            ++data;
                    }
                    if (*data == 'f' || *data == 'F'
                        || *data == 'l' || *data == 'L')
                        ++data;
                    break;
                case HASH:
                    if (column == 1 && mode == TokenizeCpp) {
                        mode = PreparePreprocessorStatement;
                        while (*data && (*data == ' ' || *data == '\t'))
                            ++data;
                        if (is_ident_char(*data))
                            mode = TokenizePreprocessorStatement;
                        continue;
                    }
                    break;
                case PP_HASHHASH:
                    if (mode == TokenizeCpp)
                        continue;
                    break;
                case NEWLINE:
                    ++lineNum;
                    if (mode == TokenizeDefine) {
                        mode = TokenizeCpp;
                        // emit the newline token
                        break;
                    }
                    continue;
                case BACKSLASH:
                {
                    const char *rewind = data;
                    while (*data && (*data == ' ' || *data == '\t'))
                        ++data;
                    if (*data && *data == '\n') {
                        ++data;
                        continue;
                    }
                    data = rewind;
                } break;
                case CHARACTER:
                    while (is_ident_char(*data))
                        ++data;
                    token = IDENTIFIER;
                    break;
                case C_COMMENT:
                    if (*data) {
                        if (*data == '\n')
                            ++lineNum;
                        ++data;
                        if (*data) {
                            if (*data == '\n')
                                ++lineNum;
                            ++data;
                        }
                    }
                    while (*data && (*(data-1) != '/' || *(data-2) != '*')) {
                        if (*data == '\n')
                            ++lineNum;
                        ++data;
                    }
                    token = WHITESPACE; // one comment, one whitespace
                    Q_FALLTHROUGH();
                case WHITESPACE:
                    if (column == 1)
                        column = 0;
                    while (*data && (*data == ' ' || *data == '\t'))
                        ++data;
                    if (Preprocessor::preprocessOnly) // tokenize whitespace
                        break;
                    continue;
                case CPP_COMMENT:
                    while (*data && *data != '\n')
                        ++data;
                    continue; // ignore safely, the newline is a separator
                default:
                    continue; //ignore
                }
            }
            symbols += Symbol(lineNum, token, input, lexem-begin, data-lexem);
 
        } else { //   Preprocessor
 
            const char *lexem = data;
            int state = 0;
            Token token = NOTOKEN;
            if (mode == TokenizePreprocessorStatement) {
                state = pp_keyword_trans[0][(int)'#'];
                mode = TokenizePreprocessor;
            }
            for (;;) {
                if (static_cast<signed char>(*data) < 0) {
                    ++data;
                    continue;
                }
                int nextindex = pp_keywords[state].next;
                int next = 0;
                if (*data == pp_keywords[state].defchar)
                    next = pp_keywords[state].defnext;
                else if (!state || nextindex)
                    next = pp_keyword_trans[nextindex][(int)*data];
                if (!next)
                    break;
                state = next;
                token = pp_keywords[state].token;
                ++data;
            }
            // suboptimal, is_ident_char  should use a table
            if (pp_keywords[state].ident && is_ident_char(*data))
                token = pp_keywords[state].ident;
 
            switch (token) {
            case NOTOKEN:
                if (*data)
                    ++data;
                break;
            case PP_DEFINE:
                mode = PrepareDefine;
                break;
            case PP_IFDEF:
                symbols += Symbol(lineNum, PP_IF);
                symbols += Symbol(lineNum, PP_DEFINED);
                continue;
            case PP_IFNDEF:
                symbols += Symbol(lineNum, PP_IF);
                symbols += Symbol(lineNum, PP_NOT);
                symbols += Symbol(lineNum, PP_DEFINED);
                continue;
            case PP_INCLUDE:
                mode = TokenizeInclude;
                break;
            case PP_QUOTE:
                data = skipQuote(data);
                token = PP_STRING_LITERAL;
                break;
            case PP_SINGLEQUOTE:
                while (*data && (*data != '\''
                                 || (*(data-1)=='\\'
                                     && *(data-2)!='\\')))
                    ++data;
                if (*data)
                    ++data;
                token = PP_CHARACTER_LITERAL;
                break;
            case PP_DIGIT:
                while (isAsciiDigit(*data) || *data == '\'')
                    ++data;
                if (!*data || *data != '.') {
                    token = PP_INTEGER_LITERAL;
                    if (data - lexem == 1 &&
                        (*data == 'x' || *data == 'X')
                        && *lexem == '0') {
                        ++data;
                        while (isHexDigit(*data) || *data == '\'')
                            ++data;
                    } else if (*data == 'L') // TODO: handle other suffixes
                        ++data;
                    break;
                }
                token = PP_FLOATING_LITERAL;
                ++data;
                Q_FALLTHROUGH();
            case PP_FLOATING_LITERAL:
                while (isAsciiDigit(*data) || *data == '\'')
                    ++data;
                if (*data == '+' || *data == '-')
                    ++data;
                if (*data == 'e' || *data == 'E') {
                    ++data;
                    while (isAsciiDigit(*data) || *data == '\'')
                        ++data;
                }
                if (*data == 'f' || *data == 'F'
                    || *data == 'l' || *data == 'L')
                    ++data;
                break;
            case PP_CHARACTER:
                if (mode == PreparePreprocessorStatement) {
                    // rewind entire token to begin
                    data = lexem;
                    mode = TokenizePreprocessorStatement;
                    continue;
                }
                while (is_ident_char(*data))
                    ++data;
                token = PP_IDENTIFIER;
 
                if (mode == PrepareDefine) {
                    symbols += Symbol(lineNum, token, input, lexem-begin, data-lexem);
                    // make sure we explicitly add the whitespace here if the next char
                    // is not an opening brace, so we can distinguish correctly between
                    // regular and function macros
                    if (*data != '(')
                        symbols += Symbol(lineNum, WHITESPACE);
                    mode = TokenizeDefine;
                    continue;
                }
                break;
            case PP_C_COMMENT:
                if (*data) {
                    if (*data == '\n')
                        ++lineNum;
                    ++data;
                    if (*data) {
                        if (*data == '\n')
                            ++lineNum;
                        ++data;
                    }
                }
                while (*data && (*(data-1) != '/' || *(data-2) != '*')) {
                    if (*data == '\n')
                        ++lineNum;
                    ++data;
                }
                token = PP_WHITESPACE; // one comment, one whitespace
                Q_FALLTHROUGH();
            case PP_WHITESPACE:
                while (*data && (*data == ' ' || *data == '\t'))
                    ++data;
                continue; // the preprocessor needs no whitespace
            case PP_CPP_COMMENT:
                while (*data && *data != '\n')
                    ++data;
                continue; // ignore safely, the newline is a separator
            case PP_NEWLINE:
                ++lineNum;
                mode = TokenizeCpp;
                break;
            case PP_BACKSLASH:
            {
                const char *rewind = data;
                while (*data && (*data == ' ' || *data == '\t'))
                    ++data;
                if (*data && *data == '\n') {
                    ++data;
                    continue;
                }
                data = rewind;
            } break;
            case PP_LANGLE:
                if (mode != TokenizeInclude)
                    break;
                token = PP_STRING_LITERAL;
                while (*data && *data != '\n' && *(data-1) != '>')
                    ++data;
                break;
            default:
                break;
            }
            if (mode == PreparePreprocessorStatement)
                continue;
            symbols += Symbol(lineNum, token, input, lexem-begin, data-lexem);
        }
    }
    symbols += Symbol(); // eof symbol
    return symbols;
}
 
void Preprocessor::macroExpand(Symbols *into, Preprocessor *that, const Symbols &toExpand, qsizetype &index,
                                  int lineNum, bool one, const QSet<QByteArray> &excludeSymbols)
{
    SymbolStack symbols;
    symbols.reserve(8);
    SafeSymbols sf;
    sf.symbols = toExpand;
    sf.index = index;
    sf.excludedSymbols = excludeSymbols;
    symbols.push(std::move(sf));
 
    if (toExpand.isEmpty())
        return;
 
    for (;;) {
        QByteArray macro;
        Symbols newSyms = macroExpandIdentifier(that, symbols, lineNum, &macro);
 
        if (macro.isEmpty()) {
            // not a macro
            Symbol s = symbols.symbol();
            s.lineNum = lineNum;
            *into += s;
        } else {
            SafeSymbols sf;
            sf.symbols = newSyms;
            sf.index = 0;
            sf.expandedMacro = macro;
            symbols.push(std::move(sf));
        }
        if (!symbols.hasNext() || (one && symbols.size() == 1))
                break;
        symbols.next();
    }
 
    if (symbols.size())
        index = symbols.top().index;
    else
        index = toExpand.size();
}
 
 
Symbols Preprocessor::macroExpandIdentifier(Preprocessor *that, SymbolStack &symbols, int lineNum, QByteArray *macroName)
{
    Symbol s = symbols.symbol();
 
    // not a macro
    if (s.token != PP_IDENTIFIER || !that->macros.contains(s) || symbols.dontReplaceSymbol(s.lexem())) {
        return Symbols();
    }
 
    const Macro &macro = that->macros.value(s);
    *macroName = s.lexem();
 
    Symbols expansion;
    if (!macro.isFunction) {
        expansion = macro.symbols;
    } else {
        bool haveSpace = false;
        while (symbols.test(PP_WHITESPACE)) { haveSpace = true; }
        if (!symbols.test(PP_LPAREN)) {
            *macroName = QByteArray();
            Symbols syms;
            if (haveSpace)
                syms += Symbol(lineNum, PP_WHITESPACE);
            syms += s;
            syms.last().lineNum = lineNum;
            return syms;
        }
        QVarLengthArray<Symbols, 5> arguments;
        while (symbols.hasNext()) {
            Symbols argument;
            // strip leading space
            while (symbols.test(PP_WHITESPACE)) {}
            int nesting = 0;
            bool vararg = macro.isVariadic && (arguments.size() == macro.arguments.size() - 1);
            while (symbols.hasNext()) {
                Token t = symbols.next();
                if (t == PP_LPAREN) {
                    ++nesting;
                } else if (t == PP_RPAREN) {
                    --nesting;
                    if (nesting < 0)
                        break;
                } else if (t == PP_COMMA && nesting == 0) {
                    if (!vararg)
                        break;
                }
                argument += symbols.symbol();
            }
            arguments += argument;
 
            if (nesting < 0)
                break;
            else if (!symbols.hasNext())
                that->error("missing ')' in macro usage");
        }
 
        // empty VA_ARGS
        if (macro.isVariadic && arguments.size() == macro.arguments.size() - 1)
            arguments += Symbols();
 
        // now replace the macro arguments with the expanded arguments
        enum Mode {
            Normal,
            Hash,
            HashHash
        } mode = Normal;
 
        const auto end = macro.symbols.cend();
        auto it = macro.symbols.cbegin();
        const auto lastSym = std::prev(macro.symbols.cend(), !macro.symbols.isEmpty() ? 1 : 0);
        for (; it != end; ++it) {
            const Symbol &s = *it;
            if (s.token == HASH || s.token == PP_HASHHASH) {
                mode = (s.token == HASH ? Hash : HashHash);
                continue;
            }
            const qsizetype index = macro.arguments.indexOf(s);
            if (mode == Normal) {
                if (index >= 0 && index < arguments.size()) {
                    // each argument undoergoes macro expansion if it's not used as part of a # or ##
                    if (it == lastSym || std::next(it)->token != PP_HASHHASH) {
                        Symbols arg = arguments.at(index);
                        qsizetype idx = 1;
                        macroExpand(&expansion, that, arg, idx, lineNum, false, symbols.excludeSymbols());
                    } else {
                        expansion += arguments.at(index);
                    }
               } else {
                    expansion += s;
                }
            } else if (mode == Hash) {
                if (index < 0) {
                    that->error("'#' is not followed by a macro parameter");
                    continue;
                } else if (index >= arguments.size()) {
                    that->error("Macro invoked with too few parameters for a use of '#'");
                    continue;
                }
 
                const Symbols &arg = arguments.at(index);
                QByteArray stringified;
                if (!arg.empty()) {
                    stringified = arg.front().lexem();
                    for (auto it = arg.cbegin(); std::next(it) != arg.cend(); ++it) {
                        const auto next = std::next(it);
                        if (next->from - (it->from + it->len) > 0)
                            stringified += ' ' + next->lexem();
                        else
                            stringified += next->lexem();
                    }
 
                    stringified.replace('"', "\\\"");
                    stringified.prepend('"');
                    stringified.append('"');
                }
 
                expansion += Symbol(lineNum, STRING_LITERAL, stringified);
            } else if (mode == HashHash){
                if (s.token == WHITESPACE)
                    continue;
 
                while (expansion.size() && expansion.constLast().token == PP_WHITESPACE)
                    expansion.pop_back();
 
                Symbol next = s;
                if (index >= 0 && index < arguments.size()) {
                    const Symbols &arg = arguments.at(index);
                    if (arg.size() == 0) {
                        mode = Normal;
                        continue;
                    }
                    next = arg.at(0);
                }
 
                if (!expansion.isEmpty() && expansion.constLast().token == s.token
                    && expansion.constLast().token != STRING_LITERAL) {
                    Symbol last = expansion.takeLast();
 
                    QByteArray lexem = last.lexem() + next.lexem();
                    expansion += Symbol(lineNum, last.token, lexem);
                } else {
                    expansion += next;
                }
 
                if (index >= 0 && index < arguments.size()) {
                    const Symbols &arg = arguments.at(index);
                    if (!arg.isEmpty())
                        expansion.append(arg.cbegin() + 1, arg.cend());
                }
            }
            mode = Normal;
        }
        if (mode != Normal)
            that->error("'#' or '##' found at the end of a macro argument");
 
    }
 
    return expansion;
}
 
void Preprocessor::substituteUntilNewline(Symbols &substituted)
{
    while (hasNext()) {
        Token token = next();
        if (token == PP_IDENTIFIER) {
            macroExpand(&substituted, this, symbols, index, symbol().lineNum, true);
        } else if (token == PP_DEFINED) {
            bool braces = test(PP_LPAREN);
            if (test(PP_HAS_INCLUDE)) {
                // __has_include is always supported
                Symbol definedOrNotDefined = symbol();
                definedOrNotDefined.token = PP_MOC_TRUE;
                substituted += definedOrNotDefined;
            } else {
                next(PP_IDENTIFIER);
                Symbol definedOrNotDefined = symbol();
                definedOrNotDefined.token = macros.contains(definedOrNotDefined)? PP_MOC_TRUE : PP_MOC_FALSE;
                substituted += definedOrNotDefined;
            }
            if (braces)
                test(PP_RPAREN);
            continue;
        } else if (token == PP_NEWLINE) {
            substituted += symbol();
            break;
        } else if (token == PP_HAS_INCLUDE) {
            next(LPAREN);
            Token tok = next(); // quote or LANGLE
            bool usesAngleInclude = false;
            QByteArray includeAsString;
            Symbols innerSymbols;
            if (tok == PP_LANGLE) {
                usesAngleInclude = true;
                next();
                do {
                    Symbol currentSymbol  = symbol();
                    includeAsString += currentSymbol.lexem();
                    if (currentSymbol.token == PP_IDENTIFIER)
                        macroExpand(&innerSymbols, this, symbols, index, symbol().lineNum, true);
                    else
                        innerSymbols.append(currentSymbol);
                } while (next() != PP_RANGLE);
            } else {
                includeAsString = unquotedLexem();
            }
            next(RPAREN);
            const QByteArray &relative  = usesAngleInclude ? QByteArray() : currentFilenames.top();
            bool result = !resolveInclude(includeAsString, relative).isNull();
            if (usesAngleInclude && !result) {
                // try with expansion
                includeAsString = {};
                for (const auto &innerSymbol: innerSymbols)
                    includeAsString.append(innerSymbol.lexem());
                result = !resolveInclude(includeAsString, relative).isNull();
            }
            Symbol definedOrNotDefined = symbol();
            definedOrNotDefined.token = result ? PP_MOC_TRUE : PP_MOC_FALSE;
            substituted += definedOrNotDefined;
        } else  {
            substituted += symbol();
        }
    }
}
 
 
class PP_Expression : public Parser
{
public:
    int value() { index = 0; return unary_expression_lookup() ?  conditional_expression() : 0; }
 
    int conditional_expression();
    int logical_OR_expression();
    int logical_AND_expression();
    int inclusive_OR_expression();
    int exclusive_OR_expression();
    int AND_expression();
    int equality_expression();
    int relational_expression();
    int shift_expression();
    int additive_expression();
    int multiplicative_expression();
    int unary_expression();
    bool unary_expression_lookup();
    int primary_expression();
    bool primary_expression_lookup();
};
 
int PP_Expression::conditional_expression()
{
    int value = logical_OR_expression();
    if (test(PP_QUESTION)) {
        int alt1 = conditional_expression();
        int alt2 = test(PP_COLON) ? conditional_expression() : 0;
        return value ? alt1 : alt2;
    }
    return value;
}
 
int PP_Expression::logical_OR_expression()
{
    int value = logical_AND_expression();
    if (test(PP_OROR))
        return logical_OR_expression() || value;
    return value;
}
 
int PP_Expression::logical_AND_expression()
{
    int value = inclusive_OR_expression();
    if (test(PP_ANDAND))
        return logical_AND_expression() && value;
    return value;
}
 
int PP_Expression::inclusive_OR_expression()
{
    int value = exclusive_OR_expression();
    if (test(PP_OR))
        return value | inclusive_OR_expression();
    return value;
}
 
int PP_Expression::exclusive_OR_expression()
{
    int value = AND_expression();
    if (test(PP_HAT))
        return value ^ exclusive_OR_expression();
    return value;
}
 
int PP_Expression::AND_expression()
{
    int value = equality_expression();
    if (test(PP_AND))
        return value & AND_expression();
    return value;
}
 
int PP_Expression::equality_expression()
{
    int value = relational_expression();
    switch (next()) {
    case PP_EQEQ:
        return value == equality_expression();
    case PP_NE:
        return value != equality_expression();
    default:
        prev();
        return value;
    }
}
 
int PP_Expression::relational_expression()
{
    int value = shift_expression();
    switch (next()) {
    case PP_LANGLE:
        return value < relational_expression();
    case PP_RANGLE:
        return value > relational_expression();
    case PP_LE:
        return value <= relational_expression();
    case PP_GE:
        return value >= relational_expression();
    default:
        prev();
        return value;
    }
}
 
int PP_Expression::shift_expression()
{
    int value = additive_expression();
    switch (next()) {
    case PP_LTLT:
        return value << shift_expression();
    case PP_GTGT:
        return value >> shift_expression();
    default:
        prev();
        return value;
    }
}
 
int PP_Expression::additive_expression()
{
    int value = multiplicative_expression();
    switch (next()) {
    case PP_PLUS:
        return value + additive_expression();
    case PP_MINUS:
        return value - additive_expression();
    default:
        prev();
        return value;
    }
}
 
int PP_Expression::multiplicative_expression()
{
    int value = unary_expression();
    switch (next()) {
    case PP_STAR:
    {
        // get well behaved overflow behavior by converting to long
        // and then back to int
        // NOTE: A conformant preprocessor would need to work intmax_t/
        // uintmax_t according to [cpp.cond], 19.1 §10
        // But we're not compliant anyway
        qint64 result = qint64(value) * qint64(multiplicative_expression());
        return int(result);
    }
    case PP_PERCENT:
    {
        int remainder = multiplicative_expression();
        return remainder ? value % remainder : 0;
    }
    case PP_SLASH:
    {
        int div = multiplicative_expression();
        return div ? value / div : 0;
    }
    default:
        prev();
        return value;
    };
}
 
int PP_Expression::unary_expression()
{
    switch (next()) {
    case PP_PLUS:
        return unary_expression();
    case PP_MINUS:
        return -unary_expression();
    case PP_NOT:
        return !unary_expression();
    case PP_TILDE:
        return ~unary_expression();
    case PP_MOC_TRUE:
        return 1;
    case PP_MOC_FALSE:
        return 0;
    default:
        prev();
        return primary_expression();
    }
}
 
bool PP_Expression::unary_expression_lookup()
{
    Token t = lookup();
    return (primary_expression_lookup()
            || t == PP_PLUS
            || t == PP_MINUS
            || t == PP_NOT
            || t == PP_TILDE
            || t == PP_DEFINED);
}
 
int PP_Expression::primary_expression()
{
    int value;
    if (test(PP_LPAREN)) {
        value = conditional_expression();
        test(PP_RPAREN);
    } else {
        next();
        auto lexView = lexemView();
        if (lexView.endsWith('L'))
            lexView.chop(1);
        value = lexView.toInt(nullptr, 0);
    }
    return value;
}
 
bool PP_Expression::primary_expression_lookup()
{
    Token t = lookup();
    return (t == PP_IDENTIFIER
            || t == PP_INTEGER_LITERAL
            || t == PP_FLOATING_LITERAL
            || t == PP_MOC_TRUE
            || t == PP_MOC_FALSE
            || t == PP_LPAREN);
}
 
int Preprocessor::evaluateCondition()
{
    PP_Expression expression;
    expression.currentFilenames = currentFilenames;
 
    substituteUntilNewline(expression.symbols);
 
    return expression.value();
}
 
static QByteArray readOrMapFile(QFile *file)
{
    const qint64 size = file->size();
    char *rawInput = reinterpret_cast<char*>(file->map(0, size));
    return rawInput ? QByteArray::fromRawData(rawInput, size) : file->readAll();
}
 
void Symbol::mergeStringLiteral(const Symbol &next)
{
    Q_ASSERT(len >= 2); // at least `""`
    Q_ASSERT(from + len <= lex.size());
    Q_ASSERT(next.len >= 2); // at least `""`
    Q_ASSERT(next.from + next.len <= next.lex.size());
 
    if (len != lex.size()) {
        // "rubbish" around lexem() in `lex`: clean up (`lex` may be the whole file)
        QByteArray l = lexemView().chopped(1) % next.lexemView().sliced(1);
        lex = std::move(l); // lexemView() aliases `lex`; only clobber it now
        from = 0;
    } else {
        // like QByteArray::append(), but dealing with the "" around each lexem:
        const auto unquoted = next.unquotedLexemView();
        lex.insert(from + len - 1, // before closing `"`
                   unquoted);
    }
    len = lex.size();
}
 
static void mergeStringLiterals(Symbols &symbols)
{
    // like std::unique, but merges instead of skips adjacent STRING_LITERALs:
 
    const auto mergeable = [](const Symbol &lhs, const Symbol &rhs) {
        return lhs.token == STRING_LITERAL && rhs.token == STRING_LITERAL;
    };
 
    auto end = symbols.end();
    auto it = std::adjacent_find(symbols.begin(), symbols.end(), mergeable);
    if (it == end) // none found
        return;
 
    // we know `it`, `it + 1` are both STRING_LITERAL (adjacent_find post-condition)
    // in particular: it + 1 < end
 
    auto dst = it;
    auto lit = dst;
    ++it;
    lit->mergeStringLiteral(*it);
 
    while (++it != end) {
        // Loop Invariants:
        // - [begin(), dst] is already processed
        // - `lit` is the last string literal
        //   - we can merge if lit == dst
        // - [it, end[ still to be checked
        if (it->token == STRING_LITERAL) {
            if (lit == dst) {            // can merge
                lit->mergeStringLiteral(*it);
            } else {                     // can't merge: not adjacent to previous STRING_LITERAL
                *++dst = std::move(*it);
                lit = dst;               // remember that this was a literal
            }
        } else {
            *++dst = std::move(*it);
        }
    }
 
    ++dst;
 
    symbols.erase(dst, end);
}
 
static QByteArray searchIncludePaths(const QList<Parser::IncludePath> &includepaths,
                                     const QByteArray &include,
                                     const bool debugIncludes)
{
    QFileInfo fi;
 
    if (Q_UNLIKELY(debugIncludes)) {
        fprintf(stderr, "debug-includes: searching for '%s'\n", include.constData());
    }
 
    for (const Parser::IncludePath &p : includepaths) {
        if (fi.exists())
            break;
 
        if (p.isFrameworkPath) {
            const qsizetype slashPos = include.indexOf('/');
            if (slashPos == -1)
                continue;
            fi.setFile(QString::fromLocal8Bit(p.path + '/' + include.left(slashPos) + ".framework/Headers/"),
                       QString::fromLocal8Bit(include.mid(slashPos + 1)));
        } else {
            fi.setFile(QString::fromLocal8Bit(p.path), QString::fromLocal8Bit(include));
        }
 
        if (Q_UNLIKELY(debugIncludes)) {
            const auto candidate = fi.filePath().toLocal8Bit();
            fprintf(stderr, "debug-includes: considering '%s'\n", candidate.constData());
        }
 
        // try again, maybe there's a file later in the include paths with the same name
        // (186067)
        if (fi.isDir()) {
            fi = QFileInfo();
            continue;
        }
    }
 
    if (!fi.exists() || fi.isDir()) {
        if (Q_UNLIKELY(debugIncludes)) {
            fprintf(stderr, "debug-includes: can't find '%s'\n", include.constData());
        }
        return QByteArray();
    }
 
    const auto result = fi.canonicalFilePath().toLocal8Bit();
 
    if (Q_UNLIKELY(debugIncludes)) {
        fprintf(stderr, "debug-includes: found '%s'\n", result.constData());
    }
 
    return result;
}
 
QByteArray Preprocessor::resolveInclude(const QByteArray &include, const QByteArray &relativeTo)
{
    if (!relativeTo.isEmpty()) {
        QFileInfo fi;
        fi.setFile(QFileInfo(QString::fromLocal8Bit(relativeTo)).dir(), QString::fromLocal8Bit(include));
        if (fi.exists() && !fi.isDir())
            return fi.canonicalFilePath().toLocal8Bit();
    }
 
    auto it = nonlocalIncludePathResolutionCache.find(include);
    if (it == nonlocalIncludePathResolutionCache.end())
       it = nonlocalIncludePathResolutionCache.insert(include,
                                                      searchIncludePaths(
                                                          includes,
                                                          include,
                                                          debugIncludes));
    return it.value();
}
 
void Preprocessor::preprocess(const QByteArray &filename, Symbols &preprocessed)
{
    currentFilenames.push(filename);
    preprocessed.reserve(preprocessed.size() + symbols.size());
    while (hasNext()) {
        Token token = next();
 
        switch (token) {
        case PP_INCLUDE:
        {
            int lineNum = symbol().lineNum;
            QByteArray include;
            bool local = false;
            if (test(PP_STRING_LITERAL)) {
                local = lexemView().startsWith('\"');
                include = unquotedLexem();
            } else
                continue;
            until(PP_NEWLINE);
 
            include = resolveInclude(include, local ? filename : QByteArray());
            if (include.isNull())
                continue;
 
            if (Preprocessor::preprocessedIncludes.contains(include))
                continue;
            Preprocessor::preprocessedIncludes.insert(include);
 
            QFile file(QString::fromLocal8Bit(include.constData()));
            if (!file.open(QFile::ReadOnly))
                continue;
 
            QByteArray input = readOrMapFile(&file);
 
            file.close();
            if (input.isEmpty())
                continue;
 
            Symbols saveSymbols = symbols;
            qsizetype saveIndex = index;
 
            // phase 1: get rid of backslash-newlines
            input = cleaned(input);
 
            // phase 2: tokenize for the preprocessor
            symbols = tokenize(input);
            input.clear();
 
            index = 0;
 
            // phase 3: preprocess conditions and substitute macros
            preprocessed += Symbol(0, MOC_INCLUDE_BEGIN, include);
            preprocess(include, preprocessed);
            preprocessed += Symbol(lineNum, MOC_INCLUDE_END, include);
 
            symbols = saveSymbols;
            index = saveIndex;
            continue;
        }
        case PP_DEFINE:
        {
            next();
            QByteArray name = lexem();
            if (name.isEmpty() || !is_ident_start(name[0]))
                error();
            Macro macro;
            macro.isVariadic = false;
            if (test(LPAREN)) {
                // we have a function macro
                macro.isFunction = true;
                parseDefineArguments(&macro);
            } else {
                macro.isFunction = false;
            }
            qsizetype start = index;
            until(PP_NEWLINE);
            macro.symbols.reserve(index - start - 1);
 
            // remove whitespace where there shouldn't be any:
            // Before and after the macro, after a # and around ##
            Token lastToken = HASH; // skip shitespace at the beginning
            for (qsizetype i = start; i < index - 1; ++i) {
                Token token = symbols.at(i).token;
                if (token == WHITESPACE) {
                    if (lastToken == PP_HASH || lastToken == HASH ||
                        lastToken == PP_HASHHASH ||
                        lastToken == WHITESPACE)
                        continue;
                } else if (token == PP_HASHHASH) {
                    if (!macro.symbols.isEmpty() &&
                        lastToken == WHITESPACE)
                        macro.symbols.pop_back();
                }
                macro.symbols.append(symbols.at(i));
                lastToken = token;
            }
            // remove trailing whitespace
            while (!macro.symbols.isEmpty() &&
                   (macro.symbols.constLast().token == PP_WHITESPACE || macro.symbols.constLast().token == WHITESPACE))
                macro.symbols.pop_back();
 
            if (!macro.symbols.isEmpty()) {
                if (macro.symbols.constFirst().token == PP_HASHHASH ||
                    macro.symbols.constLast().token == PP_HASHHASH) {
                    error("'##' cannot appear at either end of a macro expansion");
                }
            }
            macros.insert(name, macro);
            continue;
        }
        case PP_UNDEF: {
            next();
            QByteArray name = lexem();
            until(PP_NEWLINE);
            macros.remove(name);
            continue;
        }
        case PP_IDENTIFIER: {
            // substitute macros
            macroExpand(&preprocessed, this, symbols, index, symbol().lineNum, true);
            continue;
        }
        case PP_HASH:
            until(PP_NEWLINE);
            continue; // skip unknown preprocessor statement
        case PP_IFDEF:
        case PP_IFNDEF:
        case PP_IF:
            while (!evaluateCondition()) {
                if (!skipBranch())
                    break;
                if (test(PP_ELIF)) {
                } else {
                    until(PP_NEWLINE);
                    break;
                }
            }
            continue;
        case PP_ELIF:
        case PP_ELSE:
            skipUntilEndif();
            Q_FALLTHROUGH();
        case PP_ENDIF:
            until(PP_NEWLINE);
            continue;
        case PP_NEWLINE:
            continue;
        case SIGNALS:
        case SLOTS: {
            Symbol sym = symbol();
            if (macros.contains("QT_NO_KEYWORDS"))
                sym.token = IDENTIFIER;
            else
                sym.token = (token == SIGNALS ? Q_SIGNALS_TOKEN : Q_SLOTS_TOKEN);
            preprocessed += sym;
        } continue;
        default:
            break;
        }
        preprocessed += symbol();
    }
 
    currentFilenames.pop();
}
 
Symbols Preprocessor::preprocessed(const QByteArray &filename, QFile *file)
{
    QByteArray input = readOrMapFile(file);
 
    if (input.isEmpty())
        return symbols;
 
    // phase 1: get rid of backslash-newlines
    input = cleaned(input);
 
    // phase 2: tokenize for the preprocessor
    index = 0;
    symbols = tokenize(input);
 
#if 0
    for (int j = 0; j < symbols.size(); ++j)
        fprintf(stderr, "line %d: %s(%s)\n",
               symbols[j].lineNum,
               symbols[j].lexem().constData(),
               tokenTypeName(symbols[j].token));
#endif
 
    // phase 3: preprocess conditions and substitute macros
    Symbols result;
    // Preallocate some space to speed up the code below.
    // The magic value was found by logging the final size
    // and calculating an average when running moc over FOSS projects.
    result.reserve(file->size() / 300000);
    preprocess(filename, result);
    mergeStringLiterals(result);
 
#if 0
    for (int j = 0; j < result.size(); ++j)
        fprintf(stderr, "line %d: %s(%s)\n",
               result[j].lineNum,
               result[j].lexem().constData(),
               tokenTypeName(result[j].token));
#endif
 
    return result;
}
 
void Preprocessor::parseDefineArguments(Macro *m)
{
    Symbols arguments;
    while (hasNext()) {
        while (test(PP_WHITESPACE)) {}
        Token t = next();
        if (t == PP_RPAREN)
            break;
        if (t != PP_IDENTIFIER) {
            QByteArrayView l = lexemView();
            if (l == "...") {
                m->isVariadic = true;
                arguments += Symbol(symbol().lineNum, PP_IDENTIFIER, "__VA_ARGS__");
                while (test(PP_WHITESPACE)) {}
                if (!test(PP_RPAREN))
                    error("missing ')' in macro argument list");
                break;
            } else if (!is_identifier(l.constData(), l.size())) {
                error("Unexpected character in macro argument list.");
            }
        }
 
        Symbol arg = symbol();
        if (arguments.contains(arg))
            error("Duplicate macro parameter.");
        arguments += symbol();
 
        while (test(PP_WHITESPACE)) {}
        t = next();
        if (t == PP_RPAREN)
            break;
        if (t == PP_COMMA)
            continue;
        if (lexemView() == "...") {
            //GCC extension:    #define FOO(x, y...) x(y)
            // The last argument was already parsed. Just mark the macro as variadic.
            m->isVariadic = true;
            while (test(PP_WHITESPACE)) {}
            if (!test(PP_RPAREN))
                error("missing ')' in macro argument list");
            break;
        }
        error("Unexpected character in macro argument list.");
    }
    m->arguments = arguments;
    while (test(PP_WHITESPACE)) {}
}
 
void Preprocessor::until(Token t)
{
    while(hasNext() && next() != t)
        ;
}
 
void Preprocessor::setDebugIncludes(bool value)
{
    debugIncludes = value;
}
 
 
QT_END_NAMESPACE