yyindent.cpp

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/*
    This file is a self-contained interactive indenter for C++ and Qt
    Script.

    The general problem of indenting a C++ program is ill posed. On
    the one hand, an indenter has to analyze programs written in a
    free-form formal language that is best described in terms of
    tokens, not characters, not lines. On the other hand, indentation
    applies to lines and white space characters matter, and otherwise
    the programs to indent are formally invalid in general, as they
    are begin edited.

    The approach taken here works line by line. We receive a program
    consisting of N lines or more, and we want to compute the
    indentation appropriate for the Nth line. Lines beyond the Nth
    lines are of no concern to us, so for simplicity we pretend the
    program has exactly N lines and we call the Nth line the "bottom
    line". Typically, we have to indent the bottom line when it's
    still empty, so we concentrate our analysis on the N - 1 lines
    that precede.

    By inspecting the (N - 1)-th line, the (N - 2)-th line, ...
    backwards, we determine the kind of the bottom line and indent it
    accordingly.

      * The bottom line is a comment line. See
        bottomLineStartsInCComment() and
        indentWhenBottomLineStartsInCComment().
      * The bottom line is a continuation line. See isContinuationLine()
        and indentForContinuationLine().
      * The bottom line is a standalone line. See
        indentForStandaloneLine().

    Certain tokens that influence the indentation, notably braces,
    are looked for in the lines. This is done by simple string
    comparison, without a real tokenizer. Confusing constructs such
    as comments and string literals are removed beforehand.
*/

#include <qregexp.h>
#include <qstringlist.h>

QT_BEGIN_NAMESPACE

/* qmake ignore Q_OBJECT */

/*
    The indenter avoids getting stuck in almost infinite loops by
    imposing arbitrary limits on the number of lines it analyzes when
    looking for a construct.

    For example, the indenter never considers more than BigRoof lines
    backwards when looking for the start of a C-style comment.
*/
static const int SmallRoof = 40;
static const int BigRoof = 400;

/*
    The indenter supports a few parameters:

      * ppHardwareTabSize is the size of a '\t' in your favorite editor.
      * ppIndentSize is the size of an indentation, or software tab
        size.
      * ppContinuationIndentSize is the extra indent for a continuation
        line, when there is nothing to align against on the previous
        line.
      * ppCommentOffset is the indentation within a C-style comment,
        when it cannot be picked up.
*/

static int ppHardwareTabSize = 8;
static int ppIndentSize = 4;
static int ppContinuationIndentSize = 8;

static const int ppCommentOffset = 2;

void setTabSize( int size )
{
    ppHardwareTabSize = size;
}

void setIndentSize( int size )
{
    ppIndentSize = size;
    ppContinuationIndentSize = 2 * size;
}

static QRegExp *literal = 0;
static QRegExp *label = 0;
static QRegExp *inlineCComment = 0;
static QRegExp *braceX = 0;
static QRegExp *iflikeKeyword = 0;

/*
    Returns the first non-space character in the string t, or
    QChar::Null if the string is made only of white space.
*/
static QChar firstNonWhiteSpace( const QString& t )
{
    int i = 0;
    while ( i < (int) t.length() ) {
        if ( !t[i].isSpace() )
            return t[i];
        i++;
    }
    return QChar::Null;
}

/*
    Returns true if string t is made only of white space; otherwise
    returns false.
*/
static bool isOnlyWhiteSpace( const QString& t )
{
    return firstNonWhiteSpace( t ).isNull();
}

/*
    Assuming string t is a line, returns the column number of a given
    index. Column numbers and index are identical for strings that don't
    contain '\t's.
*/
int columnForIndex( const QString& t, int index )
{
    int col = 0;
    if ( index > (int) t.length() )
        index = t.length();

    for ( int i = 0; i < index; i++ ) {
        if ( t[i] == QChar('\t') ) {
            col = ( (col / ppHardwareTabSize) + 1 ) * ppHardwareTabSize;
        } else {
            col++;
        }
    }
    return col;
}

/*
    Returns the indentation size of string t.
*/
int indentOfLine( const QString& t )
{
    return columnForIndex( t, t.indexOf(firstNonWhiteSpace(t)) );
}

/*
    Replaces t[k] by ch, unless t[k] is '\t'. Tab characters are better
    left alone since they break the "index equals column" rule. No
    provisions are taken against '\n' or '\r', which shouldn't occur in
    t anyway.
*/
static inline void eraseChar( QString& t, int k, QChar ch )
{
    if ( t[k] != '\t' )
        t[k] = ch;
}

/*
   Removes some nefast constructs from a code line and returns the
   resulting line.
*/
static QString trimmedCodeLine( const QString& t )
{
    QString trimmed = t;
    int k;

    /*
        Replace character and string literals by X's, since they may
        contain confusing characters (such as '{' and ';'). "Hello!" is
        replaced by XXXXXXXX. The literals are rigourously of the same
        length before and after; otherwise, we would break alignment of
        continuation lines.
    */
    k = 0;
    while ( (k = trimmed.indexOf(*literal, k)) != -1 ) {
        for ( int i = 0; i < literal->matchedLength(); i++ )
            eraseChar( trimmed, k + i, 'X' );
        k += literal->matchedLength();
    }

    /*
        Replace inline C-style comments by spaces. Other comments are
        handled elsewhere.
    */
    k = 0;
    while ( (k = trimmed.indexOf(*inlineCComment, k)) != -1 ) {
        for ( int i = 0; i < inlineCComment->matchedLength(); i++ )
            eraseChar( trimmed, k + i, ' ' );
        k += inlineCComment->matchedLength();
    }

    /*
        Replace goto and switch labels by whitespace, but be careful
        with this case:

        foo1: bar1;
                bar2;
    */
    while ( trimmed.lastIndexOf(':') != -1 && trimmed.indexOf(*label) != -1 ) {
        QString cap1 = label->cap( 1 );
        int pos1 = label->pos( 1 );
        int stop = cap1.length();

        if ( pos1 + stop < (int) trimmed.length() && ppIndentSize < stop )
            stop = ppIndentSize;

        int i = 0;
        while ( i < stop ) {
            eraseChar( trimmed, pos1 + i, ' ' );
            i++;
        }
        while ( i < (int) cap1.length() ) {
            eraseChar( trimmed, pos1 + i, ';' );
            i++;
        }
    }

    /*
        Remove C++-style comments.
    */
    k = trimmed.indexOf( "//" );
    if ( k != -1 )
        trimmed.truncate( k );

    return trimmed;
}

/*
    Returns '(' if the last parenthesis is opening, ')' if it is
    closing, and QChar::Null if there are no parentheses in t.
*/
static inline QChar lastParen( const QString& t )
{
    int i = t.length();
    while ( i > 0 ) {
        i--;
        if ( t[i] == QChar('(') || t[i] == QChar(')') )
            return t[i];
    }
    return QChar::Null;
}

/*
    Returns true if typedIn the same as okayCh or is null; otherwise
    returns false.
*/
static inline bool okay( QChar typedIn, QChar okayCh )
{
    return typedIn == QChar::Null || typedIn == okayCh;
}

/*
    The "linizer" is a group of functions and variables to iterate
    through the source code of the program to indent. The program is
    given as a list of strings, with the bottom line being the line
    to indent. The actual program might contain extra lines, but
    those are uninteresting and not passed over to us.
*/

struct LinizerState
{
    QString line;
    int braceDepth;
    bool leftBraceFollows;

    QStringList::ConstIterator iter;
    bool inCComment;
    bool pendingRightBrace;
};

static QStringList *yyProgram = 0;
static LinizerState *yyLinizerState = 0;

// shorthands
static const QString *yyLine = 0;
static const int *yyBraceDepth = 0;
static const bool *yyLeftBraceFollows = 0;

/*
    Saves and restores the state of the global linizer. This enables
    backtracking.
*/
#define YY_SAVE() \
        LinizerState savedState = *yyLinizerState
#define YY_RESTORE() \
        *yyLinizerState = savedState

/*
    Advances to the previous line in yyProgram and update yyLine
    accordingly. yyLine is cleaned from comments and other damageable
    constructs. Empty lines are skipped.
*/
static bool readLine()
{
    int k;

    yyLinizerState->leftBraceFollows =
            ( firstNonWhiteSpace(yyLinizerState->line) == QChar('{') );

    do {
        if ( yyLinizerState->iter == yyProgram->begin() ) {
            yyLinizerState->line.clear();
            return false;
        }

        --yyLinizerState->iter;
        yyLinizerState->line = *yyLinizerState->iter;

        yyLinizerState->line = trimmedCodeLine( yyLinizerState->line );

        /*
            Remove C-style comments that span multiple lines. If the
            bottom line starts in a C-style comment, we are not aware
            of that and eventually yyLine will contain a slash-aster.

            Notice that both if's can be executed, since
            yyLinizerState->inCComment is potentially set to false in
            the first if. The order of the if's is also important.
        */

        if ( yyLinizerState->inCComment ) {
            QString slashAster( "/*" );

            k = yyLinizerState->line.indexOf( slashAster );
            if ( k == -1 ) {
                yyLinizerState->line.clear();
            } else {
                yyLinizerState->line.truncate( k );
                yyLinizerState->inCComment = false;
            }
        }

        if ( !yyLinizerState->inCComment ) {
            QString asterSlash( "*/" );

            k = yyLinizerState->line.indexOf( asterSlash );
            if ( k != -1 ) {
                for ( int i = 0; i < k + 2; i++ )
                    eraseChar( yyLinizerState->line, i, ' ' );
                yyLinizerState->inCComment = true;
            }
        }

        /*
            Remove preprocessor directives.
        */
        k = 0;
        while ( k < (int) yyLinizerState->line.length() ) {
            QChar ch = yyLinizerState->line[k];
            if ( ch == QChar('#') ) {
                yyLinizerState->line.clear();
            } else if ( !ch.isSpace() ) {
                break;
            }
            k++;
        }

        /*
            Remove trailing spaces.
        */
        k = yyLinizerState->line.length();
        while ( k > 0 && yyLinizerState->line[k - 1].isSpace() )
            k--;
        yyLinizerState->line.truncate( k );

        /*
            '}' increment the brace depth and '{' decrements it and not
            the other way around, as we are parsing backwards.
        */
        yyLinizerState->braceDepth +=
                yyLinizerState->line.count( '}' ) -
                yyLinizerState->line.count( '{' );

        /*
            We use a dirty trick for

                } else ...

            We don't count the '}' yet, so that it's more or less
            equivalent to the friendly construct

                }
                else ...
        */
        if ( yyLinizerState->pendingRightBrace )
            yyLinizerState->braceDepth++;
        yyLinizerState->pendingRightBrace =
                ( yyLinizerState->line.indexOf(*braceX) == 0 );
        if ( yyLinizerState->pendingRightBrace )
            yyLinizerState->braceDepth--;
    } while ( yyLinizerState->line.isEmpty() );

    return true;
}

/*
    Resets the linizer to its initial state, with yyLine containing the
    line above the bottom line of the program.
*/
static void startLinizer()
{
    yyLinizerState->braceDepth = 0;
    yyLinizerState->inCComment = false;
    yyLinizerState->pendingRightBrace = false;

    yyLine = &yyLinizerState->line;
    yyBraceDepth = &yyLinizerState->braceDepth;
    yyLeftBraceFollows = &yyLinizerState->leftBraceFollows;

    yyLinizerState->iter = yyProgram->end();
    --yyLinizerState->iter;
    yyLinizerState->line = *yyLinizerState->iter;
    readLine();
}

/*
    Returns true if the start of the bottom line of yyProgram (and
    potentially the whole line) is part of a C-style comment;
    otherwise returns false.
*/
static bool bottomLineStartsInCComment()
{
    QString slashAster( "/*" );
    QString asterSlash( "*/" );

    /*
        We could use the linizer here, but that would slow us down
        terribly. We are better to trim only the code lines we need.
    */
    QStringList::ConstIterator p = yyProgram->end();
    --p; // skip bottom line

    for ( int i = 0; i < BigRoof; i++ ) {
        if ( p == yyProgram->begin() )
            return false;
        --p;

        if ( (*p).indexOf(slashAster) != -1 || (*p).indexOf(asterSlash) != -1 ) {
            QString trimmed = trimmedCodeLine( *p );

            if ( trimmed.indexOf(slashAster) != -1 ) {
                return true;
            } else if ( trimmed.indexOf(asterSlash) != -1 ) {
                return false;
            }
        }
    }
    return false;
}

/*
    Returns the recommended indent for the bottom line of yyProgram
    assuming that it starts in a C-style comment, a condition that is
    tested elsewhere.

    Essentially, we're trying to align against some text on the
    previous line.
*/
static int indentWhenBottomLineStartsInCComment()
{
    int k = yyLine->lastIndexOf( "/*" );
    if ( k == -1 ) {
        /*
          We found a normal text line in a comment. Align the
          bottom line with the text on this line.
        */
        return indentOfLine( *yyLine );
    } else {
        /*
          The C-style comment starts on this line. If there is
          text on the same line, align with it. Otherwise, align
          with the slash-aster plus a given offset.
        */
        int indent = columnForIndex( *yyLine, k );
        k += 2;
        while ( k < (int) yyLine->length() ) {
            if ( !(*yyLine)[k].isSpace() )
                return columnForIndex( *yyLine, k );
            k++;
        }
        return indent + ppCommentOffset;
    }
}

/*
    A function called match...() modifies the linizer state. If it
    returns true, yyLine is the top line of the matched construct;
    otherwise, the linizer is left in an unknown state.

    A function called is...() keeps the linizer state intact.
*/

/*
    Returns true if the current line (and upwards) forms a braceless
    control statement; otherwise returns false.

    The first line of the following example is a "braceless control
    statement":

        if ( x )
            y;
*/
static bool matchBracelessControlStatement()
{
    int delimDepth = 0;

    if ( yyLine->endsWith("else") )
        return true;

    if ( !yyLine->endsWith(")") )
        return false;

    for ( int i = 0; i < SmallRoof; i++ ) {
        int j = yyLine->length();
        while ( j > 0 ) {
            j--;
            QChar ch = (*yyLine)[j];

            switch ( ch.unicode() ) {
            case ')':
                delimDepth++;
                break;
            case '(':
                delimDepth--;
                if ( delimDepth == 0 ) {
                    if ( yyLine->indexOf(*iflikeKeyword) != -1 ) {
                        /*
                            We have

                                if ( x )
                                    y

                            "if ( x )" is not part of the statement
                            "y".
                        */
                        return true;
                    }
                }
                if ( delimDepth == -1 ) {
                    /*
                      We have

                          if ( (1 +
                                2)

                      and not

                          if ( 1 +
                               2 )
                    */
                    return false;
                }
                break;
            case '{':
            case '}':
            case ';':
                /*
                    We met a statement separator, but not where we
                    expected it. What follows is probably a weird
                    continuation line. Be careful with ';' in for,
                    though.
                */
                if ( ch != QChar(';') || delimDepth == 0 )
                    return false;
            }
        }

        if ( !readLine() )
            break;
    }
    return false;
}

/*
    Returns true if yyLine is an unfinished line; otherwise returns
    false.

    In many places we'll use the terms "standalone line", "unfinished
    line" and "continuation line". The meaning of these should be
    evident from this code example:

        a = b;    // standalone line
        c = d +   // unfinished line
            e +   // unfinished continuation line
            f +   // unfinished continuation line
            g;    // continuation line
*/
static bool isUnfinishedLine()
{
    bool unf = false;

    YY_SAVE();

    if ( yyLine->isEmpty() )
        return false;

    QChar lastCh = (*yyLine)[(int) yyLine->length() - 1];
    if ( QString("{};").indexOf(lastCh) == -1 && !yyLine->endsWith("...") ) {
        /*
          It doesn't end with ';' or similar. If it's neither
          "Q_OBJECT" nor "if ( x )", it must be an unfinished line.
        */
        unf = ( yyLine->indexOf("Q_OBJECT") == -1 &&
                !matchBracelessControlStatement() );
    } else if ( lastCh == QChar(';') ) {
        if ( lastParen(*yyLine) == QChar('(') ) {
            /*
              Exception:

                  for ( int i = 1; i < 10;
            */
            unf = true;
        } else if ( readLine() && yyLine->endsWith(";") &&
                    lastParen(*yyLine) == QChar('(') ) {
            /*
              Exception:

                  for ( int i = 1;
                        i < 10;
            */
            unf = true;
        }
    }

    YY_RESTORE();
    return unf;
}

/*
    Returns true if yyLine is a continuation line; otherwise returns
    false.
*/
static bool isContinuationLine()
{
    bool cont = false;

    YY_SAVE();
    if ( readLine() )
        cont = isUnfinishedLine();
    YY_RESTORE();
    return cont;
}

/*
    Returns the recommended indent for the bottom line of yyProgram,
    assuming it's a continuation line.

    We're trying to align the continuation line against some parenthesis
    or other bracked left opened on a previous line, or some interesting
    operator such as '='.
*/
static int indentForContinuationLine()
{
    int braceDepth = 0;
    int delimDepth = 0;

    bool leftBraceFollowed = *yyLeftBraceFollows;

    for ( int i = 0; i < SmallRoof; i++ ) {
        int hook = -1;

        int j = yyLine->length();
        while ( j > 0 && hook < 0 ) {
            j--;
            QChar ch = (*yyLine)[j];

            switch ( ch.unicode() ) {
            case ')':
            case ']':
                delimDepth++;
                break;
            case '}':
                braceDepth++;
                break;
            case '(':
            case '[':
                delimDepth--;
                /*
                    An unclosed delimiter is a good place to align at,
                    at least for some styles (including Qt's).
                */
                if ( delimDepth == -1 )
                    hook = j;
                break;
            case '{':
                braceDepth--;
                /*
                    A left brace followed by other stuff on the same
                    line is typically for an enum or an initializer.
                    Such a brace must be treated just like the other
                    delimiters.
                */
                if ( braceDepth == -1 ) {
                    if ( j < (int) yyLine->length() - 1 ) {
                        hook = j;
                    } else {
                        return 0; // shouldn't happen
                    }
                }
                break;
            case '=':
                /*
                    An equal sign is a very natural alignment hook
                    because it's usually the operator with the lowest
                    precedence in statements it appears in. Case in
                    point:

                        int x = 1 +
                                2;

                    However, we have to beware of constructs such as
                    default arguments and explicit enum constant
                    values:

                        void foo( int x = 0,
                                  int y = 0 );

                    And not

                        void foo( int x = 0,
                                        int y = 0 );

                    These constructs are caracterized by a ',' at the
                    end of the unfinished lines or by unbalanced
                    parentheses.
                */
                if ( QString("!=<>").indexOf((*yyLine)[j - 1]) == -1 &&
                     (*yyLine)[j + 1] != '=' ) {
                    if ( braceDepth == 0 && delimDepth == 0 &&
                         j < (int) yyLine->length() - 1 &&
                         !yyLine->endsWith(",") &&
                         (yyLine->contains('(') == yyLine->contains(')')) )
                        hook = j;
                }
            }
        }

        if ( hook >= 0 ) {
            /*
                Yes, we have a delimiter or an operator to align
                against! We don't really align against it, but rather
                against the following token, if any. In this example,
                the following token is "11":

                    int x = ( 11 +
                              2 );

                If there is no such token, we use a continuation indent:

                    static QRegExp foo( QString(
                            "foo foo foo foo foo foo foo foo foo") );
            */
            hook++;
            while ( hook < (int) yyLine->length() ) {
                if ( !(*yyLine)[hook].isSpace() )
                    return columnForIndex( *yyLine, hook );
                hook++;
            }
            return indentOfLine( *yyLine ) + ppContinuationIndentSize;
        }

        if ( braceDepth != 0 )
            break;

        /*
            The line's delimiters are balanced. It looks like a
            continuation line or something.
        */
        if ( delimDepth == 0 ) {
            if ( leftBraceFollowed ) {
                /*
                    We have

                        int main()
                        {

                    or

                        Bar::Bar()
                            : Foo( x )
                        {

                    The "{" should be flush left.
                */
                if ( !isContinuationLine() )
                    return indentOfLine( *yyLine );
            } else if ( isContinuationLine() || yyLine->endsWith(",") ) {
                /*
                    We have

                        x = a +
                            b +
                            c;

                    or

                        int t[] = {
                            1, 2, 3,
                            4, 5, 6

                    The "c;" should fall right under the "b +", and the
                    "4, 5, 6" right under the "1, 2, 3,".
                */
                return indentOfLine( *yyLine );
            } else {
                /*
                    We have

                        stream << 1 +
                                2;

                    We could, but we don't, try to analyze which
                    operator has precedence over which and so on, to
                    obtain the excellent result

                        stream << 1 +
                                  2;

                    We do have a special trick above for the assignment
                    operator above, though.
                */
                return indentOfLine( *yyLine ) + ppContinuationIndentSize;
            }
        }

        if ( !readLine() )
            break;
    }
    return 0;
}

/*
    Returns the recommended indent for the bottom line of yyProgram if
    that line is standalone (or should be indented likewise).

    Indenting a standalone line is tricky, mostly because of braceless
    control statements. Grossly, we are looking backwards for a special
    line, a "hook line", that we can use as a starting point to indent,
    and then modify the indentation level according to the braces met
    along the way to that hook.

    Let's consider a few examples. In all cases, we want to indent the
    bottom line.

    Example 1:

        x = 1;
        y = 2;

    The hook line is "x = 1;". We met 0 opening braces and 0 closing
    braces. Therefore, "y = 2;" inherits the indent of "x = 1;".

    Example 2:

        if ( x ) {
            y;

    The hook line is "if ( x ) {". No matter what precedes it, "y;" has
    to be indented one level deeper than the hook line, since we met one
    opening brace along the way.

    Example 3:

        if ( a )
            while ( b ) {
                c;
            }
        d;

    To indent "d;" correctly, we have to go as far as the "if ( a )".
    Compare with

        if ( a ) {
            while ( b ) {
                c;
            }
            d;

    Still, we're striving to go back as little as possible to
    accommodate people with irregular indentation schemes. A hook line
    near at hand is much more reliable than a remote one.
*/
static int indentForStandaloneLine()
{
    for ( int i = 0; i < SmallRoof; i++ ) {
        if ( !*yyLeftBraceFollows ) {
            YY_SAVE();

            if ( matchBracelessControlStatement() ) {
                /*
                    The situation is this, and we want to indent "z;":

                        if ( x &&
                             y )
                            z;

                    yyLine is "if ( x &&".
                */
                return indentOfLine( *yyLine ) + ppIndentSize;
            }
            YY_RESTORE();
        }

        if ( yyLine->endsWith(";") || yyLine->contains('{') ) {
            /*
                The situation is possibly this, and we want to indent
                "z;":

                    while ( x )
                        y;
                    z;

                We return the indent of "while ( x )". In place of "y;",
                any arbitrarily complex compound statement can appear.
            */

            if ( *yyBraceDepth > 0 ) {
                do {
                    if ( !readLine() )
                        break;
                } while ( *yyBraceDepth > 0 );
            }

            LinizerState hookState;

            while ( isContinuationLine() )
                readLine();
            hookState = *yyLinizerState;

            readLine();
            if ( *yyBraceDepth <= 0 ) {
                do {
                    if ( !matchBracelessControlStatement() )
                        break;
                    hookState = *yyLinizerState;
                } while ( readLine() );
            }

            *yyLinizerState = hookState;

            while ( isContinuationLine() )
                readLine();

            /*
              Never trust lines containing only '{' or '}', as some
              people (Richard M. Stallman) format them weirdly.
            */
            if ( yyLine->trimmed().length() > 1 )
                return indentOfLine( *yyLine ) - *yyBraceDepth * ppIndentSize;
        }

        if ( !readLine() )
            return -*yyBraceDepth * ppIndentSize;
    }
    return 0;
}

/*
    Constructs global variables used by the indenter.
*/
static void initializeIndenter()
{
    literal = new QRegExp( "([\"'])(?:\\\\.|[^\\\\])*\\1" );
    literal->setMinimal( true );
    label = new QRegExp(
        "^\\s*((?:case\\b([^:]|::)+|[a-zA-Z_0-9]+)(?:\\s+slots)?:)(?!:)" );
    inlineCComment = new QRegExp( "/\\*.*\\*/" );
    inlineCComment->setMinimal( true );
    braceX = new QRegExp( "^\\s*\\}\\s*(?:else|catch)\\b" );
    iflikeKeyword = new QRegExp( "\\b(?:catch|do|for|if|while)\\b" );

    yyLinizerState = new LinizerState;
}

/*
    Destroys global variables used by the indenter.
*/
static void terminateIndenter()
{
    delete literal;
    delete label;
    delete inlineCComment;
    delete braceX;
    delete iflikeKeyword;
    delete yyLinizerState;
}

/*
    Returns the recommended indent for the bottom line of program.
    Unless null, typedIn stores the character of yyProgram that
    triggered reindentation.

    This function works better if typedIn is set properly; it is
    slightly more conservative if typedIn is completely wild, and
    slighly more liberal if typedIn is always null. The user might be
    annoyed by the liberal behavior.
*/
int indentForBottomLine( const QStringList& program, QChar typedIn )
{
    if ( program.isEmpty() )
        return 0;

    initializeIndenter();

    yyProgram = new QStringList( program );
    startLinizer();

    const QString& bottomLine = program.last();
    QChar firstCh = firstNonWhiteSpace( bottomLine );
    int indent;

    if ( bottomLineStartsInCComment() ) {
        /*
            The bottom line starts in a C-style comment. Indent it
            smartly, unless the user has already played around with it,
            in which case it's better to leave her stuff alone.
        */
        if ( isOnlyWhiteSpace(bottomLine) ) {
            indent = indentWhenBottomLineStartsInCComment();
        } else {
            indent = indentOfLine( bottomLine );
        }
    } else if ( okay(typedIn, '#') && firstCh == QChar('#') ) {
        /*
            Preprocessor directives go flush left.
        */
        indent = 0;
    } else {
        if ( isUnfinishedLine() ) {
            indent = indentForContinuationLine();
        } else {
            indent = indentForStandaloneLine();
        }

        if ( okay(typedIn, '}') && firstCh == QChar('}') ) {
            /*
                A closing brace is one level more to the left than the
                code it follows.
            */
            indent -= ppIndentSize;
        } else if ( okay(typedIn, ':') ) {
            QRegExp caseLabel(
                "\\s*(?:case\\b(?:[^:]|::)+"
                "|(?:public|protected|private|signals|default)(?:\\s+slots)?\\s*"
                ")?:.*" );

            if ( caseLabel.exactMatch(bottomLine) ) {
                /*
                    Move a case label (or the ':' in front of a
                    constructor initialization list) one level to the
                    left, but only if the user did not play around with
                    it yet. Some users have exotic tastes in the
                    matter, and most users probably are not patient
                    enough to wait for the final ':' to format their
                    code properly.

                    We don't attempt the same for goto labels, as the
                    user is probably the middle of "foo::bar". (Who
                    uses goto, anyway?)
                */
                if ( indentOfLine(bottomLine) <= indent )
                    indent -= ppIndentSize;
                else
                    indent = indentOfLine( bottomLine );
            }
        }
    }
    delete yyProgram;
    terminateIndenter();
    return qMax( 0, indent );
}

QT_END_NAMESPACE

#ifdef Q_TEST_YYINDENT
/*
  Test driver.
*/

#include <qfile.h>
#include <qtextstream.h>

#include <errno.h>

QT_BEGIN_NAMESPACE

static QString fileContents( const QString& fileName )
{
    QFile f( fileName );
    if ( !f.open(QFile::ReadOnly) ) {
        qWarning( "yyindent error: Cannot open file '%s' for reading: %s",
                  fileName.toLatin1().data(), strerror(errno) );
        return QString();
    }

    QTextStream t( &f );
    QString contents = t.read();
    f.close();
    if ( contents.isEmpty() )
        qWarning( "yyindent error: File '%s' is empty", fileName.toLatin1().data() );
    return contents;
}

QT_END_NAMESPACE

int main( int argc, char **argv )
{
    QT_USE_NAMESPACE

    if ( argc != 2 ) {
        qWarning( "usage: yyindent file.cpp" );
        return 1;
    }

    QString code = fileContents( argv[1] );
    QStringList program = QStringList::split( '\n', code, true );
    QStringList p;
    QString out;

    while ( !program.isEmpty() && program.last().trimmed().isEmpty() )
        program.remove( program.fromLast() );

    QStringList::ConstIterator line = program.begin();
    while ( line != program.end() ) {
        p.push_back( *line );
        QChar typedIn = firstNonWhiteSpace( *line );
        if ( p.last().endsWith(":") )
            typedIn = ':';

        int indent = indentForBottomLine( p, typedIn );

        if ( !(*line).trimmed().isEmpty() ) {
            for ( int j = 0; j < indent; j++ )
                out += " ";
            out += (*line).trimmed();
        }
        out += "\n";
        ++line;
    }

    while ( out.endsWith("\n") )
        out.truncate( out.length() - 1 );

    printf( "%s\n", out.toLatin1().data() );
    return 0;
}

#endif // Q_TEST_YYINDENT