source: trunk/tools/qdoc3/yyindent.cpp@ 683

/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation ([email protected])
**
** This file is part of the tools applications of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at [email protected].
** $QT_END_LICENSE$
**
****************************************************************************/

/*
    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;
}

/*