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#include "qsyntaxhighlighter.h"

#ifndef QT_NO_SYNTAXHIGHLIGHTER

#include <private/qobject_p.h>

#include <qtextdocument.h>

#include <private/qtextdocument_p.h>

#include <qtextlayout.h>

#include <qpointer.h>

#include <qtextobject.h>

#include <qtextcursor.h>

#include <qdebug.h>

#include <qtextedit.h>

#include <qtimer.h>

QT_BEGIN_NAMESPACE

class QSyntaxHighlighterPrivate : public QObjectPrivate

{

    Q_DECLARE_PUBLIC(QSyntaxHighlighter)

public:

    inline QSyntaxHighlighterPrivate() : rehighlightPending(false) {}

    QPointer<QTextDocument> doc;

    void _q_reformatBlocks(int from, int charsRemoved, int charsAdded);

    void reformatBlock(QTextBlock block);

    inline void rehighlight(QTextCursor &cursor, QTextCursor::MoveOperation operation) {

        QObject::disconnect(doc, SIGNAL(contentsChange(int,int,int)),

                            q_func(), SLOT(_q_reformatBlocks(int,int,int)));

        cursor.beginEditBlock();

        int from = cursor.position();

        cursor.movePosition(operation);

        _q_reformatBlocks(from, 0, cursor.position() - from);

        cursor.endEditBlock();

        QObject::connect(doc, SIGNAL(contentsChange(int,int,int)),

                         q_func(), SLOT(_q_reformatBlocks(int,int,int)));

    }

    inline void _q_delayedRehighlight() {

        if (!rehighlightPending)

            return;

        rehighlightPending = false;

        q_func()->rehighlight();

        return;

    }

    void applyFormatChanges();

    QVector<QTextCharFormat> formatChanges;

    QTextBlock currentBlock;

    bool rehighlightPending;

};

void QSyntaxHighlighterPrivate::applyFormatChanges()

{

    QTextLayout *layout = currentBlock.layout();

    QList<QTextLayout::FormatRange> ranges = layout->additionalFormats();

    const int preeditAreaStart = layout->preeditAreaPosition();

    const int preeditAreaLength = layout->preeditAreaText().length();

    QList<QTextLayout::FormatRange>::Iterator it = ranges.begin();

    while (it != ranges.end()) {

        if (it->start >= preeditAreaStart

            && it->start + it->length <= preeditAreaStart + preeditAreaLength)

            ++it;

        else

            it = ranges.erase(it);

    }

    QTextCharFormat emptyFormat;

    QTextLayout::FormatRange r;

    r.start = r.length = -1;

    int i = 0;

    while (i < formatChanges.count()) {

        while (i < formatChanges.count() && formatChanges.at(i) == emptyFormat)

            ++i;

        if (i >= formatChanges.count())

            break;

        r.start = i;

        r.format = formatChanges.at(i);

        while (i < formatChanges.count() && formatChanges.at(i) == r.format)

            ++i;

        if (i >= formatChanges.count())

            break;

        r.length = i - r.start;

        if (r.start >= preeditAreaStart) {

            r.start += preeditAreaLength;

        } else if (r.start + r.length >= preeditAreaStart) {

            r.length += preeditAreaLength;

        }

        ranges << r;

        r.start = r.length = -1;

    }

    if (r.start != -1) {

        r.length = formatChanges.count() - r.start;

        if (r.start >= preeditAreaStart) {

            r.start += preeditAreaLength;

        } else if (r.start + r.length >= preeditAreaStart) {

            r.length += preeditAreaLength;

        }

        ranges << r;

    }

    layout->setAdditionalFormats(ranges);

}

void QSyntaxHighlighterPrivate::_q_reformatBlocks(int from, int charsRemoved, int charsAdded)

{

    Q_UNUSED(charsRemoved);

    rehighlightPending = false;

    QTextBlock block = doc->findBlock(from);

    if (!block.isValid())

        return;

    int endPosition;

    QTextBlock lastBlock = doc->findBlock(from + charsAdded + (charsRemoved > 0 ? 1 : 0));

    if (lastBlock.isValid())

        endPosition = lastBlock.position() + lastBlock.length();

    else

        endPosition = doc->docHandle()->length();

    bool forceHighlightOfNextBlock = false;

    while (block.isValid() && (block.position() < endPosition || forceHighlightOfNextBlock)) {

        const int stateBeforeHighlight = block.userState();

        reformatBlock(block);

        forceHighlightOfNextBlock = (block.userState() != stateBeforeHighlight);

        block = block.next();

    }

    formatChanges.clear();

}

void QSyntaxHighlighterPrivate::reformatBlock(QTextBlock block)

{

    Q_Q(QSyntaxHighlighter);

    Q_ASSERT_X(!currentBlock.isValid(), "QSyntaxHighlighter::reformatBlock()", "reFormatBlock() called recursively");

    currentBlock = block;

    QTextBlock previous = block.previous();

    formatChanges.fill(QTextCharFormat(), block.length() - 1);

    q->highlightBlock(block.text());

    applyFormatChanges();

    doc->markContentsDirty(block.position(), block.length());

    currentBlock = QTextBlock();

}

/*!

    \class QSyntaxHighlighter

    \reentrant

    \brief The QSyntaxHighlighter class allows you to define syntax

    highlighting rules, and in addition you can use the class to query

    a document's current formatting or user data.

    \since 4.1

    \ingroup richtext-processing

    The QSyntaxHighlighter class is a base class for implementing

    QTextEdit syntax highlighters.  A syntax highligher automatically

    highlights parts of the text in a QTextEdit, or more generally in

    a QTextDocument. Syntax highlighters are often used when the user

    is entering text in a specific format (for example source code)

    and help the user to read the text and identify syntax errors.

    To provide your own syntax highlighting, you must subclass

    QSyntaxHighlighter and reimplement highlightBlock().

    When you create an instance of your QSyntaxHighlighter subclass,

    pass it the QTextEdit or QTextDocument that you want the syntax

    highlighting to be applied to. For example:

    \snippet doc/src/snippets/code/src_gui_text_qsyntaxhighlighter.cpp 0

    After this your highlightBlock() function will be called

    automatically whenever necessary. Use your highlightBlock()

    function to apply formatting (e.g. setting the font and color) to

    the text that is passed to it. QSyntaxHighlighter provides the

    setFormat() function which applies a given QTextCharFormat on

    the current text block. For example:

    \snippet doc/src/snippets/code/src_gui_text_qsyntaxhighlighter.cpp 1

    Some syntaxes can have constructs that span several text

    blocks. For example, a C++ syntax highlighter should be able to

    cope with \c{/}\c{*...*}\c{/} multiline comments. To deal with

    these cases it is necessary to know the end state of the previous

    text block (e.g. "in comment").

    Inside your highlightBlock() implementation you can query the end

    state of the previous text block using the previousBlockState()

    function. After parsing the block you can save the last state

    using setCurrentBlockState().

    The currentBlockState() and previousBlockState() functions return

    an int value. If no state is set, the returned value is -1. You

    can designate any other value to identify any given state using

    the setCurrentBlockState() function. Once the state is set the

    QTextBlock keeps that value until it is set set again or until the

    corresponding paragraph of text is deleted.

    For example, if you're writing a simple C++ syntax highlighter,

    you might designate 1 to signify "in comment":

    \snippet doc/src/snippets/code/src_gui_text_qsyntaxhighlighter.cpp 2

    In the example above, we first set the current block state to

    0. Then, if the previous block ended within a comment, we higlight

    from the beginning of the current block (\c {startIndex =

    0}). Otherwise, we search for the given start expression. If the

    specified end expression cannot be found in the text block, we

    change the current block state by calling setCurrentBlockState(),

    and make sure that the rest of the block is higlighted.

    In addition you can query the current formatting and user data

    using the format() and currentBlockUserData() functions

    respectively. You can also attach user data to the current text

    block using the setCurrentBlockUserData() function.

    QTextBlockUserData can be used to store custom settings. In the

    case of syntax highlighting, it is in particular interesting as

    cache storage for information that you may figure out while

    parsing the paragraph's text. For an example, see the

    setCurrentBlockUserData() documentation.

    \sa QTextEdit, {Syntax Highlighter Example}

*/

/*!

    Constructs a QSyntaxHighlighter with the given \a parent.

*/

QSyntaxHighlighter::QSyntaxHighlighter(QObject *parent)

    : QObject(*new QSyntaxHighlighterPrivate, parent)

{

}

/*!

    Constructs a QSyntaxHighlighter and installs it on \a parent.

    The specified QTextDocument also becomes the owner of the

    QSyntaxHighlighter.

*/

QSyntaxHighlighter::QSyntaxHighlighter(QTextDocument *parent)

    : QObject(*new QSyntaxHighlighterPrivate, parent)

{

    setDocument(parent);

}

/*!

    Constructs a QSyntaxHighlighter and installs it on \a parent 's

    QTextDocument. The specified QTextEdit also becomes the owner of

    the QSyntaxHighlighter.

*/

QSyntaxHighlighter::QSyntaxHighlighter(QTextEdit *parent)

    : QObject(*new QSyntaxHighlighterPrivate, parent)

{

    setDocument(parent->document());

}

/*!

    Destructor. Uninstalls this syntax highlighter from the text document.

*/

QSyntaxHighlighter::~QSyntaxHighlighter()

{

    setDocument(0);

}

/*!

    Installs the syntax highlighter on the given QTextDocument \a doc.

    A QSyntaxHighlighter can only be used with one document at a time.

*/

void QSyntaxHighlighter::setDocument(QTextDocument *doc)

{

    Q_D(QSyntaxHighlighter);

    if (d->doc) {

        disconnect(d->doc, SIGNAL(contentsChange(int,int,int)),

                   this, SLOT(_q_reformatBlocks(int,int,int)));

        QTextCursor cursor(d->doc);

        cursor.beginEditBlock();

        for (QTextBlock blk = d->doc->begin(); blk.isValid(); blk = blk.next())

            blk.layout()->clearAdditionalFormats();

        cursor.endEditBlock();

    }

    d->doc = doc;

    if (d->doc) {

        connect(d->doc, SIGNAL(contentsChange(int,int,int)),

                this, SLOT(_q_reformatBlocks(int,int,int)));

        QTimer::singleShot(0, this, SLOT(_q_delayedRehighlight()));

        d->rehighlightPending = true;

    }

}

/*!

    Returns the QTextDocument on which this syntax highlighter is

    installed.

*/

QTextDocument *QSyntaxHighlighter::document() const

{

    Q_D(const QSyntaxHighlighter);

    return d->doc;

}

/*!

    \since 4.2

    Reapplies the highlighting to the whole document.

    \sa rehighlightBlock()

*/

void QSyntaxHighlighter::rehighlight()

{

    Q_D(QSyntaxHighlighter);

    if (!d->doc)

        return;

    QTextCursor cursor(d->doc);

    d->rehighlight(cursor, QTextCursor::End);

}

/*!

    \since 4.6

    Reapplies the highlighting to the given QTextBlock \a block.

    \sa rehighlight()

*/

void QSyntaxHighlighter::rehighlightBlock(const QTextBlock &block)

{

    Q_D(QSyntaxHighlighter);

    if (!d->doc)

        return;

    QTextCursor cursor(block);

    d->rehighlight(cursor, QTextCursor::EndOfBlock);

}

/*!

    \fn void QSyntaxHighlighter::highlightBlock(const QString &text)

    Highlights the given text block. This function is called when

    necessary by the rich text engine, i.e. on text blocks which have

    changed.

    To provide your own syntax highlighting, you must subclass

    QSyntaxHighlighter and reimplement highlightBlock(). In your

    reimplementation you should parse the block's \a text and call

    setFormat() as often as necessary to apply any font and color

    changes that you require. For example:

    \snippet doc/src/snippets/code/src_gui_text_qsyntaxhighlighter.cpp 3

    Some syntaxes can have constructs that span several text

    blocks. For example, a C++ syntax highlighter should be able to

    cope with \c{/}\c{*...*}\c{/} multiline comments. To deal with

    these cases it is necessary to know the end state of the previous

    text block (e.g. "in comment").

    Inside your highlightBlock() implementation you can query the end

    state of the previous text block using the previousBlockState()

    function. After parsing the block you can save the last state

    using setCurrentBlockState().

    The currentBlockState() and previousBlockState() functions return

    an int value. If no state is set, the returned value is -1. You

    can designate any other value to identify any given state using

    the setCurrentBlockState() function. Once the state is set the

    QTextBlock keeps that value until it is set set again or until the

    corresponding paragraph of text gets deleted.

    For example, if you're writing a simple C++ syntax highlighter,

    you might designate 1 to signify "in comment". For a text block

    that ended in the middle of a comment you'd set 1 using

    setCurrentBlockState, and for other paragraphs you'd set 0.

    In your parsing code if the return value of previousBlockState()

    is 1, you would highlight the text as a C++ comment until you

    reached the closing \c{*}\c{/}.

    \sa previousBlockState(), setFormat(), setCurrentBlockState()

*/

/*!

    This function is applied to the syntax highlighter's current text

    block (i.e. the text that is passed to the highlightBlock()

    function).

    The specified \a format is applied to the text from the \a start

    position for a length of \a count characters (if \a count is 0,

    nothing is done). The formatting properties set in \a format are

    merged at display time with the formatting information stored

    directly in the document, for example as previously set with

    QTextCursor's functions. Note that the document itself remains

    unmodified by the format set through this function.

    \sa format(), highlightBlock()

*/

void QSyntaxHighlighter::setFormat(int start, int count, const QTextCharFormat &format)

{

    Q_D(QSyntaxHighlighter);

    if (start < 0 || start >= d->formatChanges.count())

        return;

    const int end = qMin(start + count, d->formatChanges.count());

    for (int i = start; i < end; ++i)

        d->formatChanges[i] = format;

}

/*!

    \overload

    The specified \a color is applied to the current text block from

    the \a start position for a length of \a count characters.

    The other attributes of the current text block, e.g. the font and

    background color, are reset to default values.

    \sa format(), highlightBlock()

*/

void QSyntaxHighlighter::setFormat(int start, int count, const QColor &color)

{

    QTextCharFormat format;

    format.setForeground(color);

    setFormat(start, count, format);

}

/*!

    \overload

    The specified \a font is applied to the current text block from

    the \a start position for a length of \a count characters.

    The other attributes of the current text block, e.g. the font and

    background color, are reset to default values.

    \sa format(), highlightBlock()

*/

void QSyntaxHighlighter::setFormat(int start, int count, const QFont &font)

{

    QTextCharFormat format;

    format.setFont(font);

    setFormat(start, count, format);

}

/*!

    \fn QTextCharFormat QSyntaxHighlighter::format(int position) const

    Returns the format at \a position inside the syntax highlighter's

    current text block.

*/

QTextCharFormat QSyntaxHighlighter::format(int pos) const

{

    Q_D(const QSyntaxHighlighter);

    if (pos < 0 || pos >= d->formatChanges.count())

        return QTextCharFormat();

    return d->formatChanges.at(pos);

}

/*!

    Returns the end state of the text block previous to the

    syntax highlighter's current block. If no value was

    previously set, the returned value is -1.

    \sa highlightBlock(), setCurrentBlockState()

*/