path: root/noncore/apps/tinykate/libkate/qt3back/qregexp3.cpp

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** $Id$
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** Implementation of QRegExp class
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** Created : 950126
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#if QT_VERSION >= 0x030000
#error QRegExp3 is now in QT 3 use QRegExp instead
#endif

#if QT_VERSION < 0x030000
#include "./qregexp3.h"
#else
#include "qregexp.h"
#endif

/* OPIE */
#include <opie2/odebug.h>

/* QT */
#include <qarray.h>
#include <qbitarray.h>
#include <qcache.h>
#include <qintdict.h>
#include <qmap.h>
#include <qstring.h>
#include <qtl.h>
#include <qvector.h>

/* STD */
#include <limits.h>

/*
  WARNING!  Be sure to read qregexp.tex before modifying this file.
*/

/*!
  \class QRegExp3 qregexp.h

  \brief The QRegExp class provides pattern matching using regular expressions.

  \ingroup tools
  \ingroup misc
  \ingroup shared


    Regular expressions, "regexps", provide a way to find patterns
    within text. This is useful in many contexts, for example:

    <ol>
    <li>\e Validation. A regexp can be used to check whether a piece of
    text meets some criteria, e.g. is an integer or contains no
    whitespace.
    <li>\e Searching. Regexps provide a much more powerful means of
    searching text than simple string matching does. For example we can
    create a regexp which says "find one of the words 'mail', 'letter'
    or 'correspondence' but not any of the words 'email', 'mailman'
    'mailer', 'letterbox' etc."
    <li><em>Search and Replace.</em> A regexp can be used to replace a
    pattern with a piece of text, for example replace all occurrences of
    '&' with '\&amp;' except where the '&' is already followed by
    'amp;'.
    <li><em>String Splitting.</em> A regexp can be used to identify
    where a string should be split into its component fields, e.g.
    splitting tab delimited strings.
    </ol>

    We present a very brief introduction to regexps, a description of
    Qt's regexp language, some code examples, and finally the function
    documentation. QRegExp is modelled on Perl's regexp engine and fully
    supports Unicode. QRegExp may also be used in the weaker 'wildcard'
    (globbing) mode which works in a similar way to command shells. A
    good text on regexps is <i>Mastering Regular Expressions: Powerful
    Techniques for Perl and Other Tools</i> by Jeffrey E. Friedl, ISBN
    1565922573.

    Experienced regexp users may prefer to skip the introduction and
    go directly to the relevant information:

    <ul>
    <li><a href="#characters-and-abbreviations-for-sets-of-characters">
    Characters and Abbreviations for Sets of Characters</a>
    <li><a href="#sets-of-characters">Sets of Characters</a>
    <li><a href="#quantifiers">Quantifiers</a>
    <li><a href="#capturing-text">Capturing Text</a>
    <li><a href="#assertions">Assertions</a>
    <li><a href="#wildcard-matching">Wildcard Matching (globbing)</a>
    <li><a href="#perl-users">Notes for Perl Users</a>
    <li><a href="#code-examples">Code Examples</a>
    <li><a href="#member-function-documentation">Member Function Documentation</a>
    </ul>

    <b>Introduction</b>

    Regexps are built up from expressions, quantifiers and assertions.
    The simplest form of expression is simply a character, e.g. <b>x</b>
    or <b>5</b>. An expression can also be a set of characters. For
    example, <b>[ABCD]</b>, will match an <b>A</b> or a <b>B</b> or a
    <b>C</b> or a <b>D</b>. As a shorthand we could write this as
    <b>[A-D]</b>. If we want to match any of the captital letters in the
    English alphabet we can write <b>[A-Z]</b>. A quantifier tells the
    regexp engine how many occurrences of the expression we want, e.g.
    <b>x{1,1}</b> means match an <b>x</b> which occurs at least once and
    at most once. We'll look at assertions and more complex expressions
    later. Note that regexps cannot be used to check for balanced
    brackets or tags (unless you know the maximum level of nesting).


    We'll start by writing a regexp to match integers in the range 0 to
    99. We will require at least one digit so we will start with
    <b>[0-9]{1,1}</b> which means match a digit exactly once. This
    regexp alone will match integers in the range 0 to 9. To match one
    or two digits we can increase the maximum number of occurrences so
    the regexp becomes <b>[0-9]{1,2}</b> meaning match a digit at least
    once and at most twice. However, this regexp as it stands will not
    match correctly. This regexp will match one or two digits \e within
    a string. To ensure that we match against the whole string we must
    use the anchor assertions. We need <b>^</b> (caret) which when it is
    the first character in the regexp means that the regexp must match
    from the beginning of the string. And we also need <b>$</b> (dollar)
    which when it is the last character in the regexp means that the
    regexp must match until the end of the string. So now our regexp is
    <b>^[0-9]{1,2}$</b>. Note that assertions do not match any
    characters.

    If you've seen regexps elsewhere they may have looked different from
    the one above. This is because some sets of characters and some
    quantifiers are so common that they have special symbols to
    represent them. <b>[0-9]</b> can be replaced with the symbol
    <b>\d</b>. The quantifier to match exactly one occurrence,
    <b>{1,1}</b>, can be replaced with the expression itself. This means
    that <b>x{1,1}</b> is exactly the same as <b>x</b> alone. So our 0
    to 99 matcher could be written: <b>^\d{1,2}$</b>, although most
    people would write it <b>^\d\d?$</b>. The <b>?</b> is the same as
    the quantifier <b>{0,1}</b>, i.e. a minimum of no occurrences a
    maximum of one occurrence. This is used to make an expression
    optional. The regexp <b>^\d\d?$</b> means "from the beginning of the
    string match one digit followed by zero or one digits and then the
    end of the string".

    Our second example is matching the words 'mail', 'letter' or
    'correspondence' but without matching 'email', 'mailman', 'mailer',
    'letterbox' etc. We'll start by just matching 'mail'. In full the
    regexp is, <b>m{1,1}a{1,1}i{1,1}l{1,1}</b>, but since an expression
    itself is automatically quantified by <b>{1,1}</b> we can simply
    write this as <b>mail</b>; an 'm' followed by an 'a' followed by an
    'i' followed by an 'l'. The symbol '|' (bar) is used for \e
    alternation, so our regexp now becomes
    <b>mail|letter|correspondence</b> which means match 'mail' \e or
    'letter' \e or 'correspondence'. Whilst this regexp will find the
    words we want it will also find words we don't want such as 'email'.
    We will start by putting our regexp in parenthesis
    <b>(mail|letter|correspondence)</b>. Parenthesis have two effects,
    firstly they group expressions together and secondly they identify
    parts of the regexp that we wish to <a href="#capturing-text">capture</a>.
    Our regexp still matches any of the three words but now they are
    grouped together as a unit. This is useful for building up more
    complex regexps. It is also useful because it allows us to examine
    which of the words actually matched. We need to use another
    assertion, this time <b>\b</b> "word boundary":
    <b>\b(mail|letter|correspondence)\b</b>. This regexp means "match a
    word boundary followed by the expression in parenthesis followed by
    another word boundary". The <b>\b</b> assertion matches at a \e
    position in the regexp not a \e character in the regexp. A word
    boundary is any non-word character such as a space a newline or the
    beginning or end of the string.

    For our third example we want to replace ampersands with the HTML
    entity '\&amp;'. The regexp to match is simple: <b>\&</b>, i.e.
    match one ampersand. Unfortunately this will mess up our text if
    some of the ampersands have already been turned into HTML entities.
    So what we really want to say is replace an ampersand providing it
    is not followed by 'amp;'. For this we need the negative lookahead
    assertion and our regexp becomes: <b>\&(?!amp;)</b>. The negative
    lookahead assertion is introduced with '(?!' and finishes at the
    ')'. It means that the text it contains, 'amp;' in our example, must
    \e not follow the expression that preceeds it.

    Regexps provide a rich language that can be used in a variety of
    ways. For example suppose we want to count all the occurrences of
    'Eric' and 'Eirik' in a string. Two valid regexps to match these are
    <b>\\</b><b>b(Eric|Eirik)</b><b>\\</b><b>b</b> and
    <b>\\</b><b>bEi?ri[ck]</b><b>\\</b><b>b</b>. We need the word boundary
    '\b' so we don't get 'Ericsson' etc. The second regexp actually
    matches more than we want, 'Eric', 'Erik', 'Eiric' and 'Eirik'.

    We will implement some the examples above in the
    <a href="#code-examples">code examples</a> section.

    <a name="characters-and-abbreviations-for-sets-of-characters">
    <b>Characters and Abbreviations for Sets of Characters</b></a>

    <ul>

    <li><b>c</b> Any character represents itself unless it has a special regexp
    meaning. Thus <b>c</b> matches the character \e c.

    <li><b>\\</b><b>c</b> A character that follows a backslash matches the
    character itself except where mentioned below. For example if you
    wished to match a literal caret at the beginning of a string you
    would write <b>\^</b>.

    <li><b>\\</b><b>a</b> This matches the ASCII bell character (BEL, 0x07).
    <li><b>\\</b><b>f</b> This matches the ASCII form feed character (FF, 0x0C).
    <li><b>\\</b><b>n</b> This matches the ASCII line feed character (LF, 0x0A), (Unix newline).
    <li><b>\\</b><b>r</b> This matches the ASCII carriage return character (CR, 0x0D).
    <li><b>\\</b><b>t</b> This matches the ASCII horizontal tab character (HT, 0x09).
    <li><b>\\</b><b>v</b> This matches the ASCII vertical tab character (VT, 0x0B).
    <li><b>\\</b><b>xhhhh</b> This matches the Unicode character corresponding
    to the hexadecimal number hhhh (between 0x0000 and 0xFFFF). \0ooo
    (i.e., \zero ooo) matches the ASCII/Latin-1 character corresponding
    to the octal number ooo (between 0 and 0377).
    <li><b>. (dot)</b> This matches any character (including newline).
    <li><b>\\</b><b>d</b> This matches a digit (see QChar::isDigit()).
    <li><b>\\</b><b>D</b> This matches a non-digit.
    <li><b>\\</b><b>s</b> This matches a whitespace (see QChar::isSpace()).
    <li><b>\\</b><b>S</b> This matches a non-whitespace.
    <li><b>\\</b><b>w</b> This matches a word character (see QChar::isLetterOrNumber()).
    <li><b>\\</b><b>W</b> This matches a non-word character.
    <li><b>\\</b><b>n</b> The n<sup>th</sup>
    <a href="#capturing-text">backreference</a>, e.g. \1, \2, etc.
    </ul>

    <em>Note that the C++ compiler transforms backslashes in strings so
    to include a <b>\\</b> in a regexp you will need to enter it twice,
    i.e. <b>\\</b><b>\\</b>.</em>

    <a name="sets-of-characters"><b>Sets of Characters</b></a>

    Square brackets are used to match any character in the set of
    characters contained within the square brackets. All the character
    set abbreviations described above can be used within square
    brackets. Apart from the character set abbreviations and the
    following two exceptions no characters have special meanings in
    square brackets.

    <ul>

    <li><b>^</b> The caret negates the character set if it occurs as the
    first character, i.e. immediately after the opening square bracket.
    For example, <b>[abc]</b> matches 'a' or 'b' or 'c', but
    <b>[^abc]</b> matches anything \e except 'a' or 'b' or 'c'.

    <li><b>-</b> The dash is used to indicate a range of characters, for
    example <b>[W-Z]</b> matches 'W' or 'X' or 'Y' or 'Z'.

    </ul>

    Using the predefined character set abbreviations is more portable
    than using character ranges across platforms and languages. For
    example, <b>[0-9]</b> matches a digit in Western alphabets but
    <b>\d</b> matches a digit in \e any alphabet.

    Note that in most regexp literature sets of characters are called
    "character classes".

    <a name="quantifiers"><b>Quantifiers</b></a>

    By default an expression is automatically quantified by
    <b>{1,1}</b>, i.e. it should occur exactly once. In the following
    list <b><i>E</i></b> stands for any expression. An expression is a
    character or an abbreviation for a set of characters or a set of
    characters in square brackets or any parenthesised expression.

    <ul>

    <li><b><i>E</i>?</b> Matches zero or one occurrence of <i>E</i>.
    This quantifier means "the previous expression is optional" since it
    will match whether or not the expression occurs in the string.
    It is the same as <b><i>E</i>{0,1}</b>. For example <b>dents?</b>
    will match 'dent' and 'dents'.

    <li><b><i>E</i>+</b> Matches one or more occurrences of <i>E</i>.
    This is the same as <b><i>E</i>{1,MAXINT}</b>. For example,
    <b>0+</b> will match '0', '00', '000', etc.

    <li><b><i>E</i>*</b> Matches zero or more occurrences of <i>E</i>.
    This is the same as <b><i>E</i>{0,MAXINT}</b>. The <b>*</b>
    quantifier is often used by a mistake. Since it matches \e zero or
    more occurrences it will match no occurrences at all. For example if
    we want to match strings that end in whitespace and use the regexp
    <b>\s*$</b> we would get a match on every string. This is because we
    have said find zero or more whitespace followed by the end of string,
    so even strings that don't end in whitespace will match. The regexp
    we want in this case is <b>\s+$</b> to match strings that have at
    least one whitespace at the end.

    <li><b><i>E</i>{n}</b> Matches exactly \e n occurrences of the
    expression. This is the same as repeating the expression \e n times.
    For example, <b>x{5}</b> is the same as <b>xxxxx</b>. It is also the
    same as <b><i>E</i>{n,n}</b>, e.g. <b>x{5,5}</b>.

    <li><b><i>E</i>{n,}</b> Matches at least \e n occurrences of the
    expression. This is the same as <b><i>E</i>{n,MAXINT}</b>.

    <li><b><i>E</i>{,m}</b> Matches at most \e m occurrences of the
    expression. This is the same as <b><i>E</i>{0,m}</b>.

    <li><b><i>E</i>{n,m}</b> Matches at least \e n occurrences of the
    expression and at most \e m occurrences of the expression.

    </ul>

    (MAXINT is implementation dependent but will not be smaller than
    16384.)

    If we wish to apply a quantifier to more than just the preceeding
    character we can use parenthesis to group characters together in an
    expression. For example, <b>tag+</b> matches a 't' followed by an
    'a' followed by at least one 'g', whereas <b>(tag)+</b> matches at
    least one occurrence of 'tag'.

    Note that quantifiers are "greedy", they will match as much text as
    they can. For example, <b>0+</b> will match as many zeros as it can
    from the first zero it finds, e.g. '2.<u>000</u>5'. Quantifiers can
    be made non-greedy, see setMinimal().

    <a name="capturing-text"><b>Capturing Text</b></a>

    Parenthesis allow us to group elements together so that we can
    quantify and capture them. For example if we have the expression
    <b>mail|letter|correspondence</b> that matches a string we know that
    \e one of the words matched but not which one. Using  parenthesis
    allows us to "capture" whatever is matched within their bounds, so
    if we used <b>(mail|letter|correspondence)</b> and matched this
    regexp against the string "I sent you some email" we can use the
    cap() or capturedTexts() functions to extract the matched
    characters, in this case 'mail'.

    We can use captured text within the regexp itself. To refer to the
    captured text we use \e backreferences which are indexed from 1 the
    same as for cap(). For example we could search for duplicate words
    in a string using <b>\b(\w+)\W+\1\b</b> which means match a word
    boundary followed by one or more word characters followed by one or
    more non-word characters followed by the same text as the first
    parenthesised expression followed by a word boundary.

    If we want to use parenthesis purely for grouping and not for
    capturing we use the non-capturing syntax, e.g.
    <b>(?:green|blue)</b>. Non-capturing parenthesis begin '(?:' and end
    ')'. In this example we match either 'green' or 'blue' but we do not
    capture the match so we can only know whether or not we matched but
    not which color we actually found. Using non-capturing parenthesis
    is more efficient than using capturing parenthesis since the regexp
    engine has to do less book-keeping.

    Both capturing and non-capturing parenthesis may be nested.

    <a name="assertions"><b>Assertions</b></a>

    Assertions make some statement about the text at the point where
    they occur in the regexp but they do not match any characters.
    In the following list <b><i>E</i></b> stands for any expression.

    <ul>
    <li><b>^</b> If the caret is the first character in the regexp
    (apart from opening parenthesis) it signifies the beginning of the
    string. It has no special meaning elsewhere (except as the first
    character of a set of characters in square brackets). For example,
    <b>^#include</b> will only match strings which \e begin with the
    characters '#include'.

    <li><b>$</b> If the dollar is the last character in the regexp
    (apart from closing parenthesis) it signifies the end of the string.
    It has no special meaning elsewhere. For example, <b>\d\s*$</b>
    will match strings which end with a digit optionally followed by
    whitespace.

    <li><b>\\</b><b>b</b> A word boundary. For example the regexp
    <b>\\</b><b>bOK</b>\\</b><b>b</b> means match immediately after a
    word boundary (e.g. start of string or whitespace) the letter 'O'
    then the letter 'K' immediately before another word boundary (e.g.
    end of string or whitespace). But note that the assertion does not
    actually match any whitespace so if we write
    <b>(</b><b>\\</b><b>bOK</b>\\</b><b>b)</b> and we have a match it
    will only contain 'OK' even if the string is "Its <u>OK</u> now".

    <li><b>\\</b><b>B</b> A non-word boundary. This assertion is true
    wherever <b>\\</b><b>b</b> is false. For example if we searched for
    <b>\\</b><b>Bon</b>\\</b><b>B</b> in "Left on" the match would fail
    (space and end of string aren't non-word boundaries), but it would
    match in "t<u>on</u>ne".

    <li><b>(?=<i>E</i>)</b> Positive lookahead. This assertion is true
    if the expression matches at this point in the regex. This assertion
    does not match any characters. For example,
    <b>^#define\s+(\w+)(?=MAX)</b> will match strings which begin with
    '#define' followed by at least one whitespace followed by at least
    one word character followed by 'MAX'. The first set of parenthesis
    will capture the word character(s) matched. This regexp will not
    match '#define DEBUG' but will match '#define <u>INT</u>MAX
    32767'.

    <li><b>(?!<i>E</i>)</b> Negative lookahead. This assertion is true
    if the expression does not match at this point in the regex. This
    assertion does not match any characters. For example,
    <b>^#define\s+(\w+)\s*$</b> will match strings which begin with
    '#define' followed by at least one whitespace followed by at least
    one word character optionally followed by whitespace. This regexp
    will match define's that exist but have no value, i.e. it will not
    match '#define INTMAX 32767' but it will match '#define <u>DEBUG</u>'.

    </ul>

    <a name="wildcard-matching"><b>Wildcard Matching (globbing)</b></a>

    Most command shells such as \e bash or \e cmd support "file
    globbing", the ability to identify a group of files by using
    wildcards. Wildcard matching is much simpler than full regexps and
    has only four features:

    <ul>

    <li><b>c</b> Any character represents itself apart from those
    mentioned below. Thus <b>c</b> matches the character \e c.

    <li><b>?</b> This matches any single character. It is the same as
    <b>.</b> in full regexps.

    <li><b>*</b> This matches zero or more of any characters. It is the
    same as <b>.*</b> in full regexps.

    <li><b>[...]</b> Sets of characters can be represented in square
    brackets the same as for full regexps.

    <!-- JASMIN: Are the character classes, \w, etc supported in
    wildcards? -->

    </ul>

    For example if we are in wildcard mode and have strings which
    contain filenames we could identify HTML files with <b>*.html</b>.
    This will match zero or more characters followed by a dot followed
    by 'h', 't', 'm' and 'l'.

    <a name="perl-users"><b>Notes for Perl Users</b></a>

    Most of the character class abbreviations supported by Perl are
    supported by QRegExp, see
    <a href="#characters-and-abbreviations-for-sets-of-characters">
    characters and abbreviations for sets of characters</a>.

    QRegExp's quantifiers are the same as Perl's greedy quantifiers.
    Non-greedy matching cannot be applied to individual quantifiers, but
    can be applied to all the quantifiers in the pattern. For example,
    to match the Perl regex <b>ro+?m</b> requires:
    \code
    QRegExp rx( "ro+m" );
    rx.setMinimal( TRUE );
    \endcode

    The equivalent of Perl's <tt>/i</tt> option is
    setCaseSensitive(FALSE).

    Perl's <tt>/g</tt> option can be emulated using a
    <a href="#cap_in_a_loop">loop</a>.

    In QRegExp <b>.</b> matches any character, therefore all QRegExp
    regexps have the equivalent of Perl's <tt>/s</tt> option. QRegExp
    does not have an equivalent to Perl's <tt>/m</tt> option, but this
    can be emulated in various ways for example by splitting the input
    into lines or by looping with a regexp that searches for newlines.

    Because QRegExp is string oriented there are no \A, \Z or \z
    assertions. The \G assertion is not supported but can be emulated in
    a loop.

    Perl's $& is cap(0) or capturedTexts()[0]. There are no QRegExp
    equivalents for $`, $' or $+. $1, $2 etc correspond to
    cap(1) or capturedTexts()[1], cap(2) or capturedTexts()[2], etc.

    To substitute a pattern use QString::replace().

    Perl's extended <tt>/x</tt> syntax is not supported, nor are regexp
    comments (?#comment) or directives, e.g. (?i).

    Both zero-width positive and zero-width negative lookahead
    assertions (?=pattern) and (?!pattern) are supported with the same
    syntax as Perl. Perl's lookbehind assertions, "independent"
    subexpressions and conditional expressions are not supported.

    Non-capturing parenthesis are also supported, with the same
    (?:pattern) syntax.

    See QStringList::split() and QStringList::join() for equivalents to
    Perl's split and join functions.

    Note: because C++ transforms \\'s they must be written \e twice in
    code, e.g. <b>\\</b><b>b</b> must be written <b>\\</b><b>\\</b><b>b</b>.

    <a name="code-examples"><b>Code Examples</b></a>

    \code
    QRegExp rx( "^\\d\\d?$" );  // Match integers 0 to 99
    rx.search( "123" );     // Returns -1 (no match)
    rx.search( "-6" );      // Returns -1 (no match)
    rx.search( "6" );       // Returns 0 (matched as position 0)
    \endcode

    The third string matches '<u>6</u>'. This is a simple validation
    regexp for integers in the range 0 to 99.

    \code
    QRegExp rx( "^\\S+$" ); // Match strings which have no whitespace
    rx.search( "Hello world" ); // Returns -1 (no match)
    rx.search( "This_is-OK" );  // Returns 0 (matched at position 0)
    \endcode

    The second string matches '<u>This_is-OK</u>'. We've used the
    character set abbreviation '\S' (non-whitespace) and the anchors to
    match strings which contain no whitespace.

    In the following example we match strings containing 'mail' or
    'letter' or 'correspondence' but only match whole words i.e. not
    'email'

    \code
    QRegExp rx( "\\b(mail|letter|correspondence)\\b" );
    rx.search( "I sent you an email" );     // Returns -1 (no match)
    rx.search( "Please write the letter" ); // Returns 17 (matched at position 17)
    \endcode

    The second string matches "Please write the <u>letter</u>". The word
    'letter' is also captured (because of the parenthesis). We can see
    what text we've captured like this:

    \code
    QString captured = rx.cap( 1 ); // captured contains "letter"
    \endcode

    This will capture the text from the first set of capturing
    parenthesis (counting capturing left parenthesis from left to
    right). The parenthesis are counted from 1 since cap( 0 ) is the
    whole matched regexp (equivalent to '&' in most regexp engines).

    \code
    QRegExp rx( "&(?!amp;)" );      // Match ampersands but not &amp;
    QString line1 = "This & that";
    line1.replace( rx, "&amp;" );
    // line1 == "This &amp; that"
    QString line2 = "His &amp; hers & theirs";
    line2.replace( rx, "&amp;" );
    // line2 == "His &amp; hers &amp; theirs"
    \endcode

    Here we've passed the QRegExp to QString's replace() function to
    replace the matched text with new text.

    \code
    QString str = "One Eric another Eirik, and an Ericsson. How many Eiriks, Eric?";
    QRegExp rx( "\\b(Eric|Eirik)\\b" ); // Match Eric or Eirik
    int pos = 0;    // Where we are in the string
    int count = 0;  // How many Eric and Eirik's we've counted
    while ( pos >= 0 ) {
    pos = rx.search( str, pos );
    if ( pos >= 0 ) {
        pos++;  // Move along in str
        count++;    // Count our Eric or Eirik
    }
    }
    \endcode

    We've used the search() function to repeatedly match the regexp in
    the string. Note that instead of moving forward by one character at
    a time <tt>pos++</tt> we could have written <tt>pos +=
    rx.matchedLength()</tt> to skip over the already matched string. The
    count will equal 3, matching 'One <u>Eric</u> another <u>Eirik</u>,
    and an Ericsson. How many Eiriks, <u>Eric</u>?'; it doesn't match
    'Ericsson' or 'Eiriks' because they are not bounded by non-word
    boundaries.

    One common use of regexps is to split lines of delimited data into
    their component fields.

    \code
    str = "Trolltech AS\twww.trolltech.com\tNorway";
    QString company, web, country;
    rx.setPattern( "^([^\t]+)\t([^\t]+)\t([^\t]+)$" );
    if ( rx.search( str ) != -1 ) {
    company = rx.cap( 1 );
    web = rx.cap( 2 );
    country = rx.cap( 3 );
    }
    \endcode

    In this example our input lines have the format company name, web
    address and country. Unfortunately the regexp is rather long and not
    very versatile -- the code will break if we add any more fields. A
    simpler and better solution is to look for the separator, '\t' in
    this case, and take the surrounding text. The QStringList split()
    function can take a separator string or regexp as an argument and
    split a string accordingly.

    \code
    QStringList field = QStringList::split( "\t", str );
    \endcode

    Here field[0] is the company, field[1] the web address and so on.

    To immitate the matching of a shell we can use wildcard mode.

    \code
    QRegExp rx( "*.html" ); // Invalid regexp: * doesn't quantify anything
    rx.setWildcard( TRUE ); // Now its a valid wildcard regexp
    rx.search( "index.html" );  // Returns 0 (matched at position 0)
    rx.search( "default.htm" ); // Returns -1 (no match)
    rx.search( "readme.txt" );  // Returns -1 (no match)
    \endcode

    Wildcard matching can be convenient because of its simplicity, but
    any wildcard regex can be defined using full regexps, e.g.
    <b>.*\.html$</b>. Notice that we can't match both \c .html and \c
    .htm files with a wildcard unless we use <b>*.htm*</b> which will
    also match 'test.html.bak'. A full regexp gives us the precision we
    need, <b>.*\.html?$</b>.

    QRegExp can match case insensitively using setCaseSensitive(), and
    can use non-greedy matching, see setMinimal(). By default QRegExp
    uses full regexps but this can be changed with setWildcard().
    Searching can be forward with search() or backward with searchRev().
    Captured text can be accessed using capturedTexts() which returns a
    string list of all captured strings, or using cap() which returns
    the captured string for the given index. The pos() function takes a
    match index and returns the position in the string where the match
    was made (or -1 if there was no match).

  \sa QRegExpValidator QString QStringList

    <a name="member-function-documentation"/>
*/

static const int NumBadChars = 128;
#define BadChar( ch ) ( (ch).cell() % NumBadChars )

static const int NoOccurrence = INT_MAX;
static const int EmptyCapture = INT_MAX;
static const int InftyLen = INT_MAX;
static const int InftyRep = 1000;
static const int EOS = -1;

#ifndef QT_NO_REGEXP_OPTIM
static int engCount = 0;
static QArray<int> *noOccurrences = 0;
static QArray<int> *firstOccurrenceAtZero = 0;
#endif

/*
  Merges two QArrays of ints and puts the result into the first one.
*/
static void mergeInto( QArray<int> *a, const QArray<int>& b )
{
    int asize = a->size();
    int bsize = b.size();
    if ( asize == 0 ) {
    *a = b.copy();
#ifndef QT_NO_REGEXP_OPTIM
    } else if ( bsize == 1 && (*a)[asize - 1] < b[0] ) {
    a->resize( asize + 1 );
    (*a)[asize] = b[0];
#endif
    } else if ( bsize >= 1 ) {
    int csize = asize + bsize;
    QArray<int> c( csize );
    int i = 0, j = 0, k = 0;
    while ( i < asize ) {
        if ( j < bsize ) {
        if ( (*a)[i] == b[j] ) {
            i++;
            csize--;
        } else if ( (*a)[i] < b[j] ) {
            c[k++] = (*a)[i++];
        } else {
            c[k++] = b[j++];
        }
        } else {
        memcpy( c.data() + k, (*a).data() + i,
            (asize - i) * sizeof(int) );
        break;
        }
    }
    c.resize( csize );
    if ( j < bsize )
        memcpy( c.data() + k, b.data() + j, (bsize - j) * sizeof(int) );
    *a = c;
    }
}

/*
  Merges two disjoint QMaps of (int, int) pairs and puts the result into the
  first one.
*/
static void mergeInto( QMap<int, int> *a, const QMap<int, int>& b )
{
    QMap<int, int>::ConstIterator it;
    for ( it = b.begin(); it != b.end(); ++it )
    a->insert( it.key(), *it );
}

/*
  Returns the value associated to key k in QMap m of (int, int) pairs, or 0 if
  no such value is explicitly present.
*/
static int at( const QMap<int, int>& m, int k )
{
    QMap<int, int>::ConstIterator it = m.find( k );
    if ( it == m.end() )
    return 0;
    else
    return *it;
}

#ifndef QT_NO_REGEXP_WILDCARD
/*
  Translates a wildcard pattern to an equivalent regular expression pattern
  (e.g., *.cpp to .*\.cpp).
*/
static QString wc2rx( const QString& wc )
{
    int wclen = wc.length();
    QString rx = QString::fromLatin1( "" );
    int i = 0;
    while ( i < wclen ) {
    QChar c = wc[i++];
    switch ( c.unicode() ) {
    case '*':
        rx += QString::fromLatin1( ".*" );
        break;
    case '?':
        rx += QChar( '.' );
        break;
    case '$':
    case '(':
    case ')':
    case '+':
    case '.':
    case '\\':
    case '^':
    case '{':
    case '|':
    case '}':
        rx += QChar( '\\' );
        rx += c;
        break;
    case '[':
        rx += c;
        if ( wc[i] == QChar('^') )
        rx += wc[i++];
        if ( i < wclen ) {
        if ( rx[i] == ']' )
            rx += wc[i++];
        while ( i < wclen && wc[i] != QChar(']') ) {
            if ( wc[i] == '\\' )
            rx += QChar( '\\' );
            rx += wc[i++];
        }
        }
        break;
    default:
        rx += c;
    }
    }
    return rx;
}
#endif

/*
  The class QRegExpEngine encapsulates a modified nondeterministic finite
  automaton (NFA).
*/
class QRegExpEngine : public QShared
{
public:
#ifndef QT_NO_REGEXP_CCLASS
    /*
      The class CharClass represents a set of characters, such as can be found
      in regular expressions (e.g., [a-z] denotes the set {a, b, ..., z}).
    */
    class CharClass
    {
    public:
    CharClass();
    CharClass( const CharClass& cc ) { operator=( cc ); }

    CharClass& operator=( const CharClass& cc );

    void clear();
    bool negative() const { return n; }
    void setNegative( bool negative );
    void addCategories( int cats );
    void addRange( ushort from, ushort to );
    void addSingleton( ushort ch ) { addRange( ch, ch ); }

    bool in( QChar ch ) const;
#ifndef QT_NO_REGEXP_OPTIM
    const QArray<int>& firstOccurrence() const { return occ1; }
#endif

#if defined(QT_DEBUG)
    void dump() const;
#endif

    private:
    /*
      The struct Range represents a range of characters (e.g., [0-9] denotes
      range 48 to 57).
    */
    struct Range
    {
        ushort from; // 48
        ushort to; // 57
    };

    int c; // character classes
    QArray<Range> r; // character ranges
    bool n; // negative?
#ifndef QT_NO_REGEXP_OPTIM
    QArray<int> occ1; // first-occurrence array
#endif
    };
#else
    struct CharClass
    {
    int x; // dummy

#ifndef QT_NO_REGEXP_OPTIM
    const QArray<int>& firstOccurrence() const {
        return *firstOccurrenceAtZero;
    }
#endif
    };
#endif

    QRegExpEngine( bool caseSensitive ) { setup( caseSensitive ); }
    QRegExpEngine( const QString& rx, bool caseSensitive );
#ifndef QT_NO_REGEXP_OPTIM
    ~QRegExpEngine();
#endif

    bool isValid() const { return valid; }
    bool caseSensitive() const { return cs; }
    int numCaptures() const { return realncap; }
    QArray<int> match( const QString& str, int pos, bool minimal,
               bool oneTest );
    int matchedLength() const { return mmMatchedLen; }

    int createState( QChar ch );
    int createState( const CharClass& cc );
#ifndef QT_NO_REGEXP_BACKREF
    int createState( int bref );
#endif

    void addCatTransitions( const QArray<int>& from, const QArray<int>& to );
#ifndef QT_NO_REGEXP_CAPTURE
    void addPlusTransitions( const QArray<int>& from, const QArray<int>& to,
                 int atom );
#endif

#ifndef QT_NO_REGEXP_ANCHOR_ALT
    int anchorAlternation( int a, int b );
    int anchorConcatenation( int a, int b );
#else
    int anchorAlternation( int a, int b ) { return a & b; }
    int anchorConcatenation( int a, int b ) { return a | b; }
#endif
    void addAnchors( int from, int to, int a );

#ifndef QT_NO_REGEXP_OPTIM
    void setupGoodStringHeuristic( int earlyStart, int lateStart,
                   const QString& str );
    void setupBadCharHeuristic( int minLen, const QArray<int>& firstOcc );
    void heuristicallyChooseHeuristic();
#endif

#if defined(QT_DEBUG)
    void dump() const;
#endif

private:
    enum { CharClassBit = 0x10000, BackRefBit = 0x20000 };

    /*
      The struct State represents one state in a modified NFA.  The input
      characters matched are stored in the state instead of on the transitions,
      something possible for an automaton constructed from a regular expression.
    */
    struct State
    {
#ifndef QT_NO_REGEXP_CAPTURE
    int atom; // which atom does this state belong to?
#endif
    int match; // what does it match? (see CharClassBit and BackRefBit)
    QArray<int> outs; // out-transitions
    QMap<int, int> *reenter; // atoms reentered when transiting out
    QMap<int, int> *anchors; // anchors met when transiting out

#ifndef QT_NO_REGEXP_CAPTURE
    State( int a, int m )
        : atom( a ), match( m ), reenter( 0 ), anchors( 0 ) { }
#else
    State( int m )
        : match( m ), reenter( 0 ), anchors( 0 ) { }
#endif
    ~State() { delete reenter; delete anchors; }
    };

#ifndef QT_NO_REGEXP_LOOKAHEAD
    /*
      The struct Lookahead represents a lookahead a la Perl (e.g., (?=foo) and
      (?!bar)).
    */
    struct Lookahead
    {
    QRegExpEngine *eng; // NFA representing the embedded regular expression
    bool neg; // negative lookahead?

    Lookahead( QRegExpEngine *eng0, bool neg0 )
        : eng( eng0 ), neg( neg0 ) { }
    ~Lookahead() { delete eng; }
    };
#endif

#ifndef QT_NO_REGEXP_CAPTURE
    /*
      The struct Atom represents one node in the hierarchy of regular expression
      atoms.
    */
    struct Atom
    {
    int parent; // index of parent in array of atoms
    int capture; // index of capture, from 1 to ncap
    };
#endif

#ifndef QT_NO_REGEXP_ANCHOR_ALT
    /*
      The struct AnchorAlternation represents a pair of anchors with OR
      semantics.
    */
    struct AnchorAlternation
    {
    int a; // this anchor...
    int b; // ...or this one
    };
#endif

    enum { InitialState = 0, FinalState = 1 };
    void setup( bool caseSensitive );
    int setupState( int match );

    /*
      Let's hope that 13 lookaheads and 14 back-references are enough.
     */
    enum { MaxLookaheads = 13, MaxBackRefs = 14 };
    enum { Anchor_Dollar = 0x00000001, Anchor_Caret = 0x00000002,
       Anchor_Word = 0x00000004, Anchor_NonWord = 0x00000008,
       Anchor_FirstLookahead = 0x00000010,
       Anchor_BackRef1Empty = Anchor_FirstLookahead << MaxLookaheads,
       Anchor_BackRef0Empty = Anchor_BackRef1Empty >> 1,
       Anchor_Alternation = Anchor_BackRef1Empty << MaxBackRefs,

       Anchor_LookaheadMask = ( Anchor_FirstLookahead - 1 ) ^
           ( (Anchor_FirstLookahead << MaxLookaheads) - 1 ) };
#ifndef QT_NO_REGEXP_CAPTURE
    int startAtom( bool capture );
    void finishAtom( int atom ) { cf = f[atom].parent; }
#endif

#ifndef QT_NO_REGEXP_LOOKAHEAD
    int addLookahead( QRegExpEngine *eng, bool negative );
#endif

#ifndef QT_NO_REGEXP_CAPTURE
    bool isBetterCapture( const int *begin1, const int *end1, const int *begin2,
              const int *end2 );
#endif
    bool testAnchor( int i, int a, const int *capBegin );

#ifndef QT_NO_REGEXP_OPTIM
    bool goodStringMatch();
    bool badCharMatch();
#else
    bool bruteMatch();
#endif
    bool matchHere();

    QVector<State> s; // array of states
    int ns; // number of states
#ifndef QT_NO_REGEXP_CAPTURE
    QArray<Atom> f; // atom hierarchy
    int nf; // number of atoms
    int cf; // current atom
#endif
    int realncap; // number of captures, seen from the outside
    int ncap; // number of captures, seen from the inside
#ifndef QT_NO_REGEXP_CCLASS
    QVector<CharClass> cl; // array of character classes
#endif
#ifndef QT_NO_REGEXP_LOOKAHEAD
    QVector<Lookahead> ahead; // array of lookaheads
#endif
#ifndef QT_NO_REGEXP_ANCHOR_ALT
    QArray<AnchorAlternation> aa; // array of (a, b) pairs of anchors
#endif
#ifndef QT_NO_REGEXP_OPTIM
    bool caretAnchored; // does the regexp start with ^?
#endif
    bool valid; // is the regular expression valid?
    bool cs; // case sensitive?
#ifndef QT_NO_REGEXP_BACKREF
    int nbrefs; // number of back-references
#endif

#ifndef QT_NO_REGEXP_OPTIM
    bool useGoodStringHeuristic; // use goodStringMatch? otherwise badCharMatch

    int goodEarlyStart; // the index where goodStr can first occur in a match
    int goodLateStart; // the index where goodStr can last occur in a match
    QString goodStr; // the string that any match has to contain

    int minl; // the minimum length of a match
    QArray<int> occ1; // first-occurrence array
#endif

    /*
      The class Box is an abstraction for a regular expression fragment.  It can
      also be seen as one node in the syntax tree of a regular expression with
      synthetized attributes.

      It's interface is ugly for performance reasons.
    */
    class Box
    {
    public:
    Box( QRegExpEngine *engine );
    Box( const Box& b ) { operator=( b ); }

    Box& operator=( const Box& b );

    void clear() { operator=(Box(eng)); }
    void set( QChar ch );
    void set( const CharClass& cc );
#ifndef QT_NO_REGEXP_BACKREF
    void set( int bref );
#endif

    void cat( const Box& b );
    void orx( const Box& b );
    void plus( int atom );
    void opt();
    void catAnchor( int a );
#ifndef QT_NO_REGEXP_OPTIM
    void setupHeuristics();
#endif

#if defined(QT_DEBUG)
    void dump() const;
#endif

    private:
    void addAnchorsToEngine( const Box& to ) const;

    QRegExpEngine *eng; // the automaton under construction
    QArray<int> ls; // the left states (firstpos)
    QArray<int> rs; // the right states (lastpos)
    QMap<int, int> lanchors; // the left anchors
    QMap<int, int> ranchors; // the right anchors
    int skipanchors; // the anchors to match if the box is skipped

#ifndef QT_NO_REGEXP_OPTIM
    int earlyStart; // the index where str can first occur
    int lateStart; // the index where str can last occur
    QString str; // a string that has to occur in any match
    QString leftStr; // a string occurring at the left of this box
    QString rightStr; // a string occurring at the right of this box
    int maxl; // the maximum length of this box (possibly InftyLen)
#endif

    int minl; // the minimum length of this box
#ifndef QT_NO_REGEXP_OPTIM
    QArray<int> occ1; // first-occurrence array
#endif
    };
    friend class Box;

    /*
      This is the lexical analyzer for regular expressions.
    */
    enum { Tok_Eos, Tok_Dollar, Tok_LeftParen, Tok_MagicLeftParen,
       Tok_PosLookahead, Tok_NegLookahead, Tok_RightParen, Tok_CharClass,
       Tok_Caret, Tok_Quantifier, Tok_Bar, Tok_Word, Tok_NonWord,
       Tok_Char = 0x10000, Tok_BackRef = 0x20000 };
    int getChar();
    int getEscape();
#ifndef QT_NO_REGEXP_INTERVAL
    int getRep( int def );
#endif
#ifndef QT_NO_REGEXP_LOOKAHEAD
    void skipChars( int n );
#endif
    void startTokenizer( const QChar *rx, int len );
    int getToken();

    const QChar *yyIn; // a pointer to the input regular expression pattern
    int yyPos0; // the position of yyTok in the input pattern
    int yyPos; // the position of the next character to read
    int yyLen; // the length of yyIn
    int yyCh; // the last character read
    CharClass *yyCharClass; // attribute for Tok_CharClass tokens
    int yyMinRep; // attribute for Tok_Quantifier
    int yyMaxRep; // ditto
    bool yyError; // syntax error or overflow during parsing?

    /*
      This is the syntactic analyzer for regular expressions.
    */
    int parse( const QChar *rx, int len );
    void parseAtom( Box *box );
    void parseFactor( Box *box );
    void parseTerm( Box *box );
    void parseExpression( Box *box );

    int yyTok; // the last token read
    bool yyMayCapture; // set this to FALSE to disable capturing

    /*
      This is the engine state during matching.
    */
    const QString *mmStr; // a pointer to the input QString
    const QChar *mmIn; // a pointer to the input string data
    int mmPos; // the current position in the string
    int mmLen; // the length of the input string
    bool mmMinimal; // minimal matching?
    QArray<int> mmCaptured; // an array of pairs (start, len)
    QArray<int> mmCapturedNoMatch; // an array of pairs (-1, -1)
    QArray<int> mmBigArray; // big QArray<int> array
    int *mmInNextStack; // is state is mmNextStack?
    int *mmCurStack; // stack of current states
    int *mmNextStack; // stack of next states
    int *mmCurCapBegin; // start of current states' captures
    int *mmNextCapBegin; // start of next states' captures
    int *mmCurCapEnd; // end of current states' captures
    int *mmNextCapEnd; // end of next states' captures
    int *mmTempCapBegin; // start of temporary captures
    int *mmTempCapEnd; // end of temporary captures
    int *mmCapBegin; // start of captures for a next state
    int *mmCapEnd; // end of captures for a next state
    int *mmSlideTab; // bump-along slide table for bad-character heuristic
    int mmSlideTabSize; // size of slide table
#ifndef QT_NO_REGEXP_BACKREF
    QIntDict<int> mmSleeping; // dictionary of back-reference sleepers
#endif
    int mmMatchedLen; // length of match or of matched string for partial match
};

QRegExpEngine::QRegExpEngine( const QString& rx, bool caseSensitive )
#ifndef QT_NO_REGEXP_BACKREF
    : mmSleeping( 101 )
#endif
{
    setup( caseSensitive );
    valid = ( parse(rx.unicode(), rx.length()) == (int) rx.length() );
}

#ifndef QT_NO_REGEXP_OPTIM
QRegExpEngine::~QRegExpEngine()
{
    if ( --engCount == 0 ) {
    delete noOccurrences;
    noOccurrences = 0;
    delete firstOccurrenceAtZero;
    firstOccurrenceAtZero = 0;
    }
}
#endif

/*
  Tries to match in str and returns an array of (begin, length) pairs for
  captured text.  If there is no match, all pairs are (-1, -1).
*/
QArray<int> QRegExpEngine::match( const QString& str, int pos, bool minimal,
                  bool oneTest )
{
    mmStr = &str;
    mmIn = str.unicode();
    if ( mmIn == 0 )
    mmIn = &QChar::null;
    mmPos = pos;
    mmLen = str.length();
    mmMinimal = minimal;
    mmMatchedLen = 0;

    bool matched = FALSE;
    if ( valid && mmPos >= 0 && mmPos <= mmLen ) {
#ifndef QT_NO_REGEXP_OPTIM
    if ( mmPos <= mmLen - minl ) {
        if ( caretAnchored || oneTest )
        matched = matchHere();
        else if ( useGoodStringHeuristic )
        matched = goodStringMatch();
        else
        matched = badCharMatch();
    }
#else
    matched = oneTest ? matchHere() : bruteMatch();
#endif
    }

    if ( matched ) {
    mmCaptured.detach();
    mmCaptured[0] = mmPos;
    mmCaptured[1] = mmMatchedLen;
    for ( int j = 0; j < realncap; j++ ) {
        int len = mmCapEnd[j] - mmCapBegin[j];
        mmCaptured[2 + 2 * j] = len > 0 ? mmPos + mmCapBegin[j] : 0;
        mmCaptured[2 + 2 * j + 1] = len;
    }
    return mmCaptured;
    } else {
    return mmCapturedNoMatch;
    }
}

/*
  The three following functions add one state to the automaton and return the
  number of the state.
*/

int QRegExpEngine::createState( QChar ch )
{
    return setupState( ch.unicode() );
}

int QRegExpEngine::createState( const CharClass& cc )
{
#ifndef QT_NO_REGEXP_CCLASS
    int n = cl.size();
    cl.resize( n + 1 );
    cl.insert( n, new CharClass(cc) );
    return setupState( CharClassBit | n );
#else
    Q_UNUSED( cc );
    return setupState( CharClassBit );
#endif
}

#ifndef QT_NO_REGEXP_BACKREF
int QRegExpEngine::createState( int bref )
{
    if ( bref > nbrefs ) {
    nbrefs = bref;
    if ( nbrefs > MaxBackRefs ) {
        yyError = TRUE;
        return 0;
    }
    }
    return setupState( BackRefBit | bref );
}
#endif

/*
  The two following functions add a transition between all pairs of states
  (i, j) where i is fond in from, and j is found in to.

  Cat-transitions are distinguished from plus-transitions for capturing.
*/

void QRegExpEngine::addCatTransitions( const QArray<int>& from,
                       const QArray<int>& to )
{
    for ( int i = 0; i < (int) from.size(); i++ ) {
    State *st = s[from[i]];
    mergeInto( &st->outs, to );
    }
}

#ifndef QT_NO_REGEXP_CAPTURE
void QRegExpEngine::addPlusTransitions( const QArray<int>& from,
                    const QArray<int>& to, int atom )
{
    for ( int i = 0; i < (int) from.size(); i++ ) {
    State *st = s[from[i]];
    QArray<int> oldOuts = st->outs.copy();
    mergeInto( &st->outs, to );
    if ( f[atom].capture >= 0 ) {
        if ( st->reenter == 0 )
        st->reenter = new QMap<int, int>;
        for ( int j = 0; j < (int) to.size(); j++ ) {
        if ( !st->reenter->contains(to[j]) &&
             oldOuts.bsearch(to[j]) < 0 )
            st->reenter->insert( to[j], atom );
        }
    }
    }
}
#endif

#ifndef QT_NO_REGEXP_ANCHOR_ALT
/*
  Returns an anchor that means a OR b.
*/
int QRegExpEngine::anchorAlternation( int a, int b )
{
    if ( ((a & b) == a || (a & b) == b) && ((a | b) & Anchor_Alternation) == 0 )
    return a & b;

    int n = aa.size();
    aa.resize( n + 1 );
    aa[n].a = a;
    aa[n].b = b;
    return Anchor_Alternation | n;
}

/*
  Returns an anchor that means a AND b.
*/
int QRegExpEngine::anchorConcatenation( int a, int b )
{
    if ( ((a | b) & Anchor_Alternation) == 0 )
    return a | b;
    if ( (b & Anchor_Alternation) != 0 )
    qSwap( a, b );
    int aprime = anchorConcatenation( aa[a ^ Anchor_Alternation].a, b );
    int bprime = anchorConcatenation( aa[a ^ Anchor_Alternation].b, b );
    return anchorAlternation( aprime, bprime );
}
#endif

/*
  Adds anchor a on a transition caracterised by its from state and its to state.
*/
void QRegExpEngine::addAnchors( int from, int to, int a )
{
    State *st = s[from];
    if ( st->anchors == 0 )
    st->anchors = new QMap<int, int>;
    if ( st->anchors->contains(to) )
    a = anchorAlternation( (*st->anchors)[to], a );
    st->anchors->insert( to, a );
}

#ifndef QT_NO_REGEXP_OPTIM
/*
  The two following functions provide the engine with the information needed by
  its matching heuristics.
*/

void QRegExpEngine::setupGoodStringHeuristic( int earlyStart, int lateStart,
                          const QString& str )
{
    goodEarlyStart = earlyStart;
    goodLateStart = lateStart;
    goodStr = cs ? str : str.lower();
}

void QRegExpEngine::setupBadCharHeuristic( int minLen,
                       const QArray<int>& firstOcc )
{
    minl = minLen;
    occ1 = cs ? firstOcc : *firstOccurrenceAtZero;
}

/*
  This function chooses between the good-string and the bad-character
  heuristics.  It computes two scores and chooses the heuristic with the highest
  score.

  Here are some common-sense constraints on the scores that should be respected
  if the formulas are ever modified:  (1) If goodStr is empty, the good-string
  heuristic scores 0.  (2) If the search is case insensitive, the good-string
  heuristic should be used, unless it scores 0.  (Case insensitivity
  turns all entries of occ1 to 0.)  (3) If (goodLateStart - goodEarlyStart) is
  big, the good-string heuristic should score less.
*/
void QRegExpEngine::heuristicallyChooseHeuristic()
{
    int i;

    if ( minl == 0 )
    return;

    /*
      Magic formula:  The good string has to constitute a good proportion of the
      minimum-length string, and appear at a more-or-less known index.
    */
    int goodStringScore = ( 64 * goodStr.length() / minl ) -
              ( goodLateStart - goodEarlyStart );

    /*
      Less magic formula:  We pick a couple of characters at random, and check
      whether they are good or bad.
    */
    int badCharScore = 0;
    int step = QMAX( 1, NumBadChars / 32 );
    for ( i = 1; i < NumBadChars; i += step ) {
    if ( occ1[i] == NoOccurrence )
        badCharScore += minl;
    else
        badCharScore += occ1[i];
    }
    badCharScore /= minl;

    useGoodStringHeuristic = ( goodStringScore > badCharScore );
}
#endif

#if defined(QT_DEBUG)
void QRegExpEngine::dump() const
{
    int i, j;
    odebug << "Case " << (cs ? "" : "in") << "sensitive engine" << oendl;
    odebug << "  States" << oendl;
    for ( i = 0; i < ns; i++ ) {
    odebug << "  " << i
           << (i == InitialState ? " (initial)" : i == FinalState ? " (final)" : "") << oendl;

#ifndef QT_NO_REGEXP_CAPTURE
    odebug << "    in atom " << s[i]->atom << oendl;
#endif
    int m = s[i]->match;
    if ( (m & CharClassBit) != 0 ) {
        odebug << "    match character class " << (m ^ CharClassBit) << oendl;
#ifndef QT_NO_REGEXP_CCLASS
        cl[m ^ CharClassBit]->dump();
#else
        odebug << "    negative character class" << oendl;
#endif
    } else if ( (m & BackRefBit) != 0 ) {
        odebug << "    match back-reference " << (m ^ BackRefBit) << oendl;
    } else if ( m >= 0x20 && m <= 0x7e ) {
        odebug << "    match " << QString().sprintf( "0x%.4x", m) << " (" << m << ")" << oendl;

    } else {
        odebug << "    match " << QString().sprintf( "0x%.4x", m) << oendl;
    }
    for ( j = 0; j < (int) s[i]->outs.size(); j++ ) {
        int next = s[i]->outs[j];
        odebug << "    -> " << next << oendl;
        if ( s[i]->reenter != 0 && s[i]->reenter->contains(next) )
        odebug << "       [reenter " << (*s[i]->reenter)[next] << "]" << oendl;
        if ( s[i]->anchors != 0 && at(*s[i]->anchors, next) != 0 )
        odebug << "       [anchors " << QString().sprintf( "0x%.8x]", (*s[i]->anchors)[next] ) << oendl;
    }
    }
#ifndef QT_NO_REGEXP_CAPTURE
    if ( nf > 0 ) {
    odebug << "  Atom    Parent  Capture" << oendl;
    for ( i = 0; i < nf; i++ )
        odebug << QString().sprintf("  %6d  %6d  %6d", i, f[i].parent, f[i].capture ) << oendl;
    }
#endif
#ifndef QT_NO_REGEXP_ANCHOR_ALT
    for ( i = 0; i < (int) aa.size(); i++ )
    odebug << QString().sprintf("  Anchor alternation 0x%.8x: 0x%.8x 0x%.9x", i, aa[i].a, aa[i].b ) << oendl;
#endif
}
#endif

void QRegExpEngine::setup( bool caseSensitive )
{
#ifndef QT_NO_REGEXP_OPTIM
    if ( engCount++ == 0 ) {
    noOccurrences = new QArray<int>( NumBadChars );
    firstOccurrenceAtZero = new QArray<int>( NumBadChars );
    noOccurrences->fill( NoOccurrence );
    firstOccurrenceAtZero->fill( 0 );
    }
#endif
    s.setAutoDelete( TRUE );
    s.resize( 32 );
    ns = 0;
#ifndef QT_NO_REGEXP_CAPTURE
    f.resize( 32 );
    nf = 0;
    cf = -1;
#endif
    realncap = 0;
    ncap = 0;
#ifndef QT_NO_REGEXP_CCLASS
    cl.setAutoDelete( TRUE );
#endif
#ifndef QT_NO_REGEXP_LOOKAHEAD
    ahead.setAutoDelete( TRUE );
#endif
#ifndef QT_NO_REGEXP_OPTIM
    caretAnchored = TRUE;
#endif
    valid = FALSE;
    cs = caseSensitive;
#ifndef QT_NO_REGEXP_BACKREF
    nbrefs = 0;
#endif
#ifndef QT_NO_REGEXP_OPTIM
    useGoodStringHeuristic = FALSE;
    minl = 0;
    occ1 = *firstOccurrenceAtZero;
#endif
    mmCapturedNoMatch.fill( -1, 2 );
}

int QRegExpEngine::setupState( int match )
{
    if ( (ns & (ns + 1)) == 0 && ns + 1 >= (int) s.size() )
    s.resize( (ns + 1) << 1 );
#ifndef QT_NO_REGEXP_CAPTURE
    s.insert( ns, new State(cf, match) );
#else
    s.insert( ns, new State(match) );
#endif
    return ns++;
}

#ifndef QT_NO_REGEXP_CAPTURE
/*
  Functions startAtom() and finishAtom() should be called to delimit atoms.
  When a state is created, it is assigned to the current atom.  The information
  is later used for capturing.
*/
int QRegExpEngine::startAtom( bool capture )
{
    if ( (nf & (nf + 1)) == 0 && nf + 1 >= (int) f.size() )
    f.resize( (nf + 1) << 1 );
    f[nf].parent = cf;
    cf = nf++;
    f[cf].capture = capture ? ncap++ : -1;
    return cf;
}
#endif

#ifndef QT_NO_REGEXP_LOOKAHEAD
/*
  Creates a lookahead anchor.
*/
int QRegExpEngine::addLookahead( QRegExpEngine *eng, bool negative )
{
    int n = ahead.size();
    if ( n == MaxLookaheads ) {
    yyError = TRUE;
    return 0;
    }
    ahead.resize( n + 1 );
    ahead.insert( n, new Lookahead(eng, negative) );
    return Anchor_FirstLookahead << n;
}
#endif

#ifndef QT_NO_REGEXP_CAPTURE
/*
  We want the longest leftmost captures.
*/
bool QRegExpEngine::isBetterCapture( const int *begin1, const int *end1,
                     const int *begin2, const int *end2 )
{
    for ( int i = 0; i < ncap; i++ ) {
    int delta = begin2[i] - begin1[i]; // it has to start early...
    if ( delta == 0 )
        delta = end1[i] - end2[i]; // ...and end late (like a party)

    if ( delta != 0 )
        return delta > 0;
    }
    return FALSE;
}
#endif

/*
  Returns TRUE if anchor a matches at position mmPos + i in the input string,
  otherwise FALSE.
*/
bool QRegExpEngine::testAnchor( int i, int a, const int *capBegin )
{
    int j;

#ifndef QT_NO_REGEXP_ANCHOR_ALT
    if ( (a & Anchor_Alternation) != 0 ) {
    return testAnchor( i, aa[a ^ Anchor_Alternation].a, capBegin ) ||
           testAnchor( i, aa[a ^ Anchor_Alternation].b, capBegin );
    }
#endif

    if ( (a & Anchor_Caret) != 0 ) {
    if ( mmPos + i != 0 )
        return FALSE;
    }
    if ( (a & Anchor_Dollar) != 0 ) {
    if ( mmPos + i != mmLen )
        return FALSE;
    }
#ifndef QT_NO_REGEXP_ESCAPE
    if ( (a & (Anchor_Word | Anchor_NonWord)) != 0 ) {
    bool before = FALSE, after = FALSE;
    if ( mmPos + i != 0 )
        before = mmIn[mmPos + i - 1].isLetterOrNumber();
    if ( mmPos + i != mmLen )
        after = mmIn[mmPos + i].isLetterOrNumber();
    if ( (a & Anchor_Word) != 0 && (before == after) )
        return FALSE;
    if ( (a & Anchor_NonWord) != 0 && (before != after) )
        return FALSE;
    }
#endif
#ifndef QT_NO_REGEXP_LOOKAHEAD
    bool catchx = TRUE;

    if ( (a & Anchor_LookaheadMask) != 0 ) {
    QConstString cstr = QConstString( (QChar *) mmIn + mmPos + i,
                       mmLen - mmPos - i );
    for ( j = 0; j < (int) ahead.size(); j++ ) {
        if ( (a & (Anchor_FirstLookahead << j)) != 0 ) {
        catchx = ( ahead[j]->eng->match(cstr.string(), 0, TRUE,
                        TRUE)[0] == 0 );
        if ( catchx == ahead[j]->neg )
            return FALSE;
        }
    }
    }
#endif
#ifndef QT_NO_REGEXP_CAPTURE
#ifndef QT_NO_REGEXP_BACKREF
    for ( j = 0; j < nbrefs; j++ ) {
    if ( (a & (Anchor_BackRef1Empty << j)) != 0 ) {
        if ( capBegin[j] != EmptyCapture )
        return FALSE;
    }
    }
#endif
#endif
    return TRUE;
}

#ifndef QT_NO_REGEXP_OPTIM
/*
  The three following functions are what Jeffrey Friedl would call transmissions
  (or bump-alongs).  Using one or the other should make no difference, except
  in performance.
*/

bool QRegExpEngine::goodStringMatch()
{
    int k = mmPos + goodEarlyStart;

    while ( (k = mmStr->find(goodStr, k, cs)) != -1 ) {
    int from = k - goodLateStart;
    int to = k - goodEarlyStart;
    if ( from > mmPos )
        mmPos = from;

    while ( mmPos <= to ) {
        if ( matchHere() )
        return TRUE;
        mmPos++;
    }
    k++;
    }
    return FALSE;
}

bool QRegExpEngine::badCharMatch()
{
    int slideHead = 0;
    int slideNext = 0;
    int i;
    int lastPos = mmLen - minl;
    memset( mmSlideTab, 0, mmSlideTabSize * sizeof(int) );

    /*
      Set up the slide table, used for the bad-character heuristic, using
      the table of first occurrence of each character.
    */
    for ( i = 0; i < minl; i++ ) {
    int sk = occ1[BadChar(mmIn[mmPos + i])];
    if ( sk == NoOccurrence )
        sk = i + 1;
    if ( sk > 0 ) {
        int k = i + 1 - sk;
        if ( k < 0 ) {
        sk = i + 1;
        k = 0;
        }
        if ( sk > mmSlideTab[k] )
        mmSlideTab[k] = sk;
    }
    }

    if ( mmPos > lastPos )
    return FALSE;

    while ( TRUE ) {
    if ( ++slideNext >= mmSlideTabSize )
        slideNext = 0;
    if ( mmSlideTab[slideHead] > 0 ) {
        if ( mmSlideTab[slideHead] - 1 > mmSlideTab[slideNext] )
        mmSlideTab[slideNext] = mmSlideTab[slideHead] - 1;
        mmSlideTab[slideHead] = 0;
    } else {
        if ( matchHere() )
        return TRUE;
    }

    if ( mmPos == lastPos )
        break;

    /*
      Update the slide table.  This code has much in common with the
      initialization code.
    */
    int sk = occ1[BadChar(mmIn[mmPos + minl])];
    if ( sk == NoOccurrence ) {
        mmSlideTab[slideNext] = minl;
    } else if ( sk > 0 ) {
        int k = slideNext + minl - sk;
        if ( k >= mmSlideTabSize )
        k -= mmSlideTabSize;
        if ( sk > mmSlideTab[k] )
        mmSlideTab[k] = sk;
    }
    slideHead = slideNext;
    mmPos++;
    }
    return FALSE;
}
#else
bool QRegExpEngine::bruteMatch()
{
    while ( mmPos <= mmLen ) {
    if ( matchHere() )
        return TRUE;
    mmPos++;
    }
    return FALSE;
}
#endif

/*
  Here's the core of the engine.  It tries to do a match here and now.
*/
bool QRegExpEngine::matchHere()
{
    int ncur = 1, nnext = 0;
    int i = 0, j, k, m;
    bool match = FALSE;

    mmMatchedLen = -1;
    mmCurStack[0] = InitialState;

#ifndef QT_NO_REGEXP_CAPTURE
    if ( ncap > 0 ) {
    for ( j = 0; j < ncap; j++ ) {
        mmCurCapBegin[j] = EmptyCapture;
        mmCurCapEnd[j] = EmptyCapture;
    }
    }
#endif

#ifndef QT_NO_REGEXP_BACKREF
    int *zzZ = 0;

    while ( (ncur > 0 || mmSleeping.count() > 0) && i <= mmLen - mmPos &&
        !match )
#else
    while ( ncur > 0 && i <= mmLen - mmPos && !match )
#endif
    {
    int ch = ( i < mmLen - mmPos ) ? mmIn[mmPos + i].unicode() : 0;
    for ( j = 0; j < ncur; j++ ) {
        int cur = mmCurStack[j];
        State *scur = s[cur];
        QArray<int>& outs = scur->outs;
        for ( k = 0; k < (int) outs.size(); k++ ) {
        int next = outs[k];
        State *snext = s[next];
        bool in = TRUE;
#ifndef QT_NO_REGEXP_BACKREF
        int needSomeSleep = 0;
#endif

        /*
          First, check if the anchors are anchored properly.
        */
        if ( scur->anchors != 0 ) {
            int a = at( *scur->anchors, next );
            if ( a != 0 && !testAnchor(i, a, mmCurCapBegin + j * ncap) )
            in = FALSE;
        }
        /*
          If indeed they are, check if the input character is correct
          for this transition.
        */
        if ( in ) {
            m = snext->match;
            if ( (m & (CharClassBit | BackRefBit)) == 0 ) {
            if ( cs )
                in = ( m == ch );
            else
                in = ( QChar(m).lower() == QChar(ch).lower() );
            } else if ( next == FinalState ) {
            mmMatchedLen = i;
            match = mmMinimal;
            in = TRUE;
            } else if ( (m & CharClassBit) != 0 ) {
#ifndef QT_NO_REGEXP_CCLASS
            const CharClass *cc = cl[m ^ CharClassBit];
            if ( cs )
                in = cc->in( ch );
            else if ( cc->negative() )
                in = cc->in( QChar(ch).lower() ) &&
                 cc->in( QChar(ch).upper() );
            else
                in = cc->in( QChar(ch).lower() ) ||
                 cc->in( QChar(ch).upper() );
#endif
#ifndef QT_NO_REGEXP_BACKREF
            } else { /* ( (m & BackRefBit) != 0 ) */
            int bref = m ^ BackRefBit;
            int ell = j * ncap + ( bref - 1 );

            in = bref <= ncap && mmCurCapBegin[ell] != EmptyCapture;
            if ( in ) {
                if ( cs )
                in = ( mmIn[mmPos + mmCurCapBegin[ell]]
                       == QChar(ch) );
                else
                in = ( mmIn[mmPos + mmCurCapBegin[ell]].lower()
                       == QChar(ch).lower() );
            }

            if ( in ) {
                int delta;
                if ( mmCurCapEnd[ell] == EmptyCapture )
                delta = i - mmCurCapBegin[ell];
                else
                delta = mmCurCapEnd[ell] - mmCurCapBegin[ell];

                in = ( delta <= mmLen - mmPos );
                if ( in && delta > 1 ) {
                int n;
                if ( cs ) {
                    for ( n = 1; n < delta; n++ ) {
                    if ( mmIn[mmPos +
                          mmCurCapBegin[ell] + n] !=
                         mmIn[mmPos + i + n] )
                        break;
                    }
                } else {
                    for ( n = 1; n < delta; n++ ) {
                    QChar a = mmIn[mmPos +
                               mmCurCapBegin[ell] + n];
                    QChar b = mmIn[mmPos + i + n];
                    if ( a.lower() != b.lower() )
                        break;
                    }
                }
                in = ( n == delta );
                if ( in )
                    needSomeSleep = delta - 1;
                }
            }
#endif
            }
        }

        /*
          All is right.  We must now update our data structures.
        */
        if ( in ) {
#ifndef QT_NO_REGEXP_CAPTURE
            int *capBegin, *capEnd;
#endif
            /*
              If the next state was not encountered yet, all is fine.
            */
            if ( (m = mmInNextStack[next]) == -1 ) {
            m = nnext++;
            mmNextStack[m] = next;
            mmInNextStack[next] = m;
#ifndef QT_NO_REGEXP_CAPTURE
            capBegin = mmNextCapBegin + m * ncap;
            capEnd = mmNextCapEnd + m * ncap;

            /*
              Otherwise, we'll first maintain captures in temporary
              arrays, and decide at the end whether it's best to keep
              the previous capture zones or the new ones.
            */
            } else {
            capBegin = mmTempCapBegin;
            capEnd = mmTempCapEnd;
#endif
            }

#ifndef QT_NO_REGEXP_CAPTURE
            /*
              Updating the capture zones is much of a task.
            */
            if ( ncap > 0 ) {
            memcpy( capBegin, mmCurCapBegin + j * ncap,
                ncap * sizeof(int) );
            memcpy( capEnd, mmCurCapEnd + j * ncap,
                ncap * sizeof(int) );
            int c = scur->atom, n = snext->atom;
            int p = -1, q = -1;
            int cap;

            /*
              Lemma 1.  For any x in the range [0..nf), we have
              f[x].parent < x.

              Proof.  By looking at startAtom(), it is clear that
              cf < nf holds all the time, and thus that
              f[nf].parent < nf.
            */

            /*
              If we are reentering an atom, we empty all capture
              zones inside it.
            */
            if ( scur->reenter != 0 &&
                 (q = at(*scur->reenter, next)) != 0 ) {
                QBitArray b;
                b.fill( FALSE, nf );
                b.setBit( q, TRUE );
                for ( int ell = q + 1; ell < nf; ell++ ) {
                if ( b.testBit(f[ell].parent) ) {
                    b.setBit( ell, TRUE );
                    cap = f[ell].capture;
                    if ( cap >= 0 ) {
                    capBegin[cap] = EmptyCapture;
                    capEnd[cap] = EmptyCapture;
                    }
                }
                }
                p = f[q].parent;

            /*
              Otherwise, close the capture zones we are leaving.
              We are leaving f[c].capture, f[f[c].parent].capture,
              f[f[f[c].parent].parent].capture, ..., until
              f[x].capture, with x such that f[x].parent is the
              youngest common ancestor for c and n.

              We go up along c's and n's ancestry until we find x.
            */
            } else {
                p = c;
                q = n;
                while ( p != q ) {
                if ( p > q ) {
                    cap = f[p].capture;
                    if ( cap >= 0 ) {
                    if ( capBegin[cap] == i ) {
                        capBegin[cap] = EmptyCapture;
                        capEnd[cap] = EmptyCapture;
                    } else {
                        capEnd[cap] = i;
                    }
                    }
                    p = f[p].parent;
                } else {
                    q = f[q].parent;
                }
                }
            }

            /*
              In any case, we now open the capture zones we are
              entering.  We work upwards from n until we reach p
              (the parent of the atom we reenter or the youngest
              common ancestor).
            */
            while ( n > p ) {
                cap = f[n].capture;
                if ( cap >= 0 ) {
                capBegin[cap] = i;
                capEnd[cap] = EmptyCapture;
                }
                n = f[n].parent;
            }
            /*
              If the next state was already in mmNextStack, we must
              choose carefully which capture zones we want to keep.
            */
            if ( capBegin == mmTempCapBegin &&
                 isBetterCapture(capBegin, capEnd,
                         mmNextCapBegin + m * ncap,
                         mmNextCapEnd + m * ncap) ) {
                memcpy( mmNextCapBegin + m * ncap, capBegin,
                    ncap * sizeof(int) );
                memcpy( mmNextCapEnd + m * ncap, capEnd,
                    ncap * sizeof(int) );
            }
            }
#ifndef QT_NO_REGEXP_BACKREF
            /*
              We are done with updating the capture zones.  It's now
              time to put the next state to sleep, if it needs to, and
              to remove it from mmNextStack.
            */
            if ( needSomeSleep > 0 ) {
            zzZ = new int[1 + 2 * ncap];
            zzZ[0] = next;
            if ( ncap > 0 ) {
                memcpy( zzZ + 1, capBegin, ncap * sizeof(int) );
                memcpy( zzZ + 1 + ncap, capEnd,
                    ncap * sizeof(int) );
            }
            mmInNextStack[mmNextStack[--nnext]] = -1;
            mmSleeping.insert( i + needSomeSleep, zzZ );
            }
#endif
#endif
        }
        }
    }
#ifndef QT_NO_REGEXP_CAPTURE
    /*
      If we reached the final state, hurray!  Copy the captured zone.
    */
    if ( ncap > 0 && (m = mmInNextStack[FinalState]) != -1 ) {
        memcpy( mmCapBegin, mmNextCapBegin + m * ncap, ncap * sizeof(int) );
        memcpy( mmCapEnd, mmNextCapEnd + m * ncap, ncap * sizeof(int) );
    }
#ifndef QT_NO_REGEXP_BACKREF
    /*
      It's time to wake up the sleepers.
    */
    if ( mmSleeping.count() > 0 ) {
        while ( (zzZ = mmSleeping.take(i)) != 0 ) {
        int next = zzZ[0];
        int *capBegin = zzZ + 1;
        int *capEnd = zzZ + 1 + ncap;
        bool copyOver = TRUE;

        if ( (m = mmInNextStack[zzZ[0]]) == -1 ) {
            m = nnext++;
            mmNextStack[m] = next;
            mmInNextStack[next] = m;
        } else {
            copyOver = isBetterCapture( mmNextCapBegin + m * ncap,
                        mmNextCapEnd + m * ncap,
                        capBegin, capEnd );
        }
        if ( copyOver ) {
            memcpy( mmNextCapBegin + m * ncap, capBegin,
                ncap * sizeof(int) );
            memcpy( mmNextCapEnd + m * ncap, capEnd,
                ncap * sizeof(int) );
        }
        delete[] zzZ;
        }
    }
#endif
#endif
    for ( j = 0; j < nnext; j++ )
        mmInNextStack[mmNextStack[j]] = -1;

    qSwap( mmCurStack, mmNextStack );
#ifndef QT_NO_REGEXP_CAPTURE
    qSwap( mmCurCapBegin, mmNextCapBegin );
    qSwap( mmCurCapEnd, mmNextCapEnd );
#endif
    ncur = nnext;
    nnext = 0;
    i++;
    }

#ifndef QT_NO_REGEXP_BACKREF
    /*
      If minimal matching is enabled, we might have some sleepers left.
    */
    while ( !mmSleeping.isEmpty() ) {
    zzZ = mmSleeping.take( *QIntDictIterator<int>(mmSleeping) );
    delete[] zzZ;
    }
#endif

    match = ( mmMatchedLen >= 0 );
    if ( !match )
    mmMatchedLen = i - 1;
    return match;
}

#ifndef QT_NO_REGEXP_CCLASS

QRegExpEngine::CharClass::CharClass()
    : c( 0 ), n( FALSE )
#ifndef QT_NO_REGEXP_OPTIM
      , occ1( *noOccurrences )
#endif
{
}

QRegExpEngine::CharClass& QRegExpEngine::CharClass::operator=(
    const CharClass& cc )
{
    c = cc.c;
    r = cc.r.copy();
    n = cc.n;
#ifndef QT_NO_REGEXP_OPTIM
    occ1 = cc.occ1;
#endif
    return *this;
}

void QRegExpEngine::CharClass::clear()
{
    c = 0;
    r.resize( 0 );
    n = FALSE;
}

void QRegExpEngine::CharClass::setNegative( bool negative )
{
    n = negative;
#ifndef QT_NO_REGEXP_OPTIM
    occ1 = *firstOccurrenceAtZero;
#endif
}

void QRegExpEngine::CharClass::addCategories( int cats )
{
    c |= cats;
#ifndef QT_NO_REGEXP_OPTIM
    occ1 = *firstOccurrenceAtZero;
#endif
}

void QRegExpEngine::CharClass::addRange( ushort from, ushort to )
{
    if ( from > to )
    qSwap( from, to );
    int n = r.size();
    r.resize( n + 1 );
    r[n].from = from;
    r[n].to = to;

#ifndef QT_NO_REGEXP_OPTIM
    int i;

    if ( to - from < NumBadChars ) {
    occ1.detach();
    if ( from % NumBadChars <= to % NumBadChars ) {
        for ( i = from % NumBadChars; i <= to % NumBadChars; i++ )
        occ1[i] = 0;
    } else {
        for ( i = 0; i <= to % NumBadChars; i++ )
        occ1[i] = 0;
        for ( i = from % NumBadChars; i < NumBadChars; i++ )
        occ1[i] = 0;
    }
    } else {
    occ1 = *firstOccurrenceAtZero;
    }
#endif
}

bool QRegExpEngine::CharClass::in( QChar ch ) const
{
#ifndef QT_NO_REGEXP_OPTIM
    if ( occ1[BadChar(ch)] == NoOccurrence )
    return n;
#endif

    if ( c != 0 && (c & (1 << (int) ch.category())) != 0 )
    return !n;
    for ( int i = 0; i < (int) r.size(); i++ ) {
    if ( ch.unicode() >= r[i].from && ch.unicode() <= r[i].to )
        return !n;
    }
    return n;
}

#if defined(QT_DEBUG)
void QRegExpEngine::CharClass::dump() const
{
    int i;
    odebug << "    " << (n ? "nega" : "posi") << "tive character class" << oendl;
#ifndef QT_NO_REGEXP_CCLASS
    if ( c != 0 )
    odebug << QString().sprintf("      categories 0x%.8x", c ) << oendl;
#endif
    for ( i = 0; i < (int) r.size(); i++ )
    odebug << QString().sprintf("      0x%.4x through 0x%.4x", r[i].from, r[i].to ) << oendl;
}
#endif
#endif

QRegExpEngine::Box::Box( QRegExpEngine *engine )
    : eng( engine ), skipanchors( 0 )
#ifndef QT_NO_REGEXP_OPTIM
      , earlyStart( 0 ), lateStart( 0 ), maxl( 0 ), occ1( *noOccurrences )
#endif
{
    minl = 0;
}

QRegExpEngine::Box& QRegExpEngine::Box::operator=( const Box& b )
{
    eng = b.eng;
    ls = b.ls;
    rs = b.rs;
    lanchors = b.lanchors;
    ranchors = b.ranchors;
    skipanchors = b.skipanchors;
#ifndef QT_NO_REGEXP_OPTIM
    earlyStart = b.earlyStart;
    lateStart = b.lateStart;
    str = b.str;
    leftStr = b.leftStr;
    rightStr = b.rightStr;
    maxl = b.maxl;
    occ1 = b.occ1;
#endif
    minl = b.minl;
    return *this;
}

void QRegExpEngine::Box::set( QChar ch )
{
    ls.resize( 1 );
    ls[0] = eng->createState( ch );
    rs = ls;
    rs.detach();
#ifndef QT_NO_REGEXP_OPTIM
    str = ch;
    leftStr = ch;
    rightStr = ch;
    maxl = 1;
    occ1.detach();
    occ1[BadChar(ch)] = 0;
#endif
    minl = 1;
}

void QRegExpEngine::Box::set( const CharClass& cc )
{
    ls.resize( 1 );
    ls[0] = eng->createState( cc );
    rs = ls;
    rs.detach();
#ifndef QT_NO_REGEXP_OPTIM
    maxl = 1;
    occ1 = cc.firstOccurrence();
#endif
    minl = 1;
}

#ifndef QT_NO_REGEXP_BACKREF
void QRegExpEngine::Box::set( int bref )
{
    ls.resize( 1 );
    ls[0] = eng->createState( bref );
    rs = ls;
    rs.detach();
    if ( bref >= 1 && bref <= MaxBackRefs )
    skipanchors = Anchor_BackRef0Empty << bref;
#ifndef QT_NO_REGEXP_OPTIM
    maxl = InftyLen;
#endif
    minl = 0;
}
#endif

void QRegExpEngine::Box::cat( const Box& b )
{
    eng->addCatTransitions( rs, b.ls );
    addAnchorsToEngine( b );
    if ( minl == 0 ) {
    mergeInto( &lanchors, b.lanchors );
    if ( skipanchors != 0 ) {
        for ( int i = 0; i < (int) b.ls.size(); i++ ) {
        int a = eng->anchorConcatenation( at(lanchors, b.ls[i]),
                          skipanchors );
        lanchors.insert( b.ls[i], a );
        }
    }
    mergeInto( &ls, b.ls );
    }
    if ( b.minl == 0 ) {
    mergeInto( &ranchors, b.ranchors );
    if ( b.skipanchors != 0 ) {
        for ( int i = 0; i < (int) rs.size(); i++ ) {
        int a = eng->anchorConcatenation( at(ranchors, rs[i]),
                          b.skipanchors );
        ranchors.insert( rs[i], a );
        }
    }
    mergeInto( &rs, b.rs );
    } else {
    ranchors = b.ranchors;
    rs = b.rs;
    }

#ifndef QT_NO_REGEXP_OPTIM
    if ( maxl != InftyLen ) {
    if ( rightStr.length() + b.leftStr.length() >
         QMAX(str.length(), b.str.length()) ) {
        earlyStart = minl - rightStr.length();
        lateStart = maxl - rightStr.length();
        str = rightStr + b.leftStr;
    } else if ( b.str.length() > str.length() ) {
        earlyStart = minl + b.earlyStart;
        lateStart = maxl + b.lateStart;
        str = b.str;
    }
    }

    if ( (int) leftStr.length() == maxl )
    leftStr += b.leftStr;
    if ( (int) b.rightStr.length() == b.maxl )
    rightStr += b.rightStr;
    else
    rightStr = b.rightStr;

    if ( maxl == InftyLen || b.maxl == InftyLen )
    maxl = InftyLen;
    else
    maxl += b.maxl;

    occ1.detach();
    for ( int i = 0; i < NumBadChars; i++ ) {
    if ( b.occ1[i] != NoOccurrence && minl + b.occ1[i] < occ1[i] )
        occ1[i] = minl + b.occ1[i];
    }
#endif

    minl += b.minl;
    if ( minl == 0 )
    skipanchors = eng->anchorConcatenation( skipanchors, b.skipanchors );
    else
    skipanchors = 0;
}

void QRegExpEngine::Box::orx( const Box& b )
{
    mergeInto( &ls, b.ls );
    mergeInto( &lanchors, b.lanchors );
    mergeInto( &rs, b.rs );
    mergeInto( &ranchors, b.ranchors );
    skipanchors = eng->anchorAlternation( skipanchors, b.skipanchors );

#ifndef QT_NO_REGEXP_OPTIM
    occ1.detach();
    for ( int i = 0; i < NumBadChars; i++ ) {
    if ( occ1[i] > b.occ1[i] )
        occ1[i] = b.occ1[i];
    }
    earlyStart = 0;
    lateStart = 0;
    str = QString::null;
    leftStr = QString::null;
    rightStr = QString::null;
    if ( b.maxl > maxl )
    maxl = b.maxl;
#endif
    if ( b.minl < minl )
    minl = b.minl;
}

void QRegExpEngine::Box::plus( int atom )
{
#ifndef QT_NO_REGEXP_CAPTURE
    eng->addPlusTransitions( rs, ls, atom );
#else
    Q_UNUSED( atom );
    eng->addCatTransitions( rs, ls );
#endif
    addAnchorsToEngine( *this );
#ifndef QT_NO_REGEXP_OPTIM
    maxl = InftyLen;
#endif
}

void QRegExpEngine::Box::opt()
{
#ifndef QT_NO_REGEXP_OPTIM
    earlyStart = 0;
    lateStart = 0;
    str = QString::null;
    leftStr = QString::null;
    rightStr = QString::null;
#endif
    skipanchors = 0;
    minl = 0;
}

void QRegExpEngine::Box::catAnchor( int a )
{
    if ( a != 0 ) {
    for ( int i = 0; i < (int) rs.size(); i++ ) {
        a = eng->anchorConcatenation( at(ranchors, rs[i]), a );
        ranchors.insert( rs[i], a );
    }
    if ( minl == 0 )
        skipanchors = eng->anchorConcatenation( skipanchors, a );
    }
}

#ifndef QT_NO_REGEXP_OPTIM
void QRegExpEngine::Box::setupHeuristics()
{
    eng->setupGoodStringHeuristic( earlyStart, lateStart, str );

    /*
      A regular expression such as 112|1 has occ1['2'] = 2 and minl = 1 at this
      point.  An entry of occ1 has to be at most minl or infinity for the rest
      of the algorithm to go well.

      We waited until here before normalizing these cases (instead of doing it
      in Box::orx()) because sometimes things improve by themselves; consider
      (112|1)34.
    */
    for ( int i = 0; i < NumBadChars; i++ ) {
    if ( occ1[i] != NoOccurrence && occ1[i] >= minl )
        occ1[i] = minl;
    }
    eng->setupBadCharHeuristic( minl, occ1 );

    eng->heuristicallyChooseHeuristic();
}
#endif

#if defined(QT_DEBUG)
void QRegExpEngine::Box::dump() const
{
    int i;
    odebug << "Box of at least " << minl << " character" << (minl == 1 ? "" : "s") << oendl;
    odebug << "  Left states:" << oendl;
    for ( i = 0; i < (int) ls.size(); i++ ) {
    if ( at(lanchors, ls[i]) == 0 )
        odebug << "    " << ls[i] << oendl;
    else
        odebug << "    " << ls[i] << QString().sprintf(" [anchors 0x%.8x]", lanchors[ls[i]]) << oendl;
    }
    odebug << "  Right states:" << oendl;
    for ( i = 0; i < (int) rs.size(); i++ ) {
    if ( at(ranchors, ls[i]) == 0 )
        odebug << "    " << rs[i] << oendl;
    else
        odebug << "    " << rs[i] << QString().sprintf(" [anchors 0x%.8x]", ranchors[rs[i]]) << oendl;
    }
    odebug << QString().sprintf("  Skip anchors: 0x%.8x", skipanchors) << oendl;
}
#endif

void QRegExpEngine::Box::addAnchorsToEngine( const Box& to ) const
{
    for ( int i = 0; i < (int) to.ls.size(); i++ ) {
    for ( int j = 0; j < (int) rs.size(); j++ ) {
        int a = eng->anchorConcatenation( at(ranchors, rs[j]),
                          at(to.lanchors, to.ls[i]) );
        eng->addAnchors( rs[j], to.ls[i], a );
    }
    }
}

int QRegExpEngine::getChar()
{
    return ( yyPos == yyLen ) ? EOS : yyIn[yyPos++].unicode();
}

int QRegExpEngine::getEscape()
{
#ifndef QT_NO_REGEXP_ESCAPE
    const char tab[] = "afnrtv"; // no b, as \b means word boundary
    const char backTab[] = "\a\f\n\r\t\v";
    ushort low;
    int i;
#endif
    ushort val;
    int prevCh = yyCh;

    if ( prevCh == EOS ) {
    yyError = TRUE;
    return Tok_Char | '\\';
    }
    yyCh = getChar();
#ifndef QT_NO_REGEXP_ESCAPE
    if ( (prevCh & ~0xff) == 0 ) {
    const char *p = strchr( tab, prevCh );
    if ( p != 0 )
        return Tok_Char | backTab[p - tab];
    }
#endif

    switch ( prevCh ) {
#ifndef QT_NO_REGEXP_ESCAPE
    case '0':
    val = 0;
    for ( i = 0; i < 3; i++ ) {
        if ( yyCh >= '0' && yyCh <= '7' )
        val = ( val << 3 ) | ( yyCh - '0' );
        else
        break;
        yyCh = getChar();
    }
    if ( (val & ~0377) != 0 )
        yyError = TRUE;
    return Tok_Char | val;
#endif
#ifndef QT_NO_REGEXP_ESCAPE
    case 'B':
    return Tok_NonWord;
#endif
#ifndef QT_NO_REGEXP_CCLASS
    case 'D':
    // see QChar::isDigit()
    yyCharClass->addCategories( 0x7fffffef );
    return Tok_CharClass;
    case 'S':
    // see QChar::isSpace()
    yyCharClass->addCategories( 0x7ffff87f );
    yyCharClass->addRange( 0x0000, 0x0008 );
    yyCharClass->addRange( 0x000e, 0x001f );
    yyCharClass->addRange( 0x007f, 0x009f );
    return Tok_CharClass;
    case 'W':
    // see QChar::isLetterOrNumber()
    yyCharClass->addCategories( 0x7ff07f8f );
    return Tok_CharClass;
#endif
#ifndef QT_NO_REGEXP_ESCAPE
    case 'b':
    return Tok_Word;
#endif
#ifndef QT_NO_REGEXP_CCLASS
    case 'd':
    // see QChar::isDigit()
    yyCharClass->addCategories( 0x00000010 );
    return Tok_CharClass;
    case 's':
    // see QChar::isSpace()
    yyCharClass->addCategories( 0x00000380 );
    yyCharClass->addRange( 0x0009, 0x000d );
    return Tok_CharClass;
    case 'w':
    // see QChar::isLetterOrNumber()
    yyCharClass->addCategories( 0x000f8070 );
    return Tok_CharClass;
#endif
#ifndef QT_NO_REGEXP_ESCAPE
    case 'x':
    val = 0;
    for ( i = 0; i < 4; i++ ) {
        low = QChar( yyCh ).lower();
        if ( low >= '0' && low <= '9' )
        val = ( val << 4 ) | ( low - '0' );
        else if ( low >= 'a' && low <= 'f' )
        val = ( val << 4 ) | ( low - 'a' + 10 );
        else
        break;
        yyCh = getChar();
    }
    return Tok_Char | val;
#endif
    default:
    if ( prevCh >= '1' && prevCh <= '9' ) {
#ifndef QT_NO_REGEXP_BACKREF
        val = prevCh - '0';
        while ( yyCh >= '0' && yyCh <= '9' ) {
        val = ( val *= 10 ) | ( yyCh - '0' );
        yyCh = getChar();
        }
        return Tok_BackRef | val;
#else
        yyError = TRUE;
#endif
    }
    return Tok_Char | prevCh;
    }
}

#ifndef QT_NO_REGEXP_INTERVAL
int QRegExpEngine::getRep( int def )
{
    if ( yyCh >= '0' && yyCh <= '9' ) {
    int rep = 0;
    do {
        rep = 10 * rep + yyCh - '0';
        if ( rep >= InftyRep ) {
        yyError = TRUE;
        rep = def;
        }
        yyCh = getChar();
    } while ( yyCh >= '0' && yyCh <= '9' );
    return rep;
    } else {
    return def;
    }
}
#endif

#ifndef QT_NO_REGEXP_LOOKAHEAD
void QRegExpEngine::skipChars( int n )
{
    if ( n > 0 ) {
    yyPos += n - 1;
    yyCh = getChar();
    }
}
#endif

void QRegExpEngine::startTokenizer( const QChar *rx, int len )
{
    yyIn = rx;
    yyPos0 = 0;
    yyPos = 0;
    yyLen = len;
    yyCh = getChar();
    yyCharClass = new CharClass;
    yyMinRep = 0;
    yyMaxRep = 0;
    yyError = FALSE;
}

int QRegExpEngine::getToken()
{
#ifndef QT_NO_REGEXP_CCLASS
    ushort pendingCh = 0;
    bool charPending;
    bool rangePending;
    int tok;
#endif
    int prevCh = yyCh;

    yyPos0 = yyPos - 1;
#ifndef QT_NO_REGEXP_CCLASS
    yyCharClass->clear();
#endif
    yyMinRep = 0;
    yyMaxRep = 0;
    yyCh = getChar();
    switch ( prevCh ) {
    case EOS:
    yyPos0 = yyPos;
    return Tok_Eos;
    case '$':
    return Tok_Dollar;
    case '(':
    if ( yyCh == '?' ) {
        prevCh = getChar();
        yyCh = getChar();
        switch ( prevCh ) {
#ifndef QT_NO_REGEXP_LOOKAHEAD
        case '!':
        return Tok_NegLookahead;
        case '=':
        return Tok_PosLookahead;
#endif
        case ':':
        return Tok_MagicLeftParen;
        default:
        yyError = TRUE;
        return Tok_MagicLeftParen;
        }
    } else {
        return Tok_LeftParen;
    }
    case ')':
    return Tok_RightParen;
    case '*':
    yyMinRep = 0;
    yyMaxRep = InftyRep;
    return Tok_Quantifier;
    case '+':
    yyMinRep = 1;
    yyMaxRep = InftyRep;
    return Tok_Quantifier;
    case '.':
#ifndef QT_NO_REGEXP_CCLASS
    yyCharClass->setNegative( TRUE );
#endif
    return Tok_CharClass;
    case '?':
    yyMinRep = 0;
    yyMaxRep = 1;
    return Tok_Quantifier;
    case '[':
#ifndef QT_NO_REGEXP_CCLASS
    if ( yyCh == '^' ) {
        yyCharClass->setNegative( TRUE );
        yyCh = getChar();
    }
    charPending = FALSE;
    rangePending = FALSE;
    do {
        if ( yyCh == '-' && charPending && !rangePending ) {
        rangePending = TRUE;
        yyCh = getChar();
        } else {
        if ( charPending && !rangePending ) {
            yyCharClass->addSingleton( pendingCh );
            charPending = FALSE;
        }
        if ( yyCh == '\\' ) {
            yyCh = getChar();
            tok = getEscape();
            if ( tok == Tok_Word )
            tok = '\b';
        } else {
            tok = Tok_Char | yyCh;
            yyCh = getChar();
        }
        if ( tok == Tok_CharClass ) {
            if ( rangePending ) {
            yyCharClass->addSingleton( '-' );
            yyCharClass->addSingleton( pendingCh );
            charPending = FALSE;
            rangePending = FALSE;
            }
        } else if ( (tok & Tok_Char) != 0 ) {
            if ( rangePending ) {
            yyCharClass->addRange( pendingCh, tok ^ Tok_Char );
            charPending = FALSE;
            rangePending = FALSE;
            } else {
            pendingCh = tok ^ Tok_Char;
            charPending = TRUE;
            }
        } else {
            yyError = TRUE;
        }
        }
    }  while ( yyCh != ']' && yyCh != EOS );
    if ( rangePending )
        yyCharClass->addSingleton( '-' );
    if ( charPending )
        yyCharClass->addSingleton( pendingCh );
    if ( yyCh == EOS )
        yyError = TRUE;
    else
        yyCh = getChar();
    return Tok_CharClass;
#else
    yyError = TRUE;
    return Tok_Char | '[';
#endif
    case '\\':
    return getEscape();
    case ']':
    yyError = TRUE;
    return Tok_Char | ']';
    case '^':
    return Tok_Caret;
#ifndef QT_NO_REGEXP_INTERVAL
    case '{':
    yyMinRep = getRep( 0 );
    yyMaxRep = yyMinRep;
    if ( yyCh == ',' ) {
        yyCh = getChar();
        yyMaxRep = getRep( InftyRep );
    }
    if ( yyMaxRep < yyMinRep )
        qSwap( yyMinRep, yyMaxRep );
    if ( yyCh != '}' )
        yyError = TRUE;
    yyCh = getChar();
    return Tok_Quantifier;
#else
    yyError = TRUE;
    return Tok_Char | '{';
#endif
    case '|':
    return Tok_Bar;
    case '}':
    yyError = TRUE;
    return Tok_Char | '}';
    default:
    return Tok_Char | prevCh;
    }
}

int QRegExpEngine::parse( const QChar *pattern, int len )
{
    valid = TRUE;
    startTokenizer( pattern, len );
    yyTok = getToken();
#ifndef QT_NO_REGEXP_CAPTURE
    yyMayCapture = TRUE;
#else
    yyMayCapture = FALSE;
#endif

#ifndef QT_NO_REGEXP_CAPTURE
    int atom = startAtom( FALSE );
#endif
    CharClass anything;
    Box box( this ); // create InitialState
    box.set( anything );
    Box rightBox( this ); // create FinalState
    rightBox.set( anything );

    Box middleBox( this );
    parseExpression( &middleBox );
#ifndef QT_NO_REGEXP_CAPTURE
    finishAtom( atom );
#endif
#ifndef QT_NO_REGEXP_OPTIM
    middleBox.setupHeuristics();
#endif
    box.cat( middleBox );
    box.cat( rightBox );
    delete yyCharClass;
    yyCharClass = 0;

    realncap = ncap;
#ifndef QT_NO_REGEXP_BACKREF
    if ( nbrefs > ncap )
    ncap = nbrefs;
#endif

    mmCaptured.resize( 2 + 2 * realncap );
    mmCapturedNoMatch.fill( -1, 2 + 2 * realncap );

    /*
      We use one QArray<int> for all the big data used a lot in matchHere() and
      friends.
    */
#ifndef QT_NO_REGEXP_OPTIM
    mmSlideTabSize = QMAX( minl + 1, 16 );
#else
    mmSlideTabSize = 0;
#endif
    mmBigArray.resize( (3 + 4 * ncap) * ns + 4 * ncap + mmSlideTabSize );

    mmInNextStack = mmBigArray.data();
    memset( mmInNextStack, -1, ns * sizeof(int) );
    mmCurStack = mmInNextStack + ns;
    mmNextStack = mmInNextStack + 2 * ns;

    mmCurCapBegin = mmInNextStack + 3 * ns;
    mmNextCapBegin = mmCurCapBegin + ncap * ns;
    mmCurCapEnd = mmCurCapBegin + 2 * ncap * ns;
    mmNextCapEnd = mmCurCapBegin + 3 * ncap * ns;

    mmTempCapBegin = mmCurCapBegin + 4 * ncap * ns;
    mmTempCapEnd = mmTempCapBegin + ncap;
    mmCapBegin = mmTempCapBegin + 2 * ncap;
    mmCapEnd = mmTempCapBegin + 3 * ncap;

    mmSlideTab = mmTempCapBegin + 4 * ncap;

    if ( yyError )
    return -1;

#ifndef QT_NO_REGEXP_OPTIM
    State *sinit = s[InitialState];
    caretAnchored = ( sinit->anchors != 0 );
    if ( caretAnchored ) {
    QMap<int, int>& anchors = *sinit->anchors;
    QMap<int, int>::ConstIterator a;
    for ( a = anchors.begin(); a != anchors.end(); ++a ) {
#ifndef QT_NO_REGEXP_ANCHOR_ALT
        if ( (*a & Anchor_Alternation) != 0 )
        break;
#endif
        if ( (*a & Anchor_Caret) == 0 ) {
        caretAnchored = FALSE;
        break;
        }
    }
    }
#endif
    return yyPos0;
}

void QRegExpEngine::parseAtom( Box *box )
{
#ifndef QT_NO_REGEXP_LOOKAHEAD
    QRegExpEngine *eng = 0;
    bool neg;
    int len;
#endif

    switch ( yyTok ) {
    case Tok_Dollar:
    box->catAnchor( Anchor_Dollar );
    break;
    case Tok_Caret:
    box->catAnchor( Anchor_Caret );
    break;
#ifndef QT_NO_REGEXP_LOOKAHEAD
    case Tok_PosLookahead:
    case Tok_NegLookahead:
    neg = ( yyTok == Tok_NegLookahead );
    eng = new QRegExpEngine( cs );
    len = eng->parse( yyIn + yyPos - 1, yyLen - yyPos + 1 );
    if ( len >= 0 )
        skipChars( len );
    else
        yyError = TRUE;
    box->catAnchor( addLookahead(eng, neg) );
    yyTok = getToken();
    if ( yyTok != Tok_RightParen )
        yyError = TRUE;
    break;
#endif
#ifndef QT_NO_REGEXP_ESCAPE
    case Tok_Word:
    box->catAnchor( Anchor_Word );
    break;
    case Tok_NonWord:
    box->catAnchor( Anchor_NonWord );
    break;
#endif
    case Tok_LeftParen:
    case Tok_MagicLeftParen:
    yyTok = getToken();
    parseExpression( box );
    if ( yyTok != Tok_RightParen )
        yyError = TRUE;
    break;
    case Tok_CharClass:
    box->set( *yyCharClass );
    break;
    default:
    if ( (yyTok & Tok_Char) != 0 )
        box->set( QChar(yyTok ^ Tok_Char) );
#ifndef QT_NO_REGEXP_BACKREF
    else if ( (yyTok & Tok_BackRef) != 0 )
        box->set( yyTok ^ Tok_BackRef );
#endif
    else
        yyError = TRUE;
    }
    yyTok = getToken();
}

void QRegExpEngine::parseFactor( Box *box )
{
#ifndef QT_NO_REGEXP_CAPTURE
    int atom = startAtom( yyMayCapture && yyTok == Tok_LeftParen );
#else
    static const int atom = 0;
#endif

#ifndef QT_NO_REGEXP_INTERVAL
#define YYREDO() \
    yyIn = in, yyPos0 = pos0, yyPos = pos, yyLen = len, yyCh = ch, \
    *yyCharClass = charClass, yyMinRep = 0, yyMaxRep = 0, yyTok = tok

    const QChar *in = yyIn;
    int pos0 = yyPos0;
    int pos = yyPos;
    int len = yyLen;
    int ch = yyCh;
    CharClass charClass;
    if ( yyTok == Tok_CharClass )
    charClass = *yyCharClass;
    int tok = yyTok;
    bool mayCapture = yyMayCapture;
#endif

    parseAtom( box );
#ifndef QT_NO_REGEXP_CAPTURE
    finishAtom( atom );
#endif

    if ( yyTok == Tok_Quantifier ) {
    if ( yyMaxRep == InftyRep ) {
        box->plus( atom );
#ifndef QT_NO_REGEXP_INTERVAL
    } else if ( yyMaxRep == 0 ) {
        box->clear();
#endif
    }
    if ( yyMinRep == 0 )
        box->opt();

#ifndef QT_NO_REGEXP_INTERVAL
    yyMayCapture = FALSE;
    int alpha = ( yyMinRep == 0 ) ? 0 : yyMinRep - 1;
    int beta = ( yyMaxRep == InftyRep ) ? 0 : yyMaxRep - ( alpha + 1 );

    Box rightBox( this );
    int i;

    for ( i = 0; i < beta; i++ ) {
        YYREDO();
        Box leftBox( this );
        parseAtom( &leftBox );
        leftBox.cat( rightBox );
        leftBox.opt();
        rightBox = leftBox;
    }
    for ( i = 0; i < alpha; i++ ) {
        YYREDO();
        Box leftBox( this );
        parseAtom( &leftBox );
        leftBox.cat( rightBox );
        rightBox = leftBox;
    }
    rightBox.cat( *box );
    *box = rightBox;
#endif
    yyTok = getToken();
#ifndef QT_NO_REGEXP_INTERVAL
    yyMayCapture = mayCapture;
#endif
    }
#undef YYREDO
}

void QRegExpEngine::parseTerm( Box *box )
{
#ifndef QT_NO_REGEXP_OPTIM
    if ( yyTok != Tok_Eos && yyTok != Tok_RightParen && yyTok != Tok_Bar )
    parseFactor( box );
#endif
    while ( yyTok != Tok_Eos && yyTok != Tok_RightParen && yyTok != Tok_Bar ) {
    Box rightBox( this );
    parseFactor( &rightBox );
    box->cat( rightBox );
    }
}

void QRegExpEngine::parseExpression( Box *box )
{
    parseTerm( box );
    while ( yyTok == Tok_Bar ) {
    Box rightBox( this );
    yyTok = getToken();
    parseTerm( &rightBox );
    box->orx( rightBox );
    }
}

/*
  The class QRegExpPrivate contains the private data of a regular expression
  other than the automaton.  It makes it possible for many QRegExp objects to
  use the same QRegExpEngine object with different QRegExpPrivate objects.
*/
struct QRegExpPrivate
{
    QString pattern; // regular-expression or wildcard pattern
    QString rxpattern; // regular-expression pattern
#ifndef QT_NO_REGEXP_WILDCARD
    bool wc; // wildcard mode?
#endif
    bool min; // minimal matching? (instead of maximal)
#ifndef QT_NO_REGEXP_CAPTURE
    QString t; // last string passed to QRegExp::search() or searchRev()
    QStringList capturedCache; // what QRegExp::capturedTexts() returned last
#endif
    QArray<int> captured; // what QRegExpEngine::search() returned last

    QRegExpPrivate() { captured.fill( -1, 2 ); }
};

#ifndef QT_NO_REGEXP_OPTIM
static QCache<QRegExpEngine> *engineCache = 0;
#endif

static QRegExpEngine *newEngine( const QString& pattern, bool caseSensitive )
{
#ifndef QT_NO_REGEXP_OPTIM
    if ( engineCache != 0 ) {
    QRegExpEngine *eng = engineCache->take( pattern );
    if ( eng == 0 || eng->caseSensitive() != caseSensitive ) {
        delete eng;
    } else {
        eng->ref();
        return eng;
    }
    }
#endif
    return new QRegExpEngine( pattern, caseSensitive );
}

static void derefEngine( QRegExpEngine *eng, const QString& pattern )
{
    if ( eng != 0 && eng->deref() ) {
#ifndef QT_NO_REGEXP_OPTIM
    if ( engineCache == 0 ) {
        engineCache = new QCache<QRegExpEngine>;
        engineCache->setAutoDelete( TRUE );
    }
    if ( !pattern.isNull() &&
         engineCache->insert(pattern, eng, 4 + pattern.length() / 4) )
        return;
#else
    Q_UNUSED( pattern );
#endif
    delete eng;
    }
}

/*!
  Constructs an empty regexp.

  \sa isValid()
*/
QRegExp3::QRegExp3()
{
    eng = new QRegExpEngine( TRUE );
    priv = new QRegExpPrivate;
    priv->pattern = QString::null;
#ifndef QT_NO_REGEXP_WILDCARD
    priv->wc = FALSE;
#endif
    priv->min = FALSE;
    compile( TRUE );
}

/*!
  Constructs a regular expression object for the given \a pattern
  string.  The pattern must be given using wildcard notation if \a
  wildcard is TRUE (default is FALSE). The pattern is case sensitive,
  unless \a caseSensitive is FALSE.  Matching is greedy (maximal), but
  can be changed by calling setMinimal().

  \sa setPattern() setCaseSensitive() setWildcard() setMinimal()
*/
QRegExp3::QRegExp3( const QString& pattern, bool caseSensitive, bool wildcard )
{
    eng = 0;
    priv = new QRegExpPrivate;
    priv->pattern = pattern;
#ifndef QT_NO_REGEXP_WILDCARD
    priv->wc = wildcard;
#endif
    priv->min = FALSE;
    compile( caseSensitive );
}

/*!
  Constructs a regular expression as a copy of \a rx.

  \sa operator=()
*/
QRegExp3::QRegExp3( const QRegExp3& rx )
{
    eng = 0;
    priv = new QRegExpPrivate;
    operator=( rx );
}

/*!
  Destroys the regular expression and cleans up its internal data.
*/
QRegExp3::~QRegExp3()
{
    derefEngine( eng, priv->rxpattern );
    delete priv;
}

/*!
  Copies the regular expression \a rx and returns a reference to the copy.
  The case sensitivity, wildcard and minimal matching options are copied as
  well.
*/
QRegExp3& QRegExp3::operator=( const QRegExp3& rx )
{
    rx.eng->ref();
    derefEngine( eng, priv->rxpattern );
    eng = rx.eng;
    priv->pattern = rx.priv->pattern;
    priv->rxpattern = rx.priv->rxpattern;
#ifndef QT_NO_REGEXP_WILDCARD
    priv->wc = rx.priv->wc;
#endif
    priv->min = rx.priv->min;
#ifndef QT_NO_REGEXP_CAPTURE
    priv->t = rx.priv->t;
    priv->capturedCache = rx.priv->capturedCache;
#endif
    priv->captured = rx.priv->captured;
    return *this;
}

/*!
  Returns TRUE if this regular expression is equal to \a rx, otherwise
  returns FALSE.

  Two QRegExp3 objects are equal if they have the same pattern strings
  and the same settings for case sensitivity, wildcard and minimal
  matching.
*/
bool QRegExp3::operator==( const QRegExp3& rx ) const
{
    return priv->pattern == rx.priv->pattern &&
       eng->caseSensitive() == rx.eng->caseSensitive() &&
#ifndef QT_NO_REGEXP_WILDCARD
       priv->wc == rx.priv->wc &&
#endif
       priv->min == rx.priv->min;
}

/*!  \fn bool QRegExp3::operator!=( const QRegExp& rx ) const

  Returns TRUE if this regular expression is not equal to \a rx, otherwise
  FALSE.

  \sa operator==()
*/

/*!
  Returns TRUE if the pattern string is empty, otherwise FALSE.

  If you call match() with an empty pattern on an empty string it will
  return TRUE otherwise it returns FALSE since match() operates over the
  whole string. If you call search() with an empty pattern on \e any
  string it will return the start position (0 by default) since it will
  match at the start position, because the empty pattern matches the
  'emptiness' at the start of the string, and the length of the match
  returned by matchedLength() will be 0.

  See QString::isEmpty().
*/

bool QRegExp3::isEmpty() const
{
    return priv->pattern.isEmpty();
}

/*!
  Returns TRUE if the regular expression is valid, or FALSE if it's invalid.  An
  invalid regular expression never matches.

  The pattern <b>[a-z</b> is an example of an invalid pattern, since it lacks
  a closing square bracket.

  Note that the validity of a regexp may also depend on the setting of
  the wildcard flag, for example <b>*.html</b> is a valid wildcard
  regexp but an invalid full regexp.
*/
bool QRegExp3::isValid() const
{
    return eng->isValid();
}

/*!
  Returns the pattern string of the regular expression.  The pattern has either
  regular expression syntax or wildcard syntax, depending on wildcard().

  \sa setPattern()
*/
QString QRegExp3::pattern() const
{
    return priv->pattern;
}

/*!
  Sets the pattern string to \a pattern and returns a reference to this regular
  expression.  The case sensitivity, wildcard and minimal matching options are
  not changed.

  \sa pattern()
*/
void QRegExp3::setPattern( const QString& pattern )
{
    if ( priv->pattern != pattern ) {
    priv->pattern = pattern;
    compile( caseSensitive() );
    }
}

/*!
  Returns TRUE if case sensitivity is enabled, otherwise FALSE.  The default is
  TRUE.

  \sa setCaseSensitive()
*/
bool QRegExp3::caseSensitive() const
{
    return eng->caseSensitive();
}

/*!
  Sets case sensitive matching to \a sensitive.

  If \a sensitive is TRUE, <b>\\</b><b>.txt$</b> matches
  <tt>readme.txt</tt> but not <tt>README.TXT</tt>.

  \sa caseSensitive()
*/
void QRegExp3::setCaseSensitive( bool sensitive )
{
    if ( sensitive != eng->caseSensitive() )
    compile( sensitive );
}

#ifndef QT_NO_REGEXP_WILDCARD
/*!
  Returns TRUE if wildcard mode is enabled, otherwise FALSE.  The default is
  FALSE.

  \sa setWildcard()
*/
bool QRegExp3::wildcard() const
{
    return priv->wc;
}

/*!  Sets the wildcard mode for the regular expression.  The default is FALSE.

  Setting \a wildcard to TRUE enables simple shell-like wildcard
  matching.
  (See <a href="#wildcard-matching">wildcard matching (globbing)</a>.)

  For example, <b>r*.txt</b> matches the string <tt>readme.txt</tt> in wildcard
  mode, but does not match <tt>readme</tt>.

  \sa wildcard()
*/
void QRegExp3::setWildcard( bool wildcard )
{
    if ( wildcard != priv->wc ) {
    priv->wc = wildcard;
    compile( caseSensitive() );
    }
}
#endif

/*!  Returns TRUE if minimal (non-greedy) matching is enabled, otherwise
    returns FALSE.

  \sa setMinimal()
*/
bool QRegExp3::minimal() const
{
    return priv->min;
}

/*!
  Enables or disables minimal matching.  If \a minimal is FALSE, matching is
  greedy (maximal) which is the default.

    For example, suppose we have the input string "We must be \<b>bold\</b>,
    very \<b>bold\</b>!" and the pattern <b>\<b>.*\</b></b>. With
    the default greedy (maximal) matching, the match is
    "We must be <u>\<b>bold\</b>, very \<b>bold\</b></u>!". But with
    minimal (non-greedy) matching the first match is:
    "We must be <u>\<b>bold\</b></u>, very \<b>bold\</b>!" and the
    second match is
    "We must be \<b>bold\</b>, very <u>\<b>bold\</b></u>!".
    In practice we might use the pattern <b>\<b>[^\<]+\</b></b>,
    although this will still fail for nested tags.

  \sa minimal()
*/
void QRegExp3::setMinimal( bool minimal )
{
    priv->min = minimal;
}

/*!
  Returns TRUE if \a str is matched exactly by this regular expression
  otherwise it returns FALSE. You can determine how much of the string was
  matched by calling matchedLength().

    For a given regexp string, R, <tt>match("R")</tt> is the equivalent
    of <tt>search("^R$")</tt> since match() effectively encloses the
    regexp in the start of string and end of string anchors.

  For example, if the regular expression is <b>blue</b>, then match()
  returns TRUE only for input <tt>blue</tt>.  For inputs
  <tt>bluebell</tt>, <tt>blutak</tt> and <tt>lightblue</tt>, match()
  returns FALSE and matchedLength() will return 4, 3 and 0 respectively.

  \sa search() searchRev() QRegExpValidator
*/
bool QRegExp3::exactMatch( const QString& str )
{
#ifndef QT_NO_REGEXP_CAPTURE
    priv->t = str;
    priv->capturedCache.clear();
#endif

    priv->captured = eng->match( str, 0, priv->min, TRUE );
    if ( priv->captured[1] == (int) str.length() ) {
    return TRUE;
    } else {
    priv->captured.detach();
    priv->captured[0] = 0;
    priv->captured[1] = eng->matchedLength();
    return FALSE;
    }
}

/*! \overload

  This version does not set matchedLength(), capturedTexts() and friends.
*/
bool QRegExp3::exactMatch( const QString& str ) const
{
   return eng->match(str, 0, priv->min, TRUE)[0] == 0 &&
      eng->matchedLength() == (int) str.length();
}

/*! \obsolete

  Attempts to match in \a str, starting from position \a index.  Returns the
  position of the match, or -1 if there was no match.

  The length of the match is stored in \a *len, unless \a len is a null pointer.

  If \a indexIsStart is TRUE (the default), the position \a index in the string
  will match the start of string anchor, <b>^</b>, in the regexp, if present.
  Otherwise, position 0 in \a str will match.

  Use search() and matchedLength() instead of this function.

  If you really need the \a indexIsStart functionality, try this:

  \code
    QRegExp3 rx( "some pattern" );
    int pos = rx.search( str.mid( index ) );
    if ( pos != -1 )
    pos += index;
    int len = rx.matchedLength();
  \endcode
*/
#ifndef QT_NO_COMPAT
int QRegExp3::match( const QString& str, int index, int *len,
            bool indexIsStart )
{
    int pos;
    if ( indexIsStart ) {
    pos = search( str.mid(index) );
    if ( pos >= 0 ) {
        pos += index;
        if ( len != 0 )
        *len = matchedLength();
    } else {
        if ( len != 0 )
        *len = 0;
    }
    } else {
    pos = search( str, index );
    if ( len != 0 )
        *len = matchedLength();
    }
    return pos;
}
#endif

/*!
  Attempts to find a match in \a str from position \a start (0 by default).  If
  \a start is -1, the search starts at the last character; if -2, at the next to
  last character; etc.

  Returns the position of the first match, or -1 if there was no match.

  You might prefer to use QString::find(), QString::contains() or even
  QStringList::grep(). To replace matches use QString::replace().

  Example:
  \code
    QString str = "offsets: 1.23 .50 71.00 6.00";
    QRegExp3 rx( "\\d*\\.\\d+" );    // very simple floating point matching
    int count = 0;
    int pos = 0;
    while ( pos >= 0 ) {
    pos = rx.search( str, pos );
    count++;
    }
    // pos will be 9, 14, 18 and finally 24; count will end up as 4.
  \endcode

  \sa searchRev() match() matchedLength() capturedTexts()
*/
// QChar versions

#ifdef QCHAR_SUPPORT
const QString makeString(const QChar *str)
{
// A sentinel value checked in case the QChar *ptr is never null terminated
    const uint MAXLENGTH=65535;

    const QChar *s=str;
    uint i=0;
    while(i < MAXLENGTH && *s != QChar::null) {  i++;s++ ;}
    return QString(str,i);

}
int QRegExp3::search(const QChar *str,int start)
{
    return search(makeString(str),start);
}
int QRegExp3::search(const QChar *str,int start) const
{
    return search(makeString(str),start);
}
int QRegExp3::searchRev(const QChar *str,int start)
{
    return searchRev(makeString(str),start);
}
int QRegExp3::searchRev(const QChar *str,int start) const
{
    return searchRev(makeString(str),start);
}
bool QRegExp3::exactMatch(const QChar *str)
{
    return exactMatch(makeString(str));
}
bool QRegExp3::exactMatch(const QChar *str) const
{
    return exactMatch(makeString(str));
}
#endif // QCHAR_SUPPORT

int QRegExp3::search( const QString& str, int start )
{
    if ( start < 0 )
    start += str.length();
#ifndef QT_NO_REGEXP_CAPTURE
    priv->t = str;
    priv->capturedCache.clear();
#endif
    priv->captured = eng->match( str, start, priv->min, FALSE );
    return priv->captured[0];
}

/*! \overload

  This version does not set matchedLength(), capturedTexts() and friends.
*/
int QRegExp3::search( const QString& str, int start ) const
{
    if ( start < 0 )
    start += str.length();
    return eng->match( str, start, priv->min, FALSE )[0];
}

/*!
  Attempts to find a match backwards in \a str from position \a start.  If
  \a start is -1 (the default), the search starts at the last character; if -2,
  at the next to last character; etc.

  Returns the position of the first match, or -1 if there was no match.

  You might prefer to use QString::findRev().

  \sa search() matchedLength() capturedTexts()
*/
int QRegExp3::searchRev( const QString& str, int start )
{
    if ( start < 0 )
    start += str.length();
#ifndef QT_NO_REGEXP_CAPTURE
    priv->t = str;
    priv->capturedCache.clear();
#endif
    if ( start < 0 || start > (int) str.length() ) {
    priv->captured.detach();
    priv->captured.fill( -1 );
    return -1;
    }

    while ( start >= 0 ) {
    priv->captured = eng->match( str, start, priv->min, TRUE );
    if ( priv->captured[0] == start )
        return start;
    start--;
    }
    return -1;
}

/*! \overload

  This version does not set matchedLength(), capturedText() and friends.
*/
int QRegExp3::searchRev( const QString& str, int start ) const
{
    if ( start < 0 )
    start += str.length();
    if ( start < 0 || start > (int) str.length() )
    return -1;

    while ( start >= 0 ) {
    if ( eng->match(str, start, priv->min, TRUE)[0] == start )
        return start;
    start--;
    }
    return -1;
}

/*!
  Returns the length of the last matched string, or -1 if there was no match.

  \sa match() search()
*/
int QRegExp3::matchedLength()
{
    return priv->captured[1];
}

#ifndef QT_NO_REGEXP_CAPTURE
/*!
  Returns a list of the captured text strings.

    The first string in the list is the entire matched string. Each
    subsequent list element contains a string that matched a
    (capturing) subexpression of the regexp.

    For example:
  \code
    QRegExp3 rx( "(\\d+)(\\s*)(cm|inch(es)?)" );
    int pos = rx.search( "Length: 36 inches" );
    QStringList list = rx.capturedTexts();
    // list is now ( "36 inches", "36", " ", "inches", "es" ).
    \endcode

    The above example also captures elements
    that may be present but which we have no interest in. This problem
    can be solved by using non-capturing parenthesis:

    \code
    QRegExp3 rx( "(\\d+)(?:\\s*)(cm|inch(?:es)?)" );
    int pos = rx.search( "Length: 36 inches" );
    QStringList list = rx.capturedTexts();
    // list is now ( "36 inches", "36", "inches" ).
  \endcode

  Some regexps can match an indeterminate number of times. For example
  if the input string is "Offsets: 12 14 99 231 7" and the regexp,
  <tt>rx</tt>, is <b>(</b><b>\\</b><b>d+)+</b>, we would hope to get a
  list of all the numbers matched. However, after calling
  <tt>rx.search(str)</tt>, capturedTexts() will return the list ( "12",
  "12" ), i.e. the entire match was "12" and the first subexpression
  matched was "12". The correct approach is to use cap() in a
  <a href="#cap_in_a_loop">loop</a>.

  The order of elements in the string list is as follows. The first
  element is the entire matching string. Each subsequent element
  corresponds to the next capturing open left parenthesis. Thus
  capturedTexts()[1] is the text of the first capturing parenthesis,
  capturedTexts()[2] is the text of the second and so on (corresponding
  to $1, $2 etc. in some other regexp languages).

  \sa cap() pos()
*/
QStringList QRegExp3::capturedTexts()
{
    if ( priv->capturedCache.isEmpty() ) {
    for ( int i = 0; i < (int) priv->captured.size(); i += 2 ) {
        QString m;
        if ( priv->captured[i + 1] == 0 )
        m = QString::fromLatin1( "" );
        else if ( priv->captured[i] >= 0 )
        m = priv->t.mid( priv->captured[i],
                 priv->captured[i + 1] );
        priv->capturedCache.append( m );
    }
    priv->t = QString::null;
    }
    return priv->capturedCache;
}

/*! Returns the text captured by the \a nth subexpression. The entire match
  has index 0 and the parenthesised subexpressions have indices starting
  from 1 (excluding non-capturing parenthesis).

  \code
    QRegExp3 rxlen( "(\\d+)(?:\\s*)(cm|inch)" );
    int pos = rxlen.search( "Length: 189cm" );
    if ( pos > -1 ) {
    QString value = rxlen.cap( 1 ); // "189"
    QString unit  = rxlen.cap( 2 ); // "cm"
    // ...
    }
  \endcode

    <a name="cap_in_a_loop">
    Some patterns may lead to a number of matches which cannot be
    determined in advance, for example:</a>

    \code
    QRegExp3 rx( "(\\d+)" );
    str = "Offsets: 12 14 99 231 7";
    QStringList list;
    pos = 0;
    while ( pos >= 0 ) {
    pos = rx.search( str, pos );
    if ( pos > -1 ) {
        list += rx.cap( 1 );
        pos  += rx.matchedLength();
    }
    }
    // list contains: ( "12", "14", "99", "231", "7" ).
    \endcode

  The order of elements matched by cap() is as follows. The first
  element, cap( 0 ), is the entire matching string. Each subsequent
  element corresponds to the next capturing open left parenthesis. Thus
  cap( 1 ) is the text of the first capturing parenthesis, cap( 2 ) is
  the text of the second and so on.

  \sa search() pos() capturedTexts()
*/
QString QRegExp3::cap( int nth )
{
    if ( nth < 0 || nth >= (int) priv->captured.size() / 2 )
    return QString::null;
    else
    return capturedTexts()[nth];
}

/*! Returns the position of the \a nth captured text in the
    searched string.  If \a nth is 0 (the default), pos() returns the
    position of the whole match.

  Example:
  \code
    QRegExp3 rx( "/([a-z]+)/([a-z]+)" );
    rx.search( "Output /dev/null" );    // Returns  7 (position of /dev/null)
    rx.pos( 0 );                        // Returns  7 (position of /dev/null)
    rx.pos( 1 );                        // Returns  8 (position of dev)
    rx.pos( 2 );                        // Returns 12 (position of null)
  \endcode

  Note that pos() returns -1 for zero-length matches. (For example, if
  cap(4) would return an empty string, pos(4) returns -1.) This is due
  to an implementation tradeoff.

  \sa capturedTexts() cap()
*/
int QRegExp3::pos( int nth )
{
    if ( nth < 0 || nth >= (int) priv->captured.size() / 2 )
    return -1;
    else
    return priv->captured[2 * nth];
}
#endif

void QRegExp3::compile( bool caseSensitive )
{
    derefEngine( eng, priv->rxpattern );
#ifndef QT_NO_REGEXP_WILDCARD
    if ( priv->wc )
    priv->rxpattern = wc2rx( priv->pattern );
    else
#endif
    priv->rxpattern = priv->pattern.isNull() ? QString::fromLatin1( "" )
              : priv->pattern;
    eng = newEngine( priv->rxpattern, caseSensitive );
#ifndef QT_NO_REGEXP_CAPTURE
    priv->t = QString::null;
    priv->capturedCache.clear();
#endif
    priv->captured.detach();
    priv->captured.fill( -1, 2 + 2 * eng->numCaptures() );
}