qregexp.cpp

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

    parentheses is more efficient than using capturing parentheses
    since the regexp engine has to do less book-keeping.

    Both capturing and non-capturing parentheses may be nested.

    \target assertions
    \section1 Assertions

    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>\e {E}</b> stands for any expression.

    \table
    \row \i <b>^</b>
	 \i The caret signifies the beginning of the string. If you
	 wish to match a literal \c{^} you must escape it by
	 writing \c{\\^}. For example, <b>^#include</b> will only
	 match strings which \e begin with the characters '#include'.
	 (When the caret is the first character of a character set it
	 has a special meaning, see \link #sets-of-characters Sets of
	 Characters \endlink.)

    \row \i <b>$</b>
	 \i The dollar signifies the end of the string. For example
	 <b>\d\s*$</b> will match strings which end with a digit
	 optionally followed by whitespace. If you wish to match a
	 literal \c{$} you must escape it by writing
	 \c{\\$}.

    \row \i <b>\\b</b>
	 \i A word boundary. For example the regexp
	 <b>\\bOK\\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>(\\bOK\\b)</b> and we have a match it will only
	 contain 'OK' even if the string is "Its <u>OK</u> now".

    \row \i <b>\\B</b>
	 \i A non-word boundary. This assertion is true wherever
	 <b>\\b</b> is false. For example if we searched for
	 <b>\\Bon\\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".

    \row \i <b>(?=\e E)</b>
	 \i Positive lookahead. This assertion is true if the
	 expression matches at this point in the regexp. For example,
	 <b>const(?=\\s+char)</b> matches 'const' whenever it is
	 followed by 'char', as in 'static <u>const</u> char *'.
	 (Compare with <b>const\\s+char</b>, which matches 'static
	 <u>const char</u> *'.)

    \row \i <b>(?!\e E)</b>
	 \i Negative lookahead. This assertion is true if the
	 expression does not match at this point in the regexp. For
	 example, <b>const(?!\\s+char)</b> matches 'const' \e except
	 when it is followed by 'char'.
    \endtable

    \target wildcard-matching
    \section1 Wildcard Matching (globbing)

    Most command shells such as \e bash or \e cmd.exe support "file
    globbing", the ability to identify a group of files by using
    wildcards. The setWildcard() function is used to switch between
    regexp and wildcard mode. Wildcard matching is much simpler than
    full regexps and has only four features:

    \table
    \row \i <b>c</b>
	 \i Any character represents itself apart from those mentioned
	 below. Thus <b>c</b> matches the character \e c.
    \row \i <b>?</b>
	 \i This matches any single character. It is the same as
	 <b>.</b> in full regexps.
    \row \i <b>*</b>
	 \i This matches zero or more of any characters. It is the
	 same as <b>.*</b> in full regexps.
    \row \i <b>[...]</b>
	 \i Sets of characters can be represented in square brackets,
	 similar to full regexps. Within the character class, like
	 outside, backslash has no special meaning.
    \endtable

    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'.

    \target perl-users
    \section1 Notes for Perl Users

    Most of the character class abbreviations supported by Perl are
    supported by QRegExp, see \link
    #characters-and-abbreviations-for-sets-of-characters characters
    and abbreviations for sets of characters \endlink.

    In QRegExp, apart from within character classes, \c{^} always
    signifies the start of the string, so carets must always be
    escaped unless used for that purpose. In Perl the meaning of caret
    varies automagically depending on where it occurs so escaping it
    is rarely necessary. The same applies to \c{$} which in
    QRegExp always signifies the end of the string.

    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 regexp <b>ro+?m</b> requires:
    \code
    QRegExp rx( "ro+m" );
    rx.setMinimal( TRUE );
    \endcode

    The equivalent of Perl's \c{/i} option is
    setCaseSensitive(FALSE).

    Perl's \c{/g} option can be emulated using a \link
    #cap_in_a_loop loop \endlink.

    In QRegExp <b>.</b> matches any character, therefore all QRegExp
    regexps have the equivalent of Perl's \c{/s} option. QRegExp
    does not have an equivalent to Perl's \c{/m} 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 $+. Perl's capturing variables, $1, $2,
    ... correspond to cap(1) or capturedTexts()[1], cap(2) or
    capturedTexts()[2], etc.

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

    Perl's extended \c{/x} syntax is not supported, nor are
    directives, e.g. (?i), or regexp comments, e.g. (?#comment). On
    the other hand, C++'s rules for literal strings can be used to
    achieve the same:
    \code
    QRegExp mark( "\\b" // word boundary
		  "[Mm]ark" // the word we want to match
		);
    \endcode

    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 parentheses 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> must be written <b>\\\\b</b>.

    \target code-examples
    \section1 Code Examples

    \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 without 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
    \endcode

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

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

    This will capture the text from the first set of capturing
    parentheses (counting capturing left parentheses from left to
    right). The parentheses 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 \c pos++ we could have written \c {pos +=
    rx.matchedLength()} 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 imitate the matching of a shell we can use wildcard mode.

    \code
    QRegExp rx( "*.html" );         // invalid regexp: * doesn't quantify anything
    rx.setWildcard( TRUE );         // now it's a valid wildcard regexp
    rx.exactMatch( "index.html" );  // returns TRUE
    rx.exactMatch( "default.htm" ); // returns FALSE
    rx.exactMatch( "readme.txt" );  // returns FALSE
    \endcode

    Wildcard matching can be convenient because of its simplicity, but
    any wildcard regexp 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

    \target member-function-documentation
*/

const int NumBadChars = 64;
#define BadChar( ch ) ( (ch).unicode() % NumBadChars )

const int NoOccurrence = INT_MAX;
const int EmptyCapture = INT_MAX;
const int InftyLen = INT_MAX;
const int InftyRep = 1025;
const int EOS = -1;

static bool isWord( QChar ch )
{
    return ch.isLetterOrNumber() || ch == QChar( '_' );
}

/*
  Merges two QMemArrays of ints and puts the result into the first
  one.
*/
static void mergeInto( QMemArray<int> *a, const QMemArray<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;
	QMemArray<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_str )
{
    int wclen = wc_str.length();
    QString rx = QString::fromLatin1( "" );
    int i = 0;
    const QChar *wc = wc_str.unicode();
    while ( i < wclen ) {
	QChar c = wc[i++];
	switch ( c.unicode() ) {
	case '*':
	    rx += QString::fromLatin1( ".*" );
	    break;
	case '?':
	    rx += QChar( '.' );
	    break;
	case '$':
	case '(':
	case ')':