Colorer library regular expressions syntax description
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    1. It is.
All  work  of  Colorer  library  is based on using regular expressions
(regexp).  They let you create universal syntax rules of highlighting,
but   regexp  is  an  independent  instrument,  which  could  be  used
in different applications. Here you'll find description of my regexps,
they limitations, secrets and other rocks of their using.
    Here  I'll  assume, that you little know what is regexps - and why
and  how  they used. At first I'll describe regexp's syntax, and after
it  try to help you to understand them. At all you can read some other
documents - perl regexps (man perlre) or something other...
    My   regexps  has  one  main difference  against  the perl  -  all
operators in  my  regexps  are  written  after pattern. It means, that
perl-like regexp
    /foo(?=bar)/
in my variant will be the next:
    /foo(bar)?=/
May  be less looked, but more logical. All standard regexp's operators
are  like  in  perl.  You  can  ask  me: why we need all this extended
operators?  And  I'll answer: try to edit Hrcs an hour-two-three - and
you will understand me.

    2. So, let start:
All regexps must be in slashes /.../
After the end slash could be a parameters:
    i  -  Don't match case.
    x  -  Ignore real spaces (for comfort).

    In  regexp  each  symbol  linearly  compared  with target  string.
Everything,  that  not  it  the  next  symbols range means as a simple
characters.

    2.1. Special metacharacters:
    ^       Match the beginning of line
    $       Match the end of line
    .       Match any character
    [ ]     Match characters in set
    [^ ]    Match characters not in set
            Here all the operators are disabled, but you can
            use other metacharacters,  and  range  operator:
            a-z means all chars from first to second (a - z)
    \#      Next symbol after slash (except a-z and 1-9)
    \b      Start of word
    \B      End of word
    \xNN    NN - ASCII char (hex)
    \n      0x10 (lf)
    \r      0x13 (cr)
    \t      0x09 (tab)
    \s      tab/space
    \S      Non-space
    \w      Word symbol (chars, digits, _)
    \W      Non-word symbol
    \d      Digit
    \D      Non-Digit
    \u      Uppercase symbol
    \l      Lowercase symbol

    2.2. Extended metacharacters:
    \c      Non-word before
    \m      Change start of regexp
    \M      Change end of regexp
    \N      Link inside of regexp to one of its brackets.
            N  - needed brackets pair.  This operator  works
            only with non-operator symbols in a bracket.
    \yN     Link  to  the   external  regexp (in End  to the
            Start param). N - needed brackets pair.

    2.3. Operators.
Here we are. They can't be used without everything. Each operator must
apply to the appropriate character, metacharacter,  or block of  their
combination (brackets).
    ( )     Group and remember characters to form one pattern.
    |       Match previous or next pattern.
    *       Match previous pattern 0 or more times.
    +       Match previous pattern 1 or more times.
    ?       Match previous pattern 0 or 1 times.
    {n}     Repeat n times.
    {n,}    Repeat n or more times.
    {n,m}   Repeat from n to m times.
If  you  add  ?  after operator,  it becomes nongreedy.   For  example
*  operator  becomes nongreedy  after substitution *? Greedy operators
tries  to  take  as  much  in  string,  as  they  can. NonGreedy takes
by minimum.
    2.4. Extended operators.
    ?#N     Look-behind. N - symbols number.
    ?~N     Inverted Look-behind.
    ?=      Look-ahead.
    ?!      Inverted Look-ahead.

    Is it horrible? yes?

    3. And, at the end some examples.
/foobar/
    will match "foobar", "foobar barfoo"
/ FOO bar /ix
    will match "foobar" "FOOBAR" "foobar and two other foos"
/(foo)?bar/
    will match "foobar", "bar"
/^foobar$/
    will match _only_ with "foobar"
/([\d\.])+/
    Any number
/((foo)|(bar))+/
    will match "foofoofoobarfoobar", "bar"