NAME
Tk::TextHighlight - a TextUndo/SuperText widget with syntax highlighting
capabilities, can also use Kate languages.
Tk::ROTextHighlight - a Read-only version of this widget.
SYNOPSIS
use Tk;
my $haveKateInstalled = 0;
eval "use Syntax::Highlight::Engine::Kate; \$haveKateInstalled = 1; 1";
require Tk::TextHighlight;
my $m = new MainWindow;
my $e = $m->Scrolled("TextHighlight",
-syntax => "Perl",
-scrollbars => "se",
)->pack(-expand => 1, -fill => "both");
if ($haveKateInstalled) {
my ($sections, $kateExtensions) = $e->fetchKateInfo;
$e->addKate2ViewMenu($sections);
}
$m->configure(-menu => $e->menu);
$m->MainLoop;
DESCRIPTION
Tk::TextHighlight inherits Tk::TextUndo and all its options and methods.
Besides syntax highlighting, methods are provided for commenting and
uncommenting as well as indenting and unindenting a selected area,
matching pairs of braces, brackets and brackets and curlies and
automatic indenting of new lines. The included companion module
Tk::ROTextHighlight provides all the same functionality in a "readonly"
widget for text viewers, etc. Tk::TextHighlight also supports
highlighting of all the lauguages of the
Syntax::Highlight::Engine::Kate, if that module is installed.
If you want your widget to be read-only, then require
Tk::ROTextHighlight, which is based on Tk::ROText instead of
Tk::TextUndo.
Syntax highlighting is done through a plugin approach. Adding languages
is a matter of writing plugin modules. Theoretically this is not limited
to programming languages. The plugin approach could also provide the
possibility for grammar or spell checking in spoken languages.
Currently there is support for Bash, HTML, Perl, Pod, Kate, and
Xresources.
OPTIONS
Name: autoindent
Class: Autoindent
Switch: -autoindent
Boolean, when you press the enter button, should the next line begin
at the same position as the current line or not. By default false.
Name: commentchar
Class: Commentchar
Switch: -commentchar
By default "#".
Name: disablemenu
Class: Disablemenu
Switch: -disablemenu
Boolean, by default 0. In case you don't want the menu under the
right mouse button to pop up.
Name: highlightInBackground
Class: highlightInBackground
Switch: -highlightInBackground
Whether or not to do highlighting in background freeing up the mouse
and keyboard for most events (experimental). May be 1 or 0. Default
0 (Do not highlight in background - block input until highlighting
completed).
Name: indentchar
Class: Indentchar
Switch: -indentchar
String to be inserted when the [Tab] key is pressed or when
indenting. Default "\t".
Name: match
Class: Match
Switch: -match
string of pairs for brace/bracket/curlie etc matching. If this
description doesn't make anything clear, don't worry, the default
setting will:
'[]{}()'
if you don't want matching to be available, simply set it to ''.
Name: matchoptions
Class: Matchoptions
Switch: -matchoptions
Options list for the tag 'Match'. By default:
[-background => 'red', -foreground => 'yellow']
You can also specify this option as a space separated string. Might
come in handy for your Xresource files.
"-background red -foreground yellow"
Name: not available
Class: not available
Switch -rules
Specify the color and font options for highlighting. You specify a
list looking a bit like this.
[
['Tagname1', @options1],
['Tagname2', @options2],
]
The names of the tags are depending on the syntax that is
highlighted. See the language modules for more information about
this data structure.
Name: rulesdir
Class: Rulesdir
Switch -rulesdir
Specify the directory where this widget stores its coloring
defenitions. Files in this directory are stored as "HTML.rules",
"Perl.rules" etc. By default it is set to '', which means that when
you switch syntax the highlighting rules are not loaded or stored.
The hard coded defaults in the language modules will be used.
Name: syntax
Class: Syntax
Switch: -syntax
Specifies the language for highlighting. At this moment the possible
values are None, HTML, Perl, Pod Kate:Language, and Xresources.
Default: None
If Syntax::Highlight::Engine::Kate is installed, you may specify any
language that the Kate syntax highlight engine supports.
Alternatively it is possible to specify a reference to your
independent plugin.
Name: Not available
Class: Not available
Switch: -updatecall
Here you can specify a callback that will be executed whenever the
insert cursor has moved or text has been modified, so your
application can keep track of position etc. Don't make this callback
to heavy, the widget will get sluggish quickly.
Name: Not available
Class: Not available
Switch: -noPlugInit
Disables TextHighlight feature of initializing default rules when no
.rules file present.
Name: Not available
Class: Not available
Switch: -noSyntaxMenu
Don't show the Syntax submenu option in the View submenu of the
right-click menu.
Name: Not available
Class: Not available
Switch: -noSaveRulesMenu
Don't show the Save Rules submenu option in the View submenu of the
right-click menu.
Name: Not available
Class: Not available
Switch: -noRulesEditMenu
Don't show the Rules Editor option in the View submenu of the
right-click menu.
Name: Not available
Class: Not available
Switch: -noRulesMenu
Don't show any of the TextHighlight menu items (combines
-noSyntaxMenu, -noRulesEditMenu, and -noSaveRulesMenu options.
There are some undocumented options. They are used internally. It is
propably best to leave them alone.
METHODS
doAutoIndent
Checks the indention of the previous line and indents the line where
the cursor is equally deep.
highlight(*$begin*, *$end*);
Does syntax highlighting on the section of text indicated by $begin
and $end. $begin and $end are linenumbers not indexes!
highlightCheck>(*$begin*, *$end*);
An insert or delete has taken place affecting the section of text
between $begin and $end. highlightCheck is being called after and
insert or delete operation. $begin and $end (again, linenumbers, not
indexes) indicate the section of text affected. highlightCheck
checks what needs to be highlighted again and does the highlighting.
highlightLine(*$line*);
Does syntax highlighting on linenumber $line.
highlightPlug
Checks wether the appropriate highlight plugin has been loaded. If
none or the wrong one is loaded, it loads the correct plugin. It
returns a reference to the plugin loaded. It also checks wether the
rules have changed. If so, it restarts highlighting from the
beginning of the text.
highlightPlugInit
Loads and initalizes a highlighting plugin. First it checks the
value of the -syntax option to see which plugin should be loaded.
Then it checks wether a set of rules is defined to this plugin in
the -rules option. If not, it tries to obtain a set of rules from
disk using rulesFetch. If this fails as well it will use the
hardcoded rules from the syntax plugin.
highlightPurge(*$line*);
Tells the widget that the text from linenumber $line to the end of
the text is not to be considered highlighted any more.
highlightVisual
Calls visualEnd to see what part of the text is visible on the
display, and adjusts highlighting accordingly.
linenumber(*$index*);
Returns the linenumber part of an index. You may also specify
indexes like 'end' or 'insert' etc.
matchCheck
Checks wether the character that is just before the 'insert'-mark
should be matched, and if so, should it match forwards or backwards.
It then calls matchFind.
matchFind(*$direction*, *$char*, *$match*, *$start*, *$stop*);
Matches $char to $match, skipping nested $char/$match pairs, and
displays the match found (if any).
rulesEdit
Pops up a window that enables the user to set the color and font
options for the current syntax.
rulesFetch
Checks wether the file
$text->cget('-rulesdir') . '/' . $text->cget('-syntax') . '.rules'
exists, and if so attempts to load this as a set of rules.
rulesSave
Saves the currently loaded rules as
$text->cget('-rulesdir') . '/' . $text->cget('-syntax') . '.rules'
selectionComment
Comment currently selected text.
selectionIndent
Indent currently selected text.
selectionModify
Used by the other selection... methods to do the actual work.
selectionUnComment
Uncomment currently selected text.
selectionUnIndent
Unindent currently selected text.
setRule(rulename,colorattribute,color)
Allows altering of individual rules by the programmer.
fetchKateInfo
Fetches 3 hashrefs containing information about the installed Kate
highlight engine (if installed). The three hashrefs contain in
order: The first can be passed to the addkate2viewmenu() method to
add the Kate languages to the Syntax.View menu. the keys are
"Kate::language" and the values are what's needed to instantiate
Kate for that language. the 2nd is a list of file- extension pattern
suitable for matching against file-names and the values are the
reccomended Kate language for that file-extension. It will return
(undef, undef, undef) if Kate is not installed.
addKate2ViewMenu($sections)
Inserts the list of Kate-supported languages to the widget's
Syntax.View right-mousebutton popup menu along with the basic
TextHight-supported choices. These choices can then be selected to
change the current language-highlighting used in the text in the
widget. $sections is a hash-ref normally returned as the 1st item in
the list returned by fetchKateInfo. NOTE: No menu items will be
added if Kate is not installed or if -noRulesMenu or -noSyntaxMenu
is set!
SYNTAX HIGHLIGHTING
This section is a brief description of how the syntax highlighting
process works.
Initiating plugin
The highlighting plugin is only then initiated when it is needed. When
some highlighting needs to be done, the widget calls highlightPlug to
retrieve a reference to the plugin.
highlightPlug checks wether a plugin is present. Next it will check
whether the -rules option has been specified or wether the -rules option
has changed. If no rules are specified in -rules, it will look for a
pathname in the -rulesdir option. If that is found it will try to load a
file called '*.rules', where * is the value of -syntax.
If no plugin is present, or the -syntax option has changed value,
highlightPlug loads the plugin. and constructs optionally giving it a
reference to the found rules as parameter. if no rules are specified,
the plugin will use its internal hardcoded defaults.
Changing the rules
A set of rules is a list, containing lists of tagnames, followed by
options. If you want to see what they look like, you can have a look at
the constructors of each plugin module. Every plugin has a fixed set of
tagnames it can handle.
There are two ways to change the rules.
You can invoke the rulesEdit method, which is also available through the
View menu. The result is a popup in which you can specify color and font
options for each tagname. After pressing 'Ok', the edited rules will be
applied. If -rulesdir is specified, the rules will be saved on disk as
*rulesdir/syntax.rules*.
You can also use configure to specify a new set of rules. In this you
have ofcause more freedom to use all available tag options. For more
details about those there is a nice section about tag options in the
Tk::Text documentation. After the call to configure it is wise to call
highlightPlug.
Highlighting text
Syntax highlighting is done in a lazy manor. Only that piece of text is
highlighted that is needed to present the user a pretty picture. This is
done to minimize use of system resources. Highlighting is running on the
foreground. Jumping directly to the end of a long fresh loaded textfile
may very well take a couple of seconds.
Highlighting is done on a line to line basis. At the end of each line
the highlighting status is saved in the list in -colorinf, so when
highlighting the next line, the highlight method of TextHighlight will
know how to begin.
The line that needs highlighting is offered to the highlight method of
the plugin. This method returns a list of offset and tagname pairs. Take
for example the following line of perl code.
my $mother = 'older than i am';
The highlight method of the Perl plugin will return the following list;
(2 => 'Reserved', #'my' is a reserved word
1 => 'DEFAULT', #Space
7 => 'Variable', #$mother
1 => 'DEFAULT', #Space
1 => 'Operator', #'='
1 => 'DEFAULT', #Space
17 => 'String', #'older than i am'
1 => 'DEFAULT',) #;
The highlight method of TextHighlight will then mark positions 0 to 2 as
'Reserved', positions 2 to 3 as 'DEFAULT', positions 3 to 10 as
'Variable', etc.
WRITING PLUGINS
After writing a couple of plugins myself i have come to a couple of
guidelines about how to set them up. If you are interested in adding
support for your own syntax highlighting problem or language this
section is of interest to you.
From scratch
If you choose to build a plugin completely from scratch, your module
needs to meet the following requirements.
- If you want to write a formal addition to Tk::TextHighlight,
your plugin must be in the namespace
Tk::TextHighlight::YourSyntax.
- The constructor is called 'new', and it should accept
a reference a reference to a list of rules as parameters.
- The following methods will be called upon by Tk::TextHighlight:
highlight, stateCompare, rules, setSate, getState, syntax.
More information about those methods is available in the documentation
of Tk::TextHighlight::None and Tk::TextHighlight::Template.
Inheriting Tk::TextHighlight::Template
For many highlighting problems Tk::TextHighlight::Template provides a
nice basis to start from. Your code could look like this:
package Tk::TextHighlight::MySyntax;
use strict;
use base('Tk::TextHighlight::Template');
sub new {
my ($proto, $wdg, $rules) = @_;
my $class = ref($proto) || $proto;
Next, specify the set of hardcoded rules.
if (not defined($rules)) {
$rules = [
['Tagname1', -foreground => 'red'],
['Tagname1', -foreground => 'red'],
];
};
Call the constructor of Tk::TextHighlight::Template and bless your
object.
my $self = $class->SUPER::new($rules);
So now we have the SUPER class avalable and we can start defining a
couple of things.
You could add a couple of lists, usefull for keywords etc.
$self->lists({
'Keywords' => ['foo', 'bar'],
'Operators' => ['and', 'or'],
});
For every tag you have to define a corresponding callback like this.
$self->callbacks({
'Tagname1' => \&Callback1,
'Tagname2' => \&Callback2,
});
You have to define a default tagname like this:
$self->stackPush('Tagname1');
Perhaps do a couple of other things but in the end, wrap up the new
method.
bless ($self, $class);
return $self;
}
Then you need define the callbacks that are mentioned in the callbacks
hash. When you just start writing your plugin i suggest you make them
look like this:
sub callback1 {
my ($self $txt) = @_;
return $self->parserError($txt); #for debugging your later additions
}
Later you add matching statements inside these callback methods. For
instance, if you want *callback1* to parse spaces it is going to look
like this:
sub callback1 {
my ($self $txt) = @_;
if ($text =~ s/^(\s+)//) { #spaces
$self->snippetParse($1, 'Tagname1'); #the tagname here is optional
return $text;
}
return $self->parserError($txt); #for debugging your later additions
}
If *callback1* is the callback that is called by default, you have to
add the mechanism for checking lists to it. Hnce, the code will look
like this:
sub callback1 {
my ($self $txt) = @_;
if ($text =~ s/^(\s+)//) { #spaces
$self->snippetParse($1, 'Tagname1'); #the tagname here is optional
return $text;
}
if ($text =~ s/^([^$separators]+)//) { #fetching a bare part
if ($self->tokenTest($1, 'Reserved')) {
$self->snippetParse($1, 'Reserved');
} elsif ($self->tokenTest($1, 'Keyword')) {
$self->snippetParse($1, 'Keyword');
} else { #unrecognized text
$self->snippetParse($1);
}
return $text
}
return $self->parserError($txt); #for debugging your later additions
}
Have a look at the code of Tk::TextHighlight::Bash. Things should clear
up. Then, last but not least, you need a syntax method.
Using another module as basis
An example of this approach is the Perl syntax module.
Also with this approach you will have to meet the minimum criteria as
set out in the From scratch section.
CONTRIBUTIONS
If you have written a plugin, i will be happy to include it in the next
release of Tk::TextHighlight. If you send it to me, please have it
accompanied with the sample of code that you used for testing.
AUTHOR
This module is Copyright (C) 2007-2024 by
Jim Turner, "<turnerjw784 at yahoo.com>"
All rights reserved.
You may distribute this module under the terms of either the GNU General
Public License or the Artistic License, as specified in the Perl README
file.
This is a derived work from Tk::CodeText, by Hans Jeuken (haje at
toneel.demon.nl)
Thanks go to Mr. Hans Jeuken for his great work in making this and the
Kate modules possible. He did the hard work!
LICENSE AND COPYRIGHT
Copyright 2007-2024 Jim Turner.
This program is free software; you can redistribute it and/or modify it
under the terms of the the Artistic License (2.0). You may obtain a copy
of the full license at:
<http://www.perlfoundation.org/artistic_license_2_0>
Any use, modification, and distribution of the Standard or Modified
Versions is governed by this Artistic License. By using, modifying or
distributing the Package, you accept this license. Do not use, modify,
or distribute the Package, if you do not accept this license.
If your Modified Version has been derived from a Modified Version made
by someone other than you, you are nevertheless required to ensure that
your Modified Version complies with the requirements of this license.
This license does not grant you the right to use any trademark, service
mark, tradename, or logo of the Copyright Holder.
This license includes the non-exclusive, worldwide, free-of-charge
patent license to make, have made, use, offer to sell, sell, import and
otherwise transfer the Package with respect to any patent claims
licensable by the Copyright Holder that are necessarily infringed by the
Package. If you institute patent litigation (including a cross-claim or
counterclaim) against any party alleging that the Package constitutes
direct or contributory patent infringement, then this Artistic License
to you shall terminate on the date that such litigation is filed.
Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT HOLDER
AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES.
THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE EXTENT PERMITTED BY
YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO COPYRIGHT HOLDER OR
CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT OF THE USE OF THE PACKAGE,
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
BUGS
Unknown. If you find any, please contact the author.
TODO
Add additional language modules. I am going to need help on this one. We
currently support all the original Tk::CodeText languages (included)
plus all those supported by Syntax::Highlight::Engine::Kate, if it's
installed.
The sample files in the test suite should be set up so that conformity
with the language specification can actually be verified.
SEE ALSO
Tk::Text, Tk::TextUndo, Tk::Text::SuperText, Tk::TextHighlight::Bash,
Tk::CodeText, Syntax::Highlight::Perl::Improved,
Syntax::Highlight::Engine::Kate