slackbuilds/libraries/gtksourceview5

GtkSourceView is a GNOME library that extends GtkTextView, the
standard GTK+ widget for multiline text editing. GtkSourceView adds
support for syntax highlighting, undo/redo, file loading and saving,
search and replace, a completion system, printing, displaying line
numbers, and other features typical of a source code editor.

Features:
  * Accurate syntax highlighting for most popular programming languages
    (C, C++, Java, C#, Fortran, etc.), scripting languages (sh, Python,
    Perl, Ruby, PHP, TCL, etc.), markup languages (XML, HTML, DocBook,
    LaTeX, etc.) and many others
  * Customizable visual style using style schemes
  * Unlimited Undo/Redo
  * File loading and saving
  * Extensible completion framework
  * Search and replace, with regex support
  * Line numbers
  * Line marks (useful for bookmarks, breakpoints, etc.)
  * Printing through easy integration with the GtkPrintOperation API
  * Highlight the current line
  * Highlight the matching bracket
  * Right margin
  * Represent whitespace characters with symbols
  * A minimap, which shows an overview of the text
  * Extended keyboard navigation (smart Home/End, smart backspace,
    auto indentation, line moving, etc.)
  * Can be used from many programming languages. Thanks to GObject
    Introspection, automatic bindings are available for JavaScript,
    Python, Vala and others. For C++, there is gtksourceviewmm

If you would like to build the HTML documentation, pass DOCS=true
to the build script. This introduces dependencies on gi-docgen and
python-toml.