LEXX is a
text editor
A text editor is a type of computer program that edits plain text. Such programs are sometimes known as "notepad" software (e.g. Windows Notepad). Text editors are provided with operating systems and software development packages, and can be u ...
which was possibly the first to use ''live parsing'' and colour
syntax highlighting
Syntax highlighting is a feature of text editors that are used for programming, scripting, or markup languages, such as HTML. The feature displays text, especially source code, in different colours and fonts according to the category of terms. ...
. It was written by
Mike Cowlishaw of IBM in 1985. The name was chosen because he wrote it as a tool for lexicographers, during an assignment for Oxford University Press's 'New Oxford English Dictionary' (NOED; the second edition of the
Oxford English Dictionary
The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
).
The program ran (and still, in 2018, runs) on mainframes under
VM/CMS.
LEXX's design was based on several other editors written by the same author (such as
STET) augmented by the ability to dynamically parse text and display colour on the new colour terminals that had recently become available (PC-based, and stand-alone such as the
IBM 3279). It was programmable using dynamically-loaded compiled commands (usually written in
PL/I
PL/I (Programming Language One, pronounced and sometimes written PL/1) is a procedural, imperative computer programming language developed and published by IBM. It is designed for scientific, engineering, business and system programming. It ...
) or using interpreted commands (usually written in
REXX
Rexx (Restructured Extended Executor) is a programming language that can be interpreted or compiled. It was developed at IBM by Mike Cowlishaw. It is a structured, high-level programming language designed for ease of learning and reading. ...
-- hence the 'XX' in 'LEXX').
LEXX uses dynamically-loaded parsers which assign classes of elements (tokens formed from character strings) to fonts and colors.
It allows indentation to be used to format and show the structure of the file being edited, and other formatting options allow (for example) the hiding of selected classes of text, such as tags. A collection of screenshots is available.
LPEX ('Live Parsing Editor"
) is a reim