textX 4.0.1

Description:

textX 4.0.1

textX is a meta-language for building Domain-Specific Languages (DSLs) in
Python. It is inspired by Xtext.
In a nutshell, textX will help you build your textual language in an easy way.
You can invent your own language or build a support for already existing textual
language or file format.
From a single language description (grammar), textX will build a parser and a
meta-model (a.k.a. abstract syntax) for the language. See the docs for the
details.
textX follows the syntax and semantics of Xtext but differs in some
places and is
implemented 100% in Python using Arpeggio PEG parser - no grammar ambiguities,
unlimited lookahead, interpreter style of work.
Quick intro
Here is a complete example that shows the definition of a simple DSL for
drawing. We also show how to define a custom class, interpret models and search
for instances of a particular type.
from textx import metamodel_from_str, get_children_of_type

grammar = """
Model: commands*=DrawCommand;
DrawCommand: MoveCommand | ShapeCommand;
ShapeCommand: LineTo | Circle;
MoveCommand: MoveTo | MoveBy;
MoveTo: 'move' 'to' position=Point;
MoveBy: 'move' 'by' vector=Point;
Circle: 'circle' radius=INT;
LineTo: 'line' 'to' point=Point;
Point: x=INT ',' y=INT;
"""

# We will provide our class for Point.
# Classes for other rules will be dynamically generated.
class Point:
def __init__(self, parent, x, y):
self.parent = parent
self.x = x
self.y = y

def __str__(self):
return "{},{}".format(self.x, self.y)

def __add__(self, other):
return Point(self.parent, self.x + other.x, self.y + other.y)

# Create meta-model from the grammar. Provide `Point` class to be used for
# the rule `Point` from the grammar.
mm = metamodel_from_str(grammar, classes=[Point])

model_str = """
move to 5, 10
line to 10, 10
line to 20, 20
move by 5, -7
circle 10
line to 10, 10
"""

# Meta-model knows how to parse and instantiate models.
model = mm.model_from_str(model_str)

# At this point model is a plain Python object graph with instances of
# dynamically created classes and attributes following the grammar.

def cname(o):
return o.__class__.__name__

# Let's interpret the model
position = Point(None, 0, 0)
for command in model.commands:
if cname(command) == 'MoveTo':
print('Moving to position', command.position)
position = command.position
elif cname(command) == 'MoveBy':
position = position + command.vector
print('Moving by', command.vector, 'to a new position', position)
elif cname(command) == 'Circle':
print('Drawing circle at', position, 'with radius', command.radius)
else:
print('Drawing line from', position, 'to', command.point)
position = command.point
print('End position is', position)

# Output:
# Moving to position 5,10
# Drawing line from 5,10 to 10,10
# Drawing line from 10,10 to 20,20
# Moving by 5,-7 to a new position 25,13
# Drawing circle at 25,13 with radius 10
# Drawing line from 25,13 to 10,10

# Collect all points starting from the root of the model
points = get_children_of_type("Point", model)
for point in points:
print('Point: {}'.format(point))

# Output:
# Point: 5,10
# Point: 10,10
# Point: 20,20
# Point: 5,-7
# Point: 10,10

Video tutorials
Introduction to textX

Implementing Martin Fowler's State Machine DSL in textX

Docs and tutorials
The full documentation with tutorials is available at
http://textx.github.io/textX/stable/
Support in IDE/editors
Projects that are currently in progress are:

textX-LS - support for Language Server
Protocol and VS Code for any textX based language. This project is about to
supersede the following projects:

textX-languageserver -
Language Server Protocol support for textX languages
textX-extensions - syntax
highlighting, code outline


viewX - creating visualizers
for textX languages

If you are a vim editor user check
out support for vim.
For emacs there is textx-mode which is
also available in MELPA.
You can also check
out textX-ninja project. It is
currently unmaintained.
Discussion and help
For general questions, suggestions, and feature requests please use GitHub
Discussions.
For issues please use GitHub issue
tracker.
Citing textX
If you are using textX in your research project we would be very grateful if you
cite our paper:
Dejanović I., Vaderna R., Milosavljević G., Vuković Ž. (2017). TextX: A Python
tool for Domain-Specific Languages
implementation.
Knowledge-Based Systems, 115, 1-4.
License
MIT
Python versions
Tested for 3.8+