Domain-Specific Languages and parsers in Python made easy
Python Other
Clone or download


PyPI Version license build-status Documentation Status

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

from textx import metamodel_from_str, get_children_of_type

grammar = """
Model: shapes*=Shape;
Shape: Circle | Line;
Circle: 'circle' center=Point '/' radius=INT;
Line: 'line' start=Point '/' end=Point;
Point: x=INT ',' y=INT;

mm = metamodel_from_str(grammar)

# Meta-model knows how to parse and instantiate models.
model = mm.model_from_str("""
    line 10, 10 / 20, 20
    line 14, 78 / 89, 33
    circle 14, 20/10
    line 18, 89 / 78, 65

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

def _(p):
    "returns coordinate of the given Point as string"
    return "{},{}".format(p.x, p.y)

for shape in model.shapes:
    if shape.__class__.__name__ == 'Circle':
        print('Circle: center={}, radius={}'
              .format(_(, shape.radius))
        print('Line: from={} to={}'.format(_(shape.start), _(shape.end)))

# Output:
# Line: from=10,10 to=20,20
# Line: from=14,78 to=89,33
# Circle: center=14,20, radius=10
# Line: from=18,89 to=78,65

# 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: 10,10
# Point: 20,20
# Point: 14,78
# Point: 89,33
# Point: 14,20
# Point: 18,89
# Point: 78,65

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

Discussion and help

For bug report, general discussion and help please use GitHub issue tracker.



Python versions

Tested for 2.7, 3.3+