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Meta-language for DSL implementation inspired by Xtext

Project description

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.metamodel import metamodel_from_str
from textx.model import 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 = 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



Python versions

Tested for 2.7, 3.3+

Project details

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