asuivelentine / textx

Domain-Specific Languages and parsers in Python made easy http://textx.github.io/textX/

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.center), shape.radius))
    else:
        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 http://textx.github.io/textX/stable/

Support in IDE/editors

• textX-languageserver -Language Server Protocol support for any textX based language
• textX-extensions - syntax highlighting, code outline for Visual Studio Code
• textx.vim -Highlighting and outline of textX grammars
• textx-mode -Emacs mode for textX grammars

Discussion and help

For general questions and help please use StackOverflow. Just make sure to tag your question with the textx tag.

For issues, suggestions and feature request please use GitHub issue tracker.

License

MIT

Python versions

Tested for 2.7, 3.4+