Quick Start

Installing

The EBNFParser only supports Python 3.6+ now.

You can install it by using PyPI.

pip install -U EBNFParser

Hello World

We can try to parse Lisp grammar syntax into AST(Abstract Synatx Tree) as our first attempt.

(define add3 (x y z)
          (add x
              (add y z)))

Here is a source code example:

• lisp.ruiko

ignore [space]  # ignore the tokens with this(these) name(s).

space   := R'\s';

Atom    := R'[^\(\)\s\`]+'; # use Regex

Expr    ::= Atom
        | Quote
        | '(' Expr* ')';


Quote   ::=  '`' Expr ;

Stmts   ::= Expr*;

And then use it to generate a parser and make a test script automatically by EBNFParser.

Finally, test it.

ruiko lisp.ruiko lisp_parser.py --test
python test_lang.py Stmts "(definie f (x y z) (add (add x y) z))"
 =========================ebnfparser test script================================
Stmts[
    Expr[
        [name: auto_const, string: "("]
        Expr[
            [name: Atom, string: "definie"]
...(omit)

Integrate EBNFParser Into Your Own Project

For example, if we have generated the lisp parser file like the above as a module MyProject.Lisp.parser .

from Ruikowa.ObjectRegex.ASTDef import Ast
from Ruikowa.ErrorHandler import ErrorHandler
from Ruikowa.ObjectRegex.MetaInfo import MetaInfo
from Ruikowa.ObjectRegex.Tokenizer import Tokenizer

from lisp_parser import Stmts, token_table

import typing as t

def token_func(src_code: str) -> t.Iterable[Tokenizer]:
    return Tokenizer.from_raw_strings(
        src_code, token_table, ({"space"}, {}))

parser = ErrorHandler(Stmts.match, token_func)

def parse(filename: str) -> Ast:

    return parser.from_file(filename)

# just create a file `test.lisp` and write some lisp codes.
print(parse("./test.lisp"))

An Ruikowa.ObjectRegex.Ast is a nested list of Tokenizers, for instance:

AstName[
    AstName[
        Tokenizer1
        Tokenizer2
        AstName[
            ...
        ]
    ]
    Tokenizer3
]

You can use obj.name to get the name of an instance of Ast or Tokenizer.