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Description:

reparsec 0.4.3

reparsec
Small parsec-like parser combinators library with semi-automatic error recovery.
Installation
pip install reparsec

Usage

Tutorial
Documentation

Example
With reparsec, simple arithmetic expression parser and evaluator could be written like this:
from typing import Callable

from reparsec import Delay
from reparsec.scannerless import literal, parse, regexp
from reparsec.sequence import eof

def op_action(op: str) -> Callable[[int, int], int]:
return {
"+": lambda a, b: a + b,
"-": lambda a, b: a - b,
"*": lambda a, b: a * b,
}[op]

spaces = regexp(r"\s*")
number = regexp(r"\d+").fmap(int) << spaces
mul_op = regexp(r"[*]").fmap(op_action) << spaces
add_op = regexp(r"[-+]").fmap(op_action) << spaces
l_paren = literal("(") << spaces
r_paren = literal(")") << spaces

expr = Delay[str, int]()
expr.define(
(
number |
expr.between(l_paren, r_paren)
)
.chainl1(mul_op)
.chainl1(add_op)
)

parser = expr << eof()

This parser can:

evaluate an expression:
>>> parser.parse("1 + 2 * (3 + 4)").unwrap()
15

report first syntax error:
>>> parser.parse("1 + 2 * * (3 + 4 5)").unwrap()
Traceback (most recent call last):
...
reparsec.types.ParseError: at 8: expected '('

attempt to recover and report multiple syntax errors:
>>> parser.parse("1 + 2 * * (3 + 4 5)", recover=True).unwrap()
Traceback (most recent call last):
...
reparsec.types.ParseError: at 8: expected '(' (skipped 2 tokens), at 17: expected ')' (skipped 1 token)

automatically repair input and return some result:
>>> parser.parse("1 + 2 * * (3 + 4 5)", recover=True).unwrap(recover=True)
15

track line and column numbers:
>>> parse(parser, """1 +
... 2 * * (
... 3 + 4 5)""", recover=True).unwrap()
Traceback (most recent call last):
...
reparsec.types.ParseError: at 2:5: expected '(' (skipped 2 tokens), at 3:7: expected ')' (skipped 1 token)

More examples:

JSON parser
Scannerless JSON parser