gistfile1.py

from ometa.grammar import OMeta
from ometa.interp import TrampolinedGrammarInterpreter
from parsley import makeGrammar

import sys


grammar = """
hex_digit = digit | 'A' | 'B' | 'C' | 'D' | 'E' | 'F'

byte = <hex_digit hex_digit>:b -> int(b, 16)
"""

hex = makeGrammar(grammar, {}, name='hex', unwrap=True)


def iter_grammar(grammar, rule, input_stream, name='Grammar', buffer_size=1):
    tokens = []  # Should really be an explicit queue.
    interp = None
    while True:
        data = input_stream.read(buffer_size)
        if not data:
            break
        if interp is None or interp.ended:
            interp = TrampolinedGrammarInterpreter(
                OMeta(grammar).parseGrammar(name), rule, callback=lambda *a: tokens.append(a))
        interp.receive(data)
        for token in tokens:
            yield token
        tokens[:] = []
    interp.end()


for token in iter_grammar(grammar, 'byte', sys.stdin):
    print token

gistfile2.txt

A0B0FFCD010283

gistfile3.txt

$ python streaming.py  < eg.data 
(160, ParseError(2, None))
(176, ParseError(2, None))
(255, ParseError(2, None))
(205, ParseError(2, None))
(1, ParseError(2, None))
(2, ParseError(2, None))
(131, ParseError(2, None))
Traceback (most recent call last):
  File "gistfile1.py", line 34, in <module>
    for token in iter_grammar(grammar, 'byte', sys.stdin):
  File "gistfile1.py", line 27, in iter_grammar
    interp.receive(data)
  File "/usr/local/lib/python2.7/site-packages/ometa/interp.py", line 48, in receive
    for x in self.next:
  File "/usr/local/lib/python2.7/site-packages/ometa/interp.py", line 166, in apply
    for x in self._apply(f, ruleName, argvals):
  File "/usr/local/lib/python2.7/site-packages/ometa/interp.py", line 104, in _apply
    for x in rule():
  File "/usr/local/lib/python2.7/site-packages/ometa/interp.py", line 255, in parse_Or
    raise self.err(joinErrors(errors))
  File "/usr/local/lib/python2.7/site-packages/ometa/interp.py", line 482, in err
    raise e
ometa.runtime.ParseError:

^
Parse error at line 2, column -1: expected one of 'A', 'B', 'C', 'D', 'E', 'F', or a digit. trail: []