grammar.py

from plex import *
from washr.parser.types import Variable, BlockStart, BlockEnd
from cStringIO import StringIO

left_edge = Str("{")

right_edge = Str("}")

block_token = NoCase(Str("block:"))

end_token = Str("/")

identifier = Rep1(Range("azAZ09") | Str("-"))

variable = left_edge + identifier + right_edge

block_ident = block_token + identifier

block_begin = left_edge + block_ident + right_edge

block_end = left_edge + end_token + block_ident + right_edge

lex = Lexicon([
    (block_begin, lambda s, t: BlockStart(t[1:-1])),
    (block_end, lambda s, t: BlockEnd(t[2:-1])),
    (variable, lambda s, t: Variable(t[1:-1], '')),
    (AnyChar, TEXT),
])


def parse(stream):
    if isinstance(stream, str) or isinstance(stream, unicode):
        stream = StringIO(stream)
    scanner = Scanner(lex, stream)
    while 1:
        token = scanner.read()
        if token[0] is None:
            break
        yield token