Source code for sfepy.base.parse_conf

"""
Create pyparsing grammar for problem configuration and options.
"""
from pyparsing import (Word, Group, Suppress, Combine, Optional,
                       Forward, Empty, quotedString, oneOf, removeQuotes,
                       delimitedList, nums, alphas, alphas8bit, alphanums,
                       Keyword)

word_free = Word(alphas8bit + '_-/.+**' + alphanums)
word_strict = Word(alphas8bit + alphas, alphas8bit + alphanums + '_' )

(lparen, rparen, lbrack, rbrack,
lbrace, rbrace, colon) = map(Suppress, '()[]{}:')

integer = Combine(Optional(oneOf('+ -')) + Word(nums)).setName('integer')
cvt_int = lambda toks: int(toks[0])
integer.setParseAction(cvt_int)

boolean = Keyword('False', caseless=True)
cvt_bool = lambda toks: toks[0].lower == 'true'
boolean.setParseAction(cvt_bool)

none = Keyword('None', caseless=True)

cvt_none =  lambda toks: [None]
none.setParseAction(cvt_none)

real = Combine(Optional(oneOf('+ -'))+ Word(nums)
               + '.' + Optional(Word(nums))
               + Optional('e' + Optional(oneOf('+ -'))
                          + Word(nums))).setName('real')
cvt_real = lambda toks: float(toks[0])
real.setParseAction(cvt_real)

array_index = Word(nums) + Optional(colon + integer
				+ Optional(colon + integer))
cvt_array_index = lambda toks: int(toks[0]) if len(toks) == 1 \
                  else slice(*toks)
array_index.setParseAction(cvt_array_index)
array_braces = lbrack + array_index + rbrack

def create_bnf(allow_tuple=False, free_word=False):
    word = word_free if free_word else word_strict
    defs = get_standard_type_defs(word)

    if allow_tuple:
        return defs['dict'].inner | defs['tuple'].inner
    else:
        return defs['dict'].inner

def list_of(element, *elements):
    for e in elements:
        element |= e
    lst = delimitedList(element)
    return lst + Optional(Suppress(','))

def get_standard_type_defs(word):
    tuple_str = Forward()
    list_str = Forward()
    dict_str = Forward()
    cvt_tuple = lambda toks : tuple(toks.asList())
    cvt_dict = lambda toks: dict(toks.asList())

    list_item = (none | boolean | real | integer | list_str | tuple_str
                 | dict_str
                 | quotedString.setParseAction(removeQuotes)
                 | word )
    list_item2 = list_item | Empty().setParseAction(lambda: [None])

    tuple_str.inner = list_of(list_item)
    tuple_str.inner.setParseAction(cvt_tuple)
    tuple_str << (lparen + tuple_str.inner + rparen)

    list_str.inner = tuple_str.inner.copy()
    list_str.inner.setParseAction(lambda toks: list(toks))
    list_str << (lbrack + list_str.inner + rbrack)

    dict_entry = Group(list_item + colon + list_item2)
    dict_str.inner = list_of(dict_entry)
    dict_str.inner.setParseAction(cvt_dict)
    dict_str << (lbrace + Optional(dict_str.inner) + rbrace)

    return {'tuple' : tuple_str,
            'list' : list_str,
            'dict' : dict_str,
            'list_item' : list_item}