Source code for sfepy.discrete.parse_equations

from __future__ import print_function
from __future__ import absolute_import
from pyparsing import Combine, Literal, Word, delimitedList, Group, Optional,\
     ZeroOrMore, OneOrMore, nums, alphas, alphanums,\
     StringStart, StringEnd, CaselessLiteral, Forward, oneOf
import six

[docs]class TermParse(object): def __str__(self): ss = "%s\n" % self.__class__ for key, val in six.iteritems(self.__dict__): ss += " %s:\n %s\n" % (key, self.__dict__[key]) return ss
[docs]def collect_term(term_descs, lc): signs = {'+': 1.0, '-': -1.0} def append(str, loc, toks): tp = TermParse() if len(toks.mul): tp.sign = eval(''.join(toks.mul)) * signs[lc[0]] else: tp.sign = signs[toks.sign] * signs[lc[0]] tp.integral = toks.term_desc.integral if not tp.integral: tp.integral = 'a' tp.region = toks.term_desc.region tp.flag = toks.term_desc.flag tp.name = toks.term_desc.name tp.args = ', '.join(toks.args[0]) term_descs.append(tp) return append
[docs]def rhs(lc): def aux(str, loc, toks): if toks: lc[0] = '-' return aux
[docs]def create_bnf(term_descs): """term_descs .. list of TermParse objects (sign, term_name, term_arg_names), where sign can be real or complex multiplier""" lc = ['+'] # Linear combination context. equal = Literal("=").setParseAction(rhs(lc)) zero = Literal("0").suppress() point = Literal(".") e = CaselessLiteral("E") inumber = Word("+-" + nums, nums) fnumber = Combine(Word("+-" + nums, nums) + Optional(point + Optional(Word(nums))) + Optional(e + Word("+-" + nums, nums))) number = fnumber + Optional(Literal('j'), default='') add_op = oneOf('+ -') number_expr = Forward() number_expr << Optional(add_op) + ZeroOrMore('(') + number \ + ZeroOrMore(add_op + number_expr) \ + ZeroOrMore(')') ident = Word(alphas, alphanums + "_") integral = Combine((Literal('i') + Word(alphanums)) | Literal('i') | Literal('a') | Word(nums))("integral") history = Optional('[' + inumber + ']', default='')("history") variable = Combine(Word(alphas, alphanums + '._') + history) derivative = Combine(Literal('d') + variable \ + Literal('/') + Literal('dt')) trace = Combine(Literal('tr') + '(' + Optional(ident + Literal(',')) + variable + ')', adjacent=False) generalized_var = derivative | trace | variable args = Group(delimitedList(generalized_var)) flag = Literal('a') term = ((Optional(Literal('+') | Literal('-'), default='+')("sign") ^ Optional(number_expr + Literal('*').suppress(), default=['1.0', ''])("mul")) + Combine( ident("name") + Optional( "." + (integral + "." + ident("region") + "." + flag("flag") | integral + "." + ident("region") | ident("region")) ))("term_desc") + "(" + Optional(args, default=[''])("args") + ")") term.setParseAction(collect_term(term_descs, lc)) rhs1 = equal + OneOrMore(term) rhs2 = equal + zero equation = StringStart() + OneOrMore(term) \ + Optional(rhs1 | rhs2) + StringEnd() ## term.setDebug() return equation
if __name__ == "__main__": test_str = """d_term1.Y(fluid, u, w, Nu, dcf, mode) + 5.0 * d_term2.Omega(u, w, Nu, dcf, mode) - d_another_term.Elsewhere(w, p[-1], Nu, dcf, mode) = - dw_rhs.a.Y3(u, q, Nu, dcf, mode)""" term_descs = [] bnf = create_bnf(term_descs) out = bnf.parseString(test_str) print('out:', out, '\n') for tp in term_descs: print(tp)