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#602054
void parser ( list<node *> & input ) { list<node *>::iterator i = input.begin(), i1, o ; char const * op [] = {"*","/","-","+"} ; list<string> operators(op,op+sizeof(op)/sizeof(op[0])) ; list<string>::iterator str_i = operators.begin() ; int state = state::binary ; while ( state != state::quit ) { switch (state) { case state::binary : if ( i != input.end() && ((*i)->type == state::value || (*i)->type == state::expression) ) { i1 = i ; ++i ; if ( i != input.end() && ((*i)->type == state::operation || (*i)->type == state::expression) && (*i)->token == *str_i ) { node *o = *i ; ++i ; if ( i != input.end() && ((*i)->type == state::value || (*i)->type == state::expression) ) { o->left = *i1 ; o->right = *i; o->type = state::expression ; input.erase(i1) ; input.erase( find(input.begin(), input.end(), o->right ) ) ; i = input.begin() ; state = state::binary ; } } } else if ( i != input.end() ) { state = state::binary ; ++i ; } else if ( i == input.end() && str_i != operators.end() ) { i = input.begin() ; state = state::binary ; ++str_i ; } else state = state::quit ; break ; } } }