语义分析器
prog->{decsstms}decs->decdecs|dec->typeid;type->int|boolstms->stmstms|stm->id=exp;|printi(exp);|printb(exp);exp->intnum|true|false|id|(exp)|exp+exp|exp-
prog->{decsstms}decs->decdecs|dec->typeid;type->int|boolstms->stmstms|stm->id=exp;|printi(exp);|printb(exp);exp->intnum|true|false|id|(exp)|exp+exp|exp-