czero t.txt

北京航空航天大学计算机系要求的编译器大作业。大概6000行代码。

<add_op>::= +|-

<mul_op>::= *|/

<rel_op>::= <| <= | > | >= | != | ==

<character>::=_|a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z|
				A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z

<digits>::=0|<nzdigits>

<nzdigits>::=1|2|3|4|5|6|7|8|9

<string>::="{<legalchar>}"

<legalchar>::=0|...|127

<program>::={<const_dec>}{<var_dec>}{<func_def>}<main_func>

<const_dec>::=const<const_def>{,<const_def>}

<const_def>::= <identifier>=<integer>

<integer>::= {+|-}<nzdigits>{<digits>}|0

<identifier>::=<character>{<character>|<digits>}

<dec_h>::= int<identifier>

<var_dec>::= <dec_h>{,<identifier>}

<func_def>::=(<dec_h>|void <identifier>)<param><com_stmt>

<param>::='('<param_list>')'

<param_list>::=int <identifier>{,int <identifier>}|<null>

<main_func>::= void main'('')'<com_stmt>

<exp>::={+|-}<item>{<add_op><item>}

<item>::=<factor>{<mul_op><factor>}

<factor>::= <identifier>|'('<exp>')'|<integer>
			|<call_func>;

<stmt>::= <con_stmt>|<loop_stmt>|'{'<stmt_list>'}'
		|<call_func>;|<assign_stmt>;|<rtn_stmt>;|<r_stmt>;|<w_stmt>;

<assign_stmt>::=<identifier>=<exp>

<con_stmt>::=if'('<condition>')'<stmt>{else<stmt>}

<condition>::=<exp><rel_op><exp>|<exp>

<loop_stmt>::=while'('<condition>')'<stmt>

<call_func>::= <identifier>'('<vparam_list>')'

<vparam_list>::= <exp>{,<exp>}|<null>

<stmt_list>::= <stmt>{<stmt>}

<r_stmt>::=scanf'('<identifier>')'

<w_stmt>::=printf'('<string>,<exp>|<string>|<exp>')'

<rtn_stmt>::= return ['('<exp>')']