语句，表达式

/**语句<statement>::=<compound_statement>    |<if_statement>    |<return_statement>    |<break_statement>    |<continue_statement>    |<for_statement>    |<expression_statement>**/void statement(){    switch(token)    {    case TK_BEGIN:        compound_statement();        break;    case KW_IF:        if_statement();        break;    case KW_RETURN:        return_statement();        break;    case KW_BREAK:        break_statement();        break;    case KW_CONTINUE:        continue_statement();        break;    case KW_FOR:        for_statement();        break;    default:        expression_statement();        break;    }}/**复合语句<compound_statement>::=<TK_BEGIN>{<declaration>}{<statement>}<TK_END>**/void compound_statement(){    syntax_state=SNTX_LF_HT;    syntax_level++;                     //复合语句，缩进加一级    get_token();    while(is_type_specifier(token))     //判断是否是声明    {        external_declaration(SC_LOCAL);    }    while(token!=TK_END)    {        statement();    }    syntax_state=SNTX_LF_HT;    get_token();}/**判断是否为类型区分符v:      单词编号**/int is_type_specifier(int v){    switch(v)    {    case KW_CHAR:    case KW_SHORT:    case KW_VOID:    case KW_INT:    case KW_STRUCT:        return 1;    default:        break;    }    return 0;}/**表达式语句<expression_statement>::=<TK_SEMICOLON>|<expression><TK_SEMICOLON>**/void expression_statement(){    if(token!=TK_SEMICOLON)    {        expression();    }    syntax_state=SNTX_LF_HT;    skip(TK_SEMICOLON);}/**选择语句<if_statement>::=<KW_IF><TK_OPENPA><expression>    <TK_CLOSEPA><statement>[<KW_ELSE><statement>]**/void if_statement(){    syntax_state=SNTX_SP;    get_token();    skip(TK_OPENPA);    expression();    syntax_state=SNTX_LF_HT;    skip(TK_CLOSEPA);    statement();    if(token==KW_ELSE)    {        syntax_state=SNTX_LF_HT;        get_token();        statement();    }}/**循环语句<for_statement>::=<KW_FOR><TK_OPENPA><expression_statement>    <expression_statement><expression><TK_CLOSEPA><statement>**/void for_statement(){    get_token();    skip(TK_OPENPA);    if(token!=TK_SEMICOLON)    {        expression();    }    skip(TK_SEMICOLON);    if(token!=TK_SEMICOLON)    {        expression();    }    skip(TK_SEMICOLON);    if(token!=TK_CLOSEPA)    {        expression();    }    syntax_state=SNTX_LF_HT;    skip(TK_CLOSEPA);    statement();}/**continue语句<continue_statement>::=<KW_CONTINUE><TK_SEMICOLON>**/void continue_statement(){    get_token();    syntax_state=SNTX_LF_HT;    skip(TK_SEMICOLON);}/**break语句<break_statement>::=<KW_BREAK><TK_SEMICOLON>**/void break_statement(){    get_token();    syntax_state=SNTX_LF_HT;    skip(TK_SEMICOLON);}/**return 语句<return_statement>::<KW_RETURN><TK_SEMICOLON>    |<KW_RETURN><expression><TK_SEMICOLON>**/void return_statement(){    syntax_state=SNTX_DELAY;    get_token();    if(token==TK_SEMICOLON)     //适用于return        syntax_state=SNTX_NUL;    else                         //适用于return expression        syntax_state=SNTX_SP;    syntax_indent();    if(token!=TK_SEMICOLON)    {        expression();    }    syntax_state=SNTX_LF_HT;    skip(TK_SEMICOLON);}/**表达式<expression>::=<assignment_expression>{<TK_COMMA><assignment_expression>}**/void expression(){    while(1)    {        assignment_expression();        if(token!=TK_COMMA)            break;        get_token();    }}/**赋值表达式<assignment_expression>::=<equality_expression>    |<unary_expression><TK_ASSIGN><assignment_expression>非等价转换后文法<assignment_expression>::=<equality_expression>    {<TK_ASSIGN><assignment_expression>}**/void assignment_expression(){    equality_expression();    if(token==TK_ASSIGN)    {        get_token();        assignment_expression();    }}/**相等类表达式<equality_expression>::=<relational_expression>    {<TK_EQ><relational_expression>    |<TK_NEQ><relational_expression>    }**/void equality_expression(){    relational_expression();    while(token==TK_EQ||token==TK_NEQ)    {        get_token();        relational_expression();    }}/**关系表达式<relational_expression>::=<additive_expression>{    <TK_LT><additive_expression>    |<TK_GT><additive_expression>    |<TK_LEQ><additive_expression>    |<TK_GEQ><additive_expression>}**/void relational_expression(){    additive_expression();    while(token==TK_LT||token==TK_LEQ||token==TK_GT||token==TK_GEQ)    {        get_token();        additive_expression();    }}/**加减类表达式<additive_expression>::=<multiplicative_expression>    {<TK_PLUS><multiplicative_expression>    |<TK_MINUS><multiplicative_expression>    }**/void additive_expression(){    multiplicative_expression();    while(token==TK_PLUS||token==TK_MINUS)    {        get_token();        multiplicative_expression();    }}/**乘除类表达式<multiplicative_expression>::=<unary_expression>    {<TK_STAR><unary_expression>    |<TK_DIVIDE><unary_expression>    |<TK_MOD><unary_expression>    }**/void multiplicative_expression(){    unary_expression();    while(token==TK_STAR||token==TK_DIDIVE||token==TK_MOD)    {        get_token();        unary_expression();    }}/**一元表达式<unary_expression>::=            <postfix_expression>            |<TK_AND><unary_expression>            |<TK_STAR><unary_expression>            |<TK_PLUS><unary_expression>            |<TK_MINUS><unary_expression>            |<sizeof_expression>**/void unary_expression(){    switch(token)    {    case TK_AND:    case TK_STAR:    case TK_PLUS:    case TK_MINUS:        get_token();        unary_expression();        break;    case KW_SIZEOF:        sizeof_expression();        break;    default:        postfix_expression();        break;    }}/**<sizeof_expression>::=    <KW_SIZEOF><TK_OPENPA><type_specifier><TK_CLOSEPA>**/void sizeof_expression(){    get_token();    skip(TK_OPENPA);    type_specifier();    skip(TK_CLOSEPA);}/**后缀表达式<postfix_expression>::=<primary_expression>    {<TK_OPENBR><expression><TK_CLOSEBR>    |<TK_OPENPA><TK_CLOSEPA>    |<TK_OPENPA><argument_expression_list><TK_CLOSEPA>    |<TK_DOT><IDENTIFIER>    |<TK_POINTSTO><IDENTIFIER>    }**/void postfix_expression(){    primary_expression();    while(1)    {        if(token==TK_DOT||token==TK_POINTSTO)        {            get_token();            token|=SC_MEMBER;       /**?**/            get_token();        }        else if(token==TK_OPENBR)        {            get_token();            expression();            skip(TK_CLOSEBR);        }        else if(token==TK_OPENPA)        {            argument_expression_list();        }        else            break;    }}/**<primary_expression>::=<IDENTIFIER>    |<TK_CINT>    |<TK_CSTR>    |<TK_CCHAR>    |<TK_OPENPA><expression><TK_CLOSEPA>**/void primary_expression(){    int t;    switch(token)    {    case TK_CINT:    case TK_CCHAR:    case TK_CSTR:        get_token();        break;    case TK_OPENPA:        get_token();        expression();        skip(TK_CLOSEPA);        break;    default:        t=token;        get_token();        if(t<TK_IDENT)            expect("标识符或常量");        break;    }}/**<argument_expression_list>::=<assignment_expression>        {<TK_COMMA><assignment_expression>}**/void argument_expression_list(){    get_token();    if(token!=TK_CLOSEPA)    {        for(;;)        {            assignment_expression();            if(token==TK_CLOSEPA)                break;            skip(TK_COMMA);        }    }    skip(TK_CLOSEPA);}