编译原理：TINY语言的语法、词法单元与文法的最全总结

深藏阁楼爱情的钟 2023-02-20 02:14 6阅读 0赞

下面是一段YINY语言源代码：

{ Sample program
 in TINY language -
 computes factorial
 }
 read x; { input an integer }
 if 0 < x then { don't compute if x <= 0 }
 fact := 1;
 repeat
 fact := fact * x;
 x := x - 1
 until x = 0;
 write fact { output factorial of x }
 end

在学习编译原理时，由于网上没有对TINY词法与文法的总结，这一块自己摸索很久。现在分享给大家，这里是乔卿的博客。下面对TINY语言的语法、词法单元与文法进行总结，涉及到编译原理中的词法分析、语法分析。

**TINY语言的语法为：**

1. 注释：放在一对大括号内，不能嵌套；
2. 关键字：read write if end repeat until else；
3. 类型：只支持整型和布尔型；
4. 运算符：+ - \* / ( ) < = :=，其中:=为赋值运算，=为判断。没有>和<=和>=。

**TINY的词法单元为：**

<table style="margin-left:39pt;"> 
 <tbody> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> 词法单元类型 </td> 
 <td style="vertical-align:top;width:74.95pt;"> 词法单元 </td> 
 <td style="vertical-align:top;width:74.95pt;"> 词素（例） </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> 关键字 （预定义符） </td> 
 <td style="vertical-align:top;width:74.95pt;"> IF </td> 
 <td style="vertical-align:top;width:74.95pt;"> if </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> THEN </td> 
 <td style="vertical-align:top;width:74.95pt;"> then </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> ELSE </td> 
 <td style="vertical-align:top;width:74.95pt;"> else </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> END </td> 
 <td style="vertical-align:top;width:74.95pt;"> end </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> REPEAT </td> 
 <td style="vertical-align:top;width:74.95pt;"> repeat </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> UNTIL </td> 
 <td style="vertical-align:top;width:74.95pt;"> until </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> READ </td> 
 <td style="vertical-align:top;width:74.95pt;"> read </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> WRITE </td> 
 <td style="vertical-align:top;width:74.95pt;"> write </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> 自定义符 </td> 
 <td style="vertical-align:top;width:74.95pt;"> ID </td> 
 <td style="vertical-align:top;width:74.95pt;"> myName </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> NUM </td> 
 <td style="vertical-align:top;width:74.95pt;"> 123 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> 运算符 </td> 
 <td style="vertical-align:top;width:74.95pt;"> ASSIGN </td> 
 <td style="vertical-align:top;width:74.95pt;"> := </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> EQ </td> 
 <td style="vertical-align:top;width:74.95pt;"> = </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> LT </td> 
 <td style="vertical-align:top;width:74.95pt;"> &lt; </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> PLUS </td> 
 <td style="vertical-align:top;width:74.95pt;"> + </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> MINUS </td> 
 <td style="vertical-align:top;width:74.95pt;"> - </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> TIMES </td> 
 <td style="vertical-align:top;width:74.95pt;"> * </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> OVER </td> 
 <td style="vertical-align:top;width:74.95pt;"> / </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> LPAREN </td> 
 <td style="vertical-align:top;width:74.95pt;"> ( </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> RPAREN </td> 
 <td style="vertical-align:top;width:74.95pt;"> ) </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> SEMI </td> 
 <td style="vertical-align:top;width:74.95pt;"> ; </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.95pt;"> 错误 </td> 
 <td style="vertical-align:top;width:74.95pt;"> ERROR </td> 
 <td style="vertical-align:top;width:74.95pt;"> &gt;= </td> 
 </tr> 
 </tbody> 
</table>

**TINY的文法为：**

<table style="margin-left:39pt;"> 
 <tbody> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> 非终结符 </td> 
 <td style="vertical-align:top;width:63.8pt;"> 含义 </td> 
 <td style="vertical-align:top;width:250.7pt;"> 展开 </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> program </td> 
 <td style="vertical-align:top;width:63.8pt;"> 程序 </td> 
 <td style="vertical-align:top;width:250.7pt;"> stmt_seq </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> stmt_seq </td> 
 <td style="vertical-align:top;width:63.8pt;"> 若干条语句 </td> 
 <td style="vertical-align:top;width:250.7pt;"> stmt_seq SEMI stmt | stmt </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> stmt </td> 
 <td style="vertical-align:top;width:63.8pt;"> 单条语句 </td> 
 <td style="vertical-align:top;width:250.7pt;"> if_stmt | repeat_stmt | assign_stmt | read_stmt | write_stmt | error </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> if_stmt </td> 
 <td style="vertical-align:top;width:63.8pt;"> 判断语句 </td> 
 <td style="vertical-align:top;width:250.7pt;"> IF exp THEN stmt_seq END | IF exp THEN stmt_seq ELSE stmt_seq END </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> repeat_stmt </td> 
 <td style="vertical-align:top;width:63.8pt;"> 循环语句 </td> 
 <td style="vertical-align:top;width:250.7pt;"> REPEAT stmt_seq UNTIL exp </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> assign_stmt </td> 
 <td style="vertical-align:top;width:63.8pt;"> 赋值语句 </td> 
 <td style="vertical-align:top;width:250.7pt;"> ID ASSIGN exp </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> read_stmt </td> 
 <td style="vertical-align:top;width:63.8pt;"> 输入语句 </td> 
 <td style="vertical-align:top;width:250.7pt;"> READ ID </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> write_stmt </td> 
 <td style="vertical-align:top;width:63.8pt;"> 输出语句 </td> 
 <td style="vertical-align:top;width:250.7pt;"> WRITE exp </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> exp </td> 
 <td style="vertical-align:top;width:63.8pt;"> 判断表达式 </td> 
 <td style="vertical-align:top;width:250.7pt;"> simple_exp LT simple_exp | simple_exp EQ simple_exp| simple_exp </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> simple_exp </td> 
 <td style="vertical-align:top;width:63.8pt;"> 加减表达式 </td> 
 <td style="vertical-align:top;width:250.7pt;"> simple_exp PLUS term | simple_exp MINUS term | term </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> term </td> 
 <td style="vertical-align:top;width:63.8pt;"> 乘除表达式 </td> 
 <td style="vertical-align:top;width:250.7pt;"> term TIMES factor | term OVER factor | factor </td> 
 </tr> 
 <tr> 
 <td style="vertical-align:top;width:74.15pt;"> factor </td> 
 <td style="vertical-align:top;width:63.8pt;"> 括号表达式 </td> 
 <td style="vertical-align:top;width:250.7pt;"> LPAREN exp RPAREN | NUM | ID | error </td> 
 </tr> 
 </tbody> 
</table>

即：

program->stmt_seq
 stmt_seq->stmt_seq;stmt
 stmt_seq->stmt
 stmt->if_stmt
 stmt->repeat_stmt
 stmt->assign_stmt
 stmt->read_stmt
 stmt->write_stmt
 stmt->error
 if_stmt->IF exp THEN stmt_seq END
 if_stmt->IF exp THEN stmt_seq ELSE stmt_seq END
 repeat_stmt->REPEAT stmt_seq UNTIL exp
 assign_stmt->ID:=exp
 read_stmt->READ ID
 write_stmt->WRITE exp
 exp->simple_exp<simple_exp
 exp->simple_exp=simple_exp
 simple_exp->simple_exp+term
 simple_exp->simple_exp-term
 term->term*factor
 term->term/factor
 factor->(exp)
 factor->NUM
 factor->ID
 factor->error

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本文链接：https://blog.csdn.net/qq\_41112170/article/details/106880776  
本文作者：乔卿