Java实现词法分析器 java实现语法分析器

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夜行者3号 2023-07-24 21:53:47

文章标签 Java实现词法分析器 Java 语法分析语法分析器课程设计 文章分类 Java 后端开发

语法分析器的简单实现

一、实验目的

通过构建一个简单的语法分析程序，进一步熟悉语法分析的过程以及加深对 First 和Follow 的认识。

二、实验描述

本次实验使用 Java 语言编写，简单实现了对 C 语言程序的语法分析。程序的输入是 C 语言程序代码 program.c 文件以及已经定义好的文法 CFG.txt 文件。程序的输出是控制台和 output.txt 文件，内容是语法分析的过程。本实验中用到的词法分析部分是实验一的词法分析器。

三、实验方法

本次实验选用的方法是 PPT 中给出的第一种方法中的 a 方法，根据文法编程构建 LL(1) 预测分析表来进行语法分析。

实验设想

无。

四、数据结构的定义

Lex 类：词法分析程序

Token 类：Token 序列中的元素

Production 类：产生式类，包括两个属性，一个是 left（String 类型），表示产生式的左部；另一个是 right（List类型），表示产生式的右部。
FirstFollow 类：表示 First 或 Follow 的类，包括两个属性，一个是 left（String 类型），另一个是 right（List类型）。
Syntax 类：语法分析程序核心终结符和非终结符分别用 List类型来表示。

产生式用 List类型来表示。

符号的 First 和 Follow 分别用 List类型来表示。

预测分析表用 Production[][]类型表示，还需要借助终结符和非终结符的 List作为表头。

语法分析过程中的栈用 Java 自带的 Stack来表示。

Token 序列（简化版）用 List类型来表示。

五、核心算法描述

程序的核心算法主要有四个：

getFirst()：获得符号的 First 集合，算法在龙书的 P140.

getFollow()：获得符号的 Follow 集合，算法在龙书的 P140-141.

getParsingTable()：构建预测分析表，算法在龙书的 P142-143，算法 4.31

syntaxParsing()：表驱动的预测语法分析，算法在龙书的 P144，算法 4.34

语法分析的过程输出 output.txt：

Match:  	 
Stack: 	 	$ Function  
Input: 	 	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else 
{ int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $  
Action:  	输出: Program -> Function  
Match:  	 
Stack: 	 	$ } Return Statement { ) Para ( FuncName DataType  
Input: 	 	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else 
{ int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $  
Action:  	输出: Function -> DataType FuncName ( Para ) { Statement Return }  
Match:  	 
Stack: 	 	$ } Return Statement { ) Para ( FuncName int  
Input: 	 	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else 
{ int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $  
Action:  	输出: DataType -> int  
Match:  	int  
Stack: 	 	$ } Return Statement { ) Para ( FuncName  
Input: 	 	ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int 
ID = NUM ; ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 int

Match:  	int  
Stack: 	 	$ } Return Statement { ) Para ( ID  
Input: 	 	ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int 
ID = NUM ; ID = ID + NUM ; } } return NUM ; } $  
Action:  	输出: FuncName -> ID  
Match:  	int ID  
Stack: 	 	$ } Return Statement { ) Para (  
Input: 	 	( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID 
= NUM ; ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 ID

Match: 	int ID (  
Stack: 	 	$ } Return Statement { ) Para  
Input: 	 	float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = 
NUM ; ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 (

Match:  	int ID (  
Stack: 	 	$ } Return Statement { ) ID DataType  
Input: 	 	float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = 
NUM ; ID = ID + NUM ; } } return NUM ; } $  
Action:  	输出: Para -> DataType ID  
Match:  	int ID (  
Stack: 	 	$ } Return Statement { ) ID float  
Input: 	 	float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = 
NUM ; ID = ID + NUM ; } } return NUM ; } $  
Action:  	输出: DataType -> float  
Match:  	int ID ( float  
Stack: 	 	$ } Return Statement { ) ID  
Input: 	 	ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; 
ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 float

Match:  	int ID ( float ID  
Stack: 	 	$ } Return Statement { )  
Input: 	 	) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; 
ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 ID

Match:  	int ID ( float ID )  
Stack: 	 	$ } Return Statement {  
Input: 	 	{ while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID 
= ID + NUM ; } } return NUM ; } $

Action: 匹配 )

Match:  	int ID ( float ID ) {  
Stack: 	 	$ } Return Statement  
Input: 	 	while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID 
= ID + NUM ; } } return NUM ; } $

Action: 匹配 {

Match:  	int ID ( float ID ) {  
Stack: 	 	$ } Return Statement S  
Input: 	while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID 
= ID + NUM ; } } return NUM ; } $  
Action:  	输出: Statement -> S Statement  
Match:  	int ID ( float ID ) {  
Stack: 	 	$ } Return Statement B ) C ( while  
Input: 	 	while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID 
= ID + NUM ; } } return NUM ; } $  
Action:  	输出: S -> while ( C ) B  
Match:  	int ID ( float ID ) { while  
Stack: 	 	$ } Return Statement B ) C (  
Input: 	 	( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + 
NUM ; } } return NUM ; } $

Action: 匹配 while

Match:  	int ID ( float ID ) { while (  
Stack: 	 	$ } Return Statement B ) C  
Input: 	 	ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + 
NUM ; } } return NUM ; } $

Action: 匹配 (

Match:  	int ID ( float ID ) { while (  
Stack: 	 	$ } Return Statement B ) Keyword CompareOP Keyword  
Input: 	 	ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + 
NUM ; } } return NUM ; } $  
Action:  	输出: C -> Keyword CompareOP Keyword  
Match:  	int ID ( float ID ) { while (  
Stack: 	 	$ } Return Statement B ) Keyword CompareOP ID  
Input: 	 	ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + 
NUM ; } } return NUM ; } $  
Action:  	输出: Keyword -> ID  
Match:  	int ID ( float ID ) { while ( ID  
Stack: 	 	$ } Return Statement B ) Keyword CompareOP  
Input: 	 	<= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + 
NUM ; } } return NUM ; } $

Action: 匹配 ID


Match:		int ID ( float ID ) { while ( ID
Stack:		$ } Return Statement B ) Keyword <=
Input:		<= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID +

NUM ; } } return NUM ; } $  
Action: 	输出: CompareOP -> <=  
Match:  	int ID ( float ID ) { while ( ID <=  
Stack: 	 	$ } Return Statement B ) Keyword  
Input:  NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 <=

Match:  	int ID ( float ID ) { while ( ID <=  
Stack: 	 	$ } Return Statement B ) NUM  
Input:  NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $  
Action:  	输出: Keyword -> NUM  
Match:  	int ID ( float ID ) { while ( ID <= NUM  
Stack: 	 	$ } Return Statement B )  
Input:  ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 NUM

Match:  	int ID ( float ID ) { while ( ID <= NUM )  
Stack: 	 	$ } Return Statement B  
Input:  { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 )

Match:  	int ID ( float ID ) { while ( ID <= NUM )  
Stack: 	 	$ } Return Statement } Statement {  
Input:  { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $  
Action:  	输出: B -> { Statement }  
Match:  	int ID ( float ID ) { while ( ID <= NUM ) {  
Stack: 	 	$ } Return Statement } Statement  
Input: 	 	if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $

Action: 匹配 {

Match:  	int ID ( float ID ) { while ( ID <= NUM ) {

Stack:	$ } Return Statement } Statement S
Input: ；NUM ; } $	if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return
Action:	输出: Statement -> S Statement

Match:	int ID ( float ID ) { while ( ID <= NUM ) {
Stack:	$ } Return Statement } Statement D B ) C ( if
Input:	if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return
NUM ; } $ Action: ；	输出: S -> if ( C ) B D
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if
Stack:	$ } Return Statement } Statement D B ) C (
Input:	( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return
NUM ; } $ Action: ；	匹配 if
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if (
Stack:	$ } Return Statement } Statement D B ) C
Input:	ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return
NUM ; } $ Action: ；	匹配 (
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if (
Stack:	$ } Return Statement } Statement D B ) Keyword CompareOP Keyword
Input:	ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return
NUM ; } $ Action: ；	输出: C -> Keyword CompareOP Keyword
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if (
Stack:	$ } Return Statement } Statement D B ) Keyword CompareOP ID
Input:	ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return
NUM ; } $ Action: ；	输出: Keyword -> ID
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID
Stack:	$ } Return Statement } Statement D B ) Keyword CompareOP
Input:	== NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; }
$ ；Action: ；	匹配 ID
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID
Stack:	$ } Return Statement } Statement D B ) Keyword ==
Input:	== NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; }
$ ；Action: ；	输出: CompareOP -> ==
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID ==
Stack:	$ } Return Statement } Statement D B ) Keyword

Input:		NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; }
$ Action: ；		匹配 ==
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID ==
Stack:		$ } Return Statement } Statement D B ) NUM
Input:		NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; }
$ ；Action:		输出: Keyword -> NUM
；Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM
Stack:		$ } Return Statement } Statement D B )
Input:		) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		匹配 NUM
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM )
Stack:		$ } Return Statement } Statement D B
Input:		{ ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		匹配 )
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM )
Stack:		$ } Return Statement } Statement D } Statement {
Input:		{ ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:		输出: B -> { Statement }
；Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) {
Stack:		$ } Return Statement } Statement D } Statement
Input:		ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		匹配 {
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) {
Stack:		$ } Return Statement } Statement D } Statement S
Input:		ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:		输出: Statement -> S Statement
；Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) {
Stack:		$ } Return Statement } Statement D } Statement N Keyword = ID
Input:		ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		输出: S -> ID = Keyword N
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID
Stack:		$ } Return Statement } Statement D } Statement N Keyword =
Input:		= NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:		匹配 ID

；Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID =
Stack:		$ } Return Statement } Statement D } Statement N Keyword
Input:		NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		匹配 =
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID =
Stack:		$ } Return Statement } Statement D } Statement N NUM
Input:		NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:		输出: Keyword -> NUM
；Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM
Stack:		$ } Return Statement } Statement D } Statement N
Input:		; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:		匹配 NUM
；Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM
Stack:		$ } Return Statement } Statement D } Statement ;
Input:		; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		输出: N -> ;
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ;
Stack:		$ } Return Statement } Statement D } Statement
Input:		} else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		匹配 ;
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ;
Stack:		$ } Return Statement } Statement D }
Input:		} else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		输出: Statement -> ε
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; }
Stack:		$ } Return Statement } Statement D
Input:		else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；		匹配 }
Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; }
Stack:		$ } Return Statement } Statement B else
Input:		else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:		输出: D -> else B
；Match:		int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else
Stack:		$ } Return Statement } Statement B
Input:		{ int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $

Action: ；	匹配 else
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else
Stack:	$ } Return Statement } Statement } Statement {
Input:	{ int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；	输出: B -> { Statement }
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else {
Stack:	$ } Return Statement } Statement } Statement
Input:	int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；	匹配 {
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else {
Stack:	$ } Return Statement } Statement } Statement S
Input:	int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:	输出: Statement -> S Statement
；Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else {
Stack:	$ } Return Statement } Statement } Statement M ID DataType
Input:	int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:	输出: S -> DataType ID M
；Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else {
Stack:	$ } Return Statement } Statement } Statement M ID int
Input:	int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action: ；	输出: DataType -> int
Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else
{ int ； Stack:	$ } Return Statement } Statement } Statement M ID
Input:	ID = NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:	匹配 int
；Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else
{ int ID ； Stack:	$ } Return Statement } Statement } Statement M
Input:	= NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:	匹配 ID
；Match:	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else
{ int ID ； Stack:	$ } Return Statement } Statement } Statement ; NUM =
Input:	= NUM ; ID = ID + NUM ; } } return NUM ; } $
Action:	输出: M -> = NUM ;

Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID =  
	Stack: 	 	$ } Return Statement } Statement } Statement ; NUM  
	Input: 	 	NUM ; ID = ID + NUM ; } } return NUM ; } $  
	Action:  	匹配 = 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM  
	Stack: 	 	$ } Return Statement } Statement } Statement ;  
	Input: 	 	; ID = ID + NUM ; } } return NUM ; } $  
	Action:  	匹配 NUM 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ;  
	Stack: 	 	$ } Return Statement } Statement } Statement  
	Input: 	 	ID = ID + NUM ; } } return NUM ; } $  
	Action:  	匹配 ; 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ;  
	Stack: 	 	$ } Return Statement } Statement } Statement S  
	Input: 	 	ID = ID + NUM ; } } return NUM ; } $  
	Action:  	输出: Statement -> S Statement  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ;  
	Stack: 	 	$ } Return Statement } Statement } Statement N Keyword = ID  
	Input: 	 	ID = ID + NUM ; } } return NUM ; } $  
	Action:  	输出: S -> ID = Keyword N  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID  
	Stack: 	 	$ } Return Statement } Statement } Statement N Keyword =  
	Input: 	 	= ID + NUM ; } } return NUM ; } $  
	Action:  	匹配 ID 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID =  
	Stack: 	 	$ } Return Statement } Statement } Statement N Keyword  
	Input: 	 	ID + NUM ; } } return NUM ; } $  
	Action:  	匹配 = 
 
	Match:  	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else

{ int ID = NUM ; ID =  
	Stack: 	 	$ } Return Statement } Statement } Statement N ID  
	Input: 	 	ID + NUM ; } } return NUM ; } $  
	Action:  	输出: Keyword -> ID  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID  
	Stack: 	 	$ } Return Statement } Statement } Statement N  
	Input: 	 	+ NUM ; } } return NUM ; } $  
	Action:  	匹配 ID 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID  
	Stack: 	 	$ } Return Statement } Statement } Statement ; Keyword OP  
	Input: 	 	+ NUM ; } } return NUM ; } $  
	Action:  	输出: N -> OP Keyword ;  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID  
	Stack: 	 	$ } Return Statement } Statement } Statement ; Keyword +  
	Input: 	 	+ NUM ; } } return NUM ; } $  
	Action:  	输出: OP -> +  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID +  
	Stack: 	 	$ } Return Statement } Statement } Statement ; Keyword  
	Input: 	 	NUM ; } } return NUM ; } $  
	Action:  	匹配 + 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID +  
	Stack: 	 	$ } Return Statement } Statement } Statement ; NUM  
	Input: 	 	NUM ; } } return NUM ; } $  
	Action:  	输出: Keyword -> NUM  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM  
	Stack: 	 	$ } Return Statement } Statement } Statement ;  
	Input: 	 	; } } return NUM ; } $  
	Action:  	匹配 NUM 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ;  
	Stack: 	 	$ } Return Statement } Statement } Statement

Input: 	 	} } return NUM ; } $  
	Action:  	匹配 ; 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ;  
	Stack: 	 	$ } Return Statement } Statement }  
	Input: 	 	} } return NUM ; } $  
	Action:  	输出: Statement -> ε  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; }  
	Stack: 	 	$ } Return Statement } Statement  
	Input: 	 	} return NUM ; } $  
	Action:  	匹配 } 
 
	Match:  	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else 
{ int ID = NUM ; ID = ID + NUM ; }  
	Stack: 	 	$ } Return Statement }  
	Input: 	 	} return NUM ; } $  
	Action:  	输出: Statement -> ε  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } }  
	Stack: 	 	$ } Return Statement  
	Input: 	 	return NUM ; } $  
	Action:  	匹配 } 
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } }  
	Stack: 	 	$ } Return  
	Input: 	 	return NUM ; } $  
	Action:  	输出: Statement -> ε  
 
	Match:  	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else 
{ int ID = NUM ; ID = ID + NUM ; } }  
	Stack: 	 	$ } ; Keyword return  
	Input: 	 	return NUM ; } $  
	Action:  	输出: Return -> return Keyword ;  
 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return  
	Stack: 	 	$ } ; Keyword  
	Input: 	 	NUM ; } $  
	Action:  	匹配 return

Match:  	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else 
{ int ID = NUM ; ID = ID + NUM ; } } return  
Stack: 	 	$ } ; NUM  
Input: 	 	NUM ; } $  
Action:  	输出: Keyword -> NUM  
Match:  	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else 
{ int ID = NUM ; ID = ID + NUM ; } } return NUM  
Stack: 	 	$ } ;  
Input: 	 	; } $

Action: 匹配 NUM

Match:  	int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else 
{ int ID = NUM ; ID = ID + NUM ; } } return NUM ;  
Stack: 	 	$ }  
Input: 	 	} $  
Action:  	匹配 ; 
Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; }  
Stack: 	 	$  
Input: 	 	$

Action: 匹配 }

Match:  int ID ( float ID ) { while ( ID <= NUM ) { if ( ID == NUM ) { ID = NUM ; } else { int ID = NUM ; ID = ID + NUM ; } } return NUM ; } $  
Stack: 	 	 
Input:

Action: 匹配 $

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