• 基于Java实现的语法分析器

    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。

    相关的自动机描述

    大部分同词法分析。

    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    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 ; } $  

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    Action: 匹配 {

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

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    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 

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    { 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  

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    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 

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    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: 	 	; } $  

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    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: 	 	$  

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    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: 	 	 

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    Action: 匹配 $

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  • 原文地址：https://blog.csdn.net/newlw/article/details/126930509