词法分析器java语言_词法分析器java版(java词法分析器)

雨点打透心脏的1/2处 2022-11-03 10:40 250阅读 0赞

无论是词法分析，还是语法分析，给我的第一感觉就是逻辑要严谨。由于项目有自己一套完整的语言和语法，设计好其对应的词法分析器和语法分析器显得尤为重要。

这里给您提供一个免费的java词法分析器下载

java词法分析器实现原理步骤

先写其正则式，然后NFA，然后DFA，然后对其进行优化，最后准备工作做好了，就可以开始写代码了。

下面对其里面的主要函数进行讲解：

enum Token\_Type \{

keyword =1,              //关键字

Identifier,            //标识符

operatorr,             //运算符

operatorrd,             //单运算符

constant,              //常量

escape,                //转义符

separator,              //界限符

notype,                  //没有类型

zhushi                   //注释类型

\};

对其单词的类型定义成枚举。

typedef struct Token \{

Token\_Type type; //其类型

char \*lexeme ;    //字符串

int  value;       //属性值

\}Token;

//返回单词的结构。

void InitScanner(char \*ch)\{

fp1 = fopen(ch,"r+");

LineNo = 1;

\}//初始化分析器。

void CloseScanner()\{

fclose(fp1);

\}//关闭分析器

void EmptyTokenString()\{

memset(TokenBuffer,0,100);

\}//清空缓冲区

static void AddCharTokenString(char Char)

int TokenLenth=strlen(TokenBuffer);

if(TokenLenth+1==sizeof(TokenBuffer)) return;

TokenBuffer\[TokenLenth\]=Char;

TokenBuffer\[TokenLenth+1\]='\\0';

\} //将一个字符添加到缓冲区

static char GetChar()\{

char Char;

Char = fgetc(fp1);

return Char;

\}//从文件中读取一个字符

static void BackChar(char Char) \{

if(Char!=EOF)\{

ungetc(Char,fp1);

\}//将其字符后退一个。

static Token JudgeKeyToken(char \*IDstring)；//这个函数实现对关键字进行判断

下面是源代码：

/\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*

\*                CopyRight@ice-snow studio                              \*

\*               email:bingxuefenggu@126.com                             \*

\*               qq: 405116890                                           \*

\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*/

//只考虑到整形常量

//实型没考虑到

//需要解决转义符如何描述的问题

\#include

\#define TOKEN\_LEN 100

enum Token\_Type \{

keyword =1,              //关键字

Identifier,            //标识符

operatorr,             //运算符

operatorrd,             //单运算符

constant,              //常量

escape,                //转义符

separator,              //界限符

notype,                  //没有类型

zhushi                   //注释类型

\};

typedef struct Token \{

Token\_Type type; //其类型

char \*lexeme ;    //字符串

int  value;       //属性值

\}Token;

static Token Token\_Tap\[\] = \{

\{keyword,"abstract",0x103\},

\{keyword,"boolean",0x103\},

\{keyword,"break", 0x103\},

\{keyword,"byte" ,0x103\},

\{keyword,"case",0x103\},

\{keyword,"catch",0x103\},

\{keyword,"char", 0x103\},

\{keyword, "class",0x103\},

\{keyword,"const" ,0x103\},

\{keyword,"continue" ,0x103\},

\{keyword,"default" , 0x103\},

\{keyword,"do",0x103\},

\{keyword,"double",0x103\},

\{keyword,"else",0x103\},

\{keyword,"extends",0x103\},

\{keyword,"false",0x103\},

\{keyword,"final",0x103\},

\{keyword,"finally",0x103\},

\{keyword,"float",0x103\},

\{keyword,"for",0x103\},

\{keyword,"goto",0x103\},

\{keyword,"if",0x103\},

\{keyword,"implements",0x103\},

\{keyword,"import",0x103\},

\{keyword,"instanceof",0x103\},

\{keyword,"int",0x103\},

\{keyword,"interface",0x103\},

\{keyword,"long",0x103\},

\{keyword,"native",0x103\},

\{keyword,"new",0x103\},

\{keyword,"null",0x103\},

\{keyword,"package",0x103\},

\{keyword,"private",0x103\},

\{keyword,"protected",0x103\},

\{keyword,"public",0x103\},

\{keyword,"return",0x103\},

\{keyword,"short",0x103\},

\{keyword,"static",0x103\},

\{keyword,"super",0x103\},

\{keyword,"switch",0x103\},

\{keyword,"synchronized",0x103\},

\{keyword,"this",0x103\},

\{keyword,"throw",0x103\},

\{keyword,"throws",0x103\},

\{keyword,"transient",0x103\},

\{keyword,"true",0x103\},

\{keyword,"try", 0x103\},

\{keyword,"void",0x103\},

\{keyword,"volatile",0x103\},

\{keyword,"while",0x103\},

\{constant,"true",0x105\},

\{constant,"false",0x105\}

//以上是所有的关键字

\};

FILE \*fp1;// 要读文件的描述符

int LineNo;//单词所在的行数

static char TokenBuffer\[TOKEN\_LEN\];//单词符号的缓存区

void InitScanner(char \*ch)\{

fp1 = fopen(ch,"r+");

LineNo = 1;

void CloseScanner()\{

fclose(fp1);

void EmptyTokenString()\{

memset(TokenBuffer,0,100);

static void AddCharTokenString(char Char)

int TokenLenth=strlen(TokenBuffer);

if(TokenLenth+1==sizeof(TokenBuffer)) return;

TokenBuffer\[TokenLenth\]=Char;

TokenBuffer\[TokenLenth+1\]='\\0';

static char GetChar()\{

char Char;

Char = fgetc(fp1);

return Char;

static void BackChar(char Char) \{

if(Char!=EOF)\{

ungetc(Char,fp1);

static Token JudgeKeyToken(char \*IDstring)\{

int loop;

Token token;

for(loop=0;loop<51;loop++)\{

if(strcmp(Token\_Tap\[loop\].lexeme,IDstring)==0)

return Token\_Tap\[loop\];

token.type = Identifier;

//strcpy(token.lexeme,IDstring);//youwenti.

token.lexeme = IDstring;

token.value = 0x104;

return token;

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