请用JAVA编程输入一个语句进行词法分析

我最近正在学编译原理，我有c语言实现的词法分析程序，不知可不可以，识别的是TEST语言的单词。

#include<stdio.h>

#include<ctype.h>

#include<string.h>

#define keywordSum 8

char * keyword[keywordSum] = {"do", "else", "for", "if", "int", "read", "while", "write"}

char singleword[50] = "+-*(){},:"

char doubleword[10] = "><=!|&"

char Scanin[300], Scanout[300]

FILE * fin, * fout

int binaryFind(int low, int high, char * c1, char ** c2) {

int mid

if(low >high) return -1

mid = (low+high)/2

if(strcmp(c1, c2[mid]) == 0) return mid

else if(strcmp(c1, c2[mid]) >0) return binaryFind(mid+1, high, c1, c2)

else return binaryFind(low, mid-1, c1, c2)

}

int TESTscan() {

char ch, token[40]

int es = 0, j, n

printf("请输入源文件名(包括路径):")

scanf("%s", Scanin)

printf("请输入词法分析输出文件名(包括路径):")

scanf("%s", Scanout)

if((fin=fopen(Scanin, "r")) == NULL) {

printf("\n打开词法分析输入文件出错!\n")

return 1

}

if((fout=fopen(Scanout, "w")) == NULL) {

printf("\n创建词法分析输出文件出错!\n")

return 2

}

// printf("%c", getc(fin))

ch = getc(fin)

while(ch != EOF) {

while(ch==' ' || ch=='\n' || ch=='\t') {

ch = getc(fin)

}

if(isalpha(ch)) { //标识符

token[0] = ch

j = 1

ch = getc(fin)

while(isalnum(ch)) { //判断当前字符是否是字母或数字

token[j++] = ch

ch = getc(fin)

}

token[j] = '\0'

// printf("%s", token)

n = binaryFind(0, keywordSum-1, token, keyword)

if(n <0 ) {

fprintf(fout, "%s\t%s\n", "ID", token)

} else {

fprintf(fout, "%s\t%s\n", token, token)

}

} else if(isdigit(ch)) { //数字

token[0] = ch

j = 1

ch = getc(fin)

while(isdigit(ch)) {

token[j++] = ch

ch = getc(fin)

}

token[j] = '\0'

fprintf(fout, "%s\t%s\n", "NUM", token)

} else if(strchr(singleword, ch) >0) { //singleword

token[0] = ch

token[1] = '\0'

ch = getc(fin)

fprintf(fout, "%s\t%s\n", token, token)

} else if(strchr(doubleword, ch) >0) { //doubleword

token[0] = ch

ch = getc(fin)

if(ch=='=' &&(token[0]=='>'||token[0]=='<' || token[0] == '!')) {

token[1] = ch

token[2] = '\0'

ch = getc(fin)

} else if((ch=='&')||(ch=='|')||(ch=='=') &&ch==token[0]) {

token[1] = ch

token[2] = '\0'

ch = getc(fin)

} else {

token[1] = '\0'

}

fprintf(fout, "%s\t%s\n", token, token)

} else if(ch == '/') { //注释

ch = getc(fin)

if(ch == '*') {

char ch1

ch1 = getc(fin)

do {

ch = ch1

ch1 = getc(fin)

} while((ch!='*'||ch1!='/') &&ch1!=EOF)

ch = getc(fin)

} else {

token[0] = '/'

token[1] = '\0'

fprintf(fout, "%s\t%s\n", token, token)

}

} else {

token[0] = ch

token[1] = '\0'

ch = getc(fin)

es = 3

fprintf(fout, "%s\t%s\n", "ERROR", token)

}

}

fclose(fin)

fclose(fout)

return es

}

void main() {

int es = 0

es = TESTscan()

if(es >0) {

printf("词法分析有错, 编译停止!\n")

} else {

printf("词法分析成功!\n")

}

}

我也做过这个作业

package source

import java.util.LinkedList

public class LexicalAnalysis 

{

//私有变量声明

    private LinkedList<Word> optr = new LinkedList<Word>()

    private String exp

    //词法分析

    public LinkedList<Word> lexical_analysis(String exp) 

    {

char ch = '\0'          //当前文件指针内容

int index = 0           //文件指针

        StringBuffer strToken = new StringBuffer("")

//扫描处理字符串

while(true) 

{

     ch = exp.charAt(index)

     index++

     //标识符(字母开头，数字或字符组成)

     if(Character.isLetter(ch))

     {

                while(Character.isLetter(ch) || Character.isDigit(ch)) 

                {

                    strToken.append(ch)

                    ch = exp.charAt(index)

                    index++

             }

                index--

                String str = strToken.toString()

                if(str.equals("if"))

                 optr.add(new Word(str, 13))

                else if(str.equals("else"))

                 optr.add(new Word(str, 14))

                else if(str.equals("then"))

                 optr.add(new Word(str, 15))

                else

                 optr.add(new Word(str, 26))  

            }

            //数字

            else if(Character.isDigit(ch)) 

            {

                while(Character.isDigit(ch)) 

                {

                    strToken.append(ch)

     ch = exp.charAt(index)

     index++

         }

                index--

                optr.add(new Word(strToken.toString(), 26))

            }

            //加号或自加

            else if(ch == '+')

            {

             ch = exp.charAt(index)

                index++

                if(ch == '+')

                 optr.add(new Word("++", 21))

         else if(ch == '=')

         optr.add(new Word("+=", 16))

         else 

         {

     index--

     optr.add(new Word("+", 19))

                }

            }

            //加号或自加

            else if(ch == '-')

            {

             ch = exp.charAt(index)

                index++

                if(ch == '-')

                 optr.add(new Word("--", 21))

         else if(ch == '=')

         optr.add(new Word("-=", 16))

         else 

         {

     index--

     optr.add(new Word("-", 19))

                }

            }

            //乘法或乘幂

     else if(ch == '*') 

     {

         ch = exp.charAt(index)

                index++

                if(ch == '*')

                 optr.add(new Word("**", 20))

         else if(ch == '=')

         optr.add(new Word("*=", 16))

         else 

         {

     index--

     optr.add(new Word("*", 20))

                }

            }

            //除法或注释

            else if(ch == '/')

            {

         ch = exp.charAt(index)

                index++

                //多行注释

                if(ch == '*')

                {

                 while(true)

                 {

                 ch = exp.charAt(index)

                 index++

                 if(ch == '*')

                 {

                 ch = exp.charAt(index)

                 index++

                 if(ch == '/') break

                 else if(ch == '\n')

                 {

                 exp = Input.newLine()

                 index = 0

                 ch = exp.charAt(index)

                 index++

                 }

                 else index--

                 }

                 else if(ch == '#')

         {

         int tIndex = index - 1

         if(exp.length() > tIndex+9)

         {

         String end = exp.substring(tIndex, tIndex+9)

         if(end.equals("#?e_N_d?#")) break

         }

         else

         {

         System.out.println("非法符号\'#\'后的语句忽略！")

         exp = Input.newLine()

         index = 0

         break

         }

         }

         else if(ch == '\n')

                 {

                 exp = Input.newLine()

                 index = 0

                 }

                 }

                }

                //单行注释

                else if(ch == '/')

                 break 

                else if(ch == '=')

              optr.add(new Word("/=", 16))

         else 

         {

     index--

     optr.add(new Word("/", 20))

                }

            }

            //大于或大于等于或右移

            else if(ch == '>')

            {

             ch = exp.charAt(index)

             index++

             if(ch == '=')

             optr.add(new Word(">=", 18))

             else if(ch == '>')

             optr.add(new Word(">>", 20))

             else

             {

             index--

             optr.add(new Word(">", 18))

             }

            }

            //小于或小于等于或左移

            else if(ch == '<')

            {

             ch = exp.charAt(index)

             index++

             if(ch == '=')

             optr.add(new Word("<=", 18))

             else if(ch == '<')

             optr.add(new Word("<<", 20))

             else

             {

             index--

             optr.add(new Word("<", 18))

             }

            }

            //赋值或等于

            else if(ch == '=')

            {

             ch = exp.charAt(index)

             index++

             if(ch == '=')

             optr.add(new Word("==", 18))

             else

             {

             index--

             optr.add(new Word("=", 16))

             }

            }

            //或运算按位或

            else if(ch == '|')

            {

             ch = exp.charAt(index)

             index++

             if(ch == '|')

             optr.add(new Word("||", 17))

             else

             {

             index--

             optr.add(new Word("|", 20))

             }

            }

            //与运算

            else if(ch == '&')

            {

             ch = exp.charAt(index)

             index++

             if(ch == '&')

             optr.add(new Word("&&", 17))

             else

             {

             index--

             optr.add(new Word("&", 20))

             }

            }

            //非运算或不等于

            else if(ch == '!')

            {

             ch = exp.charAt(index)

             index++

             if(ch == '=')

             optr.add(new Word("!=", 18))

             else

             {

             index--

             optr.add(new Word("!", 21))

             }

            }

            //按位亦或

            else if(ch == '^')

             optr.add(new Word("^", 20))

            //取模运算

            else if(ch == '%')

             optr.add(new Word("%", 20))

            //左括号

     else if(ch == '(')

                optr.add(new Word("(", 22))

            //右括号

     else if(ch == ')')

                optr.add(new Word(")", 23))

            //左大括号

            else if(ch == '{')

             optr.add(new Word("{", 24))

            //右大括号

            else if(ch == '}')

             optr.add(new Word("}", 25))

    //结束扫描标志为：#?e_N_d?#

    else if(ch == '\n')

    {

    break

    }

         else if(ch == '#')

         {

         int tIndex = index - 1

         if(exp.length() > tIndex+9)

         {

         String end = exp.substring(tIndex, tIndex+9)

         if(end.equals("#?e_N_d?#"))

         {

         optr.add(new Word("#", 27))

         break

         }

         }

         else

         {

         System.out.println("非法符号\'#\'后的语句忽略！")

         optr.add(new Word("#", 27))

         break

         }

         }

         //清空扫描串

            strToken.setLength(0)

}

return optr

    }

}

首先看下我们要分析的代码段如下：

输出结果如下：

输出结果(a).PNG

输出结果(b).PNG

输出结果(c).PNG

括号里是一个二元式：（单词类别编码，单词位置编号）

代码如下：

?

1234567891011121314package Yue.LexicalAnalyzer import java.io.* /* * 主程序 */public class Main {  public static void main(String[] args) throws IOException {    Lexer lexer = new Lexer()    lexer.printToken()    lexer.printSymbolsTable()  }}

?

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283package Yue.LexicalAnalyzer import java.io.*import java.util.* /* * 词法分析并输出 */public class Lexer {  /*记录行号*/  public static int line = 1  /*存放最新读入的字符*/  char character = ' '   /*保留字*/  Hashtable<String, KeyWord>keywords = new Hashtable<String, KeyWord>()  /*token序列*/  private ArrayList<Token>tokens = new ArrayList<Token>()  /*符号表*/  private ArrayList<Symbol>symtable = new ArrayList<Symbol>()   /*读取文件变量*/  BufferedReader reader = null  /*保存当前是否读取到了文件的结尾*/  private Boolean isEnd = false   /* 是否读取到文件的结尾 */  public Boolean getReaderState() {    return this.isEnd  }   /*打印tokens序列*/  public void printToken() throws IOException {    FileWriter writer = new FileWriter("E:\\lex.txt")    System.out.println("词法分析结果如下：")    System.out.print("杜悦-2015220201031\r\n\n")    writer.write("杜悦-2015220201031\r\n\r\n")    while (getReaderState() == false) {      Token tok = scan()      String str = "line " + tok.line + "\t(" + tok.tag + "," + tok.pos + ")\t\t"          + tok.name + ": " + tok.toString() + "\r\n"      writer.write(str)      System.out.print(str)    }    writer.flush()   }   /*打印符号表*/  public void printSymbolsTable() throws IOException {    FileWriter writer = new FileWriter("E:\\symtab1.txt")    System.out.print("\r\n\r\n符号表\r\n")    System.out.print("编号\t行号\t名称\r\n")    writer.write("符号表\r\n")    writer.write("编号 " + "\t行号 " + "\t名称 \r\n")    Iterator<Symbol>e = symtable.iterator()    while (e.hasNext()) {      Symbol symbol = e.next()      String desc = symbol.pos + "\t" + symbol.line + "\t" + symbol.toString()      System.out.print(desc + "\r\n")      writer.write(desc + "\r\n")    }     writer.flush()  }   /*打印错误*/  public void printError(Token tok) throws IOException{    FileWriter writer = new FileWriter("E:\\error.txt")    System.out.print("\r\n\r\n错误词法如下：\r\n")    writer.write("错误词法如下：\r\n")    String str = "line " + tok.line + "\t(" + tok.tag + "," + tok.pos + ")\t\t"        + tok.name + ": " + tok.toString() + "\r\n"    writer.write(str)  }   /*添加保留字*/  void reserve(KeyWord w) {    keywords.put(w.lexme, w)  }   public Lexer() {    /*初始化读取文件变量*/    try {      reader = new BufferedReader(new FileReader("E:\\输入.txt"))    } catch (IOException e) {      System.out.print(e)    }     /*添加保留字*/    this.reserve(KeyWord.begin)    this.reserve(KeyWord.end)    this.reserve(KeyWord.integer)    this.reserve(KeyWord.function)    this.reserve(KeyWord.read)    this.reserve(KeyWord.write)    this.reserve(KeyWord.aIf)    this.reserve(KeyWord.aThen)    this.reserve(KeyWord.aElse)  }   /*按字符读*/  public void readch() throws IOException {    character = (char) reader.read()    if ((int) character == 0xffff) {      this.isEnd = true    }  }   /*判断是否匹配*/  public Boolean readch(char ch) throws IOException {    readch()    if (this.character != ch) {      return false    }     this.character = ' '    return true  }   /*数字的识别*/  public Boolean isDigit() throws IOException {    if (Character.isDigit(character)) {      int value = 0      while (Character.isDigit(character)) {        value = 10 * value + Character.digit(character, 10)        readch()      }       Num n = new Num(value)      n.line = line      tokens.add(n)      return true    } else      return false  }   /*保留字、标识符的识别*/  public Boolean isLetter() throws IOException {    if (Character.isLetter(character)) {      StringBuffer sb = new StringBuffer()       /*首先得到整个的一个分割*/      while (Character.isLetterOrDigit(character)) {        sb.append(character)        readch()      }       /*判断是保留字还是标识符*/      String s = sb.toString()      KeyWord w = keywords.get(s)       /*如果是保留字的话，w不应该是空的*/      if (w != null) {        w.line = line        tokens.add(w)      } else {        /*否则就是标识符，此处多出记录标识符编号的语句*/        Symbol sy = new Symbol(s)        Symbol mark = sy      //用于标记已存在标识符        Boolean isRepeat = false        sy.line = line        for (Symbol i : symtable) {          if (sy.toString().equals(i.toString())) {            mark = i            isRepeat = true          }        }        if (!isRepeat) {          sy.pos = symtable.size() + 1          symtable.add(sy)        } else if (isRepeat) {          sy.pos = mark.pos        }        tokens.add(sy)      }      return true    } else      return false  }   /*符号的识别*/  public Boolean isSign() throws IOException {    switch (character) {      case '#':        readch()        AllEnd.allEnd.line = line        tokens.add(AllEnd.allEnd)        return true      case '\r':        if (readch('\n')) {          readch()          LineEnd.lineEnd.line = line          tokens.add(LineEnd.lineEnd)          line++          return true        }      case '(':        readch()        Delimiter.lpar.line = line        tokens.add(Delimiter.lpar)        return true      case ')':        readch()        Delimiter.rpar.line = line        tokens.add(Delimiter.rpar)        return true      case '':        readch()        Delimiter.sem.line = line        tokens.add(Delimiter.sem)        return true      case '+':        readch()        CalcWord.add.line = line        tokens.add(CalcWord.add)        return true      case '-':        readch()        CalcWord.sub.line = line        tokens.add(CalcWord.sub)        return true      case '*':        readch()        CalcWord.mul.line = line        tokens.add(CalcWord.mul)        return true      case '/':        readch()        CalcWord.div.line = line        tokens.add(CalcWord.div)        return true      case ':':        if (readch('=')) {          readch()          CalcWord.assign.line = line          tokens.add(CalcWord.assign)          return true        }        break      case '>':        if (readch('=')) {          readch()          CalcWord.ge.line = line          tokens.add(CalcWord.ge)          return true        }        break      case '<':        if (readch('=')) {          readch()          CalcWord.le.line = line          tokens.add(CalcWord.le)          return true        }        break      case '!':        if (readch('=')) {          readch()          CalcWord.ne.line = line          tokens.add(CalcWord.ne)          return true        }        break    }    return false  }    /*下面开始分割关键字，标识符等信息*/  public Token scan() throws IOException {    Token tok    while (character == ' ')      readch()    if (isDigit() || isSign() || isLetter()) {      tok = tokens.get(tokens.size() - 1)    } else {      tok = new Token(character)      printError(tok)    }    return tok  }}

---