编译原理词法分析 java简单实现

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222

package com.csray;   import java.io.BufferedReader; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException;   public class LexicalAnalysis {     static String id;     public static void main(String[] args) throws IOException{         LexicalAnalysis la = new LexicalAnalysis();         String context = //la.BufferedReaderDemo                             //("C:"+System.getProperty("file.separator")+"Users"+System.getProperty("file.separator")+"Administrator"+System.getProperty("file.separator")+"Desktop"+System.getProperty("file.separator")+"Lexical");                         la.BufferedReaderDemo("C:\\Users\\Administrator\\Desktop\\Lexical\\lexical.c");         System.out.println(context);                   for(int i = 0; i < context.length();){             char nowc = context.charAt(i);             //System.out.println(nowc);             if(nowc == ' ' || nowc == '\n' || nowc == '\t'){                 id = "illegalCharacter";                 ++i;             }else if(isAlpha(nowc)){                 i = alphaProcess(context, nowc, i);             } else if(isDigit(nowc)){                 i = digitProcess(context, nowc, i);                 //i++;             } else {                 i = otherProcess(context, nowc, i);                 //i++;             }         }     }           //read the lexical.c file to String     public String BufferedReaderDemo(String path) throws IOException{         File file = new File(path);         if(!file.exists() || file.isDirectory())             throw new FileNotFoundException();                   BufferedReader br = new BufferedReader(new FileReader(file));         String tmp = null;         StringBuffer sbuff = new StringBuffer();         tmp = br.readLine();         while(tmp != null){             sbuff.append(tmp+" ");             tmp = br.readLine();         }         return sbuff.toString();     }           //alphaProcess     public static int alphaProcess(String context, char c, int i){         StringBuffer word = new StringBuffer();         while((isAlpha(c)) || (isDigit(c)) || c == '_'){             word.append(c);             c = context.charAt(++i);         }         //System.out.println(word.toString());                   //check this word if or not a keyword         if(checkKeyword(word.toString())){             id = "isKeyword";             System.out.println("( "+ word.toString() + ", " + id +" )");         } else {             id = "isCommonWord";             System.out.println("( "+ word.toString() + ", " + id +" )");         }                   return i;     }           // checkKeyword     public static boolean checkKeyword(String word){         String keyword = "auto double int struct break else long switch case enum register typedef char "                 + "extern return union const float short unsigned continue for signed void default goto "                 + "sizeof volatile do if while static scnaf printf";         String[] keyWords = keyword.split(" ");         for(int i = 0; i < keyWords.length; ++i){             if(word.equals(keyWords[i])){                 return true;             }         }         return false;     }           // digitProcess     public static int digitProcess(String context, char c, int i){         StringBuffer digit = new StringBuffer();         while(isDigit(c)){             digit.append(c);             c = context.charAt(++i);         }         id = "isDigit";         System.out.println("( "+ digit.toString() + ", " + id + " )");         return i;     }           // otherProcess     public static int otherProcess(String context, char c, int i){         //+ / ( ) { }  += /=  & " "         StringBuffer operator = new StringBuffer();         StringBuffer delimiter = new StringBuffer();         if(c == '+'){             operator.append(c);             id = "isOperator";             c = context.charAt(++i);             if(c == '='){                 operator.append(c);                 System.out.println("( "+ operator + ", " + id + " )");                 return ++i;             }else if(c == '+'){                 operator.append(c);                 System.out.println("( "+ operator + ", " + id + " )");                 return ++i;             }else {                 System.out.println("( "+ operator + ", " + id + " )");                 return --i;             }         } else if(c == '('){             delimiter.append(c);             id = "isDelimiter";             System.out.println("(" + delimiter + ", " + id + " )");             return ++i;         } else if(c == ')'){             delimiter.append(c);             id = "isDelimiter";             System.out.println("(" + delimiter + ", " + id + " )");             return ++i;         }else if(c == '{'){             delimiter.append(c);             id = "isDelimiter";             System.out.println("(" + delimiter + ", " + id + " )");             return ++i;         } else if(c == '}'){             delimiter.append(c);             id = "isDelimiter";             System.out.println("(" + delimiter + ", " + id + " )");             return ++i;         }else if(c == ';'){             delimiter.append(c);             id = "isDelimiter";             System.out.println("(" + delimiter + ", " + id + " )");             return ++i;         }else if(c == '='){             operator.append(c);             id = "isOperator";             c = context.charAt(++i);             if(c == '='){                 operator.append(c);                 System.out.println("( "+ operator + ", " + id + " )");                 return ++i;             }else {                 System.out.println("( "+ operator + ", " + id + " )");                 return i;             }         } else if(c == '/'){             operator.append(c);             c = context.charAt(++i);             if(c == '='){                 operator.append(c);                 id = "isOperator";                 System.out.println("( "+ operator + ", " + id + " )");                 return ++i;             }else if(c == '/'){                 operator.append(c);                 id = "isAnnotation";                 c = context.charAt(++i);                 while(c != ' '){                     operator.append(c);                     c = context.charAt(++i);                 }                 System.out.println("( "+ operator + ", " + id + " )");                 return i;             }         }else if(c == '&'){             operator.append(c);             id = "isOperator";             System.out.println("(" + operator + ", " + id + " )");             return ++i;         }else if(c == '"'){             delimiter.append(c);             id = "isDelimiter";             System.out.println("(" + delimiter + ", " + id + " )");             return ++i;         }else if(c == ','){             delimiter.append(c);             id = "isDelimiter";             System.out.println("(" + delimiter + ", " + id + " )");             return ++i;         }else if(c == '%'){             operator.append(c);             id = "isOperator";             c = context.charAt(++i);             if(c == 'd'){                 operator.append(c);                 System.out.println("(" + operator + ", " + id + " )");                 return ++i;             }                           return --i;         }         return i;     }           //isDigit     public static boolean isDigit(char c){         if(c >= '0' && c <= '9')             return true;         return false;     }           //isAlpha     public static boolean isAlpha(char c){         if(c >= 'A' && c <= 'Z')             return true;         else if(c >= 'a' && c <= 'z')             return true;         return false;     } }

　　实例：

?

1 2 3 4 5 6 7 8 9 10 11

//test int main() {           float nu0_m;     int num = 100;     num++;     scanf("%d", &num);     printf("%d", num);     return 0; }

　　结果：

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

//test int main() {        float nu0_m;    int num = 100;  num++;      scanf("%d", &num);  printf("%d", num);  return 0; } ( //test, isAnnotation ) ( int, isKeyword ) ( main, isCommonWord ) ((, isDelimiter ) (), isDelimiter ) ({, isDelimiter ) ( float, isKeyword ) ( nu0_m, isCommonWord ) (;, isDelimiter ) ( int, isKeyword ) ( num, isCommonWord ) ( =, isOperator ) ( 100, isDigit ) (;, isDelimiter ) ( num, isCommonWord ) ( ++, isOperator ) (;, isDelimiter ) ( scanf, isCommonWord ) ((, isDelimiter ) (", isDelimiter ) (%d, isOperator ) (", isDelimiter ) (,, isDelimiter ) (&, isOperator ) ( num, isCommonWord ) (), isDelimiter ) (;, isDelimiter ) ( printf, isKeyword ) ((, isDelimiter ) (", isDelimiter ) (%d, isOperator ) (", isDelimiter ) (,, isDelimiter ) ( num, isCommonWord ) (), isDelimiter ) (;, isDelimiter ) ( return, isKeyword ) ( 0, isDigit ) (;, isDelimiter ) (}, isDelimiter )