编译原理实验三实验报告.doc

实 验 报 告 第 1 页专业_软件工程_ 班级_2_ 姓名_71李飞强77欧艺欣81吴文浩 89张泰鑫_ 组别:第四组实验日期：2014年 3 月 26 日 报告退发 (订正 、 重做) 课程 编译原理 实验名称 递归下降的预测分析 一、实验目的1. 学会用语法图来形式化地描述一门简单的语言；2. 掌握递归下降的预测分析；3. 掌握词法分析。二、实验环境Visual Studio 或 GCC 或Eclipse三、实验内容、步骤和结果分析实验内容：请基于递归下降的分析方法(教材P55页)，编写一个“语法图.doc”所对应语言的语法分析器。该语法分析器能读入一个源代码文件（如“test.c”文件所示），并判断其中的源代码是否符合“语法图.doc”的规定。如果符合，打印出Yes；如果不符合，打印出No。（所用编程语言不限）C语言版:#include#include#include#define MaxIdLen 20 /标志符的最大长度#define KeyWordsCount 5 /该语言拥有的关键字个数#define BoolValueCount 2/bool类型可能取值的个数#define SymTypeCount 17/symType个数 enum SymType/枚举OR ,/或AND,/与LP,/左括号RP,/右括号ID,/标志符ASSIGN,/赋值LB,/左大括号RB,/右大括号COMMA,/逗号SEMICOLON,/分号UNDEFINED,/未定义BOOLVALUE,/bool类型的值IF,/ifELSE,/elseWHILE,/whilePRINTF,/printfBOOL,/bool;enum boolValueTRUE， FALSE,;/关键字static char * keywordsKeyWordsCount = if,else,while,printf,bool,;/关键字对应类别static int keyTypeKeyWordsCount = IF,ELSE,WHILE,PRINTF,BOOL,;/static char * boolvalueBoolValueCount=true,false，;static int boolValueTypeBoolValueCount=TRUE,FALSE,; char ch= ; /当前字符char idMaxIdLen+1;/当前符号串int token;/当前记号(的类型)int value;/当前记号的值FILE * fp;/用来打开要识别的源代码文件int lineNum=1;/要识别的代码行数bool isPass = false ;/判断识别的代码是否全部合法 void getToken();void program();void program();void statement();void definition();void term();void factor();void expression();void match(int t); void main() fopen_s(&fp,D:test.c,r);getToken();program();if(isPass)printf(Yn);else printf(Nn);fclose(fp);/*lexical*/ int getKeyWord(char * str)for(int i=0;iKeyWordsCount;i+)if(strcmp(str,keywordsi)=0) return keyTypei;return UNDEFINED;int getBoolValue(char* str) for(int i=0;i=A&ch=a&ch=0&ch=9;void nextChar() ch = fgetc(fp); void getToken() while(ch= |ch=t|ch=r|ch=n)if(ch = n)lineNum+; nextChar();if(isLetter(ch)int index=0;idindex+ = ch;nextChar();while(isLetter(ch) | isDigit(ch)if(indexMaxIdLen)idindex+ = ch;nextChar();else/coutidentifier is too long. + type);if (lookahead.tokenType.equals(type) lookahead = lexer.getToken(); else error(NO);/ 否则报错private void error(String str) / out.println(str);System.out.println(str);System.exit(-1);/* * program:程序 definition-statement- */public void program() definition();/定义statement();/ 声明/ definition:定义/* * bool-id-=-expression-; */public void definition() do match(TokenType.BOOLEAN);match(TokenType.ID);match(TokenType.EQUAL);expression();match(TokenType.SEMICOLON);/ 匹配分号 while (lookahead.isBoolean();/ statement:声明public void statement() if (lookahead.isIf() / -if-(-expression-)-statement-match(TokenType.IF);match(TokenType.LeftP);expression();match(TokenType.RightP);statement();if (lookahead.isElse() /缺陷：如果用全部代码测试时，程序走到这里停止了，while循环后的语句将不能执行！match(TokenType.ELSE);statement(); else else if (lookahead.isWhile() match(TokenType.WHILE);match(TokenType.LeftP);expression();match(TokenType.RightP);statement(); else if (lookahead.isPrint() match(TokenType.PRINT);match(TokenType.LeftP);expression();while (lookahead.isComma() match(TokenType.COMMA);expression();match(TokenType.RightP);match(TokenType.SEMICOLON); else if (lookahead.isSemicolon() / ;match(TokenType.SEMICOLON); else if (lookahead.isLeftBrace() match(TokenType.LeftBrace);statement(); while (!lookahead.isRightBrace() | lookahead.isId() )/必须加入lookahead.isId()否则a = false;运行不出来（语法图缺陷吧！） statement(); match(TokenType.RightBrace); else if (lookahead.isId() / id = expression;/System.out.println(+);match(TokenType.ID);match(TokenType.EQUAL);expression();match(TokenType.SEMICOLON); else /* * expression:式子 -term()-(-|-term()-); */private void expression() term();while (lookahead.isOr() / 如果是|就继续循环处理match(TokenType.OR);term();/* * term:项 Factor(); While(match(&) Factor(); */private void term() factor();while (lookahead.isAnd() / 判断是&就继续进行match(TokenType.AND);factor();/* * -(-expression-)- * -true- * -false- * -id- */private void factor() if (lookahead.isTrue() match(TokenType.TRUE); else if (lookahead.isLeftP() match(TokenType.LeftP);expression();match(TokenType.RightP); else if (lookahead.isFalse() match(TokenType.FALSE); else if (lookahead.isId() match(TokenType.ID); else/* * 获取下一个Token */public Token getToken() int value = 0;char cur;while (true) if (index = src.length()return Token.EOF;else / 取下一字符cur = next();/ 如果下一个字符是空白，继续读取字符if (this.isBlank(cur)continue;else if (this.isAlpha(cur) / 字符缓冲 区StringBuilder buffer = new StringBuilder();buffer.append(cur);while (isAlpha(char) peek() buffer.append(next();if (buffer.toString().equals(KeyWord.BOOLEAN) return new Token(TokenType.BOOLEAN, buffer.toString(); else if (buffer.toString().equals(KeyWord.FALSE) return new Token(TokenType.FALSE, buffer.toString(); else if (buffer.toString().equals(KeyWord.TRUE) return new Token(TokenType.TRUE, buffer.toString(); else if (buffer.toString().equals(KeyWord.IF) return new Token(TokenType.IF, buffer.toString(); else if (buffer.toString().equals(KeyWord.WHILE) return new Token(TokenType.WHILE, buffer.toString(); else if (buffer.toString().equals(KeyWord.PRINT) return new Token(TokenType.PRINT, buffer.toString(); else return new Token(TokenType.ID, buffer.toString(); else if (cur = ,) return Token.COMMA; else if (cur = () return Token.LeftP; else if (cur = ) return Token.RightP; else if (cur = | & next() = |) return Token.OR;/ 或者 else if (cur = & & next() = &) return Token.AND;/ 且 else if (cur = =) return Token.EQUAL; else if (cur = ;) return Token.SEMICOLON;/ 分号 else if (cur = ) / 左大括号return Token.LeftBrace; else if (cur = ) return Token.RightBrace; else if (cur = n) line+; else this.error();运行这个测试代码的截图：String src = boolean a = true;boolean b = false;boolean c =