javacc 语义分析

javacc 语义分析

在词法和语法分析的基础上添加语义子程序，并且掌握“拉链”、“回填”操作的原理以及实现；并且针对测试代码，输出四元式序列。

仍然是使用和语法分析相同的MiniC语法作为参考文法。

<程序> ->Type main(){<语句块>*}

<语句块> -> <语句>|{<语句块>*}

<语句> -> <顺序语句>|<条件语句>|<循环语句>

<顺序语句> ->(<声明语句>|<赋值语句>)”;”

<声明语句> ->Type ID,ID,…,ID

<赋值语句> ->ID =<表达式>

<条件语句> ->if(<条件>)<语句块>else<语句块>

<循环语句> ->while(<条件>)<语句块>

<逻辑> -><条件>(<逻辑运算符><条件>)*

<条件> -><表达式>(<关系符><表达式>)?

<表达式> ->//可以使用默认的

<关系符> -><|<=|>|>=|==|!=

<逻辑运算> ->&& | || （包含在逻辑中）

修改.jjt文件中的main方法，使其执行任务是：指定要进行语义分析的源程序，执行语义分析，输出四元式到文件中。

要想好编译程序的结构，除了JavaCC生成的类，还需要哪些辅助类。如四元式类、四元式链表类、自动产生临时变量的类等。这里的四个类都可以使用所给的类，直接添加到项目进行使用。

为了使得输出的四元式子在文件中而不输出语法树，我们可以选择将QTList类中的printQTTable方法进行修改。

 public void printQTTable() {// System.out.println(toString());Iterator itr = QTList.iterator();try {FileWriter fw = new FileWriter("./result.txt",true);BufferedWriter bw = new BufferedWriter(fw);while (itr.hasNext()) {QTInfo tmp = (QTInfo) itr.next();//System.out.println(tmp.toString());bw.write(tmp.toString());bw.newLine();}bw.close();fw.close();} catch (Exception e) {e.printStackTrace();}}

在.jjt文件中添加Minic文法表达式

SimpleNode Start() :{}{Program()//AdditiveExpression(){return jjtThis;}}void Program() ://主程序{}{Type()< MAIN >< LB >< RB >< BLB >(SentenceBlock())*//    (ReturnSentence()//    )< BRB >}void Type() ://类别{}{< INT >| < VOID >| < STRING >| < CHAR >| < DOUBLE >| < FLOAT >}void ReturnSentence()://返回{}{< RETURN >  < SEMICOLON>}​void SentenceBlock() ://语句块{}{Sentence()| < BLB > (SentenceBlock())* < BRB >}void Sentence() ://语句{}{SequenceSentence()| ConditionSentence()| LoopSentence()​}void SequenceSentence() ://顺序语句{}{StateSentence() < SEMICOLON >| AssignSentence() < SEMICOLON >}void StateSentence() ://声明语句{}{Type()Identifier() (< COMMA > Identifier())*}void AssignSentence() ://赋值语句{String str2=null,str1=null;Token op;}{str1 = Identifier()op = "="str2 = Expression(){QTInfo qt = new QTInfo(op.image,str2,"_",str1);qtList.addQTInfo(qt);}}​​​​void ConditionSentence()://条件语句{int QTSize = QTInfo.size;ConditionValue Value = null;}{< IF >< LB >(Value = ifCondition())< RB >{Value.backpatchTrueChain(QTInfo.size+1);}SentenceBlock(){Value.backpatchFalseChain(QTInfo.size+1);}(< ELSE >{QTInfo qt = new QTInfo("J","_","_","T");qtList.addQTInfo(qt);Value.mergeTrue(qt);}SentenceBlock(){Value.backpatchTrueChain(QTInfo.size+1);Value.backpatchFalseChain(QTInfo.size);})?}ConditionValue Condition() ://循环条件{ConditionValue Value = new ConditionValue();String str1 = null,str2 = null;Token op = null; }{str1 = Expression()((op = ">"|op = "<"|op = ">="|op = "<="|op = "!="|op = "||"|op = "&&")str2 = Expression())?{QTInfo qt1 = new QTInfo("J"+op.image,str1,str2,"_");qtList.addQTInfo(qt1);QTInfo qt2 = new QTInfo("J","_","_","_");qtList.addQTInfo(qt2);Value.mergeTrue(qt1);Value.mergeFalse(qt2);return Value;//  QTInfo qt1;//  if(str2 != "")//      qt1 = new QTInfo("J"+op.image,str1,str2,"_");//  else//    qt1 = new QTInfo("Jnz",str1,"_","_");//  qtList.addQTInfo(qt1);//  QTInfo qt2 = new QTInfo("J","_","_","_");//  qtList.addQTInfo(qt2);//  Value.mergeTrue(qt1);//  Value.mergeFalse(qt2);//  return Value;}}ConditionValue ifCondition() ://判定条件{ConditionValue Value = new ConditionValue();String str1 = null,str2 = null;Token op = null;int qtSize = QTInfo.size;}{str1 = Expression()((op = ">"|op = "<"|op = ">="|op = "<="|op = "!="|op = "||"|op = "&&")str2 = Expression())?{​QTInfo qt1;if(op != null) { qt1 = new QTInfo("J"+op.image,str1,str2,QTInfo.size+3);qtList.addQTInfo(qt1);//Value.mergeTrue(qt1);}else { qt1 = new QTInfo("Jnz",str1,"_",QTInfo.size+3);qtList.addQTInfo(qt1);//Value.mergeTrue(qt1);}QTInfo qt2 = new QTInfo("J","_","_","F");qtList.addQTInfo(qt2);Value.mergeFalse(qt2);return Value;}}void LoopSentence()://循环语句{int QTSize = QTInfo.size;ConditionValue Value = null;}{< WHILE >< LB >Value = Condition()< RB >{Value.backpatchTrueChain(QTInfo.size+1);}SentenceBlock(){QTInfo qt = new QTInfo("J","_","_",QTSize+1);qtList.addQTInfo(qt);Value.backpatchFalseChain(QTInfo.size+1);}}String Expression() ://表达式{String str;}{str = AdditiveExpression(){return str;}}​String AdditiveExpression() :{String str1,str2;String newTemp;Token op;}{str1 = MultiplicativeExpression(){newTemp = str1;}((op = "+"| op = "-")str2 = MultiplicativeExpression(){newTemp = VariableNameGenerator.genVariableName();QTInfo qt = new QTInfo(op.image,str1,str2,newTemp);qtList.addQTInfo(qt);str1 = newTemp;})*{return newTemp;}}​String MultiplicativeExpression() :{String str1,str2;String newTemp;Token op;}{str1 = UnaryExpression(){newTemp = str1;}((op = "*"| op = "/"| op = "%")str2 = UnaryExpression(){newTemp = VariableNameGenerator.genVariableName();QTInfo qt = new QTInfo(op.image,str1,str2,newTemp);qtList.addQTInfo(qt);str1 = newTemp;})*{return newTemp;}}​String UnaryExpression() :{String str = null;}{("(" str = Expression() ")"| str = Identifier()| str = Integer()| str = Constant()){return str;}}​​String Identifier() :{Token t = null;}{t = < IDENTIFIER >{return t.image;}}​String Integer() :{Token t = null;}{t = < INTEGER_LITERAL >{return t.image;}}String Constant() :{Token t =null;}{t = < CONSTANT >{return t.image;}}

测试代码和生成的四元式如下：

完整的jjt文件如下：

/*** JJTree template file created by SF JavaCC plugin 1.5.28+ wizard for JavaCC 1.5.0+*/options{static = true;}​PARSER_BEGIN(MyNewGrammar)package byylworkform3;import utils.*;import java.io.FileInputStream;public class MyNewGrammar{static QTList qtList = new QTList();public void printQTList() {qtList.printQTTable();}public static void main(String args []){//    System.out.println("Reading from standard input...");//    System.out.print("Enter an expression like \"1+(2+3)*var;\" :");//    MyNewGrammar input = new MyNewGrammar(System.in);try{//String file = "./text1.txt";String file = "./text2.txt";//String file = "./text3.txt";//String file = "./text4.txt";FileInputStream fin = new FileInputStream(file);MyNewGrammar input = new MyNewGrammar(fin);SimpleNode n = MyNewGrammar.Start();input.printQTList();n.dump("");System.out.println("Thank you.");}catch (Exception e){System.out.println("Oops.");System.out.println(e.getMessage());}}}​PARSER_END(MyNewGrammar)​SKIP :{" "| "\t"| "\n"| "\r"| < "//" (~[ "\n", "\r" ])*("\n"| "\r"| "\r\n") >| < "/*" (~[ "*" ])* "*"(~[ "/" ] (~[ "*" ])* "*")*"/" >}​TOKEN : /* LITERALS */{< INTEGER_LITERAL :< DECIMAL_LITERAL > ([ "l", "L" ])?| < HEX_LITERAL > ([ "l", "L" ])?| < OCTAL_LITERAL > ([ "l", "L" ])? >| < #DECIMAL_LITERAL : [ "1"-"9" ] ([ "0"-"9" ])* >| < #HEX_LITERAL : "0" [ "x", "X" ] ([ "0"-"9", "a"-"f", "A"-"F" ])+ >| < #OCTAL_LITERAL : "0" ([ "0"-"7" ])* >}​TOKEN :{< CONSTANT :(< DIGIT >)+("." (< DIGIT >)+)? >}​TOKEN : /* KEYWORDS */{< MAIN : "main" >|   < INT : "int" >|  < RETURN :"return" >| < IF:"if" >| < ELSE:"else" >| < VOID : "void" >| < DOUBLE:"double" >| < FLOAT:"float" >| < WHILE:"while" >| < DO:"do" >| < FOR:"for" >| < CHAR:"char" >| < STRING:"string" >| < BOOL:"bool" >}​TOKEN: /*OPERATORS*/{< PLUS : "+" >|   < MINUS : "-" >|   < MULTIPLY : "*" >|   < DIVIDE : "/" >| < GD:">" >| < LD:"<" >| < SQRT:"^" >| < EQ:"=" >| < GE:">=" >| < LE:"<=" >| < EQQ:"==" >| < NE:"!=" >| < ANDD:"&&" >| < ORR:"||" >}TOKEN: /* SEPARATER */{< COMMA:"," >| < SEMICOLON:";" >| < LB:"(" >| < RB:")" >| < BLB:"{" >| < BRB:"}" >| < LBB:"[" >| < RBB:"]" >​}TOKEN : /* IDENTIFIERS */{< IDENTIFIER :< LETTER >(< LETTER >| < DIGIT >)* >| < #LETTER : [ "_", "a"-"z", "A"-"Z" ] >| < #DIGIT : [ "0"-"9" ] >}​SimpleNode Start() :{}{Program()//AdditiveExpression(){return jjtThis;}}void Program() ://主程序{}{Type()< MAIN >< LB >< RB >< BLB >(SentenceBlock())*//    (ReturnSentence()//    )< BRB >}void Type() ://类别{}{< INT >| < VOID >| < STRING >| < CHAR >| < DOUBLE >| < FLOAT >}void ReturnSentence()://返回{}{< RETURN >  < SEMICOLON>}​void SentenceBlock() ://语句块{}{Sentence()| < BLB > (SentenceBlock())* < BRB >}void Sentence() ://语句{}{SequenceSentence()| ConditionSentence()| LoopSentence()​}void SequenceSentence() ://顺序语句{}{StateSentence() < SEMICOLON >| AssignSentence() < SEMICOLON >}void StateSentence() ://声明语句{}{Type()Identifier() (< COMMA > Identifier())*}void AssignSentence() ://赋值语句{String str2=null,str1=null;Token op;}{str1 = Identifier()op = "="str2 = Expression(){QTInfo qt = new QTInfo(op.image,str2,"_",str1);qtList.addQTInfo(qt);}}​​​​void ConditionSentence()://条件语句{int QTSize = QTInfo.size;ConditionValue Value = null;}{< IF >< LB >(Value = ifCondition())< RB >{Value.backpatchTrueChain(QTInfo.size+1);}SentenceBlock(){Value.backpatchFalseChain(QTInfo.size+1);}(< ELSE >{QTInfo qt = new QTInfo("J","_","_","T");qtList.addQTInfo(qt);Value.mergeTrue(qt);}SentenceBlock(){Value.backpatchTrueChain(QTInfo.size+1);Value.backpatchFalseChain(QTInfo.size);})?}ConditionValue Condition() ://循环条件{ConditionValue Value = new ConditionValue();String str1 = null,str2 = null;Token op = null; }{str1 = Expression()((op = ">"|op = "<"|op = ">="|op = "<="|op = "!="|op = "||"|op = "&&")str2 = Expression())?{QTInfo qt1 = new QTInfo("J"+op.image,str1,str2,"_");qtList.addQTInfo(qt1);QTInfo qt2 = new QTInfo("J","_","_","_");qtList.addQTInfo(qt2);Value.mergeTrue(qt1);Value.mergeFalse(qt2);return Value;//  QTInfo qt1;//  if(str2 != "")//      qt1 = new QTInfo("J"+op.image,str1,str2,"_");//  else//    qt1 = new QTInfo("Jnz",str1,"_","_");//  qtList.addQTInfo(qt1);//  QTInfo qt2 = new QTInfo("J","_","_","_");//  qtList.addQTInfo(qt2);//  Value.mergeTrue(qt1);//  Value.mergeFalse(qt2);//  return Value;}}ConditionValue ifCondition() ://判定条件{ConditionValue Value = new ConditionValue();String str1 = null,str2 = null;Token op = null;int qtSize = QTInfo.size;}{str1 = Expression()((op = ">"|op = "<"|op = ">="|op = "<="|op = "!="|op = "||"|op = "&&")str2 = Expression())?{​QTInfo qt1;if(op != null) { qt1 = new QTInfo("J"+op.image,str1,str2,QTInfo.size+3);qtList.addQTInfo(qt1);//Value.mergeTrue(qt1);}else { qt1 = new QTInfo("Jnz",str1,"_",QTInfo.size+3);qtList.addQTInfo(qt1);//Value.mergeTrue(qt1);}QTInfo qt2 = new QTInfo("J","_","_","F");qtList.addQTInfo(qt2);Value.mergeFalse(qt2);return Value;}}void LoopSentence()://循环语句{int QTSize = QTInfo.size;ConditionValue Value = null;}{< WHILE >< LB >Value = Condition()< RB >{Value.backpatchTrueChain(QTInfo.size+1);}SentenceBlock(){QTInfo qt = new QTInfo("J","_","_",QTSize+1);qtList.addQTInfo(qt);Value.backpatchFalseChain(QTInfo.size+1);}}String Expression() ://表达式{String str;}{str = AdditiveExpression(){return str;}}​String AdditiveExpression() :{String str1,str2;String newTemp;Token op;}{str1 = MultiplicativeExpression(){newTemp = str1;}((op = "+"| op = "-")str2 = MultiplicativeExpression(){newTemp = VariableNameGenerator.genVariableName();QTInfo qt = new QTInfo(op.image,str1,str2,newTemp);qtList.addQTInfo(qt);str1 = newTemp;})*{return newTemp;}}​String MultiplicativeExpression() :{String str1,str2;String newTemp;Token op;}{str1 = UnaryExpression(){newTemp = str1;}((op = "*"| op = "/"| op = "%")str2 = UnaryExpression(){newTemp = VariableNameGenerator.genVariableName();QTInfo qt = new QTInfo(op.image,str1,str2,newTemp);qtList.addQTInfo(qt);str1 = newTemp;})*{return newTemp;}}​String UnaryExpression() :{String str = null;}{("(" str = Expression() ")"| str = Identifier()| str = Integer()| str = Constant()){return str;}}​​String Identifier() :{Token t = null;}{t = < IDENTIFIER >{return t.image;}}​String Integer() :{Token t = null;}{t = < INTEGER_LITERAL >{return t.image;}}String Constant() :{Token t =null;}{t = < CONSTANT >{return t.image;}}

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