C++ EvalState类代码示例

int IdentifierExp::eval(EvalState & state) {
	if (!state.isDefined(name)) {
		cout << "VARIABLE NOT DEFINED" << endl;
		error("");
	}
	return state.getValue(name);
}

bool ExprTree::
Evaluate( Value& val, ExprTree*& sig ) const
{
	EvalState 	state;

	state.SetScopes( parentScope );
	return( Evaluate( state, val, sig  ) );
}

bool ExprTree::
Flatten( Value& val, ExprTree *&tree ) const
{
	EvalState state;

	state.SetScopes( parentScope );
	return( Flatten( state, val, tree ) );
}

void runProgram(Program & program, EvalState & state) {
    int lineNumber = program.getFirstLineNumber();
    while (lineNumber != -1) {
        Statement * stmt = program.getParsedStatement(lineNumber);
        state.setCurrentLine(program.getNextLineNumber(lineNumber));
        stmt->execute(state);
        lineNumber = state.getCurrentLine();
    }
}

  int
  classad_get_string_list_attribute (classad_context cad, 
                                     const char *attribute_name, 
                                     char ***result)
   {
    if (cad == NULL) return C_CLASSAD_INVALID_CONTEXT;

    int n_results = 0;
    (*result) = (char **)malloc(sizeof(char **));
    if ((*result) == NULL) return C_CLASSAD_OUT_OF_MEMORY;

    (*result)[0] = NULL;

    ClassAd *ad = (ClassAd *)cad;

    Value vl;
    ad->EvaluateAttr(attribute_name, vl);

    const ExprList *et_result;
    if (vl.IsListValue(et_result)) 
     {
      std::vector<ExprTree*> ads;
      et_result->GetComponents(ads);
      // Get string values.
      for(std::vector<ExprTree*>::const_iterator it = ads.begin();
          it != ads.end(); ++it) 
       {
        if ((*it)->GetKind() == ExprTree::LITERAL_NODE) 
         {
          Value v;
          EvalState       state;
          state.SetScopes( ad );

          (*it)->Evaluate(state,v);

          std::string res_str;
          if (v.IsStringValue( res_str ))
           {
            // add string value to result, which is a NULL-terminated
            // string array.
            n_results++;
            (*result) = (char **)realloc(*result, (n_results+1)*sizeof(char *));
            if ((*result) == NULL) return C_CLASSAD_OUT_OF_MEMORY;
            (*result)[n_results-1] = strdup(res_str.c_str());
            (*result)[n_results] = NULL;
           }
         }
       }
      return C_CLASSAD_NO_ERROR;
     }
    
    // The result list needs to be freed on success only.
    classad_free_string_list(*result);
    (*result) = NULL;
    return C_CLASSAD_VALUE_NOT_FOUND;
   }

void IfStmt::execute(EvalState & state) {
    if(op == "=") {
        if (lhsExp->eval(state) == rhsExp->eval(state)) {
            state.setCurrentLine(lineNumber);
        }
    } else if (op == ">") {
        if(lhsExp->eval(state) > rhsExp->eval(state))
            state.setCurrentLine(lineNumber);
    } else {
        if(lhsExp->eval(state) < rhsExp->eval(state))
            state.setCurrentLine(lineNumber);
    }
}

void processLine(string line, Program & program, EvalState & state) {
	TokenScanner scanner;
	scanner.ignoreWhitespace();
	scanner.scanNumbers();
	scanner.setInput(line);
    string str=scanner.nextToken();
    if (scanner.getTokenType(str)==NUMBER) {
		
        int lineNumber=stringToInteger(str);
        string token=scanner.nextToken();
        scanner.saveToken(token);
        if (token!="") {
            program.addSourceLine(lineNumber, line);
            program.setParsedStatement(lineNumber, parseStatement(scanner));
        }
        else {
            program.removeSourceLine(lineNumber);
        }
		
		
    }
	
    else if (str=="LIST") {
        for (int i=program.getFirstLineNumber(); i!=-1; i=program.getNextLineNumber(i)) {
            cout << program.getSourceLine(i)<<endl;
        }
    }
    else if (str=="CLEAR") {
        program.clear();
    }
    else if(str=="QUIT") exit(0);
    else if (str=="HELP") cout<<"This is a minimal BASIC interpreter."<<endl;
	
    else if (str=="RUN") {
        int currentLine=program.getFirstLineNumber();
        state.setCurrentLine(currentLine);
        while (currentLine!=-1) {                       
            program.getParsedStatement(currentLine)->execute(state);
			
            if(currentLine!=state.getCurrentLine()) {
                currentLine=state.getCurrentLine();
            }
            else {
                currentLine=program.getNextLineNumber(currentLine);
                state.setCurrentLine(currentLine);
            }
        }
    }
	
	
}

void IfStmt::execute(EvalState &state) {
    if (op == "=") {
        if (lhs->eval(state) == rhs->eval(state))
            state.setCurrentLine(nextLine);
    }
    else if (op == ">") {
        if (lhs->eval(state) > rhs->eval(state))
            state.setCurrentLine(nextLine);
    }
    else if (op == "<") {
        if (lhs->eval(state) < rhs->eval(state))
            state.setCurrentLine(nextLine);
    }
}

/*
 * Function: processLine
 * Usage: processLine(line, program, state);
 * -----------------------------------------
 * Processes a single line entered by the user.  In this version,
 * the implementation does exactly what the interpreter program
 * does in Chapter 19: read a line, parse it as an expression,
 * and then print the result.  In your implementation, you will
 * need to replace this method with one that can respond correctly
 * when the user enters a program line (which begins with a number)
 * or one of the BASIC commands, such as LIST or RUN.
 */
void processLine(string line, Program & program, EvalState & state) {
   TokenScanner scanner;
   scanner.ignoreWhitespace();
   scanner.scanNumbers();
   scanner.setInput(line);
   string token=scanner.nextToken();
   TokenType type=scanner.getTokenType(token);
   int lineNumb;
   int priorLineNumb;
   if(type==NUMBER){
     if(scanner.hasMoreTokens()){
       program.addSourceLine(stringToInteger(token),line);
       Statement *stmt=parseStatement(scanner); 
       program.setParsedStatement(stringToInteger(token),stmt);  //link statement to line number
     }
     else
       program.removeSourceLine(stringToInteger(token));
   }
   if(type==WORD){
     if(token=="LIST"){
       lineNumb=program.getFirstLineNumber();
       while(lineNumb!=-1){
	 cout<<program.getSourceLine(lineNumb)<<endl;
	 lineNumb=program.getNextLineNumber(lineNumb);
       }
     }
     else if(token=="RUN"){
       state.setCurrentLine(program.getFirstLineNumber());
       lineNumb=state.getCurrentLine();
       while(lineNumb!=-1){	 
	 if(program.hasLineNumber(lineNumb)==false)
	   error("Invalid line reference at program line "+integerToString(priorLineNumb));
	 Statement *stmt=program.getParsedStatement(lineNumb);
	 state.setCurrentLine(program.getNextLineNumber(lineNumb));
	 stmt->execute(state);
	 priorLineNumb=lineNumb;
	 lineNumb=state.getCurrentLine();
       }
     }
     else if(token=="CLEAR"){
       program.clear();
     }
     else if(token=="HELP"){
       cout<<"Minimal Basic Statements"<<endl; 
       cout<<"REM   This statement used for comments"<<endl;
       cout<<"LET   This statement is BASIC's assigment statement"<<endl;
       cout<<"PRINT In minimal BASIC, the PRINT statement has the form: "<<endl;
       cout<<"         PRINT exp"<<endl;
       cout<<"      where exp is an expression."<<endl;
       cout<<"INPUT In the minimal version of the BASIC interpreter, the INPUT statement has the form:"<<endl;
       cout<<"         INPUT var"<<endl;
       cout<<"      where var is a variable read in from the user"<<endl;
       cout<<"GOTO  This statement has the syntax"<<endl;
       cout<<"         GOTO n"<<endl;
       cout<<"      which forces the program to continue from line n instead of continuing with the next statement"<<endl;
       cout<<"IF    This statement provides conditional control. The syntax for this statement is: "<<endl;
       cout<<"      IF exp1 op exp2 THEN n"<<endl;
       cout<<"      where exp1 and exp2 are expressions and op is one of the conditional operators =, <, or >."<<endl;
       cout<<"END   This statment marks the end of the program."<<endl;
       cout<<"Commands to control the BASIC interpreter"<<endl;
       cout<<"RUN   This command starts program execution beginning at the lowest-numbered line. "<<endl;
       cout<<"LIST  This command lists the steps in the program in numerical sequence."<<endl;
       cout<<"CLEAR This command deletes the program so the user can start entering a new one."<<endl;
       cout<<"HELP  This command provides a simple help message describing the interpreter."<<endl;
       cout<<"QUIT  Typing QUIT exits from the BASIC interpreter by calling exit(0)."<<endl;	 
     }
     else if(token=="QUIT"){
       exit(0);
     }
     else
       cout<<"Invalid command"<<endl;     
   }
}

int AttributeReference::
FindExpr(EvalState &state, ExprTree *&tree, ExprTree *&sig, bool wantSig) const
{
	const ClassAd *current=NULL;
	const ExprList *adList = NULL;
	Value	val;
	bool	rval;

	sig = NULL;

	// establish starting point for search
	if( expr == NULL ) {
		// "attr" and ".attr"
		current = absolute ? state.rootAd : state.curAd;
		if( absolute && ( current == NULL ) ) {	// NAC - circularity so no root
			return EVAL_FAIL;					// NAC
		}										// NAC
	} else {
		// "expr.attr"
		rval=wantSig?expr->Evaluate(state,val,sig):expr->Evaluate(state,val);
		if( !rval ) {
			return( EVAL_FAIL );
		}

		if( val.IsUndefinedValue( ) ) {
			return( EVAL_UNDEF );
		} else if( val.IsErrorValue( ) ) {
			return( EVAL_ERROR );
		}
		
		if( !val.IsClassAdValue( current ) && !val.IsListValue( adList ) ) {
			return( EVAL_ERROR );
		}
	}

	if( val.IsListValue( ) ) {
		vector< ExprTree *> eVector;
		const ExprTree *currExpr;
			// iterate through exprList and apply attribute reference
			// to each exprTree
		for(ExprListIterator itr(adList);!itr.IsAfterLast( );itr.NextExpr( )){
 			currExpr = itr.CurrentExpr( );
			if( currExpr == NULL ) {
				return( EVAL_FAIL );
			} else {
				AttributeReference *attrRef = NULL;
				attrRef = MakeAttributeReference( currExpr->Copy( ),
												  attributeStr,
												  false );
				val.Clear( );
					// Create new EvalState, within this scope, because
					// attrRef is only temporary, so we do not want to
					// cache the evaluated result in the outer state object.
				EvalState tstate;
				tstate.SetScopes(state.curAd);
				rval = wantSig ? attrRef->Evaluate( tstate, val, sig )
					: attrRef->Evaluate( tstate, val );
				delete attrRef;
				if( !rval ) {
					return( EVAL_FAIL );
				}
				
				ClassAd *evaledAd = NULL;
				const ExprList *evaledList = NULL;
				if( val.IsClassAdValue( evaledAd ) ) {
					eVector.push_back( evaledAd );
					continue;
				}
				else if( val.IsListValue( evaledList ) ) {
					eVector.push_back( evaledList->Copy( ) );
					continue;
				}
				else {
					eVector.push_back( Literal::MakeLiteral( val ) );
				}
			}
		}
		tree = ExprList::MakeExprList( eVector );
		ClassAd *newRoot = new ClassAd( );
		((ExprList*)tree)->SetParentScope( newRoot );
		return EVAL_OK;
	}
		// lookup with scope; this may side-affect state		

		/* ClassAd::alternateScope is intended for transitioning Condor from
		 * old to new ClassAds. It allows unscoped attribute references
		 * in expressions that can't be found in the local scope to be
		 * looked for in an alternate scope. In Condor, the alternate
		 * scope is the Target ad in matchmaking.
		 * Expect alternateScope to be removed from a future release.
		 */
	if (!current) { return EVAL_UNDEF; }
	int rc = current->LookupInScope( attributeStr, tree, state );
	if ( !expr && !absolute && rc == EVAL_UNDEF && current->alternateScope ) {
		rc = current->alternateScope->LookupInScope( attributeStr, tree, state );
	}
	return rc;
}

int IdentifierExp::eval(EvalState & state) {
   if (!state.isDefined(name)) error("VARIABLE NOT DEFINED");
   return state.getValue(name);
}

  int
  unwind_attributes(classad_context cad, char *attribute_name, char ***results) 
   {
    if (cad == NULL) return C_CLASSAD_INVALID_CONTEXT;
    if ((results == NULL) || (attribute_name == NULL))
      return C_CLASSAD_INVALID_ARG;

    ClassAd *ad = (ClassAd *)cad;

    ExprTree *et;
    bool need_to_delete_et = false;

    et = ad->Lookup(attribute_name);
    if (et == NULL)
     {
      return C_CLASSAD_VALUE_NOT_FOUND;
     }

    if (et->GetKind() == ExprTree::LITERAL_NODE)
     {
      // The attribute was probably stringified. Try to parse it.
      Value v;
      EvalState state;
      state.SetScopes( ad );

      et->Evaluate(state,v);
      std::string strres;

      if (v.IsStringValue( strres ))
       {
        ClassAdParser parser;
        et=NULL;
        parser.ParseExpression(strres,et);
        need_to_delete_et = true;
       }
     }

    BinaryOpUnwind res_unp; 
    std::string result;
    res_unp.Unparse(result, et);
    int n_results;
    if (*results == NULL)
     {
      n_results = 0;
      (*results) = (char **)malloc(sizeof(char **));
      if ((*results) == NULL) return C_CLASSAD_OUT_OF_MEMORY;
      (*results)[0] = NULL;
     }
    else
     {
      for (n_results = 0; (*results)[n_results] != NULL; n_results++) /*NOP*/ ;
     }

    std::vector<std::string>::const_iterator it;
    for (it = res_unp.m_unwind_output.begin(); 
         it != res_unp.m_unwind_output.end(); ++it)
     {
      n_results++;
      char **new_results;
      new_results = (char **)realloc(*results, (n_results+1)*sizeof(char *));
      if (new_results == NULL)
       {
        if (need_to_delete_et) delete et;
        return C_CLASSAD_OUT_OF_MEMORY;
       }
      (*results) = new_results;
      (*results)[n_results] = NULL;
      (*results)[n_results-1] = strdup(it->c_str());
      if (((*results)[n_results-1]) == NULL)
       {
        if (need_to_delete_et) delete et;
        return C_CLASSAD_OUT_OF_MEMORY;
       }
     }

    if (need_to_delete_et) delete et;
    return C_CLASSAD_NO_ERROR;
   }

int IdentifierExp::eval(EvalState & state) {
   if (!state.isDefined(name)) error(name + " is undefined");
   return state.getValue(name);
}