Java And类代码示例

import org.eclipse.rdf4j.query.algebra.And; //导入依赖的package包/类
public static ValueExpr toFilter(ConjunctiveFilterExpr filterExpr) throws FilterConversionException {
	List<FilterExpr> expressions = filterExpr.getExpressions();
	
	if (expressions.size()==2) {
		return new And(expressions.get(0).getExpression(), expressions.get(0).getExpression());
	}
	
	And and = new And();
	and.setLeftArg( expressions.get(0).getExpression() );
	And tmp = and;
	int idx;
	for (idx=1; idx<expressions.size()-1; idx++) {
		And _a = new And();
		_a.setLeftArg( expressions.get(idx).getExpression() );
		tmp.setRightArg(_a);
		tmp = _a;
	}
	tmp.setRightArg( expressions.get(idx).getExpression());
	
	return and;
}
 

import org.eclipse.rdf4j.query.algebra.And; //导入依赖的package包/类
/**
 * add the conjunctive expressions to specified list, has recursive step.
 *
 * @param expr
 * 			the expr, in the best case in CNF
 * @param conjExpr
 * 			the list to which expressions will be added
 */
protected void getConjunctiveExpressions(ValueExpr expr, List<ValueExpr> conjExpr) {
	if (expr instanceof And) {
		And and = (And)expr;
		getConjunctiveExpressions(and.getLeftArg(), conjExpr);
		getConjunctiveExpressions(and.getRightArg(), conjExpr);
	} else
		conjExpr.add(expr);
}
 

import org.eclipse.rdf4j.query.algebra.And; //导入依赖的package包/类
/**
 * returns true if this filter can be used for optimization. Currently no
 * conjunctive or disjunctive expressions are supported.
 * 
 * @param e
 * @return
 */
protected boolean isCompatibleExpr(ValueExpr e) {
	
	if (e instanceof And || e instanceof Or) {
		return false;
	}
	
	if (e instanceof Not) {
		return isCompatibleExpr( ((Not)e).getArg() );
	}
	
	return true;
}
 

import org.eclipse.rdf4j.query.algebra.And; //导入依赖的package包/类
/**
 * @inheritDoc
 */
@Override
public void meet(And theAnd)
        throws Exception
{
    binaryMeet("&&", theAnd);
}
 

import org.eclipse.rdf4j.query.algebra.And; //导入依赖的package包/类
@Override
public void meet(Filter filter)  {
	
	if (filter.getArg() instanceof EmptyResult) {
		log.debug("Argument of filter expression does not yield results at the provided sources, replacing Filter node.");
		filter.replaceWith(filter.getArg());
		return;
	}
				
	/*
	 * TODO idea:
	 * if we have a FILTER such as ?s='a' OR ?s='b' OR ?s='c' handle this appropriately
	 */
	
	ValueExpr valueExpr = filter.getCondition();
	
	/*
	 * TODO transform condition into some normal form, e.g. CNF
	 */
	
	// determine conjunctive expressions
	List<ValueExpr> conjunctiveExpressions = new ArrayList<ValueExpr>();
	getConjunctiveExpressions(valueExpr, conjunctiveExpressions);
			
	FilterExprInsertVisitor filterExprVst = new FilterExprInsertVisitor();
	List<ValueExpr> remainingExpr = new ArrayList<ValueExpr>(conjunctiveExpressions.size());
	
	for (ValueExpr cond : conjunctiveExpressions) {
		
		/*
		 * Determine if this filter is applicable for optimization.
		 * Currently only leaf expressions are applicable, i.e.
		 * not combined expressions.
		 */
		if (isCompatibleExpr(cond)) {
						
			HashSet<String> exprVars = new VarFinder().findVars(cond);
			FilterExpr filterExpr = new FilterExpr(cond, exprVars);
			
			filterExprVst.initialize(filterExpr);
			filter.getArg().visit(filterExprVst);
			
			// if the filter expr. is handled in the stmt we do not have to keep it
			if (filterExprVst.canRemove())
				continue;
			
			remainingExpr.add(filterExpr.getExpression());
			
		} else {
			remainingExpr.add(cond);
		}
		
	}
	
	if (remainingExpr.size()==0) {
		filter.replaceWith(filter.getArg()); 	// remove the filter			
	}
	
	else if (remainingExpr.size()==1) {
		filter.setCondition(remainingExpr.get(0));		// just apply the remaining condition
	}
	
	else {
		
		// construct conjunctive value expr
		And root = new And();	
		root.setLeftArg(remainingExpr.get(0));
		And tmp = root;
		for (int i=1; i<remainingExpr.size()-1; i++) {
			And _a = new And();
			_a.setLeftArg(remainingExpr.get(i));
			tmp.setRightArg(_a);
			tmp = _a;				
		}
		tmp.setRightArg(remainingExpr.get(remainingExpr.size()-1));
		
		filter.setCondition(root);
	}
	
}
 

import org.eclipse.rdf4j.query.algebra.And; //导入依赖的package包/类
/**
 * Determines which evaluate method to call based on the type of {@link ValueExpr}
 * @param expr the expression to evaluate
 * @param bindings the set of named value bindings the set of named value bindings
 * @return the {@link Value} resulting from the evaluation
 * @throws ValueExprEvaluationException
 * @throws QueryEvaluationException
 */
Value evaluate(ValueExpr expr, BindingSet bindings) throws ValueExprEvaluationException, QueryEvaluationException {
    if (expr instanceof Var) {
        return evaluate((Var) expr, bindings);
    } else if (expr instanceof ValueConstant) {
        return evaluate((ValueConstant) expr, bindings);
    } else if (expr instanceof BNodeGenerator) {
        return evaluate((BNodeGenerator) expr, bindings);
    } else if (expr instanceof Bound) {
        return evaluate((Bound) expr, bindings);
    } else if (expr instanceof Str) {
        return evaluate((Str) expr, bindings);
    } else if (expr instanceof Label) {
        return evaluate((Label) expr, bindings);
    } else if (expr instanceof Lang) {
        return evaluate((Lang) expr, bindings);
    } else if (expr instanceof LangMatches) {
        return evaluate((LangMatches) expr, bindings);
    } else if (expr instanceof Datatype) {
        return evaluate((Datatype) expr, bindings);
    } else if (expr instanceof Namespace) {
        return evaluate((Namespace) expr, bindings);
    } else if (expr instanceof LocalName) {
        return evaluate((LocalName) expr, bindings);
    } else if (expr instanceof IsResource) {
        return evaluate((IsResource) expr, bindings);
    } else if (expr instanceof IsURI) {
        return evaluate((IsURI) expr, bindings);
    } else if (expr instanceof IsBNode) {
        return evaluate((IsBNode) expr, bindings);
    } else if (expr instanceof IsLiteral) {
        return evaluate((IsLiteral) expr, bindings);
    } else if (expr instanceof IsNumeric) {
        return evaluate((IsNumeric) expr, bindings);
    } else if (expr instanceof IRIFunction) {
        return evaluate((IRIFunction) expr, bindings);
    } else if (expr instanceof Regex) {
        return evaluate((Regex) expr, bindings);
    } else if (expr instanceof Coalesce) {
        return evaluate((Coalesce) expr, bindings);
    } else if (expr instanceof Like) {
        return evaluate((Like) expr, bindings);
    } else if (expr instanceof FunctionCall) {
        return evaluate((FunctionCall) expr, bindings);
    } else if (expr instanceof And) {
        return evaluate((And) expr, bindings);
    } else if (expr instanceof Or) {
        return evaluate((Or) expr, bindings);
    } else if (expr instanceof Not) {
        return evaluate((Not) expr, bindings);
    } else if (expr instanceof SameTerm) {
        return evaluate((SameTerm) expr, bindings);
    } else if (expr instanceof Compare) {
        return evaluate((Compare) expr, bindings);
    } else if (expr instanceof MathExpr) {
        return evaluate((MathExpr) expr, bindings);
    } else if (expr instanceof In) {
        return evaluate((In) expr, bindings);
    } else if (expr instanceof CompareAny) {
        return evaluate((CompareAny) expr, bindings);
    } else if (expr instanceof CompareAll) {
        return evaluate((CompareAll) expr, bindings);
    } else if (expr instanceof Exists) {
        return evaluate((Exists) expr, bindings);
    } else if (expr instanceof If) {
        return evaluate((If) expr, bindings);
    } else if (expr instanceof ListMemberOperator) {
        return evaluate((ListMemberOperator) expr, bindings);
    } else if (expr == null) {
        throw new IllegalArgumentException("expr must not be null");
    } else {
        throw new QueryEvaluationException("Unsupported value expr type: " + expr.getClass());
    }
}