/**
* 弹出(组装好的)操作符
*
* @return 操作符
*/
Operator popOperator() {
if (operatorStack.isEmpty())
throw I18nExceptionFactory.createIllegalStateException(
"ExpressionReducer.miss.left.parenthesis");
Operator operator = (Operator) operatorStack.pop();
// 从参数栈弹出所需参数组装操作表达式
if (operator instanceof BinaryOperator) {
BinaryOperator binaryOperator = (BinaryOperator) operator;
if (parameterStack.isEmpty())
throw I18nExceptionFactory.createIllegalStateException(
"ExpressionReducer.operator.miss.parameter");
Expression rightParameter = (Expression) parameterStack.pop(); // 调整参数顺序
if (parameterStack.isEmpty())
throw I18nExceptionFactory.createIllegalStateException(
"ExpressionReducer.operator.miss.parameter");
Expression leftParameter = (Expression) parameterStack.pop();
parameterStack.push(
populateBinaryOperator(
(BinaryOperatorImpl) binaryOperator,
leftParameter,
rightParameter)); // 将组装好的表达式作为参数压入
} else if (operator instanceof UnaryOperator) {
UnaryOperator unaryOperator = (UnaryOperator) operator;
if (parameterStack.isEmpty())
throw I18nExceptionFactory.createIllegalStateException(
"ExpressionReducer.operator.miss.parameter");
Expression parameter = (Expression) parameterStack.pop();
parameterStack.push(
populateUnaryOperator((UnaryOperatorImpl) unaryOperator, parameter)); // 将组装好的表达式作为参数压入
}
return operator;
}
/**
* 弹出(最后的)结果
*
* @return 结果
*/
Expression popResult() {
while (!operatorStack.isEmpty()) {
Operator operator = popOperator(); // 弹出栈中所有操作符
if (operator == Parenthesis.LEFT_PARENTHESIS)
throw I18nExceptionFactory.createIllegalStateException(
"ExpressionReducer.miss.right.parenthesis");
}
Expression result = (Expression) parameterStack.pop();
Assert.assertTrue(
parameterStack.isEmpty(), "ExpressionReducer.operator.miss.parameter"); // 后验条件
return result;
}
/**
* 处理属性
*
* @param propertyName 属性或类名
* @return 类元或类静态属性值
* @throws Exception 类或属性不存在时抛出
*/
public Object doEvaluateProperties(String propertyName) throws Exception {
String className = propertyName;
Class clazz = ClassUtils.safeForName(className);
Stack properties = new LinkedStack();
int index;
while (clazz == null && (index = className.lastIndexOf('.')) != -1) {
properties.push(className.substring(index + 1));
className = className.substring(0, index);
clazz = ClassUtils.safeForName(className);
}
Assert.assertNotNull(clazz, "不存在类:{0}", new Object[] {propertyName});
Object result = convertResult(clazz);
while (!properties.isEmpty()) {
result = dotBinaryOperatorHandler.doEvaluate(result, properties.pop());
}
return result;
}
/**
* 处理函数
*
* @param function 函数
* @return 函数值
* @throws Exception 类或属性不存在时抛出
*/
public Object doEvaluateFunction(Function function) throws Exception {
String name = function.getName();
int index = name.lastIndexOf('.');
Assert.assertTrue(index != -1, "不存在类:{0}", new Object[] {name});
String propertyName = name.substring(0, index); // 最点号前的作为类名或静态属性名
String className = propertyName;
Function callFunction =
new Function(name.substring(index + 1), function.getArgument()); // 将点号最后一截作为静态函数名
Class clazz = ClassUtils.safeForName(className);
Stack properties = new LinkedStack();
while (clazz == null && (index = className.lastIndexOf('.')) != -1) {
properties.push(className.substring(index + 1));
className = className.substring(0, index);
clazz = ClassUtils.safeForName(className);
}
Assert.assertNotNull(clazz, "不存在类:{0}", new Object[] {propertyName});
Object result = convertResult(clazz);
while (!properties.isEmpty()) {
result = dotBinaryOperatorHandler.doEvaluate(result, properties.pop());
}
return dotBinaryOperatorHandler.doEvaluate(result, callFunction);
}
/**
* 窥取栈顶操作符
*
* @return 操作符
*/
Operator peekOperator() {
if (operatorStack.isEmpty()) return null;
return (Operator) operatorStack.peek();
}