/*
* Copyright 2002-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.expression.spel;
import java.io.PrintStream;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpression;
/**
* Utilities for working with Spring Expressions.
*
* @author Andy Clement
*/
public class SpelUtilities {
/**
* Output an indented representation of the expression syntax tree to the specified output stream.
* @param printStream the output stream to print into
* @param expression the expression to be displayed
*/
public static void printAbstractSyntaxTree(PrintStream printStream, Expression expression) {
printStream.println("===> Expression '" + expression.getExpressionString() + "' - AST start");
printAST(printStream, ((SpelExpression) expression).getAST(), "");
printStream.println("===> Expression '" + expression.getExpressionString() + "' - AST end");
}
/*
* Helper method for printing the AST with indentation
*/
private static void printAST(PrintStream out, SpelNode t, String indent) {
if (t != null) {
StringBuilder sb = new StringBuilder();
sb.append(indent).append(t.getClass().getSimpleName());
sb.append(" value:").append(t.toStringAST());
sb.append(t.getChildCount() < 2 ? "" : " #children:" + t.getChildCount());
out.println(sb.toString());
for (int i = 0; i < t.getChildCount(); i++) {
printAST(out, t.getChild(i), indent + " ");
}
}
}
}