leap.lang.el.spel.SPEL Maven / Gradle / Ivy
/*
* Copyright 2014 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 leap.lang.el.spel;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import leap.lang.Objects2;
import leap.lang.Strings;
import leap.lang.el.DefaultElParseContext;
import leap.lang.el.ElException;
import leap.lang.el.ElFunction;
import leap.lang.el.ElParseContext;
import leap.lang.el.ElParseException;
import leap.lang.el.spel.parser.Parser;
import leap.lang.expression.CompositeExpression;
import leap.lang.expression.Expression;
import leap.lang.expression.ExpressionException;
/**
* SPEL means simple el
*/
public class SPEL {
private static final Map functions = new ConcurrentHashMap<>();
private static final DefaultElParseContext parseContext = new DefaultElParseContext(functions);
public static final String PREFIX = "${";
public static final String SUFFIX = "}";
/**
* Returns the global default parse context object.
*/
public static ElParseContext getDefaultParseContext() {
return parseContext;
}
/**
* Removes the prefix '${' and the suffix '}" in the given string.
*/
public static String removePrefixAndSuffix(String s){
if(null != s && s.startsWith(PREFIX)){
if(!s.endsWith(SUFFIX)) {
throw new IllegalArgumentException("Unclosed expression '" + s + "', must be ends with '}'");
}
return s.substring(2,s.length() - 1);
}
return s;
}
/**
* Returns true if the given string prefix with {@link #PREFIX} and suffix with {@link #SUFFIX}.
*/
public static boolean hasPrefixAndSuffix(String s) {
if(null == s){
return false;
}
s = s.trim();
return s.startsWith(PREFIX) && s.endsWith(SUFFIX);
}
/**
* Parses the string expression to an {@link Expression} object using the default {@link ElParseContext}.
*
*
* The expression must not prefix with '${' and suffix with '}'.
*/
public static SpelExpression createExpression(String expression) throws ElParseException {
return createExpression(parseContext, expression);
}
/**
* Parses the string expression to an {@link Expression} object using the given {@link ElParseContext}.
*
*
* The expression must not prefix with '${' and suffix with '}'.
*/
public static SpelExpression createExpression(ElParseContext context,String expression) throws ElParseException {
return new SpelExpression(Parser.parse(context, expression));
}
/**
* Parses a composite expression to an {@link Expression} object using the default {@link ElParseContext}.
*
*
*
* For example, the composite expression “${firstName} ${lastName}”
* is composed of three EL expressions: eval-expression “${firstName}”,
* literal- expression “ “, and eval-expression “${lastName}”.
*
*
* Once evaluated, the resulting String is then coerced to the expected type.
*/
public static CompositeExpression createCompositeExpression(String s) {
return parseCompositeExpression(parseContext, s);
}
/**
* Parses a composite expression to an {@link Expression} object using the default {@link ElParseContext}.
*
*
*
* For example, the composite expression “${firstName} ${lastName}”
* is composed of three EL expressions: eval-expression “${firstName}”,
* literal- expression “ “, and eval-expression “${lastName}”.
*
*
* Once evaluated, the resulting String is then coerced to the expected type.
*/
public static CompositeExpression createCompositeExpression(ElParseContext context, String s){
return parseCompositeExpression(context, s);
}
/**
* Evaluates a expression and returns the value.
*/
public static Object eval(String expression) throws ElException {
return createExpression(parseContext, expression).getValue();
}
/**
* Evaluates a expression and returns the value.
*/
public static Object eval(String expression,Object context) throws ElException {
return createExpression(parseContext, expression).getValue(context);
}
/**
* Evaluates a expression and returns the value.
*/
public static Object eval(String expression,Object context,Map vars) throws ElException {
return createExpression(parseContext, expression).getValue(context,vars);
}
protected static boolean testValue(Object v){
if(v instanceof Boolean){
return (Boolean)v;
}
return !Objects2.isEmpty(v);
}
private static CompositeExpression parseCompositeExpression(ElParseContext context, String str){
if(null == str){
return CompositeExpression.NULL;
}
if(Strings.EMPTY.equals(str)){
return CompositeExpression.EMPTY;
}
if(str.indexOf(SPEL.PREFIX) >= 0){
return new CompositeExpression(str,parseNodes(context,str));
}else{
return new CompositeExpression(str);
}
}
private static Object[] parseNodes(ElParseContext context,String s){
StringBuilder buf = new StringBuilder(s);
List