com.aspectran.core.context.expr.ExpressionEvaluation Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2022 The Aspectran Project
*
* 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 com.aspectran.core.context.expr;
import com.aspectran.core.activity.Activity;
import com.aspectran.core.activity.ActivityData;
import com.aspectran.core.context.expr.ognl.OgnlSupport;
import com.aspectran.core.context.expr.token.Token;
import com.aspectran.core.context.expr.token.TokenParser;
import com.aspectran.core.context.rule.type.TokenType;
import com.aspectran.core.util.StringUtils;
import ognl.Ognl;
import ognl.OgnlContext;
import ognl.OgnlException;
import java.util.LinkedHashSet;
import java.util.Set;
/**
* ExpressionEvaluator implementation that evaluates expressions written in
* OGNL-based Aspectran expression language.
*
* Created: 2021/01/31
*
* @since 6.11.0
*/
public class ExpressionEvaluation implements ExpressionEvaluator {
private static final String TOKEN_VAR_NAME_PREFIX = "__";
private static final String TOKEN_VAR_NAME_SUFFIX = TOKEN_VAR_NAME_PREFIX;
private static final String TOKEN_VAR_REF_SYMBOL = "#";
private static final String TOKEN_VAR_REF_NAME_PREFIX = TOKEN_VAR_REF_SYMBOL + TOKEN_VAR_NAME_PREFIX;
private final String expression;
private Object represented;
private Token[] tokens;
public ExpressionEvaluation(String expression) throws ExpressionParserException {
this.expression = expression;
parseExpression(expression);
}
public String getExpression() {
return expression;
}
public Token[] getTokens() {
return tokens;
}
@Override
@SuppressWarnings("unchecked")
public V evaluate(Activity activity, Class resultType) {
if (activity == null) {
throw new IllegalArgumentException("activity must not be null");
}
if (represented == null) {
return null;
}
try {
ActivityData activityData;
if (activity.getTranslet() != null) {
activityData = activity.getTranslet().getActivityData();
} else {
activityData = new ActivityData(activity);
}
OgnlContext ognlContext = OgnlSupport.createDefaultContext();
String[] tokenVarNames = null;
if (tokens != null && tokens.length > 0) {
TokenEvaluator tokenEvaluator = new TokenEvaluation(activity);
tokenVarNames = putTokenVariables(ognlContext, tokenEvaluator, tokens);
}
Object result = Ognl.getValue(represented, ognlContext, activityData, resultType);
if (tokenVarNames != null && result instanceof String) {
for (String tokenVarName : tokenVarNames) {
String tokenVarRefName = TOKEN_VAR_REF_SYMBOL + tokenVarName;
String str = (String)result;
if (str.contains(tokenVarRefName)) {
Object value = ognlContext.get(tokenVarName);
if (value != null) {
result = str.replace(tokenVarRefName, value.toString());
} else {
result = str.replace(tokenVarRefName, StringUtils.EMPTY);
}
}
}
}
return (V)result;
} catch (OgnlException e) {
throw new ExpressionEvaluationException(expression, e);
}
}
@Override
@SuppressWarnings("unchecked")
public V evaluate(TokenEvaluator tokenEvaluator, Class resultType) {
if (tokenEvaluator == null) {
throw new IllegalArgumentException("tokenEvaluator must not be null");
}
if (represented == null) {
return null;
}
try {
Activity activity = tokenEvaluator.getActivity();
ActivityData activityData;
if (activity.getTranslet() != null) {
activityData = activity.getTranslet().getActivityData();
} else {
activityData = new ActivityData(activity);
}
OgnlContext ognlContext = OgnlSupport.createDefaultContext();
String[] tokenVarNames = null;
if (tokens != null && tokens.length > 0) {
tokenVarNames = putTokenVariables(ognlContext, tokenEvaluator, tokens);
}
Object result = Ognl.getValue(represented, ognlContext, activityData, resultType);
if (tokenVarNames != null && result instanceof String) {
for (String tokenVarName : tokenVarNames) {
String tokenVarRefName = TOKEN_VAR_REF_NAME_PREFIX + tokenVarName;
String str = (String)result;
if (str.contains(tokenVarRefName)) {
Object value = ognlContext.get(tokenVarName);
if (value != null) {
result = str.replace(tokenVarRefName, value.toString());
} else {
result = str.replace(tokenVarRefName, StringUtils.EMPTY);
}
}
}
}
return (V)result;
} catch (OgnlException e) {
throw new ExpressionEvaluationException(expression, e);
}
}
private String[] putTokenVariables(OgnlContext ognlContext, TokenEvaluator tokenEvaluator, Token[] tokens) {
Set tokenVarNames = new LinkedHashSet<>();
for (Token token : tokens) {
if (token.getType() != TokenType.TEXT) {
String name = makeTokenVarName(token);
Object value = tokenEvaluator.evaluate(token);
ognlContext.put(name, value);
tokenVarNames.add(name);
}
}
return (tokenVarNames.isEmpty() ? null : tokenVarNames.toArray(new String[0]));
}
private void parseExpression(String expression) throws ExpressionParserException {
tokens = TokenParser.makeTokens(expression, true);
if (tokens != null && tokens.length > 0) {
if (tokens.length == 1) {
Token token = tokens[0];
if (token.getType() == TokenType.TEXT) {
represented = OgnlSupport.parseExpression(token.getDefaultValue());
} else {
String ognlVariableName = makeTokenVarRefName(token);
represented = OgnlSupport.parseExpression(ognlVariableName);
}
} else {
StringBuilder sb = new StringBuilder();
for (Token token : tokens) {
if (token.getType() == TokenType.TEXT) {
sb.append(token.getDefaultValue());
} else {
sb.append(makeTokenVarRefName(token));
}
}
represented = OgnlSupport.parseExpression(sb.toString());
}
} else {
represented = OgnlSupport.parseExpression(expression);
}
}
private String makeTokenVarName(Token token) {
return TOKEN_VAR_NAME_PREFIX + makeTokenName(token) + TOKEN_VAR_NAME_SUFFIX;
}
private String makeTokenVarRefName(Token token) {
return TOKEN_VAR_REF_NAME_PREFIX + makeTokenName(token) + TOKEN_VAR_NAME_SUFFIX;
}
private String makeTokenName(Token token) {
int hashCode = token.hashCode();
if (hashCode >= 0) {
return Long.toString(hashCode, 32);
} else {
return Long.toString(hashCode & 0x7fffffff, 32);
}
}
}