org.jeasy.rules.mvel.MVELRuleFactory Maven / Gradle / Ivy
/*
* The MIT License
*
* Copyright (c) 2022, Mahmoud Ben Hassine ([email protected])
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.jeasy.rules.mvel;
import java.io.Reader;
import java.util.List;
import org.jeasy.rules.api.Rule;
import org.jeasy.rules.api.Rules;
import org.jeasy.rules.support.AbstractRuleFactory;
import org.jeasy.rules.support.RuleDefinition;
import org.jeasy.rules.support.reader.JsonRuleDefinitionReader;
import org.jeasy.rules.support.reader.RuleDefinitionReader;
import org.jeasy.rules.support.reader.YamlRuleDefinitionReader;
import org.mvel2.ParserContext;
/**
* Factory to create {@link MVELRule} instances.
*
* @author Mahmoud Ben Hassine ([email protected])
*/
public class MVELRuleFactory extends AbstractRuleFactory {
private final RuleDefinitionReader reader;
private final ParserContext parserContext;
/**
* Create a new {@link MVELRuleFactory} with a given reader.
*
* @param reader used to read rule definitions
* @see YamlRuleDefinitionReader
* @see JsonRuleDefinitionReader
*/
public MVELRuleFactory(RuleDefinitionReader reader) {
this(reader, new ParserContext());
}
/**
* Create a new {@link MVELRuleFactory} with a given reader.
*
* @param reader used to read rule definitions
* @param parserContext used to parse condition/action expressions
* @see YamlRuleDefinitionReader
* @see JsonRuleDefinitionReader
*/
public MVELRuleFactory(RuleDefinitionReader reader, ParserContext parserContext) {
this.reader = reader;
this.parserContext = parserContext;
}
/**
* Create a new {@link MVELRule} from a Reader.
*
* The rule descriptor should contain a single rule definition. If no rule definitions are
* found, a {@link IllegalArgumentException} will be thrown. If more than a rule is defined in the
* descriptor, the first rule will be returned.
*
* @param ruleDescriptor descriptor of rule definition
* @return a new rule
* @throws Exception if unable to create the rule from the descriptor
*/
public Rule createRule(Reader ruleDescriptor) throws Exception {
List ruleDefinitions = reader.read(ruleDescriptor);
if (ruleDefinitions.isEmpty()) {
throw new IllegalArgumentException("rule descriptor is empty");
}
return createRule(ruleDefinitions.get(0));
}
/**
* Create a set of {@link MVELRule} from a rule descriptor.
*
* @param rulesDescriptor descriptor of rule definitions
* @return a set of rules
* @throws Exception if unable to create rules from the descriptor
*/
public Rules createRules(Reader rulesDescriptor) throws Exception {
Rules rules = new Rules();
List ruleDefinitions = reader.read(rulesDescriptor);
for (RuleDefinition ruleDefinition : ruleDefinitions) {
rules.register(createRule(ruleDefinition));
}
return rules;
}
protected Rule createSimpleRule(RuleDefinition ruleDefinition) {
MVELRule mvelRule =
new MVELRule(parserContext)
.name(ruleDefinition.getName())
.description(ruleDefinition.getDescription())
.priority(ruleDefinition.getPriority())
.when(ruleDefinition.getCondition());
for (String action : ruleDefinition.getActions()) {
mvelRule.then(action);
}
return mvelRule;
}
}