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/**
* The MIT License
*
* Copyright (c) 2019, 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 org.jeasy.rules.api.Rule;
import org.jeasy.rules.api.Rules;
import org.jeasy.rules.support.*;
import org.mvel2.ParserContext;
import java.io.Reader;
import java.util.Arrays;
import java.util.List;
/**
* Factory to create {@link MVELRule} instances.
*
* @author Mahmoud Ben Hassine ([email protected])
*/
public class MVELRuleFactory {
// for backward compatibility only, will be removed in v3.4
private static final RuleDefinitionReader READER = new YamlRuleDefinitionReader();
private RuleDefinitionReader reader;
private static final List ALLOWED_COMPOSITE_RULE_TYPES = Arrays.asList(
UnitRuleGroup.class.getSimpleName(),
ConditionalRuleGroup.class.getSimpleName(),
ActivationRuleGroup.class.getSimpleName()
);
/**
* Create a new {@link MVELRuleFactory} with a given reader.
*
* @param reader to use to read rule definitions
* @see YamlRuleDefinitionReader
* @see JsonRuleDefinitionReader
*/
public MVELRuleFactory(RuleDefinitionReader reader) {
this.reader = reader;
}
/**
* Create a new {@link MVELRule} from a Reader.
*
* @param ruleDescriptor as a Reader
* @return a new rule
*/
public Rule createRule(Reader ruleDescriptor) throws Exception {
return createRule(ruleDescriptor, new 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 as a Reader
* @param parserContext the MVEL parser context
* @return a new rule
*/
public Rule createRule(Reader ruleDescriptor, ParserContext parserContext) throws Exception {
List ruleDefinitions = reader.read(ruleDescriptor);
if (ruleDefinitions.isEmpty()) {
throw new IllegalArgumentException("rule descriptor is empty");
}
return createRule(ruleDefinitions.get(0), parserContext);
}
/**
* Create a new {@link MVELRule} using a {@link YamlRuleDefinitionReader}.
*
* @param ruleDescriptor as a Reader
* @return a new rule
* @deprecated Use {@link MVELRuleFactory#createRule(java.io.Reader)} instead. This method will be removed in v3.4.
*/
@Deprecated
public static Rule createRuleFrom(Reader ruleDescriptor) throws Exception {
return createRuleFrom(ruleDescriptor, new ParserContext());
}
/**
* Create a new {@link MVELRule} using a {@link YamlRuleDefinitionReader}.
*
* 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 as a Reader
* @param parserContext the MVEL parser context
* @return a new rule
* @deprecated Use {@link MVELRuleFactory#createRule(java.io.Reader, org.mvel2.ParserContext)} instead. This method will be removed in v3.4.
*/
@Deprecated
public static Rule createRuleFrom(Reader ruleDescriptor, ParserContext parserContext) throws Exception {
List ruleDefinitions = READER.read(ruleDescriptor);
if (ruleDefinitions.isEmpty()) {
throw new IllegalArgumentException("rule descriptor is empty");
}
return createRule(ruleDefinitions.get(0), parserContext);
}
/**
* Create a set of {@link MVELRule} from a Reader.
*
* @param rulesDescriptor as a Reader
* @return a set of rules
*/
public Rules createRules(Reader rulesDescriptor) throws Exception {
return createRules(rulesDescriptor, new ParserContext());
}
/**
* Create a set of {@link MVELRule} from a Reader.
*
* @param rulesDescriptor as a Reader
* @return a set of rules
*/
public Rules createRules(Reader rulesDescriptor, ParserContext parserContext) throws Exception {
Rules rules = new Rules();
List ruleDefinition = reader.read(rulesDescriptor);
for (RuleDefinition mvelRuleDefinition : ruleDefinition) {
rules.register(createRule(mvelRuleDefinition, parserContext));
}
return rules;
}
/**
* Create a set of {@link MVELRule} using a {@link YamlRuleDefinitionReader}.
*
* @param rulesDescriptor as a Reader
* @return a set of rules
* @deprecated Use {@link MVELRuleFactory#createRules(java.io.Reader)} instead. This method will be removed in v3.4.
*/
@Deprecated
public static Rules createRulesFrom(Reader rulesDescriptor) throws Exception {
return createRulesFrom(rulesDescriptor, new ParserContext());
}
/**
* Create a set of {@link MVELRule} using a {@link YamlRuleDefinitionReader}.
*
* @param rulesDescriptor as a Reader
* @return a set of rules
* @deprecated Use {@link MVELRuleFactory#createRules(java.io.Reader, org.mvel2.ParserContext)} instead. This method will be removed in v3.4.
*/
@Deprecated
public static Rules createRulesFrom(Reader rulesDescriptor, ParserContext parserContext) throws Exception {
Rules rules = new Rules();
List ruleDefinition = READER.read(rulesDescriptor);
for (RuleDefinition mvelRuleDefinition : ruleDefinition) {
rules.register(createRule(mvelRuleDefinition, parserContext));
}
return rules;
}
private static Rule createRule(RuleDefinition ruleDefinition, ParserContext context) {
if (ruleDefinition.isCompositeRule()) {
return createCompositeRule(ruleDefinition, context);
} else {
return createSimpleRule(ruleDefinition, context);
}
}
private static Rule createSimpleRule(RuleDefinition ruleDefinition, ParserContext parserContext) {
MVELRule mvelRule = new MVELRule()
.name(ruleDefinition.getName())
.description(ruleDefinition.getDescription())
.priority(ruleDefinition.getPriority())
.when(ruleDefinition.getCondition(), parserContext);
for (String action : ruleDefinition.getActions()) {
mvelRule.then(action, parserContext);
}
return mvelRule;
}
private static Rule createCompositeRule(RuleDefinition ruleDefinition, ParserContext parserContext) {
CompositeRule compositeRule;
String name = ruleDefinition.getName();
switch (ruleDefinition.getCompositeRuleType()) {
case "UnitRuleGroup":
compositeRule = new UnitRuleGroup(name);
break;
case "ActivationRuleGroup":
compositeRule = new ActivationRuleGroup(name);
break;
case "ConditionalRuleGroup":
compositeRule = new ConditionalRuleGroup(name);
break;
default:
throw new IllegalArgumentException("Invalid composite rule type, must be one of " + ALLOWED_COMPOSITE_RULE_TYPES);
}
compositeRule.setDescription(ruleDefinition.getDescription());
compositeRule.setPriority(ruleDefinition.getPriority());
for (RuleDefinition composingRuleDefinition : ruleDefinition.getComposingRules()) {
compositeRule.addRule(createRule(composingRuleDefinition, parserContext));
}
return compositeRule;
}
}
