/*
* Copyright 2005 JBoss Inc
*
* 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.drools.template.parser;
import java.io.Reader;
import java.io.StringReader;
import java.util.HashMap;
import java.util.Map;
import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.StatefulSession;
import org.drools.compiler.PackageBuilder;
import org.drools.rule.Package;
import org.drools.template.model.Condition;
import org.drools.template.model.Consequence;
import org.drools.template.model.DRLOutput;
import org.drools.template.model.Global;
import org.drools.template.model.Import;
import org.drools.template.model.Rule;
/**
*
*
* Create a rule base for the set of rule templates in the
* TemplateContainer. These rules are used internally by the
* engine to generate the actual decision table rules based on
* which columns have been filled in.
*
* Basically, if a rule template requires columns A and B then
* the template rule base will generate a rule with columns A and B
* as the LHS and a RHS which triggers the rule to be generated.
* ie.
* rule "template1"
* when
* r : Row()
* column1 : Column(name == "column1")
* Cell(row == r, column == column1)
* column2 : Column(name == "column2")
* Cell(row == r, column == column2, value == "xyz")
* then
* generator.generate( "template1", r);
* end
*/
public class DefaultTemplateRuleBase implements TemplateRuleBase {
private RuleBase ruleBase;
public DefaultTemplateRuleBase(final TemplateContainer tc) {
ruleBase = readRule(getDTRules(tc.getTemplates()));
}
/* (non-Javadoc)
* @see org.drools.decisiontable.parser.TemplateRuleBase#newWorkingMemory()
*/
public StatefulSession newStatefulSession() {
return ruleBase.newStatefulSession();
}
/**
*
* @param templates
* @return
*/
private String getDTRules(Map<String, RuleTemplate> templates) {
org.drools.template.model.Package p = new org.drools.template.model.Package(
DefaultTemplateRuleBase.class.getPackage().getName());
addImports(p);
addGlobals(p);
int i = 1;
for ( RuleTemplate template : templates.values() ) {
createTemplateRule(p, i++, template);
}
DRLOutput out = new DRLOutput();
p.renderDRL(out);
return out.getDRL();
}
private void createTemplateRule(org.drools.template.model.Package p, int index, RuleTemplate template) {
Rule rule = new Rule(template.getName(), null, index);
Condition condition = new Condition();
condition.setSnippet("r : Row()");
rule.addCondition(condition);
createColumnConditions(template, rule);
rule.addConsequence(createConsequence(template));
p.addRule(rule);
}
private void createColumnConditions(RuleTemplate template, Rule rule) {
for ( TemplateColumn column : template.getColumns() ) {
column.addCondition(rule);
}
}
private void addGlobals(org.drools.template.model.Package p) {
Global global = new Global();
global.setClassName(DefaultGenerator.class.getName());
global.setIdentifier("generator");
p.addVariable(global);
}
private void addImports(org.drools.template.model.Package p) {
Import drlImport1 = new Import();
drlImport1.setClassName(Map.class.getName());
Import drlImport2 = new Import();
drlImport2.setClassName(HashMap.class.getName());
p.addImport(drlImport1);
p.addImport(drlImport2);
}
private Consequence createConsequence(RuleTemplate template) {
StringBuffer action = new StringBuffer();
action.append("generator.generate( \"");
action.append(template.getName()).append("\", r);");
final Consequence consequence = new Consequence();
consequence.setSnippet(action.toString());
return consequence;
}
private RuleBase readRule(String drl) {
try {
// System.out.println(drl);
// read in the source
Reader source = new StringReader(drl);
PackageBuilder builder = new PackageBuilder();
builder.addPackageFromDrl(source);
Package pkg = builder.getPackage();
// add the package to a rulebase (deploy the rule package).
RuleBase ruleBase = RuleBaseFactory.newRuleBase();
ruleBase.addPackage(pkg);
return ruleBase;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}