10:26 a.m.
[ http://jira.jboss.com/jira/browse/JBRULES-1055?page=comments#action_12373328 ]
Edson Tirelli commented on JBRULES-1055:
----------------------------------------
This is actually a documentation problem and not a bug. DSL was augmented in Drools 4.0 to
support regexps as part of the mappings. This intents to make DSL mappings more robust and
allowing users to handle more situations with less effort. For instance, if you want to
handle multiple values, you could write a mapping like:
[when][]Customer code is [ABCD]=Customer( code == "premium")
The above mapping will match any of the following statements:
Customer code is A
Customer code is B
Customer code is C
Customer code is D
As [ABCD] is interpreted as a regexp.
So, in your case, the only fix you need to do is escape your [] in the same way you escape
them in regular expressions. Look at the following example:
[when][]attr {attr_name} is in \[ {values} \]={attr_name} in ( {values} )
The above mapping will match:
attr name is in [ 'Edson', 'Bob' ]
And translate that into:
name in ( 'Edson', 'Bob' )
I will look at fixing documentation. This is not backward compatible, but we feel the
added flexibility was worth breaking the compatibility in the major version release.
Regex-Special characters can not be used in DSLs.
-------------------------------------------------
Key: JBRULES-1055
URL: http://jira.jboss.com/jira/browse/JBRULES-1055
Project: JBoss Rules
Issue Type: Bug
Security Level: Public(Everyone can see)
Components: Drl Parser/Builder
Affects Versions: 4.0.0.GA
Environment: Windows XP, Java 5
Reporter: Michael Wiedmer
Assigned To: Edson Tirelli
Fix For: 4.0.1
Up until Drools 3.0.6 one could write DSLs to allow expressions such as
EXAMPLE IS IN [ "one" "two"]
This has changed now. The square brackes (being part of special characters for regular
expressions) deny the DefaultDSLMappingEntry class to define a valid keyPattern.
Here is a (not) working example, using the default sample project:
8<---- regexError.drl -----
package some.test
import com.sample.*;
expander regexError.dsl
rule "Test"
when
STRING "UK" IS IN < "USA", "UK", "GERMANY"
>
then
LOG "Square Brackets will not work."
end
8<---- regexError.dsl -----
[consequence][]LOG {msg}=System.out.println({msg});
[condition][]STRING "{string}" IS IN < {sequence} >=eval(true == true)
8<---- DroolsTest.javal -----
package com.sample;
import java.io.InputStreamReader;
import java.io.Reader;
import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.WorkingMemory;
import org.drools.compiler.PackageBuilder;
import org.drools.rule.Package;
public class DroolsTest {
public static final void main(String[] args) {
try {
// load up the rulebase
RuleBase ruleBase = readRule();
WorkingMemory workingMemory = ruleBase.newStatefulSession();
// go !
Message message = new Message();
message.setMessage("Hello World");
message.setStatus(Message.HELLO);
workingMemory.insert(message);
workingMemory.fireAllRules();
} catch (Throwable t) {
t.printStackTrace();
}
}
private static RuleBase readRule() throws Exception {
Reader source = new
InputStreamReader(DroolsTest.class.getResourceAsStream("/regexError.drl"));
Reader dsl = new
InputStreamReader(DroolsTest.class.getResourceAsStream("/regexError.dsl"));
PackageBuilder builder = new PackageBuilder();
builder.addPackageFromDrl(source, dsl);
Package pkg = builder.getPackage();
RuleBase ruleBase = RuleBaseFactory.newRuleBase();
ruleBase.addPackage(pkg);
return ruleBase;
}
}
If one was to change the files regexError.dsl and regexError.drl and use square brackets
instead of angle brackets, the DroolsTest will fail with the same error as shown in the
Eclipse IDE:
org.drools.rule.InvalidRulePackage: org.drools.lang.ExpanderException@14c1103[9,2]:
unknown:9:2 Unexpected token 'STRING'[9,22]: unknown:9:22 mismatched token:
[@31,115:119='"USA"',<20>,9:22]; expecting type
RIGHT_SQUARE[11,1]: unknown:11:1 mismatched token:
[@43,150:155='System',<8>,11:1]; expecting type RIGHT_PAREN[11,20]:
unknown:11:20 mismatched token: [@49,169:200='"Square Brackets will not
work."',<20>,11:20]; expecting type RIGHT_PAREN[12,0]: unknown:12:0
mismatched token: [@53,205:207='end',<15>,12:0]; expecting type THEN
at org.drools.rule.Package.checkValidity(Package.java:408)
at org.drools.common.AbstractRuleBase.addPackage(AbstractRuleBase.java:288)
at com.sample.DroolsTest.readRule(DroolsTest.java:44)
at com.sample.DroolsTest.main(DroolsTest.java:18)
It does not matter what the RHS of the DSL says, as the LHS will not be matched in
DefaultExpander.expandLHS(final String lhs, int lineOffset), line 231.
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