geirm 2002/06/13 09:09:54
Modified: jexl/src/java/org/apache/commons/jexl Expression.java
ExpressionImpl.java
Log:
Added resolver support
Revision Changes Path
1.2 +17 -1
jakarta-commons-sandbox/jexl/src/java/org/apache/commons/jexl/Expression.java
Index: Expression.java
===================================================================
RCS file:
/home/cvs/jakarta-commons-sandbox/jexl/src/java/org/apache/commons/jexl/Expression.java,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- Expression.java 26 Apr 2002 04:23:14 -0000 1.1
+++ Expression.java 13 Jun 2002 16:09:53 -0000 1.2
@@ -72,4 +72,20 @@
* returns the expression used
*/
public String getExpression();
+
+ /**
+ * allows addition of a resolver to allow custom interdiction of
+ * expression evaluation
+ *
+ * @param resolver resolver to be called before Jexl expression evaluated
+ */
+ public void addPreResolver(JexlExprResolver resolver);
+
+ /**
+ * allows addition of a resolver to allow custom interdiction of
+ * expression evaluation
+ *
+ * @param resolver resolver to be called if Jexl expression evaluated to null
+ */
+ public void addPostResolver(JexlExprResolver resolver);
}
1.2 +84 -2
jakarta-commons-sandbox/jexl/src/java/org/apache/commons/jexl/ExpressionImpl.java
Index: ExpressionImpl.java
===================================================================
RCS file:
/home/cvs/jakarta-commons-sandbox/jexl/src/java/org/apache/commons/jexl/ExpressionImpl.java,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- ExpressionImpl.java 26 Apr 2002 04:23:14 -0000 1.1
+++ ExpressionImpl.java 13 Jun 2002 16:09:53 -0000 1.2
@@ -59,6 +59,8 @@
import org.apache.commons.jexl.parser.ASTReference;
import java.io.StringReader;
+import java.util.ArrayList;
+import java.util.List;
/**
* Implelmentation of an Expression. Created by the ExpressionFactory.
@@ -71,6 +73,9 @@
*/
class ExpressionImpl implements Expression
{
+ List preResolvers = new ArrayList();
+ List postResolvers = new ArrayList();
+
/**
* Original expression - this is just a 'snippet', not a valid
* statement (i.e. foo.bar() vs foo.bar();
@@ -100,7 +105,67 @@
public Object evaluate(JexlContext context)
throws Exception
{
- return node.value(context);
+ Object val = null;
+
+ /*
+ * if we have pre resolvers, give them a wack
+ */
+ if (preResolvers.size() != 0)
+ {
+ val = tryResolver(preResolvers, context);
+
+ if (val != JexlExprResolver.NO_VALUE)
+ {
+ return val;
+ }
+ }
+
+ val = node.value(context);
+
+ /*
+ * if null, call post resolvers
+ */
+ if (val == null && postResolvers.size() != 0)
+ {
+ val = tryResolver(postResolvers, context);
+
+ if (val != JexlExprResolver.NO_VALUE)
+ {
+ return val;
+ }
+ }
+
+ return val;
+ }
+
+ /**
+ * Tries the resolvers in the given resolverlist against the context
+ *
+ * @param resolverList list of JexlExprResolvers
+ * @param context JexlContext to use for evauluation
+ * @return value (including null) or JexlExprResolver.NO_VALUE
+ */
+ protected Object tryResolver(List resolverList, JexlContext context)
+ {
+ Object val = JexlExprResolver.NO_VALUE;
+ String expr = getExpression();
+
+ for (int i = 0; i < resolverList.size(); i++)
+ {
+ JexlExprResolver jer = (JexlExprResolver) resolverList.get(i);
+
+ val = jer.evaluate(context, expr);
+
+ /*
+ * as long as it's not NO_VALUE, return it
+ */
+ if (val != JexlExprResolver.NO_VALUE)
+ {
+ return val;
+ }
+ }
+
+ return val;
}
/**
@@ -110,4 +175,21 @@
{
return expression;
}
+
+ public void addPreResolver(JexlExprResolver resolver)
+ {
+ preResolvers.add(resolver);
+ }
+
+ /**
+ * allows addition of a resolver to allow custom interdiction of
+ * expression evaluation
+ *
+ * @param resolver resolver to be called if Jexl expression evaluated to null
+ */
+ public void addPostResolver(JexlExprResolver resolver)
+ {
+ preResolvers.add(resolver);
+ }
+
}
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