Details
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Improvement
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Status: Closed
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Blocker
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Resolution: Fixed
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2.0
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None
Description
While working on JEXL-35 and looking at Cobertua reports, it appeared that some classes in jexl.util were not really used.
It seems that the intention in the original code line was to create specialized executors for each type of property getters and setters but was never completed. Thus, the Uberspectimpl was partly in charge of discovering methods which made things harder to follow and maintain.
The patch completes the original o.a.c.jexl.util with specialized executors for
{property, map, list, duck} setters and getters as well as methods. Since 2.0 already switched the method cache from using string as keys to using MethodKey(s), their usage has been promoted futher up (a method key is a method name and a set of parameters - not arguments!-) so MethodExecutor(s) benefit from their existence.
Since it seemed natural, IntrospectionUtils code has been displaced to MethodKey since this is where parameters type matching has to occur.
The general method (setter & getter) discovery mechanism is reusing the original algorithm, trying the different types and returning the first alive one (aka the first executor for which a java.lang.method could be found).
The patch is faithfull to the original packages however some code has migrated; most of the Uberspectimpl code has been displaced into o.a.c.jexl.util.Introspector to keep it as simple as possible and still derivable.
There were also some low-hanging fruits in this whole refactoring:
The AST nodes (now JexlNode & SimpleNode) carry a volatile value field that allows to use them as cache for executors; this improves performance and allows no locking concurrency. Since we are creating executors, we might as well reuse when possible.
The Info (debugging info) has been put to use so Jexl can create more meaningfull error message when they occur; putting the JexlEngine in debug mode will make warning/exception messages report their point of creation (file or url for scripts, method for expression).
And a 'new' function/operator has been implemented so Jexl can now instantiate objects as well.
It is a huge and worrysome patch but the Checkstyle & Corbertua reports look pretty good.
The following classes need to be removed before applying the patch:
src/java/org/apache/commons/jexl/parser/JEXLNode.java
src/java/org/apache/commons/jexl/Arithmetic.java
src/java/org/apache/commons/jexl/util/PropertyExecutor.java
src/java/org/apache/commons/jexl/util/BooleanPropertyExecutor.java
src/java/org/apache/commons/jexl/util/introspection/IntrospectionUtils.java
src/java/org/apache/commons/jexl/util/introspection/UberspectLoggable.java
src/java/org/apache/commons/jexl/util/GetExecutor.java
The pom.xml has been modified to use a newer version of the javacc plugin.
