org.jacoco.core.internal.analysis.filter
Class FinallyFilter

java.lang.Object
  org.jacoco.core.internal.analysis.filter.FinallyFilter

All Implemented Interfaces:

IFilter

public final class FinallyFilter
extends Object
implements IFilter

Filters duplicates of finally blocks that compiler generates. To understand algorithm of filtering, consider following example:

 try {
        if (x) {
                a();
                return; // 1
        }
        b(); // 2
 } catch (Exception e) {
        c(); // 3
 } finally {
        d(); // 4
 }
 

There are 4 distinct points of exit out of these "try/catch/finally" blocks - three without exception, and one with Throwable if it is thrown prior to reaching first three points of exit. "finally" block must be executed just before these points, so there must be 4 copies of its bytecode instructions. One of them handles Throwable ("catch-any") and must cover all instructions of "try/catch" blocks. But must not cover instructions of other duplicates, because instructions of "finally" block also can cause Throwable to be thrown. Therefore there will be multiple MethodNode.tryCatchBlocks with TryCatchBlockNode.type null with same TryCatchBlockNode.handler for different non-intersecting bytecode regions (TryCatchBlockNode.start, TryCatchBlockNode.end). And each exit out of these regions, except one that handles Throwable, will contain duplicate of "finally" block. To determine exits out of these regions, they all must be processed together at once, because execution can branch from one region to another (like it is in given example due to "if" statement).

Constructor Summary

FinallyFilter()

Method Summary

void	filter(org.objectweb.asm.tree.MethodNode methodNode, IFilterContext context, IFilterOutput output) This method is called for every method.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FinallyFilter

public FinallyFilter()

Method Detail

filter

public void filter(org.objectweb.asm.tree.MethodNode methodNode,
                   IFilterContext context,
                   IFilterOutput output)

Description copied from interface: IFilter

This method is called for every method. The filter implementation is expected to inspect the provided method and report its result to the given IFilterOutput instance.

Specified by:

filter in interface IFilter

Parameters:

methodNode - method to inspect

context - context information for the method

output - callback to report filtering results to