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

Constructors

Constructor	Description
FinallyFilter()

Method Summary

Modifier and Type	Method	Description
private static void	filter(IFilterOutput output, List<org.objectweb.asm.tree.TryCatchBlockNode> tryCatchBlocks, org.objectweb.asm.tree.TryCatchBlockNode catchAnyBlock)
void	filter(org.objectweb.asm.tree.MethodNode methodNode, IFilterContext context, IFilterOutput output)	This method is called for every method.
private static boolean	isSame(int size, org.objectweb.asm.tree.AbstractInsnNode e, org.objectweb.asm.tree.AbstractInsnNode n)
private static void	merge(IFilterOutput output, int size, org.objectweb.asm.tree.AbstractInsnNode e, org.objectweb.asm.tree.AbstractInsnNode n)
private static org.objectweb.asm.tree.AbstractInsnNode	next(org.objectweb.asm.tree.AbstractInsnNode i)
private static int	size(org.objectweb.asm.tree.AbstractInsnNode i)

Methods inherited from class Object

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

Constructor Details

FinallyFilter

public FinallyFilter()

Method Details

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

filter

private static void filter(IFilterOutput output,
 List<org.objectweb.asm.tree.TryCatchBlockNode> tryCatchBlocks,
 org.objectweb.asm.tree.TryCatchBlockNode catchAnyBlock)

merge

private static void merge(IFilterOutput output,
 int size,
 org.objectweb.asm.tree.AbstractInsnNode e,
 org.objectweb.asm.tree.AbstractInsnNode n)

isSame

private static boolean isSame(int size,
 org.objectweb.asm.tree.AbstractInsnNode e,
 org.objectweb.asm.tree.AbstractInsnNode n)

size

private static int size(org.objectweb.asm.tree.AbstractInsnNode i)

Returns:

number of instructions inside given "catch-any" handler

next

private static org.objectweb.asm.tree.AbstractInsnNode next(org.objectweb.asm.tree.AbstractInsnNode i)