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/*******************************************************************************
* Copyright (c) 2009, 2019 Mountainminds GmbH & Co. KG and Contributors
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Marc R. Hoffmann - initial API and implementation
*
*******************************************************************************/
package org.jacoco.core.internal.analysis;
import java.util.BitSet;
import java.util.Collection;
import org.jacoco.core.analysis.ICounter;
/**
* Execution status of a single bytecode instruction internally used for
* coverage analysis. The execution status is recorded separately for each
* outgoing branch. Each instruction has at least one branch, for example in
* case of a simple sequence of instructions (by convention branch 0). Instances
* of this class are used in two steps:
*
* <h3>Step 1: Building the CFG</h3>
*
* For each bytecode instruction of a method a {@link Instruction} instance is
* created. In correspondence with the CFG these instances are linked with each
* other with the <code>addBranch()</code> methods. The executions status is
* either directly derived from a probe which has been inserted in the execution
* flow ({@link #addBranch(boolean, int)}) or indirectly propagated along the
* CFG edges ({@link #addBranch(Instruction, int)}).
*
* <h3>Step 2: Querying the Coverage Status</h3>
*
* After all instructions have been created and linked each instruction knows
* its execution status and can be queried with:
*
* <ul>
* <li>{@link #getLine()}</li>
* <li>{@link #getInstructionCounter()}</li>
* <li>{@link #getBranchCounter()}</li>
* </ul>
*
* For the purpose of filtering instructions can be combined to new
* instructions. Note that these methods create new {@link Instruction}
* instances and do not modify the existing ones.
*
* <ul>
* <li>{@link #merge(Instruction)}</li>
* <li>{@link #replaceBranches(Collection)}</li>
* </ul>
*/
public class Instruction {
private final int line;
private int branches;
private final BitSet coveredBranches;
private Instruction predecessor;
private int predecessorBranch;
/**
* New instruction at the given line.
*
* @param line
* source line this instruction belongs to
*/
public Instruction(final int line) {
this.line = line;
this.branches = 0;
this.coveredBranches = new BitSet();
}
/**
* Adds a branch to this instruction which execution status is indirectly
* derived from the execution status of the target instruction. In case the
* branch is covered the status is propagated also to the predecessors of
* this instruction.
*
* Note: This method is not idempotent and must be called exactly once for
* every branch.
*
* @param target
* target instruction of this branch
* @param branch
* branch identifier unique for this instruction
*/
public void addBranch(final Instruction target, final int branch) {
branches++;
target.predecessor = this;
target.predecessorBranch = branch;
if (!target.coveredBranches.isEmpty()) {
propagateExecutedBranch(this, branch);
}
}
/**
* Adds a branch to this instruction which execution status is directly
* derived from a probe. In case the branch is covered the status is
* propagated also to the predecessors of this instruction.
*
* Note: This method is not idempotent and must be called exactly once for
* every branch.
*
* @param executed
* whether the corresponding probe has been executed
* @param branch
* branch identifier unique for this instruction
*/
public void addBranch(final boolean executed, final int branch) {
branches++;
if (executed) {
propagateExecutedBranch(this, branch);
}
}
private static void propagateExecutedBranch(Instruction insn, int branch) {
// No recursion here, as there can be very long chains of instructions
while (insn != null) {
if (!insn.coveredBranches.isEmpty()) {
insn.coveredBranches.set(branch);
break;
}
insn.coveredBranches.set(branch);
branch = insn.predecessorBranch;
insn = insn.predecessor;
}
}
/**
* Returns the source line this instruction belongs to.
*
* @return corresponding source line
*/
public int getLine() {
return line;
}
/**
* Merges information about covered branches of this instruction with
* another instruction.
*
* @param other
* instruction to merge with
* @return new instance with merged branches
*/
public Instruction merge(final Instruction other) {
final Instruction result = new Instruction(this.line);
result.branches = this.branches;
result.coveredBranches.or(this.coveredBranches);
result.coveredBranches.or(other.coveredBranches);
return result;
}
/**
* Creates a copy of this instruction where all outgoing branches are
* replaced with the given instructions. The coverage status of the new
* instruction is derived from the status of the given instructions.
*
* @param newBranches
* new branches to consider
* @return new instance with replaced branches
*/
public Instruction replaceBranches(
final Collection<Instruction> newBranches) {
final Instruction result = new Instruction(this.line);
result.branches = newBranches.size();
int idx = 0;
for (final Instruction b : newBranches) {
if (!b.coveredBranches.isEmpty()) {
result.coveredBranches.set(idx++);
}
}
return result;
}
/**
* Returns the instruction coverage counter of this instruction. It is
* always 1 instruction which is covered or not.
*
* @return the instruction coverage counter
*/
public ICounter getInstructionCounter() {
return coveredBranches.isEmpty() ? CounterImpl.COUNTER_1_0
: CounterImpl.COUNTER_0_1;
}
/**
* Returns the branch coverage counter of this instruction. Only
* instructions with at least 2 outgoing edges report branches.
*
* @return the branch coverage counter
*/
public ICounter getBranchCounter() {
if (branches < 2) {
return CounterImpl.COUNTER_0_0;
}
final int covered = coveredBranches.cardinality();
return CounterImpl.getInstance(branches - covered, covered);
}
}
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