Add filter for Kotlin when-expressions that list all cases of sealed class (#721)

3 files changed, 81 insertions, 1 deletions

diff --git a/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/AbstractMatcher.java b/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/AbstractMatcher.java
index d4b421ef..9e07153b 100644
--- a/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/AbstractMatcher.java
+++ b/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/AbstractMatcher.java
@@ -18,6 +18,7 @@ import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.tree.AbstractInsnNode;
 import org.objectweb.asm.tree.MethodInsnNode;
 import org.objectweb.asm.tree.MethodNode;
+import org.objectweb.asm.tree.TypeInsnNode;
 import org.objectweb.asm.tree.VarInsnNode;
 
 abstract class AbstractMatcher {
@@ -41,6 +42,22 @@ abstract class AbstractMatcher {
 	}
 
 	/**
+	 * Moves {@link #cursor} to next instruction if it is <code>NEW</code> with
+	 * given operand, otherwise sets it to <code>null</code>.
+	 */
+	final void nextIsNew(final String desc) {
+		nextIs(Opcodes.NEW);
+		if (cursor == null) {
+			return;
+		}
+		final TypeInsnNode i = (TypeInsnNode) cursor;
+		if (desc.equals(i.desc)) {
+			return;
+		}
+		cursor = null;
+	}
+
+	/**
 	 * Moves {@link #cursor} to next instruction if it is
 	 * <code>INVOKESPECIAL &lt;init&gt;</code> with given owner and descriptor,
 	 * otherwise sets it to <code>null</code>.
diff --git a/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/Filters.java b/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/Filters.java
index 68e9b234..2e719221 100644
--- a/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/Filters.java
+++ b/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/Filters.java
@@ -33,7 +33,8 @@ public final class Filters implements IFilter {
 			new FinallyFilter(), new PrivateEmptyNoArgConstructorFilter(),
 			new StringSwitchJavacFilter(), new LombokGeneratedFilter(),
 			new GroovyGeneratedFilter(), new EnumEmptyConstructorFilter(),
-			new KotlinGeneratedFilter(), new KotlinLateinitFilter());
+			new KotlinGeneratedFilter(), new KotlinLateinitFilter(),
+			new KotlinWhenSealedFilter());
 
 	private final IFilter[] filters;
 
diff --git a/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/KotlinWhenSealedFilter.java b/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/KotlinWhenSealedFilter.java
new file mode 100644
index 00000000..ae0d8455
--- /dev/null
+++ b/org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/KotlinWhenSealedFilter.java
@@ -0,0 +1,62 @@
+/*******************************************************************************
+ * Copyright (c) 2009, 2018 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:
+ *    Evgeny Mandrikov - initial API and implementation
+ *
+ *******************************************************************************/
+package org.jacoco.core.internal.analysis.filter;
+
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.InsnNode;
+import org.objectweb.asm.tree.JumpInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+
+/**
+ * Filters bytecode that Kotlin compiler generates for <code>when</code>
+ * expressions which list all cases of <code>sealed class</code>, i.e. which
+ * don't require explicit <code>else</code>.
+ */
+public final class KotlinWhenSealedFilter implements IFilter {
+
+	private static final String EXCEPTION = "kotlin/NoWhenBranchMatchedException";
+
+	private final Matcher matcher = new Matcher();
+
+	public void filter(final MethodNode methodNode,
+			final IFilterContext context, final IFilterOutput output) {
+		for (AbstractInsnNode i = methodNode.instructions
+				.getFirst(); i != null; i = i.getNext()) {
+			matcher.match(i, output);
+		}
+	}
+
+	private static class Matcher extends AbstractMatcher {
+		void match(final AbstractInsnNode start, final IFilterOutput output) {
+			if (start.getType() != InsnNode.LABEL) {
+				return;
+			}
+			cursor = start;
+
+			nextIsNew(EXCEPTION);
+			nextIs(Opcodes.DUP);
+			nextIsInvokeSuper(EXCEPTION, "()V");
+			nextIs(Opcodes.ATHROW);
+
+			for (AbstractInsnNode i = cursor; i != null; i = i.getPrevious()) {
+				if (i.getOpcode() == Opcodes.IFEQ
+						&& ((JumpInsnNode) i).label == start) {
+					output.ignore(i, i);
+					output.ignore(start, cursor);
+					return;
+				}
+			}
+		}
+	}
+
+}