1 files changed, 75 insertions, 0 deletions
diff --git a/src/main/java/com/code_intelligence/jazzer/mutation/api/ValueMutator.java b/src/main/java/com/code_intelligence/jazzer/mutation/api/ValueMutator.java
new file mode 100644
index 00000000..aa2b551e
--- /dev/null
+++ b/src/main/java/com/code_intelligence/jazzer/mutation/api/ValueMutator.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2023 Code Intelligence GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.code_intelligence.jazzer.mutation.api;
+
+import com.google.errorprone.annotations.CheckReturnValue;
+
+/**
+ * Knows how to initialize and mutate objects of type {@code T} and how to incorporate
+ * (cross over) parts of another object of the same type.
+ *
+ * <p>Certain types can be mutated fully in place. In such cases, prefer implementing the more
+ * versatile {@link InPlaceMutator} instead.
+ *
+ * <p>Implementations
+ * <ul>
+ *   <li>MAY weakly associate mutable state with the identity (not equality class) of objects they
+ *   have been passed as arguments or returned from initialization functions;
+ *   <li>MAY assume that they are only passed arguments that they have initialized or mutated;</li>
+ *   <li>SHOULD use {@link com.code_intelligence.jazzer.mutation.support.WeakIdentityHashMap} for
+ *   this purpose;
+ *   <li>MUST otherwise be deeply immutable;
+ *   <li>SHOULD override {@link Object#toString()} to return {@code
+ * Debuggable.getDebugString(this)}.
+ * </ul>
+ *
+ * @param <T> the type this mutator operates on
+ */
+public interface ValueMutator<T> extends Debuggable {
+  /**
+   * Implementations
+   * <ul>
+   *   <li>SHOULD, when called repeatedly, return a low amount of duplicates.
+   * </ul>
+   *
+   * @return an instance of {@code T}
+   */
+  @CheckReturnValue T init(PseudoRandom prng);
+
+  /**
+   * Implementations
+   * <ul>
+   *   <li>MUST return a value that does not {@link Object#equals(Object)} the argument (if
+   * possible);
+   *   <li>SHOULD, when called repeatedly, be able to eventually return any valid value of
+   * type {@code T};
+   *   <li>MAY mutate the argument.
+   * </ul>
+   */
+  @CheckReturnValue T mutate(T value, PseudoRandom prng);
+
+  /**
+   * Implementations
+   * <ul>
+   *   <li>MUST return a value that does not {@link Object#equals(Object)} the arguments (if
+   * possible);
+   *   <li>MAY mutate {@code value}.
+   *   <li>MUST NOT mutate {@code otherValue}.
+   * </ul>
+   */
+  @CheckReturnValue T crossOver(T value, T otherValue, PseudoRandom prng);
+}