factor AbstractDetectorForParameterArray2 out of ManualMessageDetector

so that in the next commit the upcoming ManualGetStackTraceDetector for
a SLF4J_GET_STACK_TRACE (issue KengoTODA#70) does not have to copy/paste 3/4 of
the ManualMessageDetector

bug-pattern/src/main/java/jp/skypencil/findbugs/slf4j/ManualMessageDetector.java

@@ -1,77 +1,44 @@
 package jp.skypencil.findbugs.slf4j;
 
-import javax.annotation.Nullable;
-
-import jp.skypencil.findbugs.slf4j.parameter.AbstractDetectorForParameterArray;
+import jp.skypencil.findbugs.slf4j.parameter.AbstractDetectorForParameterArray2;
 import jp.skypencil.findbugs.slf4j.parameter.ArrayData;
-import jp.skypencil.findbugs.slf4j.parameter.ArrayDataHandler.Strategy;
-
 import com.google.common.base.Objects;
 
-import edu.umd.cs.findbugs.BugInstance;
 import edu.umd.cs.findbugs.BugReporter;
 import edu.umd.cs.findbugs.OpcodeStack.CustomUserValue;
 import edu.umd.cs.findbugs.OpcodeStack.Item;
 
 @CustomUserValue
-public final class ManualMessageDetector extends AbstractDetectorForParameterArray {
+public final class ManualMessageDetector extends AbstractDetectorForParameterArray2 {
+
     @Item.SpecialKind
     private final int isMessage = Item.defineNewSpecialKind("message generated by throwable object");
 
     public ManualMessageDetector(BugReporter bugReporter) {
-        super(bugReporter);
+        super(bugReporter, "SLF4J_MANUALLY_PROVIDED_MESSAGE");
     }
 
     @Override
-    protected Strategy createArrayCheckStrategy() {
-        return new Strategy() {
-            @Override
-            public void store(Item storedItem, ArrayData arrayData, int index) {
-                if (arrayData == null) {
-                    return;
-                }
-
-                if (storedItem.getSpecialKind() == isMessage) {
-                    arrayData.mark(true);
-                }
-
-                // Let developer logs exception message, only when argument does not have throwable instance
-                // https://github.com/KengoTODA/findbugs-slf4j/issues/31
-                if (index == arrayData.getSize() - 1
-                        && !getThrowableHandler().checkThrowable(storedItem)) {
-                    arrayData.mark(false);
-                }
-            }
-        };
+    protected int getIsOfInterestKind() {
+        return isMessage;
     }
 
     @Override
-    public void afterOpcode(int seen) {
-        boolean isInvokingGetMessage = isInvokingGetMessage(seen);
-        super.afterOpcode(seen);
-
-        if (isInvokingGetMessage && !stack.isTop()) {
-            stack.getStackItem(0).setSpecialKind(isMessage);
-        }
+    protected boolean isReallyOfInterest(Item storedItem, ArrayData arrayData, int index) {
+        // Let developer logs exception message, only when argument does not have throwable instance
+        // https://github.com/KengoTODA/findbugs-slf4j/issues/31
+        return !(index == arrayData.getSize() - 1
+                && !getThrowableHandler().checkThrowable(storedItem));
     }
 
-    private boolean isInvokingGetMessage(int seen) {
+
+    @Override
+    protected boolean isWhatWeWantToDetect(int seen) {
         return seen == INVOKEVIRTUAL
                 && !stack.isTop()
                 && getThrowableHandler().checkThrowable(getStack().getStackItem(0))
                 && (Objects.equal("getMessage", getNameConstantOperand()) ||
                         Objects.equal("getLocalizedMessage", getNameConstantOperand()));
     }
 
-    @Override
-    protected void onLog(@Nullable String format, @Nullable ArrayData arrayData) {
-        if (arrayData == null || !arrayData.isMarked()) {
-            return;
-        }
-        BugInstance bugInstance = new BugInstance(this,
-                "SLF4J_MANUALLY_PROVIDED_MESSAGE", NORMAL_PRIORITY)
-                .addSourceLine(this).addClassAndMethod(this)
-                .addCalledMethod(this);
-        getBugReporter().reportBug(bugInstance);
-    }
 }

bug-pattern/src/main/java/jp/skypencil/findbugs/slf4j/parameter/AbstractDetectorForParameterArray2.java

@@ -0,0 +1,65 @@
+package jp.skypencil.findbugs.slf4j.parameter;
+
+import edu.umd.cs.findbugs.BugInstance;
+import edu.umd.cs.findbugs.BugReporter;
+import edu.umd.cs.findbugs.OpcodeStack.Item;
+import javax.annotation.Nullable;
+import jp.skypencil.findbugs.slf4j.parameter.ArrayDataHandler.Strategy;
+
+public abstract class AbstractDetectorForParameterArray2 extends AbstractDetectorForParameterArray {
+
+    private final String bugPatternName;
+
+    public AbstractDetectorForParameterArray2(BugReporter bugReporter, String bugPatternName) {
+        super(bugReporter);
+        this.bugPatternName = bugPatternName;
+    }
+
+    @Override
+    protected final Strategy createArrayCheckStrategy() {
+        return (storedItem, arrayData, index) -> {
+            if (arrayData == null) {
+                return;
+            }
+
+            if (storedItem.getSpecialKind() == getIsOfInterestKind()) {
+                arrayData.mark(true);
+            }
+
+            if (!isReallyOfInterest(storedItem, arrayData, index)) {
+                arrayData.mark(false);
+            }
+        };
+    }
+
+    protected boolean isReallyOfInterest(Item storedItem, ArrayData arrayData, int index) {
+        return true;
+    }
+
+    @Override
+    public final void afterOpcode(int seen) {
+        boolean isInvokingGetMessage = isWhatWeWantToDetect(seen);
+        super.afterOpcode(seen);
+
+        if (isInvokingGetMessage && !stack.isTop()) {
+            stack.getStackItem(0).setSpecialKind(getIsOfInterestKind());
+        }
+    }
+
+    @Override
+    protected final void onLog(@Nullable String format, @Nullable ArrayData arrayData) {
+        if (arrayData == null || !arrayData.isMarked()) {
+            return;
+        }
+        BugInstance bugInstance = new BugInstance(this,
+                bugPatternName, NORMAL_PRIORITY)
+                .addSourceLine(this).addClassAndMethod(this)
+                .addCalledMethod(this);
+        getBugReporter().reportBug(bugInstance);
+    }
+
+    abstract protected boolean isWhatWeWantToDetect(int seen);
+
+    abstract protected int getIsOfInterestKind();
+
+}