1 files changed, 63 insertions, 0 deletions
diff --git a/src/main/java/org/javacs/WarnUnused.java b/src/main/java/org/javacs/WarnUnused.java
new file mode 100644
index 0000000..451a524
--- /dev/null
+++ b/src/main/java/org/javacs/WarnUnused.java
@@ -0,0 +1,63 @@
+package org.javacs;
+
+import com.sun.source.tree.*;
+import com.sun.source.util.*;
+import java.util.*;
+import javax.lang.model.element.*;
+
+class WarnUnused extends TreePathScanner<Void, Void> {
+    private final Trees trees;
+    private final Set<Element> declared = new HashSet<>(), used = new HashSet<>();
+
+    WarnUnused(JavacTask task) {
+        this.trees = Trees.instance(task);
+    }
+
+    Set<Element> notUsed() {
+        declared.removeAll(used);
+        return declared;
+    }
+
+    Element current() {
+        return trees.getElement(getCurrentPath());
+    }
+
+    boolean isPrivate(VariableTree t) {
+        return t.getModifiers().getFlags().contains(Modifier.PRIVATE);
+    }
+
+    boolean isLocal(VariableTree t) {
+        var parent = getCurrentPath().getParentPath().getLeaf();
+        return !(parent instanceof ClassTree);
+    }
+
+    boolean isPrivate(MethodTree t) {
+        return t.getModifiers().getFlags().contains(Modifier.PRIVATE);
+    }
+
+    @Override
+    public Void visitVariable(VariableTree t, Void __) {
+        if (isPrivate(t) || isLocal(t)) {
+            declared.add(current());
+        }
+        return super.visitVariable(t, null);
+    }
+
+    @Override
+    public Void visitIdentifier(IdentifierTree t, Void __) {
+        used.add(current());
+        return super.visitIdentifier(t, null);
+    }
+
+    @Override
+    public Void visitMemberSelect(MemberSelectTree t, Void __) {
+        used.add(current());
+        return super.visitMemberSelect(t, null);
+    }
+
+    @Override
+    public Void visitMemberReference(MemberReferenceTree t, Void __) {
+        used.add(current());
+        return super.visitMemberReference(t, null);
+    }
+}