Code cleanup and nullable annotation

src/org/jetbrains/java/decompiler/main/DecompilerContext.java

@@ -1,6 +1,7 @@
 // Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.java.decompiler.main;
 
+import org.jetbrains.annotations.Nullable;
 import org.jetbrains.java.decompiler.main.collectors.BytecodeSourceMapper;
 import org.jetbrains.java.decompiler.main.collectors.CounterContainer;
 import org.jetbrains.java.decompiler.main.collectors.ImportCollector;
@@ -102,7 +103,7 @@ public static void startMethod(VarProcessor varProcessor) {
   // context access
   // *****************************************************************************
 
-  public static <T> T getContextProperty(Key<T> key) {
+  public static <T> @Nullable T getContextProperty(Key<T> key) {
     return (T) getCurrentContext().staticProps.get(key);
   }
 

src/org/jetbrains/java/decompiler/modules/decompiler/StatEdge.java

@@ -1,6 +1,7 @@
 // Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.java.decompiler.modules.decompiler;
 
+import org.jetbrains.annotations.Nullable;
 import org.jetbrains.java.decompiler.modules.decompiler.stats.Statement;
 import org.jetbrains.java.decompiler.modules.decompiler.stats.Statement.EdgeDirection;
 
@@ -52,7 +53,7 @@ public class StatEdge {
   // The body of the if statement would be considered the source, and the println would be considered the destination.
   // The sequence statement enclosing the if would be considered the closure.
   // BREAK and CONTINUE edge types should always have a closure! (except for when break edges are return edges)
-  public Statement closure;
+  public @Nullable Statement closure;
 
   // Whether this edge is labeled or not.
   public boolean labeled = true;
@@ -66,7 +67,7 @@ public class StatEdge {
   // If this edge is a continue edge set as a break edge for readability
   public boolean phantomContinue = false;
 
-  public StatEdge(int type, Statement source, Statement destination, Statement closure) {
+  public StatEdge(int type, Statement source, Statement destination, @Nullable Statement closure) {
     this(type, source, destination);
     this.closure = closure;
   }
@@ -100,6 +101,7 @@ public Statement getSource() {
   }
 
   public void setSource(Statement source) {
+    ValidationHelper.assertTrue(source != null, "Should not be null");
     this.source = source;
   }
 
@@ -111,7 +113,7 @@ public void setSource(Statement source) {
    * @param newSource the new source of this edge
    */
   public void changeSource(Statement newSource) {
-    ValidationHelper.notNull(newSource);
+    ValidationHelper.assertTrue(newSource != null, "Should not be null");
 
     Statement oldSource = this.source;
     oldSource.removeEdgeInternal(EdgeDirection.FORWARD, this);
@@ -124,6 +126,7 @@ public Statement getDestination() {
   }
 
   public void setDestination(Statement destination) {
+    ValidationHelper.assertTrue(destination != null, "Should not be null");
     this.destination = destination;
   }
 
@@ -135,7 +138,7 @@ public void setDestination(Statement destination) {
    * @param newDestination the new destination of this edge
    */
   public void changeDestination(Statement newDestination) {
-    ValidationHelper.notNull(newDestination);
+    ValidationHelper.assertTrue(newDestination != null, "Should not be null");
 
     Statement oldDestination = this.destination;
     oldDestination.removeEdgeInternal(EdgeDirection.BACKWARD, this);
@@ -168,12 +171,12 @@ public void remove() {
     }
   }
 
-
   /**
    * Remove the closure of this edge. This edge will no
    * longer be labeled.
    */
   public void removeClosure() {
+    ValidationHelper.validateTrue(closure != null, "closure shouldn't be null here");
     this.closure.getLabelEdges().remove(this);
     this.labeled = false;
     this.closure = null;
@@ -183,10 +186,6 @@ public List<String> getExceptions() {
     return this.exceptions;
   }
 
-  //	public void setException(String exception) {
-  //		this.exception = exception;
-  //	}
-
   @Override
   public String toString() {
     return this.type + ": " + this.source.toString() + " -> " + this.destination.toString() + ((this.closure == null) ? "" : " (" + this.closure + ")") + ((this.exceptions == null) ? "" : " Exceptions: " + this.exceptions);

src/org/jetbrains/java/decompiler/modules/decompiler/exps/ExitExprent.java

@@ -88,8 +88,8 @@ public TextBuffer toJava(int indent) {
       return buf;
     }
     else {
-      MethodWrapper method = (MethodWrapper)DecompilerContext.getContextProperty(DecompilerContext.CURRENT_METHOD_WRAPPER);
-      ClassNode node = ((ClassNode)DecompilerContext.getContextProperty(DecompilerContext.CURRENT_CLASS_NODE));
+      MethodWrapper method = DecompilerContext.getContextProperty(DecompilerContext.CURRENT_METHOD_WRAPPER);
+      ClassNode node = DecompilerContext.getContextProperty(DecompilerContext.CURRENT_CLASS_NODE);
 
       if (method != null && node != null) {
         StructExceptionsAttribute attr = method.methodStruct.getAttribute(StructGeneralAttribute.ATTRIBUTE_EXCEPTIONS);

src/org/jetbrains/java/decompiler/modules/decompiler/vars/VarProcessor.java

@@ -1,6 +1,7 @@
 // Copyright 2000-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.java.decompiler.modules.decompiler.vars;
 
+import org.jetbrains.annotations.Nullable;
 import org.jetbrains.java.decompiler.main.collectors.VarNamesCollector;
 import org.jetbrains.java.decompiler.modules.decompiler.exps.VarExprent;
 import org.jetbrains.java.decompiler.modules.decompiler.stats.RootStatement;
@@ -25,7 +26,7 @@ public class VarProcessor {
   private Map<VarVersionPair, String> mapVarNames = new HashMap<>();
   private List<VarVersionPair> params = new ArrayList<>();
   private Map<VarVersionPair, LocalVariable> mapVarLVTs = new HashMap<>();
-  private VarVersionsProcessor varVersions;
+  private @Nullable VarVersionsProcessor varVersions;
   private final Map<VarVersionPair, String> thisVars = new HashMap<>();
   private final Set<VarVersionPair> externalVars = new HashSet<>();
   private final Map<VarVersionPair, String> clashingNames = new HashMap<>();
@@ -104,7 +105,7 @@ public void rerunClashing(RootStatement root) {
     }
   }
 
-  public Integer getVarOriginalIndex(int index) {
+  public @Nullable Integer getVarOriginalIndex(int index) {
     if (varVersions == null) {
       return null;
     }
@@ -145,11 +146,11 @@ public void setVarType(VarVersionPair pair, VarType type) {
     }
   }
 
-  public String getVarName(VarVersionPair pair) {
+  public @Nullable String getVarName(VarVersionPair pair) {
     return mapVarNames == null ? null : mapVarNames.get(pair);
   }
 
-  public String getClashingName(VarVersionPair pair) {
+  public @Nullable String getClashingName(VarVersionPair pair) {
     return this.clashingNames.get(pair);
   }
 
@@ -223,49 +224,19 @@ public void findLVT(VarExprent exprent, int start) {
     }
   }
 
-  public void copyVarInfo(VarVersionPair from, VarVersionPair to) {
-    setVarName(to, getVarName(from));
-    setVarFinal(to, getVarFinal(from));
-    setVarType(to, getVarType(from));
-    varVersions.getMapOriginalVarIndices().put(to.var, varVersions.getMapOriginalVarIndices().get(from.var));
-  }
-
   public boolean hasLVT() {
     return method.getLocalVariableAttr() != null;
   }
-
-
-  public Map<Integer, LocalVariable> getLocalVariables(Statement stat) {
-    if (!hasLVT() || stat == null)
-      return new HashMap<>();
-
-    final StartEndPair sep = stat.getStartEndRange(); 
-    final Set<Integer> blacklist = new HashSet<>();
-    Map<Integer, LocalVariable> ret = method.getLocalVariableAttr().getVariables().filter(lv -> lv.getEnd() > sep.start && lv.getStart() <= sep.end)
-      .collect(Collectors.toMap(lv -> lv.getVersion().var, lv -> lv,
-        (lv1, lv2) -> 
-        {
-          //System.out.println("DUPLICATE INDEX FOR SCOPE: (" +sep +") " + lv1.toString() + " " + lv2.toString());
-          blacklist.add(lv1.getVersion().var);
-          return lv1;
-        }
-      ));
-
-    for (int b : blacklist)
-      ret.remove(b);
-
-    return ret;
-  }
 
-  public VarVersionsProcessor getVarVersions() {
+  public @Nullable VarVersionsProcessor getVarVersions() {
     return varVersions;
   }
 
   public void setVarLVT(VarVersionPair var, LocalVariable lvt) {
     mapVarLVTs.put(var, lvt);
   }
 
-  public LocalVariable getVarLVT(VarVersionPair var) {
+  public @Nullable LocalVariable getVarLVT(VarVersionPair var) {
     return mapVarLVTs.get(var);
   }
 }

src/org/jetbrains/java/decompiler/struct/gen/VarType.java

@@ -53,7 +53,7 @@ public class VarType {  // TODO: optimize switch
 
   public final int type;
   public final int arrayDim;
-  public final String value;
+  public final @Nullable String value;
   public final int typeFamily;
   public final int stackSize;
 

src/org/jetbrains/java/decompiler/struct/gen/generics/GenericType.java

@@ -578,8 +578,7 @@ public static void cleanLoweredGenericTypes(Map<VarType, VarType> tempMap, Gener
   // In the case where Type is defined as "class Type<T>", and the in type is "Type<?>", find the base (un-remapped) type "Type<T>"
   // out of it. Essentially a wrapper to do a class lookup to find the generic class type descriptor.
   // Returns null if there is a failure at any point.
-  @Nullable
-  public GenericType findBaseType() {
+  public @Nullable GenericType findBaseType() {
     StructClass cl = DecompilerContext.getStructContext().getClass(value);
     if (cl == null) {
       return null;