Import "Enhance switches on enums." from LexManos / MinecraftForge

3 files changed, 182 insertions, 2 deletions

diff --git a/src/org/jetbrains/java/decompiler/main/rels/NestedClassProcessor.java b/src/org/jetbrains/java/decompiler/main/rels/NestedClassProcessor.java
index 25ff812..1882346 100644
--- a/src/org/jetbrains/java/decompiler/main/rels/NestedClassProcessor.java
+++ b/src/org/jetbrains/java/decompiler/main/rels/NestedClassProcessor.java
@@ -16,6 +16,7 @@
 package org.jetbrains.java.decompiler.main.rels;
 
 import org.jetbrains.java.decompiler.code.CodeConstants;
+import org.jetbrains.java.decompiler.code.cfg.BasicBlock;
 import org.jetbrains.java.decompiler.main.ClassesProcessor.ClassNode;
 import org.jetbrains.java.decompiler.main.DecompilerContext;
 import org.jetbrains.java.decompiler.main.collectors.CounterContainer;
@@ -25,8 +26,11 @@ import org.jetbrains.java.decompiler.main.extern.IFernflowerPreferences;
 import org.jetbrains.java.decompiler.modules.decompiler.exps.*;
 import org.jetbrains.java.decompiler.modules.decompiler.sforms.DirectGraph;
 import org.jetbrains.java.decompiler.modules.decompiler.sforms.DirectNode;
+import org.jetbrains.java.decompiler.modules.decompiler.stats.BasicBlockStatement;
+import org.jetbrains.java.decompiler.modules.decompiler.stats.CatchStatement;
 import org.jetbrains.java.decompiler.modules.decompiler.stats.DoStatement;
 import org.jetbrains.java.decompiler.modules.decompiler.stats.RootStatement;
+import org.jetbrains.java.decompiler.modules.decompiler.stats.SequenceStatement;
 import org.jetbrains.java.decompiler.modules.decompiler.stats.Statement;
 import org.jetbrains.java.decompiler.modules.decompiler.vars.VarTypeProcessor;
 import org.jetbrains.java.decompiler.modules.decompiler.vars.VarVersionPaar;
@@ -58,6 +62,10 @@ public class NestedClassProcessor {
       return;
     }
 
+    if (DecompilerContext.getOption(IFernflowerPreferences.DECOMPILE_ENUM)) {
+      gatherEnumSwitchMaps(node);
+    }
+
     if (node.type != ClassNode.CLASS_LAMBDA) {
 
       computeLocalVarsAndDefinitions(node);
@@ -102,6 +110,125 @@ public class NestedClassProcessor {
     }
   }
 
+  /**
+   * When Java introduced Enums they aded the ability to use them in Switch statements.
+   * This was done in a purely syntax sugar way using the old switch on int methods.
+   * The compiler creates a synthetic class with a static int array field.
+   * To support enums changing post compile, It initializes this field with a length of the current enum length.
+   * And then for every referenced enum value it adds a mapping in the form of:
+   *   try {
+   *     field[Enum.VALUE.ordinal()] = 1;
+   *   } catch (FieldNotFoundException e) {}
+   *
+   * If a class has multiple switches on multiple enums, the compiler adds the init and try list to the BEGINNING of the static initalizer.
+   * But they add the field to the END of the fields list.
+   */
+  private void gatherEnumSwitchMaps(ClassNode node) {
+    for (ClassNode child : node.nested) {
+      gatherEnumSwitchMaps(child);
+    }
+
+    MethodWrapper clinit = node.wrapper.getMethodWrapper("<clinit>", "()V");
+    if (clinit == null || clinit.root == null || clinit.root.getFirst().type != Statement.TYPE_SEQUENCE) {
+      return;
+    }
+
+    final int STATIC_FINAL_SYNTHETIC = CodeConstants.ACC_STATIC | CodeConstants.ACC_FINAL | CodeConstants.ACC_SYNTHETIC;
+    Set<String> potentialFields = new HashSet<String>();
+    for (StructField fd : node.classStruct.getFields()) {
+      if ((fd.getAccessFlags() & STATIC_FINAL_SYNTHETIC) == STATIC_FINAL_SYNTHETIC && "[I".equals(fd.getDescriptor())) {
+        potentialFields.add(fd.getName());
+      }
+    }
+
+    if (potentialFields.size() == 0) {
+      return;
+    }
+
+    SequenceStatement seq = (SequenceStatement)clinit.root.getFirst();
+    for (int x = 0; x < seq.getStats().size();) {
+      Statement stat = seq.getStats().get(x);
+      if (stat.type != Statement.TYPE_BASICBLOCK || stat.getExprents() == null || stat.getExprents().size() != 1 || stat.getExprents().get(0).type != Exprent.EXPRENT_ASSIGNMENT) {
+        break;
+      }
+      AssignmentExprent ass = (AssignmentExprent)stat.getExprents().get(0);
+      if (ass.getLeft().type != Exprent.EXPRENT_FIELD || ass.getRight().type != Exprent.EXPRENT_NEW) {
+        break;
+      }
+      FieldExprent mapField = (FieldExprent)ass.getLeft();
+      NewExprent _new = ((NewExprent)ass.getRight());
+      if (!mapField.getClassname().equals(node.classStruct.qualifiedName) || !potentialFields.contains(mapField.getName()) ||
+          _new.getNewtype().type != CodeConstants.TYPE_INT || _new.getNewtype().arraydim != 1 ||
+          _new.getLstDims().size() != 1 || _new.getLstDims().get(0).type != Exprent.EXPRENT_FUNCTION) {
+        break;
+      }
+      FunctionExprent func = (FunctionExprent)_new.getLstDims().get(0);
+      if (func.getFunctype() != FunctionExprent.FUNCTION_ARRAYLENGTH || func.getLstOperands().size() != 1 || func.getLstOperands().get(0).type != Exprent.EXPRENT_INVOCATION) {
+        break;
+      }
+      InvocationExprent invoc = (InvocationExprent)func.getLstOperands().get(0);
+      if (!"values".equals(invoc.getName()) || !("()[L" + invoc.getClassname() + ";").equals(invoc.getStringDescriptor())) {
+        break;
+      }
+
+      String fieldName = mapField.getName();
+      String enumName = invoc.getClassname();
+      Map<Integer, String> idToName = new HashMap<Integer, String>();
+
+      boolean replace = false;
+      int y = x;
+      while (++y < seq.getStats().size()) {
+        if (seq.getStats().get(y).type != Statement.TYPE_TRYCATCH) {
+          break;
+        }
+        CatchStatement _try = (CatchStatement)seq.getStats().get(y);
+        Statement first = _try.getFirst();
+        List<Exprent> exprents = first.getExprents();
+        if (_try.getVars().size() != 1 || !"java/lang/NoSuchFieldError".equals(_try.getVars().get(0).getVartype().value) ||
+            first.type != Statement.TYPE_BASICBLOCK || exprents == null || exprents.size() != 1 || exprents.get(0).type != Exprent.EXPRENT_ASSIGNMENT) {
+          break;
+        }
+        ass = (AssignmentExprent)exprents.get(0);
+        if (ass.getRight().type != Exprent.EXPRENT_CONST || (!(((ConstExprent)ass.getRight()).getValue() instanceof Integer)) ||
+            ass.getLeft().type != Exprent.EXPRENT_ARRAY){
+          break;
+        }
+        ArrayExprent array = (ArrayExprent)ass.getLeft();
+        if (array.getArray().type != Exprent.EXPRENT_FIELD || !array.getArray().equals(mapField) || array.getIndex().type != Exprent.EXPRENT_INVOCATION) {
+          break;
+        }
+        invoc = (InvocationExprent)array.getIndex();
+        if (!enumName.equals(invoc.getClassname()) || !"ordinal".equals(invoc.getName()) || !"()I".equals(invoc.getStringDescriptor()) ||
+            invoc.getInstance().type != Exprent.EXPRENT_FIELD) {
+          break;
+        }
+
+        FieldExprent enumField = (FieldExprent)invoc.getInstance();
+        if (!enumName.equals(enumField.getClassname()) || !enumField.isStatic()) {
+          break;
+        }
+
+        idToName.put((Integer)((ConstExprent)ass.getRight()).getValue(), enumField.getName());
+        seq.replaceStatement(_try, getNewEmptyStatement());
+        replace = true;
+      }
+
+      if (replace) {
+        seq.replaceStatement(seq.getStats().get(x), getNewEmptyStatement());
+        node.classStruct.enumSwitchMap.put(fieldName, idToName);
+        node.wrapper.getHiddenMembers().add(InterpreterUtil.makeUniqueKey(fieldName, "[I"));
+      }
+      x = y;
+    }
+  }
+
+  private Statement getNewEmptyStatement() {
+    BasicBlockStatement bstat = new BasicBlockStatement(new BasicBlock(
+      DecompilerContext.getCounterContainer().getCounterAndIncrement(CounterContainer.STATEMENT_COUNTER)));
+    bstat.setExprents(new ArrayList<Exprent>());
+    return bstat;
+  }
+
   private static void setLambdaVars(ClassNode parent, ClassNode child) {
 
     if (child.lambda_information.is_method_reference) { // method reference, no code and no parameters
diff --git a/src/org/jetbrains/java/decompiler/modules/decompiler/stats/SwitchStatement.java b/src/org/jetbrains/java/decompiler/modules/decompiler/stats/SwitchStatement.java
index b0ec5e3..694baae 100644
--- a/src/org/jetbrains/java/decompiler/modules/decompiler/stats/SwitchStatement.java
+++ b/src/org/jetbrains/java/decompiler/modules/decompiler/stats/SwitchStatement.java
@@ -24,6 +24,7 @@ import org.jetbrains.java.decompiler.modules.decompiler.DecHelper;
 import org.jetbrains.java.decompiler.modules.decompiler.ExprProcessor;
 import org.jetbrains.java.decompiler.modules.decompiler.StatEdge;
 import org.jetbrains.java.decompiler.modules.decompiler.exps.*;
+import org.jetbrains.java.decompiler.struct.StructClass;
 import org.jetbrains.java.decompiler.struct.gen.VarType;
 import org.jetbrains.java.decompiler.util.InterpreterUtil;
 import org.jetbrains.java.decompiler.util.Util;
@@ -137,7 +138,12 @@ public class SwitchStatement extends Statement {
       tracer.incrementCurrentSourceLine();
     }
 
-    buf.append(indstr).append(headexprent.get(0).toJava(indent, tracer)).append(" {").append(new_line_separator);
+    // Doesn't seem to be a better place to put it so enhance things here
+    Map<Integer, String> remaps = enhanceHead(headexprent.get(0), buf, indent, tracer);
+
+    if (remaps == null) {
+      buf.append(indstr).append(headexprent.get(0).toJava(indent, tracer)).append(" {").append(new_line_separator);
+    }
     tracer.incrementCurrentSourceLine();
 
     VarType switch_type = headexprent.get(0).getExprType();
@@ -157,7 +163,13 @@ public class SwitchStatement extends Statement {
           ConstExprent value = (ConstExprent)values.get(j).copy();
           value.setConsttype(switch_type);
 
-          buf.append(indstr).append("case ").append(value.toJava(indent, tracer)).append(":").append(new_line_separator);
+          buf.append(indstr).append("case ");
+          if (remaps == null) {
+            buf.append(value.toJava(indent, tracer));
+          } else {
+            buf.append(remaps.get(value.getValue()));
+          }
+          buf.append(":").append(new_line_separator);
           tracer.incrementCurrentSourceLine();
         }
       }
@@ -176,6 +188,44 @@ public class SwitchStatement extends Statement {
     return buf.toString();
   }
 
+  private Map<Integer, String> enhanceHead(Exprent exprent, StringBuilder buf, int indent, BytecodeMappingTracer tracer) {
+    if (exprent.type != Exprent.EXPRENT_SWITCH) return null;
+
+    SwitchExprent swtch = (SwitchExprent)exprent;
+    if (swtch.getValue().type != Exprent.EXPRENT_ARRAY) return null;
+
+    ArrayExprent array = (ArrayExprent)swtch.getValue();
+    if (array.getArray().type != Exprent.EXPRENT_FIELD || array.getIndex().type != Exprent.EXPRENT_INVOCATION) return null;
+
+    FieldExprent field = (FieldExprent)array.getArray();
+    InvocationExprent invoc = (InvocationExprent)array.getIndex();
+    StructClass cls = DecompilerContext.getStructContext().getClass(field.getClassname());
+    if (cls == null || !field.isStatic() || !"ordinal".equals(invoc.getName()) || !"()I".equals(invoc.getStringDescriptor())) return null;
+
+    Map<Integer, String> ret = cls.enumSwitchMap.get(field.getName());
+    if (ret == null) return null;
+
+    for (List<ConstExprent> lst : getCaseValues()) {
+      if (lst != null) {
+        for (ConstExprent cst : lst) {
+          if (cst != null && (!(cst.getValue() instanceof Integer) || !ret.containsKey(cst.getValue()))) {
+            return null;
+          }
+        }
+      }
+    }
+
+    tracer.addMapping(swtch.bytecode);
+    tracer.addMapping(field.bytecode);
+    tracer.addMapping(invoc.bytecode);
+
+    String indstr = InterpreterUtil.getIndentString(indent);
+    String new_line_separator = DecompilerContext.getNewLineSeparator();
+
+    buf.append(indstr).append("switch (").append((invoc.getInstance().toJava(indent, tracer))).append(") {").append(new_line_separator);
+    return ret;
+  }
+
   public void initExprents() {
     SwitchExprent swexpr = (SwitchExprent)first.getExprents().remove(first.getExprents().size() - 1);
     swexpr.setCaseValues(caseValues);
diff --git a/src/org/jetbrains/java/decompiler/struct/StructClass.java b/src/org/jetbrains/java/decompiler/struct/StructClass.java
index cb24ff6..13f5875 100644
--- a/src/org/jetbrains/java/decompiler/struct/StructClass.java
+++ b/src/org/jetbrains/java/decompiler/struct/StructClass.java
@@ -24,6 +24,8 @@ import org.jetbrains.java.decompiler.util.InterpreterUtil;
 import org.jetbrains.java.decompiler.util.VBStyleCollection;
 
 import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
 
 /*
   class_file {
@@ -58,6 +60,7 @@ public class StructClass extends StructMember {
   private final String[] interfaceNames;
   private final VBStyleCollection<StructField, String> fields;
   private final VBStyleCollection<StructMethod, String> methods;
+  public final Map<String, Map<Integer, String>> enumSwitchMap = new HashMap<String, Map<Integer, String>>();
 
   private ConstantPool pool;