java-decompiler: optimization (less string buffer allocations on generating text)

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

@@ -34,15 +34,13 @@ import org.jetbrains.java.decompiler.struct.attr.StructInnerClassesAttribute;
 import org.jetbrains.java.decompiler.struct.gen.VarType;
 import org.jetbrains.java.decompiler.util.InterpreterUtil;
 
-import java.io.BufferedWriter;
 import java.io.IOException;
-import java.io.StringWriter;
 import java.util.*;
 import java.util.Map.Entry;
 
 public class ClassesProcessor {
 
-  private HashMap<String, ClassNode> mapRootClasses = new HashMap<String, ClassNode>();
+  private Map<String, ClassNode> mapRootClasses = new HashMap<String, ClassNode>();
 
   public ClassesProcessor(StructContext context) {
 
@@ -96,7 +94,7 @@ public class ClassesProcessor {
               arr[3] = entry[3];
 
               // enclosing class
-              String enclClassName = null;
+              String enclClassName;
               if (entry[1] != 0) {
                 enclClassName = strentry[1];
               }
@@ -186,9 +184,9 @@ public class ClassesProcessor {
 
                 Object[] arr = mapInnerClasses.get(nestedClass);
 
-                if ((Integer)arr[2] == ClassNode.CLASS_MEMBER) {
+                //if ((Integer)arr[2] == ClassNode.CLASS_MEMBER) {
                   // FIXME: check for consistent naming
-                }
+                //}
 
                 nestednode.type = (Integer)arr[2];
                 nestednode.simpleName = (String)arr[1];
@@ -234,56 +232,49 @@ public class ClassesProcessor {
     }
   }
 
-
-  public void writeClass(StructClass cl, BufferedWriter writer) throws IOException {
-
+  public void writeClass(StructClass cl, StringBuilder buffer) throws IOException {
     ClassNode root = mapRootClasses.get(cl.qualifiedName);
     if (root.type != ClassNode.CLASS_ROOT) {
       return;
     }
 
     try {
-      DecompilerContext.setImportCollector(new ImportCollector(root));
+      ImportCollector importCollector = new ImportCollector(root);
+      DecompilerContext.setImportCollector(importCollector);
       DecompilerContext.setCounterContainer(new CounterContainer());
 
-      // lambda processing
-      LambdaProcessor lambda_proc = new LambdaProcessor();
-      lambda_proc.processClass(root);
+      new LambdaProcessor().processClass(root);
 
       // add simple class names to implicit import
-      addClassnameToImport(root, DecompilerContext.getImportCollector());
-      // build wrappers for all nested classes
-      // that's where the actual processing takes place
+      addClassnameToImport(root, importCollector);
+
+      // build wrappers for all nested classes (that's where actual processing takes place)
       initWrappers(root);
 
-      NestedClassProcessor nestedproc = new NestedClassProcessor();
-      nestedproc.processClass(root, root);
+      new NestedClassProcessor().processClass(root, root);
 
-      NestedMemberAccess nstmember = new NestedMemberAccess();
-      nstmember.propagateMemberAccess(root);
+      new NestedMemberAccess().propagateMemberAccess(root);
 
-      ClassWriter clwriter = new ClassWriter();
+      StringBuilder classBuffer = new StringBuilder();
+      new ClassWriter().classToJava(root, classBuffer, 0);
 
-      StringWriter strwriter = new StringWriter();
-      clwriter.classToJava(root, new BufferedWriter(strwriter), 0);
+      String lineSeparator = DecompilerContext.getNewLineSeparator();
 
       int index = cl.qualifiedName.lastIndexOf("/");
       if (index >= 0) {
         String packageName = cl.qualifiedName.substring(0, index).replace('/', '.');
-        writer.write("package ");
-        writer.write(packageName);
-        writer.write(";");
-        writer.write(DecompilerContext.getNewLineSeparator());
-        writer.write(DecompilerContext.getNewLineSeparator());
+        buffer.append("package ");
+        buffer.append(packageName);
+        buffer.append(";");
+        buffer.append(lineSeparator);
+        buffer.append(lineSeparator);
       }
 
-      DecompilerContext.setProperty(DecompilerContext.CURRENT_CLASS_NODE, root);
+      if (importCollector.writeImports(buffer)) {
+        buffer.append(lineSeparator);
+      }
 
-      DecompilerContext.getImportCollector().writeImports(writer);
-      writer.write(DecompilerContext.getNewLineSeparator());
-
-      writer.write(strwriter.toString());
-      writer.flush();
+      buffer.append(classBuffer);
     }
     finally {
       destroyWrappers(root);
@@ -327,7 +318,7 @@ public class ClassesProcessor {
     }
   }
 
-  public HashMap<String, ClassNode> getMapRootClasses() {
+  public Map<String, ClassNode> getMapRootClasses() {
     return mapRootClasses;
   }
 
@@ -369,7 +360,7 @@ public class ClassesProcessor {
     public ClassNode(String content_class_name,
                      String content_method_name,
                      String content_method_descriptor,
-                     int content_method_invokation_type,
+                     int content_method_invocation_type,
                      String lambda_class_name,
                      String lambda_method_name,
                      String lambda_method_descriptor,
@@ -386,7 +377,7 @@ public class ClassesProcessor {
       lambda_information.content_class_name = content_class_name;
       lambda_information.content_method_name = content_method_name;
       lambda_information.content_method_descriptor = content_method_descriptor;
-      lambda_information.content_method_invokation_type = content_method_invokation_type;
+      lambda_information.content_method_invocation_type = content_method_invocation_type;
 
       lambda_information.content_method_key =
         InterpreterUtil.makeUniqueKey(lambda_information.content_method_name, lambda_information.content_method_descriptor);
@@ -401,7 +392,7 @@ public class ClassesProcessor {
 
       lambda_information.is_method_reference = is_method_reference;
       lambda_information.is_content_method_static =
-        (lambda_information.content_method_invokation_type == CodeConstants.CONSTANT_MethodHandle_REF_invokeStatic); // FIXME: redundant?
+        (lambda_information.content_method_invocation_type == CodeConstants.CONSTANT_MethodHandle_REF_invokeStatic); // FIXME: redundant?
     }
 
     public ClassNode(int type, StructClass classStruct) {
@@ -428,7 +419,7 @@ public class ClassesProcessor {
       public String content_class_name;
       public String content_method_name;
       public String content_method_descriptor;
-      public int content_method_invokation_type; // values from CONSTANT_MethodHandle_REF_*
+      public int content_method_invocation_type; // values from CONSTANT_MethodHandle_REF_*
 
       public String content_method_key;
 

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

@@ -26,8 +26,6 @@ import org.jetbrains.java.decompiler.struct.StructClass;
 import org.jetbrains.java.decompiler.struct.StructContext;
 import org.jetbrains.java.decompiler.struct.lazy.LazyLoader;
 
-import java.io.BufferedWriter;
-import java.io.StringWriter;
 import java.util.Map;
 
 
@@ -81,9 +79,9 @@ public class Fernflower implements IDecompiledData {
 
   public String getClassContent(StructClass cl) {
     try {
-      StringWriter writer = new StringWriter();
-      classesProcessor.writeClass(cl, new BufferedWriter(writer));
-      return writer.toString();
+      StringBuilder buffer = new StringBuilder();
+      classesProcessor.writeClass(cl, buffer);
+      return buffer.toString();
     }
     catch (Throwable ex) {
       DecompilerContext.getLogger().writeMessage("Class " + cl.qualifiedName + " couldn't be fully decompiled.", ex);

src/org/jetbrains/java/decompiler/main/collectors/ImportCollector.java

@@ -20,8 +20,6 @@ import org.jetbrains.java.decompiler.main.ClassesProcessor.ClassNode;
 import org.jetbrains.java.decompiler.main.DecompilerContext;
 import org.jetbrains.java.decompiler.struct.StructContext;
 
-import java.io.BufferedWriter;
-import java.io.IOException;
 import java.util.*;
 import java.util.Map.Entry;
 
@@ -30,12 +28,9 @@ public class ImportCollector {
 
   private static final String JAVA_LANG_PACKAGE = "java.lang";
 
-  private HashMap<String, String> mapSimpleNames = new HashMap<String, String>();
-
-  private HashSet<String> setNotImportedNames = new HashSet<String>();
-
+  private Map<String, String> mapSimpleNames = new HashMap<String, String>();
+  private Set<String> setNotImportedNames = new HashSet<String>();
   private String currentPackageSlash = "";
-
   private String currentPackagePoint = "";
 
   public ImportCollector(ClassNode root) {
@@ -77,7 +72,7 @@ public class ImportCollector {
         return retname;
       }
     }
-    else if (node == null || !node.classStruct.isOwn()) {
+    else {
       fullname = fullname.replace('$', '.');
     }
 
@@ -112,18 +107,20 @@ public class ImportCollector {
     return retname == null ? nshort : retname;
   }
 
-  public void writeImports(BufferedWriter writer) throws IOException {
+  public boolean writeImports(StringBuilder buffer) {
+    List<String> imports = packImports();
 
-    for (String s : packImports()) {
-      writer.write("import ");
-      writer.write(s);
-      writer.write(";");
-      writer.write(DecompilerContext.getNewLineSeparator());
+    for (String s : imports) {
+      buffer.append("import ");
+      buffer.append(s);
+      buffer.append(";");
+      buffer.append(DecompilerContext.getNewLineSeparator());
     }
+
+    return imports.size() > 0;
   }
 
   private List<String> packImports() {
-
     List<Entry<String, String>> lst = new ArrayList<Entry<String, String>>(mapSimpleNames.entrySet());
 
     Collections.sort(lst, new Comparator<Entry<String, String>>() {
@@ -138,12 +135,11 @@ public class ImportCollector {
 
     List<String> res = new ArrayList<String>();
     for (Entry<String, String> ent : lst) {
-      if (!setNotImportedNames.contains(ent.getKey()) // not the current class or one of the nested ones. Also not the empty package.
-          && !JAVA_LANG_PACKAGE.equals(ent.getValue())
-          && ent.getValue().length() > 0) {
-
-        String imp = ent.getValue() + "." + ent.getKey();
-        res.add(imp);
+      // exclude a current class or one of the nested ones, java.lang and empty packages
+      if (!setNotImportedNames.contains(ent.getKey()) &&
+          !JAVA_LANG_PACKAGE.equals(ent.getValue()) &&
+          !ent.getValue().isEmpty()) {
+        res.add(ent.getValue() + "." + ent.getKey());
       }
     }
 

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

@@ -28,9 +28,6 @@ import org.jetbrains.java.decompiler.struct.gen.VarType;
 import org.jetbrains.java.decompiler.util.InterpreterUtil;
 import org.jetbrains.java.decompiler.util.ListStack;
 
-import java.io.BufferedWriter;
-import java.io.IOException;
-import java.io.StringWriter;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -260,29 +257,16 @@ public class NewExprent extends Exprent {
         buf.setLength(0);
       }
 
-      StringWriter strwriter = new StringWriter();
-      BufferedWriter bufstrwriter = new BufferedWriter(strwriter);
-
-      ClassWriter clwriter = new ClassWriter();
-      try {
-        if (lambda) {
-          clwriter.classLambdaToJava(child, bufstrwriter, (constructor == null ? null : constructor.getInstance()), indent);
+      if (lambda) {
+        if (!DecompilerContext.getOption(IFernflowerPreferences.LAMBDA_TO_ANONYMOUS_CLASS)) {
+          buf.setLength(0);  // remove the usual 'new <class>()', it will be replaced with lambda style '() ->'
         }
-        else {
-          clwriter.classToJava(child, bufstrwriter, indent);
-        }
-        bufstrwriter.flush();
+        Exprent methodObject = constructor == null ? null : constructor.getInstance();
+        new ClassWriter().classLambdaToJava(child, buf, methodObject, indent);
       }
-      catch (IOException ex) {
-        throw new RuntimeException(ex);
+      else {
+        new ClassWriter().classToJava(child, buf, indent);
       }
-
-      if (lambda && !DecompilerContext.getOption(IFernflowerPreferences.LAMBDA_TO_ANONYMOUS_CLASS)) {
-        buf.setLength(0); // remove the usual 'new <class>()', it will
-        // be replaced with lambda style '() ->'
-      }
-
-      buf.append(strwriter.toString());
     }
     else if (directArrayInit) {
       VarType leftType = newtype.copy();
@@ -293,10 +277,7 @@ public class NewExprent extends Exprent {
         if (i > 0) {
           buf.append(", ");
         }
-        StringBuilder buff = new StringBuilder();
-        ExprProcessor.getCastedExprent(lstArrayElements.get(i), leftType, buff, indent, false);
-
-        buf.append(buff);
+        ExprProcessor.getCastedExprent(lstArrayElements.get(i), leftType, buf, indent, false);
       }
       buf.append("}");
     }

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

@@ -26,9 +26,6 @@ import org.jetbrains.java.decompiler.modules.decompiler.vars.VarVersionPaar;
 import org.jetbrains.java.decompiler.struct.gen.VarType;
 import org.jetbrains.java.decompiler.util.InterpreterUtil;
 
-import java.io.BufferedWriter;
-import java.io.IOException;
-import java.io.StringWriter;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -84,24 +81,11 @@ public class VarExprent extends Exprent {
   }
 
   public String toJava(int indent) {
+    StringBuilder buffer = new StringBuilder();
 
     if (classdef) {
-
       ClassNode child = DecompilerContext.getClassProcessor().getMapRootClasses().get(vartype.value);
-
-      StringWriter strwriter = new StringWriter();
-      BufferedWriter bufstrwriter = new BufferedWriter(strwriter);
-
-      ClassWriter clwriter = new ClassWriter();
-      try {
-        clwriter.classToJava(child, bufstrwriter, indent);
-        bufstrwriter.flush();
-      }
-      catch (IOException ex) {
-        throw new RuntimeException(ex);
-      }
-
-      return strwriter.toString();
+      new ClassWriter().classToJava(child, buffer, indent);
     }
     else {
       String name = null;
@@ -109,18 +93,16 @@ public class VarExprent extends Exprent {
         name = processor.getVarName(new VarVersionPaar(index, version));
       }
 
-      StringBuilder buf = new StringBuilder();
-
       if (definition) {
         if (processor != null && processor.getVarFinal(new VarVersionPaar(index, version)) == VarTypeProcessor.VAR_FINALEXPLICIT) {
-          buf.append("final ");
+          buffer.append("final ");
         }
-        buf.append(ExprProcessor.getCastTypeName(getVartype())).append(" ");
+        buffer.append(ExprProcessor.getCastTypeName(getVartype())).append(" ");
       }
-      buf.append(name == null ? ("var" + index + (version == 0 ? "" : "_" + version)) : name);
-
-      return buf.toString();
+      buffer.append(name == null ? ("var" + index + (version == 0 ? "" : "_" + version)) : name);
     }
+
+    return buffer.toString();
   }
 
   public boolean equals(Object o) {

src/org/jetbrains/java/decompiler/util/InterpreterUtil.java

@@ -60,14 +60,18 @@ public class InterpreterUtil {
   }
 
   public static String getIndentString(int length) {
-    String indent = (String)DecompilerContext.getProperty(IFernflowerPreferences.INDENT_STRING);
     StringBuilder buf = new StringBuilder();
-    while (length-- > 0) {
-      buf.append(indent);
-    }
+    appendIndent(buf, length);
     return buf.toString();
   }
 
+  public static void appendIndent(StringBuilder buffer, int length) {
+    String indent = (String)DecompilerContext.getProperty(IFernflowerPreferences.INDENT_STRING);
+    while (length-- > 0) {
+      buffer.append(indent);
+    }
+  }
+
   public static boolean equalSets(Collection<?> c1, Collection<?> c2) {
     if (c1 == null) {
       return c2 == null;

test/org/jetbrains/java/decompiler/SingleClassesTest.java

@@ -28,11 +28,17 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 public class SingleClassesTest {
+  private File testDataDir;
   private File tempDir;
   private ConsoleDecompiler decompiler;
 
   @Before
   public void setUp() throws IOException {
+    testDataDir = new File("testData");
+    if (!isTestDataDir(testDataDir)) testDataDir = new File("community/plugins/java-decompiler/engine/testData");
+    if (!isTestDataDir(testDataDir)) testDataDir = new File("plugins/java-decompiler/engine/testData");
+    assertTrue(isTestDataDir(testDataDir));
+
     //noinspection SSBasedInspection
     tempDir = File.createTempFile("decompiler_test_", "_dir");
     assertTrue(tempDir.delete());
@@ -52,6 +58,7 @@ public class SingleClassesTest {
     decompiler = null;
     delete(tempDir);
     tempDir = null;
+    testDataDir = null;
   }
 
   @Test public void testClassFields() { doTest("TestClassFields"); }
@@ -69,13 +76,9 @@ public class SingleClassesTest {
 
   private void doTest(final String testName) {
     try {
-      File testDataDir = new File("testData");
-      if (!isTestDataDir(testDataDir)) testDataDir = new File("community/plugins/java-decompiler/engine/testData");
-      if (!isTestDataDir(testDataDir)) testDataDir = new File("plugins/java-decompiler/engine/testData");
-      assertTrue(isTestDataDir(testDataDir));
-
       File classFile = new File(testDataDir, "/classes/pkg/" + testName + ".class");
       assertTrue(classFile.isFile());
+
       decompiler.addSpace(classFile, true);
       File[] innerClasses = classFile.getParentFile().listFiles(new FilenameFilter() {
         @Override

testData/results/TestClassFields.dec

@@ -1,12 +1,9 @@
 package pkg;
 
-
 public class TestClassFields {
-
    private static int[] sizes;
    private static String[] names = new String[]{"name1", "name2"};
 
-
    static {
       sizes = new int[names.length];
    }

testData/results/TestClassLambda.dec

@@ -10,10 +10,8 @@ import java.util.function.Predicate;
 import java.util.function.Supplier;
 
 public class TestClassLambda {
-
    public int field = 0;
 
-
    public void testLambda() {
       List var1 = Arrays.asList(new Integer[]{Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(3), Integer.valueOf(4), Integer.valueOf(5), Integer.valueOf(6), Integer.valueOf(7)});
       int var2 = (int)Math.random();

testData/results/TestClassLoop.dec

@@ -1,8 +1,6 @@
 package pkg;
 
-
 public class TestClassLoop {
-
    public static void testSimpleInfinite() {
       while(true) {
          System.out.println();

testData/results/TestClassSwitch.dec

@@ -1,8 +1,6 @@
 package pkg;
 
-
 public class TestClassSwitch {
-
    public void testCaseOrder(int var1) {
       switch(var1) {
       case 5:

testData/results/TestClassTypes.dec

@@ -4,7 +4,6 @@ import java.util.ArrayList;
 import java.util.List;
 
 public class TestClassTypes {
-
    public void testBoolean() {
       byte var1 = 0;
       long var2 = System.currentTimeMillis();

testData/results/TestClassVar.dec

@@ -1,12 +1,9 @@
 package pkg;
 
-
 public class TestClassVar {
-
    private boolean field_boolean = Math.random() > 0.0D;
    public int field_int = 0;
 
-
    public void testFieldSSAU() {
       for(int var1 = 0; var1 < 10; ++var1) {
          try {

testData/results/TestCodeConstructs.dec

@@ -1,11 +1,8 @@
 package pkg;
 
-
 class TestCodeConstructs {
-
    private int count = 0;
 
-
    void expressions() {
       (new String()).hashCode();
    }

testData/results/TestConstants.dec

@@ -3,7 +3,6 @@ package pkg;
 import java.util.Date;
 
 public class TestConstants {
-
    static final boolean T = true;
    static final boolean F = false;
    static final char C0 = '\n';
@@ -28,7 +27,6 @@ public class TestConstants {
    static final double DMin = 4.9E-324D;
    static final double DMax = 1.7976931348623157E308D;
 
-
    @TestConstants.A(byte.class)
    void m1() {
    }
@@ -70,7 +68,6 @@ public class TestConstants {
    }
 
    @interface A {
-
       Class<?> value();
    }
 }

testData/results/TestDeprecations.dec

@@ -1,15 +1,12 @@
 package pkg;
 
-
 public class TestDeprecations {
-
    /** @deprecated */
    public int byComment;
    /** @deprecated */
    @Deprecated
    public int byAnno;
 
-
    /** @deprecated */
    public void byComment() {
    }
@@ -22,11 +19,9 @@ public class TestDeprecations {
    /** @deprecated */
    @Deprecated
    public static class ByAnno {
-
    }
 
    /** @deprecated */
    public static class ByComment {
-
    }
 }

testData/results/TestEnum.dec

@@ -1,8 +1,6 @@
 package pkg;
 
-
 public enum TestEnum {
-
    E1,
    E2 {
       public void m() {
@@ -13,8 +11,8 @@ public enum TestEnum {
       public void m() {
       }
    };
-   private String s;
 
+   private String s;
 
    public void m() {
    }
@@ -26,5 +24,4 @@ public enum TestEnum {
    private TestEnum(@Deprecated String var3) {
       this.s = var3;
    }
-
 }

testData/results/TestExtendsList.dec

@@ -1,8 +1,6 @@
 package pkg;
 
-
 public class TestExtendsList {
-
    static <T extends Comparable<? super T>> T m1(T var0) {
       return null;
    }

testData/results/TestMethodParameters.dec

@@ -1,8 +1,6 @@
 package pkg;
 
-
 public class TestMethodParameters {
-
    TestMethodParameters(@Deprecated int var1) {
    }
 
@@ -14,7 +12,6 @@ public class TestMethodParameters {
 
    void local() {
       class Local {
-
          Local(@Deprecated int var2) {
          }
 
@@ -25,7 +22,6 @@ public class TestMethodParameters {
    }
 
    static class C2 {
-
       C2(@Deprecated int var1) {
       }
 
@@ -37,7 +33,6 @@ public class TestMethodParameters {
    }
 
    class C1 {
-
       C1(@Deprecated int var2) {
       }