core: omit redundant brackets in conditions

jadx-core/src/main/java/jadx/core/codegen/InsnGen.java

@@ -214,7 +214,7 @@ public class InsnGen {
 				break;
 
 			case CHECK_CAST:
-			case CAST:
+			case CAST: {
 				boolean wrap = state.contains(IGState.BODY_ONLY);
 				if (wrap)
 					code.add("(");
@@ -225,7 +225,7 @@ public class InsnGen {
 				if (wrap)
 					code.add(")");
 				break;
-
+			}
 			case ARITH:
 				makeArith((ArithNode) insn, code, state);
 				break;
@@ -263,11 +263,18 @@ public class InsnGen {
 				code.add(String.format("(%1$s > %2$s ? 1 : (%1$s == %2$s ? 0 : -1))", arg(insn, 0), arg(insn, 1)));
 				break;
 
-			case INSTANCE_OF:
-				code.add('(').add(arg(insn, 0)).add(" instanceof ")
-						.add(useType((ArgType) ((IndexInsnNode) insn).getIndex())).add(')');
+			case INSTANCE_OF: {
+				boolean wrap = state.contains(IGState.BODY_ONLY);
+				if (wrap)
+					code.add("(");
+				code.add(arg(insn, 0));
+				code.add(" instanceof ");
+				code.add(useType((ArgType) ((IndexInsnNode) insn).getIndex()));
+				if (wrap) {
+					code.add(")");
+				}
 				break;
-
+			}
 			case CONSTRUCTOR:
 				makeConstructor((ConstructorInsn) insn, code, state);
 				break;

jadx-core/src/main/java/jadx/core/codegen/RegionGen.java

@@ -5,10 +5,13 @@ import jadx.core.dex.attributes.AttributeType;
 import jadx.core.dex.attributes.DeclareVariableAttr;
 import jadx.core.dex.attributes.ForceReturnAttr;
 import jadx.core.dex.attributes.IAttribute;
+import jadx.core.dex.instructions.ArithNode;
 import jadx.core.dex.instructions.IfOp;
+import jadx.core.dex.instructions.InsnType;
 import jadx.core.dex.instructions.SwitchNode;
 import jadx.core.dex.instructions.args.ArgType;
 import jadx.core.dex.instructions.args.InsnArg;
+import jadx.core.dex.instructions.args.InsnWrapArg;
 import jadx.core.dex.instructions.args.LiteralArg;
 import jadx.core.dex.instructions.args.RegisterArg;
 import jadx.core.dex.nodes.IBlock;
@@ -186,17 +189,38 @@ public class RegionGen extends InsnGen {
 				&& secondArg.isLiteral()
 				&& secondArg.getType().equals(ArgType.BOOLEAN)) {
 			LiteralArg lit = (LiteralArg) secondArg;
-			if (lit.getLiteral() == 0)
+			if (lit.getLiteral() == 0) {
 				op = op.invert();
-
+			}
 			if (op == IfOp.EQ) {
-				return arg(firstArg); // == true
+				return arg(firstArg, false); // == true
 			} else if (op == IfOp.NE) {
 				return "!" + arg(firstArg); // != true
 			}
 			LOG.warn(ErrorsCounter.formatErrorMsg(mth, "Unsupported boolean condition " + op.getSymbol()));
 		}
-		return arg(firstArg) + " " + op.getSymbol() + " " + arg(secondArg);
+		return arg(firstArg, isWrapNeeded(firstArg))
+				+ " " + op.getSymbol() + " "
+				+ arg(secondArg, isWrapNeeded(secondArg));
+	}
+
+	private boolean isWrapNeeded(InsnArg arg) {
+		if (!arg.isInsnWrap()) {
+			return false;
+		}
+		InsnNode insn = ((InsnWrapArg) arg).getWrapInsn();
+		if(insn.getType() == InsnType.ARITH) {
+			ArithNode arith = ((ArithNode) insn);
+			switch (arith.getOp()) {
+				case ADD:
+				case SUB:
+				case MUL:
+				case DIV:
+				case REM:
+					return false;
+			}
+		}
+		return true;
 	}
 
 	private CodeWriter makeSwitch(SwitchRegion sw, CodeWriter code) throws CodegenException {

jadx-core/src/test/java/jadx/tests/internal/TestRedundantBrackets.java

@@ -0,0 +1,46 @@
+package jadx.tests.internal;
+
+import jadx.api.InternalJadxTest;
+import jadx.core.dex.nodes.ClassNode;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.junit.Assert.assertThat;
+
+public class TestRedundantBrackets extends InternalJadxTest {
+
+	public static class TestCls {
+		public boolean method(String str) {
+			return str.indexOf('a') != -1;
+		}
+
+		public int method2(Object obj) {
+			if (obj instanceof String) {
+				return ((String) obj).length();
+			}
+			return 0;
+		}
+
+		public int method3(int a, int b) {
+			if (a + b < 10) {
+				return a;
+			}
+			if ((a & b) != 0) {
+				return a * b;
+			}
+			return b;
+		}
+	}
+
+	@Test
+	public void test() {
+		ClassNode cls = getClassNode(TestCls.class);
+
+		String code = cls.getCode().toString();
+//		assertThat(code, not(containsString("(-1)")));
+		assertThat(code, containsString("if (obj instanceof String)"));
+		assertThat(code, containsString("if (a + b < 10)"));
+		assertThat(code, containsString("if ((a & b) != 0)"));
+	}
+}