Java tutorial
/* * The MIT License (MIT) * * Copyright (c) Despector <https://despector.voxelgenesis.com> * Copyright (c) contributors * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package org.spongepowered.test.decompile; import static org.objectweb.asm.Opcodes.*; import org.junit.Assert; import org.junit.Test; import org.objectweb.asm.Label; import org.objectweb.asm.MethodVisitor; import org.objectweb.asm.Type; import org.spongepowered.test.util.TestHelper; import org.spongepowered.test.util.TestMethodBuilder; public class TryCatchTests { private static final Type THIS_TYPE = Type.getType(TryCatchTests.class); @Test public void testTryCatch() { TestMethodBuilder builder = new TestMethodBuilder("test_mth", "()V"); MethodVisitor mv = builder.getGenerator(); Label l0 = new Label(); Label l1 = new Label(); Label l2 = new Label(); Label l4 = new Label(); mv.visitTryCatchBlock(l0, l1, l2, "java/lang/NullPointerException"); mv.visitLabel(l0); mv.visitMethodInsn(INVOKESTATIC, THIS_TYPE.getInternalName(), "body", "()V", false); mv.visitLabel(l1); mv.visitJumpInsn(GOTO, l4); mv.visitLabel(l2); mv.visitVarInsn(ASTORE, 2); mv.visitVarInsn(ALOAD, 2); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/NullPointerException", "printStackTrace", "()V", false); mv.visitLabel(l4); mv.visitInsn(RETURN); Label l5 = new Label(); mv.visitLabel(l5); mv.visitLocalVariable("e", "Ljava/lang/NullPointerException;", null, l2, l5, 2); String insn = TestHelper.getAsString(builder.finish(), "test_mth"); String good = "try {\n" + " org.spongepowered.test.decompile.TryCatchTests.body();\n" + "} catch (NullPointerException e) {\n" + " e.printStackTrace();\n" + "}"; Assert.assertEquals(good, insn); } @Test public void testTryMultiCatch() { TestMethodBuilder builder = new TestMethodBuilder("test_mth", "()V"); MethodVisitor mv = builder.getGenerator(); Label l0 = new Label(); Label l1 = new Label(); Label l2 = new Label(); Label l3 = new Label(); Label l4 = new Label(); mv.visitTryCatchBlock(l0, l1, l2, "java/lang/NullPointerException"); mv.visitTryCatchBlock(l0, l1, l3, "java/lang/OutOfMemoryError"); mv.visitLabel(l0); mv.visitMethodInsn(INVOKESTATIC, THIS_TYPE.getInternalName(), "body", "()V", false); mv.visitLabel(l1); mv.visitJumpInsn(GOTO, l4); mv.visitLabel(l2); mv.visitVarInsn(ASTORE, 2); mv.visitVarInsn(ALOAD, 2); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/NullPointerException", "printStackTrace", "()V", false); mv.visitJumpInsn(GOTO, l4); mv.visitLabel(l3); mv.visitVarInsn(ASTORE, 2); mv.visitVarInsn(ALOAD, 2); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/OutOfMemoryError", "printStackTrace", "()V", false); mv.visitLabel(l4); mv.visitInsn(RETURN); Label l5 = new Label(); mv.visitLabel(l5); mv.visitLocalVariable("e", "Ljava/lang/NullPointerException;", null, l2, l3, 2); mv.visitLocalVariable("e", "Ljava/lang/OutOfMemoryError;", null, l3, l4, 2); String insn = TestHelper.getAsString(builder.finish(), "test_mth"); String good = "try {\n" + " org.spongepowered.test.decompile.TryCatchTests.body();\n" + "} catch (NullPointerException e) {\n" + " e.printStackTrace();\n" + "} catch (OutOfMemoryError e) {\n" + " e.printStackTrace();\n" + "}"; Assert.assertEquals(good, insn); } @Test public void testTryPipeCatch() { TestMethodBuilder builder = new TestMethodBuilder("test_mth", "()V"); MethodVisitor mv = builder.getGenerator(); Label l0 = new Label(); Label l1 = new Label(); Label l2 = new Label(); Label l4 = new Label(); mv.visitTryCatchBlock(l0, l1, l2, "java/lang/NullPointerException"); mv.visitTryCatchBlock(l0, l1, l2, "java/lang/OutOfMemoryError"); mv.visitLabel(l0); mv.visitMethodInsn(INVOKESTATIC, THIS_TYPE.getInternalName(), "body", "()V", false); mv.visitLabel(l1); mv.visitJumpInsn(GOTO, l4); mv.visitLabel(l2); mv.visitVarInsn(ASTORE, 2); mv.visitVarInsn(ALOAD, 2); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/NullPointerException", "printStackTrace", "()V", false); mv.visitLabel(l4); mv.visitInsn(RETURN); Label l5 = new Label(); mv.visitLabel(l5); mv.visitLocalVariable("e", "Ljava/lang/NullPointerException;", null, l2, l4, 2); String insn = TestHelper.getAsString(builder.finish(), "test_mth"); String good = "try {\n" + " org.spongepowered.test.decompile.TryCatchTests.body();\n" + "} catch (NullPointerException | OutOfMemoryError e) {\n" + " e.printStackTrace();\n" + "}"; Assert.assertEquals(good, insn); } @Test public void testTryCatchNested() { TestMethodBuilder builder = new TestMethodBuilder("test_mth", "()V"); MethodVisitor mv = builder.getGenerator(); Label l0 = new Label(); Label l1 = new Label(); Label l2 = new Label(); Label l3 = new Label(); Label l4 = new Label(); mv.visitTryCatchBlock(l0, l1, l2, "java/lang/Exception"); mv.visitTryCatchBlock(l0, l3, l4, "java/lang/NullPointerException"); mv.visitLabel(l0); mv.visitMethodInsn(INVOKESTATIC, THIS_TYPE.getInternalName(), "body", "()V", false); mv.visitLabel(l1); Label l5 = new Label(); mv.visitJumpInsn(GOTO, l5); mv.visitLabel(l2); mv.visitVarInsn(ASTORE, 3); Label l6 = new Label(); mv.visitLabel(l6); mv.visitVarInsn(ALOAD, 3); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Exception", "printStackTrace", "()V", false); mv.visitLabel(l3); mv.visitJumpInsn(GOTO, l5); mv.visitLabel(l4); mv.visitVarInsn(ASTORE, 3); Label l7 = new Label(); mv.visitLabel(l7); mv.visitVarInsn(ALOAD, 3); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/NullPointerException", "printStackTrace", "()V", false); mv.visitLabel(l5); mv.visitInsn(RETURN); Label l8 = new Label(); mv.visitLabel(l8); mv.visitLocalVariable("e", "Ljava/lang/Exception;", null, l6, l3, 3); mv.visitLocalVariable("e", "Ljava/lang/NullPointerException;", null, l7, l5, 3); String insn = TestHelper.getAsString(builder.finish(), "test_mth"); String good = "try {\n" + " try {\n" + " org.spongepowered.test.decompile.TryCatchTests.body();\n" + " } catch (Exception e) {\n" + " e.printStackTrace();\n" + " }\n" + "} catch (NullPointerException e) {\n" + " e.printStackTrace();\n" + "}"; Assert.assertEquals(good, insn); } @Test public void testTryCatchWithControlFlow() { TestMethodBuilder builder = new TestMethodBuilder("test_mth", "()V"); MethodVisitor mv = builder.getGenerator(); Label l0 = new Label(); Label l1 = new Label(); Label l2 = new Label(); Label l4 = new Label(); mv.visitTryCatchBlock(l0, l1, l2, "java/lang/NullPointerException"); mv.visitLabel(l0); mv.visitMethodInsn(INVOKESTATIC, THIS_TYPE.getInternalName(), "body", "()V", false); mv.visitLabel(l1); mv.visitJumpInsn(GOTO, l4); mv.visitLabel(l2); mv.visitVarInsn(ASTORE, 2); mv.visitVarInsn(ALOAD, 2); mv.visitJumpInsn(IFNULL, l4); mv.visitVarInsn(ALOAD, 2); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/NullPointerException", "printStackTrace", "()V", false); mv.visitLabel(l4); mv.visitInsn(RETURN); Label l5 = new Label(); mv.visitLabel(l5); mv.visitLocalVariable("e", "Ljava/lang/NullPointerException;", null, l2, l5, 2); String insn = TestHelper.getAsString(builder.finish(), "test_mth"); String good = "try {\n" + " org.spongepowered.test.decompile.TryCatchTests.body();\n" + "} catch (NullPointerException e) {\n" + " if (e != null) {\n" + " e.printStackTrace();\n" + " }\n" + "}"; Assert.assertEquals(good, insn); } @Test public void testTryCatchReturnedTernary() { TestMethodBuilder builder = new TestMethodBuilder("test_mth", "(Z)I"); MethodVisitor mv = builder.getGenerator(); Label l0 = new Label(); Label l1 = new Label(); Label l2 = new Label(); mv.visitTryCatchBlock(l0, l1, l2, "java/lang/Exception"); mv.visitLabel(l0); mv.visitVarInsn(ILOAD, 1); Label l3 = new Label(); mv.visitJumpInsn(IFEQ, l3); mv.visitIntInsn(BIPUSH, 6); mv.visitJumpInsn(GOTO, l1); mv.visitLabel(l3); mv.visitInsn(ICONST_3); mv.visitLabel(l1); mv.visitInsn(IRETURN); mv.visitLabel(l2); mv.visitVarInsn(ASTORE, 2); Label l4 = new Label(); mv.visitLabel(l4); mv.visitInsn(ICONST_0); mv.visitInsn(IRETURN); Label l5 = new Label(); mv.visitLabel(l5); mv.visitLocalVariable("a", "Z", null, l0, l5, 1); mv.visitLocalVariable("e", "Ljava/lang/Exception;", null, l4, l5, 2); String insn = TestHelper.getAsString(builder.finish(), "test_mth"); String good = "try {\n" + " return a ? 6 : 3;\n" + "} catch (Exception e) {\n" + " return 0;\n" + "}"; Assert.assertEquals(good, insn); } }