org.jayware.e2.component.impl.generation.writer.ComponentToStringMethodWriter.java Source code

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Here is the source code for org.jayware.e2.component.impl.generation.writer.ComponentToStringMethodWriter.java

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/**
 * Entity Essentials -- A Component-based Entity System
 *
 * Copyright (C) 2015 Elmar Schug <elmar.schug@jayware.org>,
 *                    Markus Neubauer <markus.neubauer@jayware.org>
 *
 *     This file is part of Entity Essentials.
 *
 *     Entity Essentials is free software; you can redistribute it and/or
 *     modify it under the terms of the GNU Lesser General Public License
 *     as published by the Free Software Foundation, either version 3 of
 *     the License, or any later version.
 *
 *     Entity Essentials is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *     Lesser General Public License for more details.
 *
 *     You should have received a copy of the GNU Lesser General Public License
 *     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.jayware.e2.component.impl.generation.writer;

import org.jayware.e2.component.api.Component;
import org.jayware.e2.component.impl.generation.plan.ComponentGenerationPlan;
import org.jayware.e2.component.impl.generation.plan.ComponentPropertyGenerationPlan;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Type;

import static org.objectweb.asm.Opcodes.ACC_PUBLIC;
import static org.objectweb.asm.Opcodes.ALOAD;
import static org.objectweb.asm.Opcodes.ARETURN;
import static org.objectweb.asm.Opcodes.BIPUSH;
import static org.objectweb.asm.Opcodes.DUP;
import static org.objectweb.asm.Opcodes.GETFIELD;
import static org.objectweb.asm.Opcodes.INVOKESPECIAL;
import static org.objectweb.asm.Opcodes.INVOKESTATIC;
import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
import static org.objectweb.asm.Opcodes.NEW;

public class ComponentToStringMethodWriter {
    public void writeToStringMethodFor(ComponentGenerationPlan componentPlan) {
        final Class<? extends Component> componentClass = componentPlan.getComponentClass();
        final String classInternalName = componentPlan.getGeneratedClassInternalName();
        final ClassWriter classWriter = componentPlan.getClassWriter();

        final MethodVisitor mv = classWriter.visitMethod(ACC_PUBLIC, "toString", "()Ljava/lang/String;", null,
                null);
        mv.visitCode();
        mv.visitTypeInsn(NEW, "java/lang/StringBuilder");
        mv.visitInsn(DUP);
        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "<init>", "()V", false);
        mv.visitLdcInsn(componentClass.getSimpleName() + "{");
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append",
                "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);

        int propertiesCount = 0;
        for (ComponentPropertyGenerationPlan propertyPlan : componentPlan.getComponentPropertyGenerationPlans()) {
            final String propertyName = propertyPlan.getPropertyName();
            final Class<?> propertyType = propertyPlan.getPropertyType();
            final String propertyTypeDescriptor = Type.getDescriptor(propertyPlan.getPropertyType());

            if (propertiesCount == 0) {
                mv.visitLdcInsn(propertyName + "='");
            } else {
                mv.visitLdcInsn("', " + propertyName + "='");
            }

            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append",
                    "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETFIELD, classInternalName, propertyName, propertyTypeDescriptor);

            if (propertyType.isPrimitive()) {
                mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append",
                        "(" + propertyTypeDescriptor + ")Ljava/lang/StringBuilder;", false);
            } else {
                mv.visitMethodInsn(INVOKESTATIC, "java/lang/String", "valueOf",
                        "(Ljava/lang/Object;)Ljava/lang/String;", false);
                mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append",
                        "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);
            }

            if (propertiesCount == componentPlan.getComponentPropertyGenerationPlans().size() - 1) {
                mv.visitIntInsn(BIPUSH, '\'');
                mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append",
                        "(C)Ljava/lang/StringBuilder;", false);
            }

            ++propertiesCount;
        }

        mv.visitLdcInsn("}");
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append",
                "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false);
        mv.visitInsn(ARETURN);
        mv.visitMaxs(0, 0);
        mv.visitEnd();
    }
}