com.asakusafw.dag.compiler.codegen.SupplierGenerator.java Source code

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Here is the source code for com.asakusafw.dag.compiler.codegen.SupplierGenerator.java

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/**
 * Copyright 2011-2017 Asakusa Framework Team.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.asakusafw.dag.compiler.codegen;

import static com.asakusafw.dag.compiler.codegen.AsmUtil.*;

import java.util.Objects;
import java.util.function.Supplier;

import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

import com.asakusafw.dag.compiler.model.ClassData;
import com.asakusafw.lang.compiler.model.description.ClassDescription;
import com.asakusafw.lang.compiler.model.description.TypeDescription;

/**
 * Generates {@link Supplier} class.
 * @since 0.4.0
 */
public final class SupplierGenerator {

    private static final String CATEGORY = "util"; //$NON-NLS-1$

    private static final String SUFFIX = "Supplier"; //$NON-NLS-1$

    private SupplierGenerator() {
        return;
    }

    /**
     * Generates {@link Supplier} class.
     * @param context the current context
     * @param type the target data model type
     * @return the generated class
     */
    public static ClassDescription get(ClassGeneratorContext context, TypeDescription type) {
        return context.addClassFile(generate(context, type));
    }

    /**
     * Generates {@link Supplier} class.
     * @param context the current context
     * @param type the target data model type
     * @return the generated class data
     */
    public static ClassData generate(ClassGeneratorContext context, TypeDescription type) {
        return context.cache(new Key(type), () -> {
            ClassDescription target = context.getClassName(CATEGORY, NameUtil.getSimpleNameHint(type, SUFFIX));
            return generate0(type, target);
        });
    }

    private static ClassData generate0(TypeDescription source, ClassDescription target) {
        ClassWriter writer = newWriter(target, Object.class, Supplier.class);
        defineEmptyConstructor(writer, Object.class);
        defineGetter(writer, typeOf(Object.class), "get", v -> {
            v.visitVarInsn(Opcodes.ALOAD, 0);
            v.visitMethodInsn(Opcodes.INVOKEVIRTUAL, target.getInternalName(), "get",
                    Type.getMethodDescriptor(typeOf(source)), false);
            v.visitInsn(Opcodes.ARETURN);
        });
        defineGetter(writer, typeOf(source), "get", v -> {
            getNew(v, source);
            v.visitInsn(Opcodes.ARETURN);
        });
        writer.visitEnd();
        return new ClassData(target, writer::toByteArray);
    }

    private static class Key {

        private final TypeDescription type;

        Key(TypeDescription type) {
            this.type = type;
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + Objects.hashCode(type);
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            Key other = (Key) obj;
            return Objects.equals(type, other.type);
        }

        @Override
        public String toString() {
            return String.format("Supplier(%s)", type); //$NON-NLS-1$
        }
    }
}