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Simple library for generating code.
There is a newer version: 5.25.1
/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.codegen;

import static org.neo4j.codegen.MethodDeclaration.TypeParameter.NO_PARAMETERS;
import static org.neo4j.codegen.MethodDeclaration.constructor;
import static org.neo4j.codegen.MethodDeclaration.method;
import static org.neo4j.codegen.MethodReference.methodReference;
import static org.neo4j.codegen.TypeReference.NO_TYPES;
import static org.neo4j.codegen.TypeReference.typeReference;

import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

/**
 * A ClassGenerator enrichs a ClassWriter with field management, and returns CodeBlocks instead of MethodWriters.
 */
public class ClassGenerator implements AutoCloseable {
    private final ClassHandle handle;
    private ClassWriter writer;
    private Map fields;
    private boolean hasConstructor;

    ClassGenerator(ClassHandle handle, ClassWriter writer) {
        this.handle = handle;
        this.writer = writer;
    }

    @Override
    public void close() {
        if (!hasConstructor) {
            generate(MethodTemplate.constructor().invokeSuper().build());
        }
        writer.done();
        handle.generator.closeClass();
        writer = InvalidState.CLASS_DONE;
    }

    public ClassHandle handle() {
        return handle;
    }

    public FieldReference field(Class type, String name) {
        return field(typeReference(type), name);
    }

    public FieldReference field(TypeReference type, String name) {
        return emitField(Modifier.PUBLIC, type, name, null);
    }

    public FieldReference privateStaticFinalField(Class type, String name, Expression value) {
        return privateStaticFinalField(typeReference(type), name, value);
    }

    public FieldReference publicStaticField(TypeReference type, String name) {
        return emitField(Modifier.PUBLIC | Modifier.STATIC, type, name, null);
    }

    public FieldReference privateStaticField(Class type, String name, Expression value) {
        return privateStaticField(typeReference(type), name, value);
    }

    public FieldReference privateStaticField(TypeReference type, String name, Expression value) {
        return emitField(Modifier.PRIVATE | Modifier.STATIC, type, name, value);
    }

    public FieldReference privateStaticFinalField(TypeReference type, String name, Expression value) {
        return emitField(
                Modifier.PRIVATE | Modifier.STATIC | Modifier.FINAL, type, name, Objects.requireNonNull(value));
    }

    private FieldReference emitField(int modifiers, TypeReference type, String name, Expression value) {
        if (fields == null) {
            fields = new HashMap<>();
        } else if (fields.containsKey(name)) {
            throw new IllegalArgumentException(handle + " already has a field '" + name + "'");
        }
        FieldReference field = new FieldReference(modifiers, handle, type, name);
        fields.put(name, field);
        writer.field(field, value);
        return field;
    }

    public MethodReference generate(MethodTemplate template, Binding... bindings) {
        try (CodeBlock generator = generate(template.declaration(handle))) {
            template.generate(generator);
        }
        return methodReference(
                handle, template.returnType(), template.name(), template.modifiers(), template.parameterTypes());
    }

    public CodeBlock generateConstructor(Parameter... parameters) {
        return generate(constructor(handle, parameters, /*throws:*/ NO_TYPES, Modifier.PUBLIC, NO_PARAMETERS));
    }

    public CodeBlock generateConstructor(int modifiers, Parameter... parameters) {
        return generate(constructor(handle, parameters, /*throws:*/ NO_TYPES, modifiers, NO_PARAMETERS));
    }

    public CodeBlock generateMethod(Class returnType, String name, Parameter... parameters) {
        return generateMethod(typeReference(returnType), name, Modifier.PUBLIC, parameters);
    }

    public CodeBlock generateMethod(Class returnType, String name, int modifiers, Parameter... parameters) {
        return generateMethod(typeReference(returnType), name, modifiers, parameters);
    }

    public CodeBlock generateMethod(TypeReference returnType, String name, Parameter... parameters) {
        return generate(
                method(handle, returnType, name, parameters, /*throws:*/ NO_TYPES, Modifier.PUBLIC, NO_PARAMETERS));
    }

    public CodeBlock generateMethod(TypeReference returnType, String name, int modifiers, Parameter... parameters) {
        return generate(method(handle, returnType, name, parameters, /*throws:*/ NO_TYPES, modifiers, NO_PARAMETERS));
    }

    public CodeBlock generate(MethodDeclaration.Builder builder) {
        return generate(builder.build(handle));
    }

    private CodeBlock generate(MethodDeclaration declaration) {
        if (declaration.isConstructor()) {
            hasConstructor = true;
        }
        return new CodeBlock(this, writer.method(declaration), declaration.parameters());
    }

    FieldReference getField(String name) {
        return fields == null ? null : fields.get(name);
    }
}