poodinis/source/poodinis/registration.d

/**
 * This module contains objects for defining and scoping dependency registrations.
 *
 * Part of the Poodinis Dependency Injection framework.
 *
 * Authors:
 *  Mike Bierlee, m.bierlee@lostmoment.com
 * Copyright: 2014-2023 Mike Bierlee
 * License:
 *  This software is licensed under the terms of the MIT license.
 *  The full terms of the license can be found in the LICENSE file.
 */

module poodinis.registration;

import poodinis.container : DependencyContainer;
import poodinis.factory : InstanceFactory, InstanceEventHandler,
    InstanceCreationException, InstanceFactoryParameters, CreatesSingleton;

class Registration
{
    private TypeInfo _registeredType = null;
    private TypeInfo_Class _instanceType = null;
    private Registration linkedRegistration;
    private shared(DependencyContainer) _originatingContainer;
    private InstanceFactory _instanceFactory;
    private void delegate() _preDestructor;

    public @property registeredType()
    {
        return _registeredType;
    }

    public @property instanceType()
    {
        return _instanceType;
    }

    public @property originatingContainer()
    {
        return _originatingContainer;
    }

    public @property instanceFactory()
    {
        return _instanceFactory;
    }

    public @property preDestructor()
    {
        return _preDestructor;
    }

    protected @property preDestructor(void delegate() preDestructor)
    {
        _preDestructor = preDestructor;
    }

    this(TypeInfo registeredType, TypeInfo_Class instanceType,
            InstanceFactory instanceFactory, shared(DependencyContainer) originatingContainer)
    {
        this._registeredType = registeredType;
        this._instanceType = instanceType;
        this._originatingContainer = originatingContainer;
        this._instanceFactory = instanceFactory;
    }

    public Object getInstance(InstantiationContext context = new InstantiationContext())
    {
        if (linkedRegistration !is null)
        {
            return linkedRegistration.getInstance(context);
        }

        if (instanceFactory is null)
        {
            throw new InstanceCreationException(
                    "No instance factory defined for registration of type " ~ registeredType.toString());
        }

        return instanceFactory.getInstance();
    }

    public Registration linkTo(Registration registration)
    {
        this.linkedRegistration = registration;
        return this;
    }

    Registration onConstructed(InstanceEventHandler handler)
    {
        if (instanceFactory !is null)
            instanceFactory.onConstructed(handler);
        return this;
    }
}

private InstanceFactoryParameters copyFactoryParameters(Registration registration)
{
    return registration.instanceFactory.factoryParameters;
}

private void setFactoryParameters(Registration registration, InstanceFactoryParameters newParameters)
{
    registration.instanceFactory.factoryParameters = newParameters;
}

/**
 * Sets the registration's instance factory type the same as the registration's.
 *
 * This is not a registration scope. Typically used by Poodinis internally only.
 */
public Registration initializeFactoryType(Registration registration)
{
    auto params = registration.copyFactoryParameters();
    params.instanceType = registration.instanceType;
    registration.setFactoryParameters(params);
    return registration;
}

/**
 * Scopes registrations to return the same instance every time a given registration is resolved.
 *
 * Effectively makes the given registration a singleton.
 */
public Registration singleInstance(Registration registration)
{
    auto params = registration.copyFactoryParameters();
    params.createsSingleton = CreatesSingleton.yes;
    registration.setFactoryParameters(params);
    return registration;
}

/**
 * Scopes registrations to return a new instance every time the given registration is resolved.
 */
public Registration newInstance(Registration registration)
{
    auto params = registration.copyFactoryParameters();
    params.createsSingleton = CreatesSingleton.no;
    params.existingInstance = null;
    registration.setFactoryParameters(params);
    return registration;
}

/**
 * Scopes registrations to return the given instance every time the given registration is resolved.
 */
public Registration existingInstance(Registration registration, Object instance)
{
    auto params = registration.copyFactoryParameters();
    params.createsSingleton = CreatesSingleton.yes;
    params.existingInstance = instance;
    registration.setFactoryParameters(params);
    return registration;
}

/**
 * Scopes registrations to create new instances using the given initializer delegate.
 */
public Registration initializedBy(T)(Registration registration, T delegate() initializer)
        if (is(T == class) || is(T == interface))
{
    auto params = registration.copyFactoryParameters();
    params.createsSingleton = CreatesSingleton.no;
    params.factoryMethod = () => cast(Object) initializer();
    registration.setFactoryParameters(params);
    return registration;
}

/**
 * Scopes registrations to create a new instance using the given initializer delegate. On subsequent resolves the same instance is returned.
 */
public Registration initializedOnceBy(T : Object)(Registration registration, T delegate() initializer)
{
    auto params = registration.copyFactoryParameters();
    params.createsSingleton = CreatesSingleton.yes;
    params.factoryMethod = () => cast(Object) initializer();
    registration.setFactoryParameters(params);
    return registration;
}

public string toConcreteTypeListString(Registration[] registrations)
{
    auto concreteTypeListString = "";
    foreach (registration; registrations)
    {
        if (concreteTypeListString.length > 0)
        {
            concreteTypeListString ~= ", ";
        }
        concreteTypeListString ~= registration.instanceType.toString();
    }
    return concreteTypeListString;
}

class InstantiationContext
{
}