refactor: reorganize folder hierarchy

18 files changed, 1202 insertions, 0 deletions

diff --git a/src/castable_factory.rs b/src/castable_factory.rs
new file mode 100644
index 0000000..5d582bb
--- /dev/null
+++ b/src/castable_factory.rs
@@ -0,0 +1,76 @@
+use crate::interfaces::factory::IFactory;
+use crate::libs::intertrait::CastFrom;
+use crate::ptr::InterfacePtr;
+
+pub trait AnyFactory: CastFrom {}
+
+pub struct CastableFactory<Args, ReturnInterface>
+where
+    Args: 'static,
+    ReturnInterface: 'static + ?Sized,
+{
+    func: &'static dyn Fn<Args, Output = InterfacePtr<ReturnInterface>>,
+}
+
+impl<Args, ReturnInterface> CastableFactory<Args, ReturnInterface>
+where
+    Args: 'static,
+    ReturnInterface: 'static + ?Sized,
+{
+    pub fn new(
+        func: &'static dyn Fn<Args, Output = InterfacePtr<ReturnInterface>>,
+    ) -> Self
+    {
+        Self { func }
+    }
+}
+
+impl<Args, ReturnInterface> IFactory<Args, ReturnInterface>
+    for CastableFactory<Args, ReturnInterface>
+where
+    Args: 'static,
+    ReturnInterface: 'static + ?Sized,
+{
+}
+
+impl<Args, ReturnInterface> Fn<Args> for CastableFactory<Args, ReturnInterface>
+where
+    Args: 'static,
+    ReturnInterface: 'static + ?Sized,
+{
+    extern "rust-call" fn call(&self, args: Args) -> Self::Output
+    {
+        self.func.call(args)
+    }
+}
+
+impl<Args, ReturnInterface> FnMut<Args> for CastableFactory<Args, ReturnInterface>
+where
+    Args: 'static,
+    ReturnInterface: 'static + ?Sized,
+{
+    extern "rust-call" fn call_mut(&mut self, args: Args) -> Self::Output
+    {
+        self.call(args)
+    }
+}
+
+impl<Args, ReturnInterface> FnOnce<Args> for CastableFactory<Args, ReturnInterface>
+where
+    Args: 'static,
+    ReturnInterface: 'static + ?Sized,
+{
+    type Output = InterfacePtr<ReturnInterface>;
+
+    extern "rust-call" fn call_once(self, args: Args) -> Self::Output
+    {
+        self.call(args)
+    }
+}
+
+impl<Args, ReturnInterface> AnyFactory for CastableFactory<Args, ReturnInterface>
+where
+    Args: 'static,
+    ReturnInterface: 'static + ?Sized,
+{
+}
diff --git a/src/di_container.rs b/src/di_container.rs
new file mode 100644
index 0000000..6982a10
--- /dev/null
+++ b/src/di_container.rs
@@ -0,0 +1,504 @@
+use std::any::{type_name, TypeId};
+use std::collections::HashMap;
+use std::marker::PhantomData;
+use std::rc::Rc;
+
+use error_stack::{Report, ResultExt};
+
+use crate::castable_factory::CastableFactory;
+use crate::errors::di_container::DIContainerError;
+use crate::interfaces::factory::IFactory;
+use crate::interfaces::injectable::Injectable;
+use crate::libs::intertrait::cast_box::CastBox;
+use crate::libs::intertrait::cast_rc::CastRc;
+use crate::provider::{FactoryProvider, IProvider, InjectableTypeProvider, Providable};
+use crate::ptr::{FactoryPtr, InterfacePtr};
+
+/// Binding builder for type `Interface` inside a [`DIContainer`].
+pub struct BindingBuilder<'di_container_lt, Interface>
+where
+    Interface: 'static + ?Sized,
+{
+    di_container: &'di_container_lt mut DIContainer,
+    interface_phantom: PhantomData<Interface>,
+}
+
+impl<'di_container_lt, Interface> BindingBuilder<'di_container_lt, Interface>
+where
+    Interface: 'static + ?Sized,
+{
+    fn new(di_container: &'di_container_lt mut DIContainer) -> Self
+    {
+        Self {
+            di_container,
+            interface_phantom: PhantomData,
+        }
+    }
+
+    /// Creates a binding of type `Interface` to type `Implementation` inside of the
+    /// associated [`DIContainer`].
+    pub fn to<Implementation>(&mut self)
+    where
+        Implementation: Injectable,
+    {
+        let interface_typeid = TypeId::of::<Interface>();
+
+        self.di_container.bindings.insert(
+            interface_typeid,
+            Rc::new(InjectableTypeProvider::<Implementation>::new()),
+        );
+    }
+
+    /// Creates a binding of factory type `Interface` to a factory inside of the
+    /// associated [`DIContainer`].
+    pub fn to_factory<Args, Return>(
+        &mut self,
+        factory_func: &'static dyn Fn<Args, Output = InterfacePtr<Return>>,
+    ) where
+        Args: 'static,
+        Return: 'static + ?Sized,
+        Interface: IFactory<Args, Return>,
+    {
+        let interface_typeid = TypeId::of::<Interface>();
+
+        let factory_impl = CastableFactory::new(factory_func);
+
+        self.di_container.bindings.insert(
+            interface_typeid,
+            Rc::new(FactoryProvider::new(FactoryPtr::new(factory_impl))),
+        );
+    }
+}
+
+/// Dependency injection container.
+///
+/// # Examples
+/// ```
+/// use std::collections::HashMap;
+///
+/// use syrette::{DIContainer, injectable};
+/// use syrette::errors::di_container::DIContainerError;
+///
+/// trait IDatabaseService
+/// {
+///     fn get_all_records(&self, table_name: String) -> HashMap<String, String>;
+/// }
+///
+/// struct DatabaseService {}
+///
+/// #[injectable(IDatabaseService)]
+/// impl DatabaseService
+/// {
+///     fn new() -> Self
+///     {
+///         Self {}
+///     }
+/// }
+///
+/// impl IDatabaseService for DatabaseService
+/// {
+///     fn get_all_records(&self, table_name: String) -> HashMap<String, String>
+///     {
+///         // Do stuff here
+///         HashMap::<String, String>::new()
+///     }
+/// }
+///
+/// fn main() -> error_stack::Result<(), DIContainerError>
+/// {
+///     let mut di_container = DIContainer::new();
+///
+///     di_container.bind::<dyn IDatabaseService>().to::<DatabaseService>();
+///
+///     let database_service = di_container.get::<dyn IDatabaseService>()?;
+///
+///     Ok(())
+/// }
+/// ```
+pub struct DIContainer
+{
+    bindings: HashMap<TypeId, Rc<dyn IProvider>>,
+}
+
+impl DIContainer
+{
+    /// Returns a new `DIContainer`.
+    #[must_use]
+    pub fn new() -> Self
+    {
+        Self {
+            bindings: HashMap::new(),
+        }
+    }
+
+    /// Returns a new [`BindingBuilder`] for the given interface.
+    pub fn bind<Interface>(&mut self) -> BindingBuilder<Interface>
+    where
+        Interface: 'static + ?Sized,
+    {
+        BindingBuilder::<Interface>::new(self)
+    }
+
+    /// Returns a new instance of the type bound with `Interface`.
+    ///
+    /// # Errors
+    /// Will return `Err` if:
+    /// - No binding for `Interface` exists
+    /// - Resolving the binding for `Interface` fails
+    /// - Casting the binding for `Interface` fails
+    /// - The binding for `Interface` is not injectable
+    pub fn get<Interface>(
+        &self,
+    ) -> error_stack::Result<InterfacePtr<Interface>, DIContainerError>
+    where
+        Interface: 'static + ?Sized,
+    {
+        let interface_typeid = TypeId::of::<Interface>();
+
+        let interface_name = type_name::<Interface>();
+
+        let binding = self.bindings.get(&interface_typeid).ok_or_else(|| {
+            Report::new(DIContainerError)
+                .attach_printable(format!("No binding exists for {}", interface_name))
+        })?;
+
+        let binding_providable = binding
+            .provide(self)
+            .change_context(DIContainerError)
+            .attach_printable(format!(
+            "Failed to resolve binding for interface {}",
+            interface_name
+        ))?;
+
+        match binding_providable {
+            Providable::Injectable(binding_injectable) => {
+                let interface_box_result = binding_injectable.cast::<Interface>();
+
+                match interface_box_result {
+                    Ok(interface_box) => Ok(interface_box),
+                    Err(_) => Err(Report::new(DIContainerError).attach_printable(
+                        format!("Unable to cast binding for {}", interface_name),
+                    )),
+                }
+            }
+            Providable::Factory(_) => Err(Report::new(DIContainerError)
+                .attach_printable(format!(
+                    "Binding for {} is not injectable",
+                    interface_name
+                ))),
+        }
+    }
+
+    /// Returns the factory bound with factory type `Interface`.
+    ///
+    /// # Errors
+    /// Will return `Err` if:
+    /// - No binding for `Interface` exists
+    /// - Resolving the binding for `Interface` fails
+    /// - Casting the binding for `Interface` fails
+    /// - The binding for `Interface` is not a factory
+    pub fn get_factory<Interface>(
+        &self,
+    ) -> error_stack::Result<FactoryPtr<Interface>, DIContainerError>
+    where
+        Interface: 'static + ?Sized,
+    {
+        let interface_typeid = TypeId::of::<Interface>();
+
+        let interface_name = type_name::<Interface>();
+
+        let binding = self.bindings.get(&interface_typeid).ok_or_else(|| {
+            Report::new(DIContainerError)
+                .attach_printable(format!("No binding exists for {}", interface_name))
+        })?;
+
+        let binding_providable = binding
+            .provide(self)
+            .change_context(DIContainerError)
+            .attach_printable(format!(
+            "Failed to resolve binding for interface {}",
+            interface_name
+        ))?;
+
+        match binding_providable {
+            Providable::Factory(binding_factory) => {
+                let factory_box_result = binding_factory.cast::<Interface>();
+
+                match factory_box_result {
+                    Ok(interface_box) => Ok(interface_box),
+                    Err(_) => Err(Report::new(DIContainerError).attach_printable(
+                        format!("Unable to cast binding for {}", interface_name),
+                    )),
+                }
+            }
+            Providable::Injectable(_) => Err(Report::new(DIContainerError)
+                .attach_printable(format!(
+                    "Binding for {} is not a factory",
+                    interface_name
+                ))),
+        }
+    }
+}
+
+impl Default for DIContainer
+{
+    fn default() -> Self
+    {
+        Self::new()
+    }
+}
+
+#[cfg(test)]
+mod tests
+{
+    use mockall::mock;
+
+    use super::*;
+    use crate::errors::injectable::ResolveError;
+
+    #[test]
+    fn can_bind_to()
+    {
+        trait IUserManager
+        {
+            fn add_user(&self, user_id: i128);
+
+            fn remove_user(&self, user_id: i128);
+        }
+
+        struct UserManager {}
+
+        impl IUserManager for UserManager
+        {
+            fn add_user(&self, _user_id: i128)
+            {
+                // ...
+            }
+
+            fn remove_user(&self, _user_id: i128)
+            {
+                // ...
+            }
+        }
+
+        impl Injectable for UserManager
+        {
+            fn resolve(
+                _di_container: &DIContainer,
+            ) -> error_stack::Result<
+                InterfacePtr<Self>,
+                crate::errors::injectable::ResolveError,
+            >
+            where
+                Self: Sized,
+            {
+                Ok(InterfacePtr::new(Self {}))
+            }
+        }
+
+        let mut di_container: DIContainer = DIContainer::new();
+
+        assert_eq!(di_container.bindings.len(), 0);
+
+        di_container.bind::<dyn IUserManager>().to::<UserManager>();
+
+        assert_eq!(di_container.bindings.len(), 1);
+    }
+
+    #[test]
+    fn can_bind_to_factory()
+    {
+        trait IUserManager
+        {
+            fn add_user(&self, user_id: i128);
+
+            fn remove_user(&self, user_id: i128);
+        }
+
+        struct UserManager {}
+
+        impl UserManager
+        {
+            fn new() -> Self
+            {
+                Self {}
+            }
+        }
+
+        impl IUserManager for UserManager
+        {
+            fn add_user(&self, _user_id: i128)
+            {
+                // ...
+            }
+
+            fn remove_user(&self, _user_id: i128)
+            {
+                // ...
+            }
+        }
+
+        type IUserManagerFactory = dyn IFactory<(), dyn IUserManager>;
+
+        let mut di_container: DIContainer = DIContainer::new();
+
+        assert_eq!(di_container.bindings.len(), 0);
+
+        di_container.bind::<IUserManagerFactory>().to_factory(&|| {
+            let user_manager: InterfacePtr<dyn IUserManager> =
+                InterfacePtr::new(UserManager::new());
+
+            user_manager
+        });
+
+        assert_eq!(di_container.bindings.len(), 1);
+    }
+
+    #[test]
+    fn can_get() -> error_stack::Result<(), DIContainerError>
+    {
+        trait IUserManager
+        {
+            fn add_user(&self, user_id: i128);
+
+            fn remove_user(&self, user_id: i128);
+        }
+
+        struct UserManager {}
+
+        use crate as syrette;
+        use crate::injectable;
+
+        #[injectable(IUserManager)]
+        impl UserManager
+        {
+            fn new() -> Self
+            {
+                Self {}
+            }
+        }
+
+        impl IUserManager for UserManager
+        {
+            fn add_user(&self, _user_id: i128)
+            {
+                // ...
+            }
+
+            fn remove_user(&self, _user_id: i128)
+            {
+                // ...
+            }
+        }
+
+        mock! {
+            Provider {}
+
+            impl IProvider for Provider
+            {
+                fn provide(
+                    &self,
+                    di_container: &DIContainer,
+                ) -> error_stack::Result<Providable, ResolveError>;
+            }
+        }
+
+        let mut di_container: DIContainer = DIContainer::new();
+
+        let mut mock_provider = MockProvider::new();
+
+        mock_provider.expect_provide().returning(|_| {
+            Ok(Providable::Injectable(
+                InterfacePtr::new(UserManager::new()),
+            ))
+        });
+
+        di_container
+            .bindings
+            .insert(TypeId::of::<dyn IUserManager>(), Rc::new(mock_provider));
+
+        di_container.get::<dyn IUserManager>()?;
+
+        Ok(())
+    }
+
+    #[test]
+    fn can_get_factory() -> error_stack::Result<(), DIContainerError>
+    {
+        trait IUserManager
+        {
+            fn add_user(&mut self, user_id: i128);
+
+            fn remove_user(&mut self, user_id: i128);
+        }
+
+        struct UserManager
+        {
+            users: Vec<i128>,
+        }
+
+        impl UserManager
+        {
+            fn new(users: Vec<i128>) -> Self
+            {
+                Self { users }
+            }
+        }
+
+        impl IUserManager for UserManager
+        {
+            fn add_user(&mut self, user_id: i128)
+            {
+                self.users.push(user_id);
+            }
+
+            fn remove_user(&mut self, user_id: i128)
+            {
+                let user_index =
+                    self.users.iter().position(|user| *user == user_id).unwrap();
+
+                self.users.remove(user_index);
+            }
+        }
+
+        use crate as syrette;
+
+        #[crate::factory]
+        type IUserManagerFactory = dyn IFactory<(Vec<i128>,), dyn IUserManager>;
+
+        mock! {
+            Provider {}
+
+            impl IProvider for Provider
+            {
+                fn provide(
+                    &self,
+                    di_container: &DIContainer,
+                ) -> error_stack::Result<Providable, ResolveError>;
+            }
+        }
+
+        let mut di_container: DIContainer = DIContainer::new();
+
+        let mut mock_provider = MockProvider::new();
+
+        mock_provider.expect_provide().returning(|_| {
+            Ok(Providable::Factory(FactoryPtr::new(CastableFactory::new(
+                &|users| {
+                    let user_manager: InterfacePtr<dyn IUserManager> =
+                        InterfacePtr::new(UserManager::new(users));
+
+                    user_manager
+                },
+            ))))
+        });
+
+        di_container
+            .bindings
+            .insert(TypeId::of::<IUserManagerFactory>(), Rc::new(mock_provider));
+
+        di_container.get_factory::<IUserManagerFactory>()?;
+
+        Ok(())
+    }
+}
diff --git a/src/errors/di_container.rs b/src/errors/di_container.rs
new file mode 100644
index 0000000..f2b8add
--- /dev/null
+++ b/src/errors/di_container.rs
@@ -0,0 +1,17 @@
+use std::fmt;
+use std::fmt::{Display, Formatter};
+
+use error_stack::Context;
+
+#[derive(Debug)]
+pub struct DIContainerError;
+
+impl Display for DIContainerError
+{
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result
+    {
+        fmt.write_str("A DI container error has occurred")
+    }
+}
+
+impl Context for DIContainerError {}
diff --git a/src/errors/injectable.rs b/src/errors/injectable.rs
new file mode 100644
index 0000000..6b0cdc5
--- /dev/null
+++ b/src/errors/injectable.rs
@@ -0,0 +1,17 @@
+use core::fmt;
+use std::fmt::{Display, Formatter};
+
+use error_stack::Context;
+
+#[derive(Debug)]
+pub struct ResolveError;
+
+impl Display for ResolveError
+{
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result
+    {
+        fmt.write_str("Failed to resolve injectable struct")
+    }
+}
+
+impl Context for ResolveError {}
diff --git a/src/errors/mod.rs b/src/errors/mod.rs
new file mode 100644
index 0000000..b0d50f0
--- /dev/null
+++ b/src/errors/mod.rs
@@ -0,0 +1,2 @@
+pub mod di_container;
+pub mod injectable;
diff --git a/src/interfaces/factory.rs b/src/interfaces/factory.rs
new file mode 100644
index 0000000..c97fc09
--- /dev/null
+++ b/src/interfaces/factory.rs
@@ -0,0 +1,10 @@
+#![allow(clippy::module_name_repetitions)]
+use crate::libs::intertrait::CastFrom;
+use crate::ptr::InterfacePtr;
+
+pub trait IFactory<Args, ReturnInterface>:
+    Fn<Args, Output = InterfacePtr<ReturnInterface>> + CastFrom
+where
+    ReturnInterface: 'static + ?Sized,
+{
+}
diff --git a/src/interfaces/injectable.rs b/src/interfaces/injectable.rs
new file mode 100644
index 0000000..24032a6
--- /dev/null
+++ b/src/interfaces/injectable.rs
@@ -0,0 +1,17 @@
+use crate::errors::injectable::ResolveError;
+use crate::libs::intertrait::CastFrom;
+use crate::ptr::InterfacePtr;
+use crate::DIContainer;
+
+pub trait Injectable: CastFrom
+{
+    /// Resolves the dependencies of the injectable.
+    ///
+    /// # Errors
+    /// Will return `Err` if resolving the dependencies fails.
+    fn resolve(
+        di_container: &DIContainer,
+    ) -> error_stack::Result<InterfacePtr<Self>, ResolveError>
+    where
+        Self: Sized;
+}
diff --git a/src/interfaces/mod.rs b/src/interfaces/mod.rs
new file mode 100644
index 0000000..921bb9c
--- /dev/null
+++ b/src/interfaces/mod.rs
@@ -0,0 +1,2 @@
+pub mod factory;
+pub mod injectable;
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..992f276
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,22 @@
+#![feature(unboxed_closures, fn_traits)]
+#![deny(clippy::all)]
+#![deny(clippy::pedantic)]
+
+//! Syrette
+//!
+//! Syrette is a collection of utilities useful for performing dependency injection.
+
+pub mod castable_factory;
+pub mod di_container;
+pub mod errors;
+pub mod interfaces;
+pub mod ptr;
+
+pub use di_container::*;
+pub use syrette_macros::*;
+
+#[doc(hidden)]
+pub mod libs;
+
+// Private
+mod provider;
diff --git a/src/libs/intertrait/LICENSE-APACHE b/src/libs/intertrait/LICENSE-APACHE
new file mode 100644
index 0000000..d9a10c0
--- /dev/null
+++ b/src/libs/intertrait/LICENSE-APACHE
@@ -0,0 +1,176 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
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+      and distribution as defined by Sections 1 through 9 of this document.
+
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+
+      "You" (or "Your") shall mean an individual or Legal Entity
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+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
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+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
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+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
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+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
diff --git a/src/libs/intertrait/LICENSE-MIT b/src/libs/intertrait/LICENSE-MIT
new file mode 100644
index 0000000..969d061
--- /dev/null
+++ b/src/libs/intertrait/LICENSE-MIT
@@ -0,0 +1,17 @@
+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.
diff --git a/src/libs/intertrait/cast_box.rs b/src/libs/intertrait/cast_box.rs
new file mode 100644
index 0000000..793efd0
--- /dev/null
+++ b/src/libs/intertrait/cast_box.rs
@@ -0,0 +1,32 @@
+/**
+ * Originally from Intertrait by CodeChain
+ *
+ * <https://github.com/CodeChain-io/intertrait>
+ * <https://crates.io/crates/intertrait/0.2.2>
+ *
+ * Licensed under either of
+ *
+ * Apache License, Version 2.0 (LICENSE-APACHE or <http://www.apache.org/licenses/LICENSE-2.0>)
+ * MIT license (LICENSE-MIT or <http://opensource.org/licenses/MIT>)
+
+ * at your option.
+*/
+use crate::libs::intertrait::{caster, CastFrom};
+
+pub trait CastBox
+{
+    /// Casts a box to this trait into that of type `T`. If fails, returns the receiver.
+    fn cast<T: ?Sized + 'static>(self: Box<Self>) -> Result<Box<T>, Box<Self>>;
+}
+
+/// A blanket implementation of `CastBox` for traits extending `CastFrom`.
+impl<S: ?Sized + CastFrom> CastBox for S
+{
+    fn cast<T: ?Sized + 'static>(self: Box<Self>) -> Result<Box<T>, Box<Self>>
+    {
+        match caster::<T>((*self).type_id()) {
+            Some(caster) => Ok((caster.cast_box)(self.box_any())),
+            None => Err(self),
+        }
+    }
+}
diff --git a/src/libs/intertrait/cast_rc.rs b/src/libs/intertrait/cast_rc.rs
new file mode 100644
index 0000000..79d8d60
--- /dev/null
+++ b/src/libs/intertrait/cast_rc.rs
@@ -0,0 +1,34 @@
+/**
+ * Originally from Intertrait by CodeChain
+ *
+ * <https://github.com/CodeChain-io/intertrait>
+ * <https://crates.io/crates/intertrait/0.2.2>
+ *
+ * Licensed under either of
+ *
+ * Apache License, Version 2.0 (LICENSE-APACHE or <http://www.apache.org/licenses/LICENSE-2.0>)
+ * MIT license (LICENSE-MIT or <http://opensource.org/licenses/MIT>)
+
+ * at your option.
+*/
+use std::rc::Rc;
+
+use crate::libs::intertrait::{caster, CastFrom};
+
+pub trait CastRc
+{
+    /// Casts an `Rc` for this trait into that for type `T`.
+    fn cast<T: ?Sized + 'static>(self: Rc<Self>) -> Result<Rc<T>, Rc<Self>>;
+}
+
+/// A blanket implementation of `CastRc` for traits extending `CastFrom`.
+impl<S: ?Sized + CastFrom> CastRc for S
+{
+    fn cast<T: ?Sized + 'static>(self: Rc<Self>) -> Result<Rc<T>, Rc<Self>>
+    {
+        match caster::<T>((*self).type_id()) {
+            Some(caster) => Ok((caster.cast_rc)(self.rc_any())),
+            None => Err(self),
+        }
+    }
+}
diff --git a/src/libs/intertrait/hasher.rs b/src/libs/intertrait/hasher.rs
new file mode 100644
index 0000000..e7f110d
--- /dev/null
+++ b/src/libs/intertrait/hasher.rs
@@ -0,0 +1,48 @@
+#![allow(clippy::module_name_repetitions)]
+
+/**
+ * Originally from Intertrait by CodeChain
+ *
+ * <https://github.com/CodeChain-io/intertrait>
+ * <https://crates.io/crates/intertrait/0.2.2>
+ *
+ * Licensed under either of
+ *
+ * Apache License, Version 2.0 (LICENSE-APACHE or <http://www.apache.org/licenses/LICENSE-2.0>)
+ * MIT license (LICENSE-MIT or <http://opensource.org/licenses/MIT>)
+
+ * at your option.
+*/
+use std::convert::TryInto;
+use std::hash::{BuildHasherDefault, Hasher};
+use std::mem::size_of;
+
+/// A simple `Hasher` implementation tuned for performance.
+#[derive(Default)]
+pub struct FastHasher(u64);
+
+/// A `BuildHasher` for `FastHasher`.
+pub type BuildFastHasher = BuildHasherDefault<FastHasher>;
+
+impl Hasher for FastHasher
+{
+    fn finish(&self) -> u64
+    {
+        self.0
+    }
+
+    fn write(&mut self, bytes: &[u8])
+    {
+        let mut bytes = bytes;
+        while bytes.len() > size_of::<u64>() {
+            let (u64_bytes, remaining) = bytes.split_at(size_of::<u64>());
+
+            self.0 ^= u64::from_ne_bytes(u64_bytes.try_into().unwrap());
+
+            bytes = remaining;
+        }
+        self.0 ^= bytes
+            .iter()
+            .fold(0u64, |result, b| (result << 8) | u64::from(*b));
+    }
+}
diff --git a/src/libs/intertrait/mod.rs b/src/libs/intertrait/mod.rs
new file mode 100644
index 0000000..1daca64
--- /dev/null
+++ b/src/libs/intertrait/mod.rs
@@ -0,0 +1,137 @@
+/**
+ * Originally from Intertrait by CodeChain
+ *
+ * <https://github.com/CodeChain-io/intertrait>
+ * <https://crates.io/crates/intertrait/0.2.2>
+ *
+ * Licensed under either of
+ *
+ * Apache License, Version 2.0 (LICENSE-APACHE or <http://www.apache.org/licenses/LICENSE-2.0>)
+ * MIT license (LICENSE-MIT or <http://opensource.org/licenses/MIT>)
+
+ * at your option.
+*/
+use std::any::{Any, TypeId};
+use std::collections::HashMap;
+use std::rc::Rc;
+use std::sync::Arc;
+
+use linkme::distributed_slice;
+use once_cell::sync::Lazy;
+
+mod hasher;
+
+use hasher::BuildFastHasher;
+
+pub mod cast_box;
+pub mod cast_rc;
+
+pub type BoxedCaster = Box<dyn Any + Send + Sync>;
+
+#[distributed_slice]
+pub static CASTERS: [fn() -> (TypeId, BoxedCaster)] = [..];
+
+static CASTER_MAP: Lazy<HashMap<(TypeId, TypeId), BoxedCaster, BuildFastHasher>> =
+    Lazy::new(|| {
+        CASTERS
+            .iter()
+            .map(|f| {
+                let (type_id, caster) = f();
+                ((type_id, (*caster).type_id()), caster)
+            })
+            .collect()
+    });
+
+pub struct Caster<T: ?Sized + 'static>
+{
+    /// Casts a `Box` holding a trait object for `Any` to another `Box` holding a trait object
+    /// for trait `T`.
+    pub cast_box: fn(from: Box<dyn Any>) -> Box<T>,
+
+    /// Casts an `Rc` holding a trait object for `Any` to another `Rc` holding a trait object
+    /// for trait `T`.
+    pub cast_rc: fn(from: Rc<dyn Any>) -> Rc<T>,
+}
+
+impl<T: ?Sized + 'static> Caster<T>
+{
+    pub fn new(
+        cast_box: fn(from: Box<dyn Any>) -> Box<T>,
+        cast_rc: fn(from: Rc<dyn Any>) -> Rc<T>,
+    ) -> Caster<T>
+    {
+        Caster::<T> { cast_box, cast_rc }
+    }
+}
+
+/// Returns a `Caster<S, T>` from a concrete type `S` to a trait `T` implemented by it.
+fn caster<T: ?Sized + 'static>(type_id: TypeId) -> Option<&'static Caster<T>>
+{
+    CASTER_MAP
+        .get(&(type_id, TypeId::of::<Caster<T>>()))
+        .and_then(|caster| caster.downcast_ref::<Caster<T>>())
+}
+
+/// `CastFrom` must be extended by a trait that wants to allow for casting into another trait.
+///
+/// It is used for obtaining a trait object for [`Any`] from a trait object for its sub-trait,
+/// and blanket implemented for all `Sized + Any + 'static` types.
+///
+/// # Examples
+/// ```ignore
+/// trait Source: CastFrom {
+///     ...
+/// }
+/// ```
+pub trait CastFrom: Any + 'static
+{
+    /// Returns a `Box` of `Any`, which is backed by the type implementing this trait.
+    fn box_any(self: Box<Self>) -> Box<dyn Any>;
+
+    /// Returns an `Rc` of `Any`, which is backed by the type implementing this trait.
+    fn rc_any(self: Rc<Self>) -> Rc<dyn Any>;
+}
+
+pub trait CastFromSync: CastFrom + Sync + Send + 'static
+{
+    fn arc_any(self: Arc<Self>) -> Arc<dyn Any + Sync + Send + 'static>;
+}
+
+impl<T: Sized + Any + 'static> CastFrom for T
+{
+    fn box_any(self: Box<Self>) -> Box<dyn Any>
+    {
+        self
+    }
+
+    fn rc_any(self: Rc<Self>) -> Rc<dyn Any>
+    {
+        self
+    }
+}
+
+impl CastFrom for dyn Any + 'static
+{
+    fn box_any(self: Box<Self>) -> Box<dyn Any>
+    {
+        self
+    }
+
+    fn rc_any(self: Rc<Self>) -> Rc<dyn Any>
+    {
+        self
+    }
+}
+
+impl CastFrom for dyn Any + Sync + Send + 'static
+{
+    fn box_any(self: Box<Self>) -> Box<dyn Any>
+    {
+        self
+    }
+
+    fn rc_any(self: Rc<Self>) -> Rc<dyn Any>
+    {
+        self
+    }
+}
diff --git a/src/libs/mod.rs b/src/libs/mod.rs
new file mode 100644
index 0000000..8d5583d
--- /dev/null
+++ b/src/libs/mod.rs
@@ -0,0 +1,3 @@
+pub mod intertrait;
+
+pub extern crate linkme;
diff --git a/src/provider.rs b/src/provider.rs
new file mode 100644
index 0000000..3b7e04c
--- /dev/null
+++ b/src/provider.rs
@@ -0,0 +1,82 @@
+#![allow(clippy::module_name_repetitions)]
+use std::marker::PhantomData;
+
+use crate::castable_factory::AnyFactory;
+use crate::errors::injectable::ResolveError;
+use crate::interfaces::injectable::Injectable;
+use crate::ptr::{FactoryPtr, InterfacePtr};
+use crate::DIContainer;
+
+extern crate error_stack;
+
+pub enum Providable
+{
+    Injectable(InterfacePtr<dyn Injectable>),
+    Factory(FactoryPtr<dyn AnyFactory>),
+}
+
+pub trait IProvider
+{
+    fn provide(
+        &self,
+        di_container: &DIContainer,
+    ) -> error_stack::Result<Providable, ResolveError>;
+}
+
+pub struct InjectableTypeProvider<InjectableType>
+where
+    InjectableType: Injectable,
+{
+    injectable_phantom: PhantomData<InjectableType>,
+}
+
+impl<InjectableType> InjectableTypeProvider<InjectableType>
+where
+    InjectableType: Injectable,
+{
+    pub fn new() -> Self
+    {
+        Self {
+            injectable_phantom: PhantomData,
+        }
+    }
+}
+
+impl<InjectableType> IProvider for InjectableTypeProvider<InjectableType>
+where
+    InjectableType: Injectable,
+{
+    fn provide(
+        &self,
+        di_container: &DIContainer,
+    ) -> error_stack::Result<Providable, ResolveError>
+    {
+        Ok(Providable::Injectable(InjectableType::resolve(
+            di_container,
+        )?))
+    }
+}
+
+pub struct FactoryProvider
+{
+    factory: FactoryPtr<dyn AnyFactory>,
+}
+
+impl FactoryProvider
+{
+    pub fn new(factory: FactoryPtr<dyn AnyFactory>) -> Self
+    {
+        Self { factory }
+    }
+}
+
+impl IProvider for FactoryProvider
+{
+    fn provide(
+        &self,
+        _di_container: &DIContainer,
+    ) -> error_stack::Result<Providable, ResolveError>
+    {
+        Ok(Providable::Factory(self.factory.clone()))
+    }
+}
diff --git a/src/ptr.rs b/src/ptr.rs
new file mode 100644
index 0000000..414d086
--- /dev/null
+++ b/src/ptr.rs
@@ -0,0 +1,6 @@
+#![allow(clippy::module_name_repetitions)]
+use std::rc::Rc;
+
+pub type InterfacePtr<Interface> = Box<Interface>;
+
+pub type FactoryPtr<FactoryInterface> = Rc<FactoryInterface>;