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// Copyright 2019-2021 Parity Technologies (UK) Ltd. // // 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. //! Builders for defining metadata for variant types (enums), and composite types (structs). //! They are designed to allow only construction of valid definitions. //! //! In most cases we recommend using the `tetsy-scale-info-derive` crate to auto generate the builder //! constructions. //! //! # Examples //! //! ## Generic struct //! ``` //! # use tetsy_scale_info::{build::Fields, MetaType, Path, Type, TypeInfo}; //! struct Foo<T> { //! bar: T, //! data: u64, //! } //! //! impl<T> TypeInfo for Foo<T> //! where //! T: TypeInfo + 'static, //! { //! type Identity = Self; //! //! fn type_info() -> Type { //! Type::builder() //! .path(Path::new("Foo", module_path!())) //! .type_params(vec![MetaType::new::<T>()]) //! .composite(Fields::named() //! .field_of::<T>("bar", "T") //! .field_of::<u64>("data", "u64") //! ) //! } //! } //! ``` //! ## Tuple struct //! ``` //! # use tetsy_scale_info::{build::Fields, MetaType, Path, Type, TypeInfo}; //! struct Foo(u32, bool); //! //! impl TypeInfo for Foo { //! type Identity = Self; //! //! fn type_info() -> Type { //! Type::builder() //! .path(Path::new("Foo", module_path!())) //! .composite(Fields::unnamed() //! .field_of::<u32>("u32") //! .field_of::<bool>("bool") //! ) //! } //! } //! ``` //! ## Enum with fields //! ``` //! # use tetsy_scale_info::{build::{Fields, Variants}, MetaType, Path, Type, TypeInfo}; //! enum Foo<T>{ //! A(T), //! B { f: u32 }, //! C, //! } //! //! impl<T> TypeInfo for Foo<T> //! where //! T: TypeInfo + 'static, //! { //! type Identity = Self; //! //! fn type_info() -> Type { //! Type::builder() //! .path(Path::new("Foo", module_path!())) //! .type_params(vec![MetaType::new::<T>()]) //! .variant( //! Variants::with_fields() //! .variant("A", Fields::unnamed().field_of::<T>("T")) //! .variant("B", Fields::named().field_of::<u32>("f", "u32")) //! .variant("C", Fields::unit()) //! ) //! } //! } //! ``` //! ## Enum without fields //! ``` //! # use tetsy_scale_info::{build::{Fields, Variants}, MetaType, Path, Type, TypeInfo}; //! enum Foo { //! A, //! B, //! C = 33, //! } //! //! impl TypeInfo for Foo { //! type Identity = Self; //! //! fn type_info() -> Type { //! Type::builder() //! .path(Path::new("Foo", module_path!())) //! .variant( //! Variants::fieldless() //! .variant("A", 1) //! .variant("B", 2) //! .variant("C", 33) //! ) //! } //! } //! ``` use crate::prelude::{ marker::PhantomData, vec::Vec, }; use crate::{ form::MetaForm, Field, MetaType, Path, Type, TypeDef, TypeDefComposite, TypeDefVariant, TypeInfo, Variant, }; /// State types for type builders which require a Path pub mod state { /// State where the builder has not assigned a Path to the type pub enum PathNotAssigned {} /// State where the builder has assigned a Path to the type pub enum PathAssigned {} } /// Builds a [`Type`](`crate::Type`) pub struct TypeBuilder<S = state::PathNotAssigned> { path: Option<Path>, type_params: Vec<MetaType>, marker: PhantomData<fn() -> S>, } impl<S> Default for TypeBuilder<S> { fn default() -> Self { TypeBuilder { path: Default::default(), type_params: Default::default(), marker: Default::default(), } } } impl TypeBuilder<state::PathNotAssigned> { /// Set the Path for the type pub fn path(self, path: Path) -> TypeBuilder<state::PathAssigned> { TypeBuilder { path: Some(path), type_params: self.type_params, marker: Default::default(), } } } impl TypeBuilder<state::PathAssigned> { fn build<D>(self, type_def: D) -> Type where D: Into<TypeDef>, { let path = self.path.expect("Path not assigned"); Type::new(path, self.type_params, type_def) } /// Construct a "variant" type i.e an `enum` pub fn variant<V>(self, builder: VariantsBuilder<V>) -> Type { self.build(builder.finalize()) } /// Construct a "composite" type i.e. a `struct` pub fn composite<F>(self, fields: FieldsBuilder<F>) -> Type { self.build(TypeDefComposite::new(fields.finalize())) } } impl<S> TypeBuilder<S> { /// Set the type parameters if it's a generic type pub fn type_params<I>(mut self, type_params: I) -> Self where I: IntoIterator<Item = MetaType>, { self.type_params = type_params.into_iter().collect(); self } } /// A fields builder has no fields (e.g. a unit struct) pub enum NoFields {} /// A fields builder only allows named fields (e.g. a struct) pub enum NamedFields {} /// A fields builder only allows unnamed fields (e.g. a tuple) pub enum UnnamedFields {} /// Provides FieldsBuilder constructors pub enum Fields {} impl Fields { /// The type construct has no fields pub fn unit() -> FieldsBuilder<NoFields> { FieldsBuilder::<NoFields>::default() } /// Fields for a type construct with named fields pub fn named() -> FieldsBuilder<NamedFields> { FieldsBuilder::default() } /// Fields for a type construct with unnamed fields pub fn unnamed() -> FieldsBuilder<UnnamedFields> { FieldsBuilder::default() } } /// Build a set of either all named (e.g. for a struct) or all unnamed (e.g. for a tuple struct) pub struct FieldsBuilder<T> { fields: Vec<Field>, marker: PhantomData<fn() -> T>, } impl<T> Default for FieldsBuilder<T> { fn default() -> Self { Self { fields: Vec::new(), marker: Default::default(), } } } impl<T> FieldsBuilder<T> { /// Complete building and return the set of fields pub fn finalize(self) -> Vec<Field<MetaForm>> { self.fields } } impl FieldsBuilder<NamedFields> { /// Add a named field with the type of the type parameter `T` pub fn field_of<T>(mut self, name: &'static str, type_name: &'static str) -> Self where T: TypeInfo + ?Sized + 'static, { self.fields.push(Field::named_of::<T>(name, type_name)); self } } impl FieldsBuilder<UnnamedFields> { /// Add an unnamed field with the type of the type parameter `T` pub fn field_of<T>(mut self, type_name: &'static str) -> Self where T: TypeInfo + ?Sized + 'static, { self.fields.push(Field::unnamed_of::<T>(type_name)); self } } /// Build a type with no variants. pub enum NoVariants {} /// Build a type where at least one variant has fields. pub enum VariantFields {} /// Build a type where *all* variants have no fields and the discriminant can /// be directly chosen or accessed pub enum Fieldless {} /// Empty enum for VariantsBuilder constructors for the type builder DSL. pub enum Variants {} impl Variants { /// Build a set of variants, at least one of which will have fields. pub fn with_fields() -> VariantsBuilder<VariantFields> { VariantsBuilder::new() } /// Build a set of variants, none of which will have fields, and the discriminant can /// be directly chosen or accessed pub fn fieldless() -> VariantsBuilder<Fieldless> { VariantsBuilder::new() } } /// Builds a definition of a variant type i.e an `enum` #[derive(Default)] pub struct VariantsBuilder<T> { variants: Vec<Variant>, marker: PhantomData<fn() -> T>, } impl VariantsBuilder<VariantFields> { /// Add a variant with fields constructed by the supplied [`FieldsBuilder`](`crate::build::FieldsBuilder`) pub fn variant<F>(mut self, name: &'static str, fields: FieldsBuilder<F>) -> Self { self.variants.push(Variant::with_fields(name, fields)); self } /// Add a variant with no fields i.e. a unit variant pub fn variant_unit(self, name: &'static str) -> Self { self.variant::<NoFields>(name, Fields::unit()) } } impl VariantsBuilder<Fieldless> { /// Add a fieldless variant, explicitly setting the discriminant pub fn variant(mut self, name: &'static str, discriminant: u64) -> Self { self.variants .push(Variant::with_discriminant(name, discriminant)); self } } impl<T> VariantsBuilder<T> { fn new() -> Self { VariantsBuilder { variants: Vec::new(), marker: Default::default(), } } fn finalize(self) -> TypeDefVariant { TypeDefVariant::new(self.variants) } }