Crate scale_info_legacy 

This crate provides a set of types which build on each other. The ultimate goal is to be able to define the necessary type information needed to describe how historic Substrate types are SCALE encoded.

The main types exposed here are as follows:

• TypeRegistry: the lowest level type which one can populate with type information (via TypeRegistry::insert() and TypeRegistry::insert_runtime_api()), and then query to resolve some type name to the relevant information (via TypeRegistry::resolve_type() and TypeRegistry::runtime_api()).
• TypeRegistrySet: a set of the above, which will resolve types (via TypeRegistrySet::resolve_type()) by working through the inner type registries until it finds the relevant information (or doesn’t find anything). This allows us to combine type registries in different ways to alter how we resolve things.
• ChainTypeRegistry: this type is constructed by deserializing some JSON (or similar) which describes all of the types that we need to know about on a given chain. The main function here is ChainTypeRegistry::for_spec_version(), which returns a TypeRegistrySet for resolving types for the given spec version.

We also expose an InsertName, which is built by parsing type names like Vec<T> from strings, and used in TypeRegistry::insert() to insert types, and then LookupName, which is built by parsing type names like Vec<T>, [u8; 32] and (bool, u32) and is used to lookup the corresponding type information via TypeRegistry::resolve_type() and similar. Finally, TypeShape is an enum used to describe the shape of the type inserted via TypeRegistry::insert().

This crate, like scale-info, can be used in conjunction with crates like:

• scale-decode to decode SCALE encoded bytes into custom types based on this type information.
• scale-encode to SCALE encode custom types into bytes based on this type information.
• scale-value to SCALE encode or decode from a Value type (a bit like serde_json’s Value type).

Re-exports

pub use chain_types::ChainTypeRegistry;

pub use insert_name::InsertName;

pub use lookup_name::LookupName;

pub use type_registry::RuntimeApiInput;

pub use type_registry::TypeRegistry;

pub use type_registry_set::TypeRegistrySet;

pub use type_shape::TypeShape;

Modules

chain_types

This module provides a ChainTypeRegistry, which is constructed by deserializing some data into it. JSON is the expected input format, though in theory others can be used too.

insert_name

This module provides the name used to insert types in a registry.

lookup_name

This module provides a struct, LookupName. This struct represents a single concrete type that can be looked up in the crate::TypeRegistry.

type_registry

This module provides a TypeRegistry, which can be used to store and resolve type information for types based on their names.

type_registry_set

This module provides a TypeRegistrySet, which is constructed from a selection of crate::TypeRegistry’s, and will resolve types by looking through each one in a known order until a match is found. This allows us to compose different sets of types into a single thing which itself also implements scale_type_resolver::TypeResolver.

type_shape

This module provides a TypeShape enum, which describes the shape of a type, or in other words, how it should be SCALE encoded/decoded.