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use crate::prelude::*; /// General function that can create any entry type. /// /// This is used under the hood by [ `create_entry` ], [ `create_cap_grant` ] and [ `create_cap_claim` ]. /// /// The host builds a [ `Create` ] header for the passed entry value and commits a new element to the /// chain. /// /// Usually you don't need to use this function directly; it is the most general way to create an /// entry and standardises the internals of higher level create functions. pub fn create(entry_def_with_id: EntryWithDefId) -> ExternResult<HeaderHash> { host_call::<EntryWithDefId, HeaderHash>(__create, entry_def_with_id) } /// Update any entry type. /// /// This is used under the hood by [ `update_entry` ], [ `update_cap_grant` ] and `update_cap_claim`. /// @todo implement update_cap_claim /// /// The host builds an [ `Update` ] header for the passed entry value and commits a new update to the /// chain. /// /// Usually you don't need to use this function directly; it is the most general way to update an /// entry and standardises the internals of higher level create functions. pub fn update(hash: HeaderHash, entry_with_def_id: EntryWithDefId) -> ExternResult<HeaderHash> { host_call::<UpdateInput, HeaderHash>(__update, UpdateInput::new(hash, entry_with_def_id)) } /// General function that can delete any entry type. /// /// This is used under the hood by [ `delete_entry` ], [ `delete_cap_grant` ] and `delete_cap_claim`. /// @todo implement delete_cap_claim /// /// The host builds a [ `Delete` ] header for the passed entry and commits a new element to the chain. /// /// Usually you don't need to use this function directly; it is the most general way to update an /// entry and standardises the internals of higher level create functions. pub fn delete(hash: HeaderHash) -> ExternResult<HeaderHash> { host_call::<HeaderHash, HeaderHash>(__delete, hash) } /// Create an app entry. /// /// Apps define app entries by registering entry def ids with the `entry_defs` callback and serialize the /// entry content when committing to the source chain. /// /// This function accepts any input that implements [ `TryInto<EntryWithDefId>` ]. /// The default impls from the `#[hdk_entry( .. )]` and [ `entry_def!` ] macros include this. /// /// With generic type handling it may make sense to directly construct [ `EntryWithDefId` ] and [ `create` ]. /// /// e.g. /// ```ignore /// #[hdk_entry(id = "foo")] /// pub struct Foo(u32); /// create_entry(Foo(50))?; /// ``` /// /// See [ `get` ] and [ `get_details` ] for more information on CRUD. pub fn create_entry<I, E>(input: I) -> ExternResult<HeaderHash> where EntryWithDefId: TryFrom<I, Error = E>, WasmError: From<E>, { create(EntryWithDefId::try_from(input)?) } /// Alias to delete /// /// Takes the [ `HeaderHash` ] of the element to delete. /// /// ```ignore /// delete_entry(entry_hash(foo_entry)?)?; /// ``` pub fn delete_entry(hash: HeaderHash) -> ExternResult<HeaderHash> { delete(hash) } /// Hash anything that that implements [ `TryInto<Entry>` ]. /// /// Hashes are typed in holochain, e.g. [ `HeaderHash` ] and [ `EntryHash` ] are different and yield different /// bytes for a given value. This ensures correctness and allows type based dispatch in various /// areas of the codebase. /// /// Usually you want to hash a value that you want to reference on the DHT with [ `get` ] etc. because /// it represents some domain-specific data sourced externally or generated within the wasm. /// [ `HeaderHash` ] hashes are _always_ generated by the process of committing something to a local /// chain. Every host function that commits an entry returns the new [ `HeaderHash` ]. The [ `HeaderHash` ] can /// also be used with [ `get` ] etc. to retreive a _specific_ element from the DHT rather than the /// oldest live element. /// However there is no way to _generate_ a header hash directly from a header from inside wasm. /// [ `Element` ] values (entry+header pairs returned by [ `get` ] etc.) contain prehashed header structs /// called [ `HeaderHashed` ], which is composed of a [ `HeaderHash` ] alongside the "raw" [ `Header` ] value. Generally the pre-hashing is /// more efficient than hashing headers ad-hoc as hashing always needs to be done at the database /// layer, so we want to re-use that as much as possible. /// The header hash can be extracted from the Element as `element.header_hashed().as_hash()`. /// @todo is there any use-case that can't be satisfied by the `header_hashed` approach? /// /// Anything that is annotated with #[hdk_entry( .. )] or entry_def!( .. ) implements this so is /// compatible automatically. /// /// [ `hash_entry` ] is "dumb" in that it doesn't check that the entry is defined, committed, on the DHT or /// any other validation, it simply generates the hash for the serialized representation of /// something in the same way that the DHT would. /// /// It is strongly recommended that you use the [ `hash_entry` ] function to calculate hashes to avoid /// inconsistencies between hashes in the wasm guest and the host. /// For example, a lot of the crypto crates in rust compile to wasm so in theory could generate the /// hash in the guest, but there is the potential that the serialization logic could be slightly /// different, etc. /// /// ```ignore /// #[hdk_entry(id="foo")] /// struct Foo; /// /// let foo_hash = hash_entry(Foo)?; /// ``` pub fn hash_entry<I, E>(input: I) -> ExternResult<EntryHash> where Entry: TryFrom<I, Error = E>, WasmError: From<E>, { host_call::<Entry, EntryHash>(__hash_entry, Entry::try_from(input)?) } /// Thin wrapper around update for app entries. /// The hash is the [ `HeaderHash` ] of the deleted element, the input is a [ `TryInto<EntryWithDefId>` ]. /// /// Updates can reference Elements which contain Entry data -- namely, Creates and other Updates -- but /// not Deletes or system Elements /// /// As updates can reference elements on other agent's source chains across unpredictable network /// topologies, they are treated as a tree structure. /// /// Many updates can point to a single create/update and continue to accumulate as long as agents /// author them against that element. It is up to happ developers to decide how to ensure the tree /// branches are walked appropriately and that updates point to the correct element, whatever that /// means for the happ. /// /// ```ignore /// #[hdk_entry(id = "foo")] /// struct Foo(u32); /// /// let foo_zero_header_hash: HeaderHash = commit_entry!(Foo(0))?; /// let foo_ten_update_header_hash: HeaderHash = update_entry(foo_zero_header_hash, Foo(10))?; /// ``` /// /// @todo in the future this will be true because we will have the concept of 'redirects': /// Works as an app entry delete+create. /// /// See [ `create_entry` ] /// See [ `update` ] /// See [ `delete_entry` ] pub fn update_entry<I, E>(hash: HeaderHash, input: I) -> ExternResult<HeaderHash> where EntryWithDefId: TryFrom<I, Error = E>, WasmError: From<E>, { update(hash, EntryWithDefId::try_from(input)?) } /// Gets an element for a given entry or header hash. /// /// The behaviour of get changes subtly per the _type of the passed hash_. /// A header hash returns the element for that header, i.e. header+entry or header+None. /// An entry hash returns the "oldest live" element, i.e. header+entry. /// /// An element is no longer live once it is referenced by a valid delete element. /// An update to an element does not change its liveness. /// See [ `get_details` ] for more information about how CRUD elements reference each other. /// /// Note: [ `get` ] __always triggers and blocks on a network call__. /// @todo implement a 'get optimistic' that returns based on the current opinion of the world /// and performs network calls in the background so they are available 'next time'. /// /// Note: Deletes are considered in the liveness but Updates are not currently followed /// automatically due to the need for the happ to disambiguate update logic. /// @todo implement 'redirect' logic so that updates are followed by [ `get` ]. /// /// Note: Updates typically point to a different entry hash than what they are updating but not /// always, e.g. consider changing `foo` to `bar` back to `foo`. The entry hashes in a crud /// tree can be circular but the header hashes are never circular. /// In this case, deleting the create for foo would make the second update pointing to foo /// the "oldest live" element. /// /// Note: "oldest live" only relates to disambiguating many creates and updates from many authors /// pointing to a single entry, it is not the "current value" of an entry in a CRUD sense. /// e.g. If "foo" is created then updated to "bar", a [ `get` ] on the hash of "foo" will return /// "foo" as part of an element with the "oldest live" header. /// To discover "bar" the agent needs to call `get_details` and decide how it wants to /// collapse many potential creates, updates and deletes down into a single or filtered /// set of updates, to "walk the tree". /// e.g. Updates could include a proof of work and a tree would collapse to a simple /// blockchain if the agent follows the "heaviest chain". /// e.g. Updates could represent turns in a 2-player game and the update with the newest /// timestamp countersigned by both players represents an opt-in chain of updates with /// support for casual "undo" with player's consent. /// e.g. Domain/user names could be claimed on a "first come, first serve" basis with only /// creates and deletes allowed by validation rules, the "oldest live" element _does_ /// represent the element pointing at the first agent to claim a name, but it could also /// be checked manually by the app with `get_details`. /// /// Note: "oldest live" is only as good as the information available to the authorities the agent /// contacts on their current network partition, there could always be an older live entry /// on another partition, and of course the oldest live entry could be deleted and no longer /// be live. pub fn get<H>(hash: H, options: GetOptions) -> ExternResult<Option<Element>> where AnyDhtHash: From<H>, { host_call::<GetInput, Option<Element>>(__get, GetInput::new(AnyDhtHash::from(hash), options)) } /// Get an element from the hash AND the details for the entry or header hash passed in. /// Returns [ `None` ] if the entry/header does not exist. /// The details returned are a contextual mix of elements and header hashes, see below. /// /// Note: The return details will be inferred by the hash type passed in, be careful to pass in the /// correct hash type for the details you want. /// /// Note: If a header hash is passed in the element returned is the specified element. /// If an entry hash is passed in all the headers (so implicitly all the elements) are /// returned for the entry that matches that hash. /// See [ `get` ] for more information about what "oldest live" means. /// /// The details returned include relevant creates, updates and deletes for the hash passed in. /// /// Creates are initial header/entry combinations (elements) produced by commit_entry! and cannot /// reference other headers. /// Updates and deletes both reference a specific header+entry combination. /// Updates must reference another create or update header+entry. /// Deletes must reference a create or update header+entry (nothing can reference a delete). /// /// Full elements are returned for direct references to the passed hash. /// Header hashes are returned for references to references to the passed hash. /// /// [ `Details` ] for a header hash return: /// - the element for this header hash if it exists /// - all update and delete _elements_ that reference that specified header /// /// [ `Details` ] for an entry hash return: /// - all creates, updates and delete _elements_ that reference that entry hash /// - all update and delete _elements_ that reference the elements that reference the entry hash /// /// Note: Entries are just values, so can be referenced by many CRUD headers by many authors. /// e.g. the number 1 or string "foo" can be referenced by anyone publishing CRUD headers at /// any time they need to represent 1 or "foo" for a create, update or delete. /// If you need to disambiguate entry values, provide uniqueness in the entry value such as /// a unique hash (e.g. current chain head), timestamp (careful about collisions!), or random /// bytes/uuid (see random_bytes() and the uuid rust crate that supports uuids from bytes). /// /// Note: There are multiple header types that exist and operate entirely outside of CRUD elements /// so they cannot reference or be referenced by CRUD, so are immutable or have their own /// mutation logic (e.g. link create/delete) and will not be included in [ `get_details` ] results /// e.g. the DNA itself, links, migrations, etc. /// However the element will still be returned by [ `get_details` ] if a header hash is passed, /// these header-only elements will have [ `None` ] as the entry value. pub fn get_details<H: Into<AnyDhtHash>>( hash: H, options: GetOptions, ) -> ExternResult<Option<Details>> { host_call::<GetInput, Option<Details>>(__get_details, GetInput::new(hash.into(), options)) } /// Trait for binding static [ `EntryDef` ] property access for a type. /// See [ `register_entry` ] pub trait EntryDefRegistration { fn entry_def() -> crate::prelude::EntryDef; fn entry_def_id() -> crate::prelude::EntryDefId; fn entry_visibility() -> crate::prelude::EntryVisibility; fn crdt_type() -> crate::prelude::CrdtType; fn required_validations() -> crate::prelude::RequiredValidations; } /// Implements conversion traits to allow a struct to be handled as an app entry. /// If you have some need to implement custom serialization logic or metadata injection /// you can do so by implementing these traits manually instead. /// /// This requires that TryFrom and TryInto [ `derive@SerializedBytes` ] is implemented for the entry type, /// which implies that [ `serde::Serialize` ] and [ `serde::Deserialize` ] is also implemented. /// These can all be derived and there is an attribute macro that both does the default defines. #[macro_export] macro_rules! app_entry { ( $t:ident ) => { impl TryFrom<&$crate::prelude::Entry> for $t { type Error = $crate::prelude::WasmError; fn try_from(entry: &$crate::prelude::Entry) -> Result<Self, Self::Error> { match entry { $crate::prelude::Entry::App(eb) => Ok(Self::try_from( $crate::prelude::SerializedBytes::from(eb.to_owned()), )?), _ => Err($crate::prelude::SerializedBytesError::Deserialize(format!( "{:?} is not an Entry::App so has no serialized bytes", entry )) .into()), } } } impl TryFrom<$crate::prelude::Entry> for $t { type Error = $crate::prelude::WasmError; fn try_from(entry: $crate::prelude::Entry) -> Result<Self, Self::Error> { Self::try_from(&entry) } } impl TryFrom<&$t> for $crate::prelude::Entry { type Error = $crate::prelude::WasmError; fn try_from(t: &$t) -> Result<Self, Self::Error> { match AppEntryBytes::try_from(SerializedBytes::try_from(t)?) { Ok(app_entry_bytes) => Ok(Self::App(app_entry_bytes)), Err(entry_error) => match entry_error { EntryError::SerializedBytes(serialized_bytes_error) => { Err(WasmError::Serialize(serialized_bytes_error)) } EntryError::EntryTooLarge(_) => { Err(WasmError::Guest(entry_error.to_string())) } }, } } } impl TryFrom<$t> for $crate::prelude::Entry { type Error = $crate::prelude::WasmError; fn try_from(t: $t) -> Result<Self, Self::Error> { Self::try_from(&t) } } }; } /// Implements a whole lot of sane defaults for a struct or enum that should behave as an entry, /// *without* implementing the app entry conversion interface. /// /// This allows crates to easily define a struct as an entry separately to binding that struct /// as an entry type in a dependent crate. /// /// For most normal applications, you should use the [ `entry_def!` ] macro instead. #[macro_export] macro_rules! register_entry { ( $t:ident $def:expr ) => { impl $crate::prelude::EntryDefRegistration for $t { fn entry_def() -> $crate::prelude::EntryDef { $def } fn entry_def_id() -> $crate::prelude::EntryDefId { Self::entry_def().id } fn entry_visibility() -> $crate::prelude::EntryVisibility { Self::entry_def().visibility } fn crdt_type() -> $crate::prelude::CrdtType { Self::entry_def().crdt_type } fn required_validations() -> $crate::prelude::RequiredValidations { Self::entry_def().required_validations } } impl From<$t> for $crate::prelude::EntryDef where $t: $crate::prelude::EntryDefRegistration, { fn from(_: $t) -> Self { $t::entry_def() } } impl From<&$t> for $crate::prelude::EntryDef where $t: $crate::prelude::EntryDefRegistration, { fn from(_: &$t) -> Self { $t::entry_def() } } impl From<$t> for $crate::prelude::EntryDefId where $t: $crate::prelude::EntryDefRegistration, { fn from(_: $t) -> Self { $t::entry_def_id() } } impl From<&$t> for $crate::prelude::EntryDefId where $t: $crate::prelude::EntryDefRegistration, { fn from(_: &$t) -> Self { $t::entry_def_id() } } impl TryFrom<&$t> for $crate::prelude::EntryWithDefId where $t: $crate::prelude::EntryDefRegistration, { type Error = $crate::prelude::WasmError; fn try_from(t: &$t) -> Result<Self, Self::Error> { Ok(Self::new($t::entry_def_id(), t.try_into()?)) } } impl TryFrom<$t> for $crate::prelude::EntryWithDefId { type Error = $crate::prelude::WasmError; fn try_from(t: $t) -> Result<Self, Self::Error> { (&t).try_into() } } impl From<$t> for $crate::prelude::EntryVisibility where $t: $crate::prelude::EntryDefRegistration, { fn from(_: $t) -> Self { $t::entry_visibility() } } impl From<&$t> for $crate::prelude::EntryVisibility where $t: $crate::prelude::EntryDefRegistration, { fn from(_: &$t) -> Self { $t::entry_visibility() } } impl From<$t> for $crate::prelude::CrdtType where $t: $crate::prelude::EntryDefRegistration, { fn from(_: $t) -> Self { $t::crdt_type() } } impl From<&$t> for $crate::prelude::CrdtType where $t: $crate::prelude::EntryDefRegistration, { fn from(_: &$t) -> Self { $t::crdt_type() } } impl From<$t> for $crate::prelude::RequiredValidations where $t: $crate::prelude::EntryDefRegistration, { fn from(_: $t) -> Self { $t::required_validations() } } impl From<&$t> for $crate::prelude::RequiredValidations where $t: $crate::prelude::EntryDefRegistration, { fn from(_: &$t) -> Self { $t::required_validations() } } }; } /// Implements a whole lot of sane defaults for a struct or enum that should behave as an entry. /// All the entry def fields are available as dedicated methods on the type and matching From impls /// are provided for each. This allows for both Foo::entry_def() and EntryDef::from(Foo::new()) /// style logic which are both useful in different scenarios. /// /// For example, the Foo::entry_def() style works best in the entry_defs callback as it doesn't /// require an instantiated Foo in order to get the definition. /// On the other hand, EntryDef::from(Foo::new()) works better when e.g. using create_entry() as /// an instance of Foo already exists and we need the entry def id back for creates and updates. /// /// If you don't want to use the macro you can simply implement similar fns youself. /// /// This is not a trait at the moment, it could be in the future but for now these functions and /// impls are just a loose set of conventions. /// /// It's actually entirely possible to interact with core directly without any of these. /// e.g. [ `create_entry` ] is just building a tuple of [ `EntryDefId` ] and [ `Entry::App` ] under the hood. /// /// This requires that TryFrom and TryInto [ `derive@SerializedBytes` ] is implemented for the entry type, /// which implies that [ `serde::Serialize` ] and [ `serde::Deserialize` ] is also implemented. /// These can all be derived and there is an attribute macro that both does the default defines. /// /// e.g. the following are equivalent /// /// ```ignore /// #[hdk_entry(id = "foo", visibility = "private", required_validations = 6, )] /// pub struct Foo; /// ``` /// /// ```ignore /// #[derive(SerializedBytes, serde::Serialize, serde::Deserialize)] /// pub struct Foo; /// entry_def!(Foo EntryDef { /// id: "foo".into(), /// visibility: EntryVisibility::Private, /// ..Default::default() /// }); /// ``` #[macro_export] macro_rules! entry_def { ( $t:ident $def:expr ) => { app_entry!($t); register_entry!($t $def); }; } /// Shorthand to implement the entry defs callback similar to the vec![ .. ] macro but for entries. /// /// e.g. the following are the same /// /// ```ignore /// entry_defs![ Foo::entry_def() ]; /// ``` /// /// ```ignore /// #[hdk_extern] /// fn entry_defs(_: ()) -> ExternResult<EntryDefsCallbackResult> { /// Ok(vec![ Foo::entry_def() ].into()) /// } /// ``` #[macro_export] macro_rules! entry_defs { [ $( $def:expr ),* ] => { #[hdk_extern] fn entry_defs(_: ()) -> $crate::prelude::ExternResult<$crate::prelude::EntryDefsCallbackResult> { Ok($crate::prelude::EntryDefsCallbackResult::from(vec![ $( $def ),* ])) } }; } /// Attempts to lookup the [ `EntryDefIndex` ] given an [ `EntryDefId` ]. /// /// The [ `EntryDefId` ] is a [ `String` ] newtype and the [ `EntryDefIndex` ] is a u8 newtype. /// The [ `EntryDefIndex` ] is used to reference the entry type in headers on the DHT and as the index of the type exported to tooling. /// The [ `EntryDefId` ] is the 'human friendly' string that the [ `entry_defs!` ] callback maps to the index. /// /// The host actually has no idea how to do this mapping, it is provided by the wasm! /// /// Therefore this is a macro that calls the [ `entry_defs!` ] callback as defined within a zome directly from the zome. /// It is a macro so that we can call a function with a known name `crate::entry_defs` from the HDK before the function is defined. /// /// Obviously this assumes and requires that a compliant [ `entry_defs!` ] callback _is_ defined at the root of the crate. #[macro_export] macro_rules! entry_def_index { ( $t:ty ) => { match crate::entry_defs(()) { Ok($crate::prelude::EntryDefsCallbackResult::Defs(entry_defs)) => { match entry_defs.entry_def_index_from_id(<$t>::entry_def_id()) { Some(entry_def_index) => Ok::< $crate::prelude::EntryDefIndex, $crate::prelude::WasmError, >(entry_def_index), None => { $crate::prelude::tracing::error!( entry_def_type = stringify!($t), ?entry_defs, "Failed to lookup index for entry def id." ); Err::<$crate::prelude::EntryDefIndex, $crate::prelude::WasmError>( $crate::prelude::WasmError::Guest( "Failed to lookup index for entry def id.".into(), ), ) } } } Ok($crate::prelude::EntryDefsCallbackResult::Err(error)) => { $crate::prelude::tracing::error!(?error, "Failed to lookup entry defs."); Err::<$crate::prelude::EntryDefIndex, $crate::prelude::WasmError>( $crate::prelude::WasmError::Guest(error), ) } Err(error) => { $crate::prelude::tracing::error!(?error, "Failed to lookup entry defs."); Err::<$crate::prelude::EntryDefIndex, $crate::prelude::WasmError>(error) } } }; }