Enum ContractMetadataKind 

#[repr(u8)]
pub enum ContractMetadataKind {
    Contract = 0,
    Trait = 1,
    Init = 2,
    UpdateStateless = 3,
    UpdateStatefulRo = 4,
    UpdateStatefulRw = 5,
    ViewStateless = 6,
    ViewStateful = 7,
    EnvRo = 8,
    EnvRw = 9,
    TmpRo = 10,
    TmpRw = 11,
    SlotRo = 12,
    SlotRw = 13,
    Input = 14,
    Output = 15,
    Return = 16,
}

Metadata for smart contact methods.

Metadata encoding consists of this enum variant treated as u8 followed by optional metadata encoding rules specific to metadata type variant (see variant’s description).

This metadata is enough to fully reconstruct the hierarchy of the type to generate language bindings, auto-generate UI forms, etc.

Variants

Contract = 0

Main contract metadata.

Contracts are encoded as follows:

• Encoding of the state type as described in IoTypeMetadataKind
• Encoding of the #[slot] type as described in IoTypeMetadataKind
• Encoding of the #[tmp] type as described in IoTypeMetadataKind
• Number of methods (u8)
• Recursive metadata of methods as defined in one of:
  • Self::Init
  • Self::UpdateStateless
  • Self::UpdateStatefulRo
  • Self::UpdateStatefulRw
  • Self::ViewStateless
  • Self::ViewStateful

Trait = 1

Trait metadata.

Traits are encoded as follows:

• Length of trait name in bytes (u8)
• Trait name as UTF-8 bytes
• Number of methods (u8)
• Recursive metadata of methods as defined in one of:
  • Self::UpdateStateless
  • Self::ViewStateless

Init = 2

#[init] method.

Initializers are encoded as follows:

• Length of method name in bytes (u8)
• Method name as UTF-8 bytes
• Number of named arguments (u8, excluding state argument &self or &mut self, but including return type that is not () or Result<(), ContactError>)

Each argument is encoded as follows:

• Argument type as u8, one of:
  • Self::EnvRo
  • Self::EnvRw
  • Self::TmpRo
  • Self::TmpRw
  • Self::SlotRo
  • Self::SlotRw
  • Self::Input
  • Self::Output
  • Self::Return (yes, this is considered to be an argument)
• Length of the argument name in bytes (u8, except for Self::EnvRo and Self::EnvRw)
• Argument name as UTF-8 bytes (except for Self::EnvRo and Self::EnvRw)
• Only for Self::Input and Self::Output recursive metadata of argument’s type as described in IoTypeMetadataKind with the following exception:
  • For last Self::Output or Self::Return this is skipped if the method is Self::Init since it is statically known to be Self and present otherwise

NOTE: Self::Return is encoded as a separate argument and counts towards the number of arguments. At the same time, self doesn’t count towards the number of arguments as it is implicitly defined by the variant of this struct.

UpdateStateless = 3

Stateless #[update] method (doesn’t have self in its arguments).

Encoding is the same as Self::Init.

UpdateStatefulRo = 4

Stateful read-only #[update] method (has &self in its arguments).

Encoding is the same as Self::Init.

UpdateStatefulRw = 5

Stateful read-write #[update] method (has &mut self in its arguments).

Encoding is the same as Self::Init.

ViewStateless = 6

Stateless #[view] method (doesn’t have self in its arguments).

Encoding is the same as Self::Init.

ViewStateful = 7

Stateful read-only #[view] method (has &self in its arguments).

Encoding is the same as Self::Init.

EnvRo = 8

Read-only #[env] argument.

Example: #[env] env: &Env,

EnvRw = 9

Read-write #[env] argument.

Example: #[env] env: &mut Env<'_>,

TmpRo = 10

Read-only #[tmp] argument.

Example: #[tmp] tmp: &MaybeData<Tmp>,

TmpRw = 11

Read-write #[tmp] argument.

Example: #[tmp] tmp: &mut MaybeData<Tmp>,

SlotRo = 12

Read-only #[slot] argument with an address.

Example: #[slot] (from_address, from): (&Address, &MaybeData<Slot>),

SlotRw = 13

Read-write #[slot] argument with an address.

Example: #[slot] (from_address, from): (&Address, &mut MaybeData<Slot>),

Input = 14

#[input] argument.

Example: #[input] balance: &Balance,

Output = 15

Explicit #[output] argument.

NOTE: Skipped if return type’s T is ().

Example: #[output] out: &mut VariableBytes<1024>,

Return = 16

T of Result<T, ContractError> return type or simply return type if it is not fallible.

NOTE: Skipped if return type’s T is ().

Example: -> Balance

Implementations

impl ContractMetadataKind

pub const fn try_from_u8(byte: u8) -> Option<Self>

Try to create an instance from its u8 representation

pub const fn compact(metadata: &[u8]) -> Option<([u8; 8192], usize)>

Produce compact metadata.

Compact metadata retains the shape but throws some details. Specifically, the following transformations are applied to metadata (crucially, method names are retained!):

• Struct, trait, enum, and enum variant names removed (replaced with 0 bytes names)
• Structs and enum variants turned into tuple variants (removing field names)
• Method argument names removed

This means that two methods with different argument names or struct field names, but the same shape otherwise are considered identical, allowing for limited future refactoring opportunities without changing compact metadata shape, which is important for MethodFingerprint (though Self::compact_external_args() is used by it internally).

Returns None if the input is invalid or too long.

pub const fn compact_external_args( metadata: &[u8], ) -> Option<([u8; 8192], usize)>

Produce compact metadata for ExternalArgs.

Similar to Self::compact(), but arguments that are not reflected in ExternalArgs will be skipped since they don’t impact ExternalArgs API. This is used for MethodFingerprint derivation.

Returns None if the input is invalid or too long.

Trait Implementations

impl Clone for ContractMetadataKind

fn clone(&self) -> ContractMetadataKind

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ContractMetadataKind

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for ContractMetadataKind

fn eq(&self, other: &ContractMetadataKind) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for ContractMetadataKind

impl Eq for ContractMetadataKind

impl StructuralPartialEq for ContractMetadataKind