com.r3corda.core.contracts.clauses / Clause

# Clause

`abstract class Clause<in S : ContractState, C : CommandData, in K : Any>`

A clause of a contract, containing a chunk of verification logic. That logic may be delegated to other clauses, or provided directly by this clause.

### Parameters

`S` - the type of contract state this clause operates on.
`C` - a common supertype of commands this clause operates on.
`K` - the type of the grouping key for states this clause operates on. Use Unit if not applicable.

See Also

CompositeClause

### Constructors

<init> | `Clause()` A clause of a contract, containing a chunk of verification logic. That logic may be delegated to other clauses, or provided directly by this clause.

### Properties

requiredCommands | `open val requiredCommands: Set<Class<out CommandData>>` Determine whether this clause runs or not

### Functions

getExecutionPath | `open fun getExecutionPath(commands: List<AuthenticatedObject<C>>): List<Clause<*, *, *>>` Determine the subclauses which will be verified as a result of verifying this clause.
verify | `abstract fun verify(tx: TransactionForContract, inputs: List<S>, outputs: List<S>, commands: List<AuthenticatedObject<C>>, groupingKey: K?): Set<C>` Verify the transaction matches the conditions from this clause. For example, a "no zero amount output" clause would check each of the output states that it applies to, looking for a zero amount, and throw IllegalStateException if any matched.

### Companion Object Properties

log | `val log: <ERROR CLASS>`

### Extension Functions

matches | `fun <C : CommandData> Clause<*, C, *>.matches(commands: List<AuthenticatedObject<C>>): Boolean` Determine if the given list of commands matches the required commands for a clause to trigger.

### Inheritors

AbstractConserveAmount | `abstract class AbstractConserveAmount<S : FungibleAsset<T>, C : CommandData, T : Any> : Clause<S, C, Issued<T>>` Standardised clause for checking input/output balances of fungible assets. Requires that a Move command is provided, and errors if absent. Must be the last clause under a grouping clause; errors on no-match, ends on match.
AbstractIssue | `abstract class AbstractIssue<in S : ContractState, C : CommandData, T : Any> : Clause<S, C, Issued<T>>` Standard issue clause for contracts that issue fungible assets.
ClauseVerifier | `class ClauseVerifier<S : LinearState, C : CommandData> : Clause<S, C, Unit>` Standard clause to verify the LinearState safety properties.
CompositeClause | `abstract class CompositeClause<in S : ContractState, C : CommandData, in K : Any> : Clause<S, C, K>` Abstract supertype for clauses which compose other clauses together in some logical manner.
FilterOn | `class FilterOn<S : ContractState, C : CommandData, K : Any> : Clause<ContractState, C, K>` Filter the states that are passed through to the wrapped clause, to restrict them to a specific type.
GroupClauseVerifier | `abstract class GroupClauseVerifier<S : ContractState, C : CommandData, K : Any> : Clause<ContractState, C, Unit>`
Move | `class Move : Clause<State, Commands, Issued<Terms>>`
NetClause | `open class NetClause<C : CommandData, P> : Clause<ContractState, C, Unit>` Clause for netting contract states. Currently only supports obligation contract.
NoZeroSizedOutputs | `open class NoZeroSizedOutputs<in S : FungibleAsset<T>, C : CommandData, T : Any> : Clause<S, C, Issued<T>>` Clause for fungible asset contracts, which enforces that no output state should have a balance of zero.
Redeem | `class Redeem : Clause<State, Commands, Issued<Terms>>`
SetLifecycle | `class SetLifecycle<P> : Clause<State<P>, Commands, Issued<Terms<P>>>` Obligation-specific clause for changing the lifecycle of one or more states.
Settle | `class Settle<P> : Clause<State<P>, Commands, Issued<Terms<P>>>` Obligation-specific clause for settling an outstanding obligation by witnessing change of ownership of other states to fulfil
VerifyLifecycle | `class VerifyLifecycle<S : ContractState, C : CommandData, T : Any, P> : Clause<S, C, T>` Obligation-specific clause for verifying that all states are in normal lifecycle. In a group clause set, this must be run after any lifecycle change clause, which is the only clause that involve non-standard lifecycle states on input/output.