cirq.decompose_once(val: Any, default=([], ), **kwargs)[source]

Decomposes a value into operations, if possible.

This method decomposes the value exactly once, instead of decomposing it
and then continuing to decomposing the decomposed operations recursively
until some criteria is met (which is what cirq.decompose does).
  • val – The value to call _decompose_ on, if possible.
  • default – A default result to use if the value doesn’t have a _decompose_ method or that method returns NotImplemented or None. If not specified, undecomposable values cause a TypeError.
  • kwargs – Arguments to forward into the _decompose_ method of val. For example, this is used to tell gates what qubits they are being applied to.

The result of val._decompose_(**kwargs), if val has a _decompose_ method and it didn’t return NotImplemented or None. Otherwise default is returned, if it was specified. Otherwise an error is raised.

val didn’t have a _decompose_ method (or that method returned NotImplemented or None) and default wasn’t set.