Qiskit / qiskit / 34398812926

88%

main: 88%

Build Type

Pull #16924

github

Committed by mtreinish

Commit Message

Add a quantum program: functions, an entry point, and I/O structures

A quantum program is a collection of program functions, the last of which is its
entry point, together with one input structure and one output structure. A
caller hands over a data tree of inputs arranged as the program declares and
receives a tree of outputs arranged the same way, so an answer arrives organised
the way it was asked for. Everything between those two boundaries stays
positional, since the structures are where all naming lives.

The structures describe the entry point, because the entry point is what a caller
invokes, so a program carries one pair and a function carries none. Assembling one
checks that there is a function to enter at — every accessor reads through the last
one — and then that each structure has as many leaves as the entry point has
parameter and result instructions. Correspondence between a structure's leaves and
a function's slots rests on order, and that leaf count is the only structural check
there is: nothing maps between the two, so whoever builds a program adds its
boundary instructions in the order its structures declare.

Evaluating checks the supplied arrangement against the declared one before
computing anything, and reports both structures whole, so that a caller sees the
arrangement that was wanted beside the one it supplied. Rendering a structure as a
skeleton, `[counts: [_, _], shots: _]`, is what makes that message legible.

The declared type of every input and output is available without evaluating,
arranged in the structure it belongs to, and `DataTree::dotted_paths` addresses
each output from the output structure. The structure is the thing worth keeping,
since a set of paths cannot reconstruct it: an empty branch contributes no leaves,
and so no path.

Pull Request Pull Request #16924: Add `QuantumProgram` to providers crate

Coverage Stats

303 of 313 new or added lines in 2 files covered. (96.81%)

10 existing lines in 2 files now uncovered.

118940 of 135090 relevant lines covered (88.05%)

967488.84 hits per line