Module session 

Sessions and the pure start and step functions (W3C SCXML Appendix D, interpret and mainEventLoop).

A Session is a value: the configuration as a bitset over states in document order, the history table, the internal queue, active invocations, the send and invoke counters, the late-binding status of data items and the options. start and step take a session (or create one) and an Input, and return the next session, the Effects to perform and a MacrostepTrace. They perform no I/O, read no clock and use no randomness; delays are durations inside effects and the time and seed of each input reach the datamodel only through Datamodel::set_environment.

The datamodel is the one mutable component kept outside the value (decision D1); it is passed as &mut dyn Datamodel. Executable content and condition evaluation live in this module and call it; the transition selection and entry/exit computations are delegated to the trait-object-free crate::kernel.

Structs

Input

One input to step: an external event or a cancel request, plus its environment.

Invocation

A started invocation.

InvokeRequest

A request to start an invocation, produced at the end of a macrostep.

Options

Interpreter options, fixed at session start.

Outcome

The result of a macrostep.

SendRequest

A request to deliver an event, produced by <send>.

Session

The state of one session, as a value.

StartInput

The input that starts a session.

Enums

Effect

An interaction with the outside world, returned by the step instead of performed.

InputKind

What an input asks the session to do.

StartError

Why a session could not start.

Status

Whether the session still accepts events.

StepError

Why a step was rejected or cut short.

Constants

COMMUNICATION_ERROR_MESSAGE

Message of an error.communication for a target the core knows is unreachable.

DEFAULT_MICROSTEP_BUDGET

The default number of microsteps one macrostep may take before it is cut off.

EXECUTION_ERROR_MESSAGE

Message of an error.execution the core raises itself, not from a datamodel failure.

SCXML_EVENT_PROCESSOR

The type URI of the SCXML Event I/O Processor.

SCXML_INVOKE_TYPE

The type URI of SCXML invocations.

Functions

parse_delay

Parse a CSS2 time (5s, 250ms, 1.5s, or a bare number of milliseconds) into milliseconds, without floating point.

start

Start a session: initialize the datamodel (all data under early binding, top-level data under late binding), run the top-level script, enter the initial configuration and run macrosteps until stable. dm must be a fresh instance of the datamodel the chart names.

step

Process one input: run one macrostep for an external event, or terminate on a cancel request. Equal sessions, inputs and datamodel states give equal results.