Function newProgram

cel/program.go:207–338

newProgram creates a program instance with an environment, an ast, and an optional list of ProgramOption values. If the program cannot be configured the prog will be nil, with a non-nil error response.

(e *Env, a *ast.AST, opts []ProgramOption)

//
// If the program cannot be configured the prog will be nil, with a non-nil error response.
func newProgram(e *Env, a *ast.AST, opts []ProgramOption) (Program, error) {
	// Build the dispatcher, interpreter, and default program value.
	disp := interpreter.NewDispatcher()

	// Ensure the default attribute factory is set after the adapter and provider are
	// configured.
	p := &prog{
		Env:            e,
		plannerOptions: []interpreter.PlannerOption{},
		dispatcher:     disp,
		costOptions:    []interpreter.CostTrackerOption{},
		drainStrategy:  async.DrainReady(100 * time.Microsecond),
	}

	// Configure the program via the ProgramOption values.
	var err error
	for _, opt := range opts {
		p, err = opt(p)
		if err != nil {
			return nil, err
		}
	}

	e.funcBindOnce.Do(func() {
		var bindings []*functions.Overload
		e.functionBindings = []*functions.Overload{}
		for _, fn := range e.functions {
			bindings, err = fn.Bindings()
			if err != nil {
				return
			}
			e.functionBindings = append(e.functionBindings, bindings...)
		}
	})
	if err != nil {
		return nil, err
	}

	// Add the function bindings created via Function() options.
	err = disp.Add(e.functionBindings...)
	if err != nil {
		return nil, err
	}

	// Determine whether the environment declares any asynchronous function. Async is a property of
	// the binding, so its presence is known from the environment alone, without inspecting the
	// program plan. The synchronous entry points (Eval, ContextEval) reject programs from an env
	// with async functions; callers needing synchronous evaluation should use a non-async env.
	for _, b := range e.functionBindings {
		if b.Async != nil {
			p.hasAsync = true
			break
		}
	}

	// Set the attribute factory after the options have been set.
	var attrFactory interpreter.AttributeFactory
	attrFactorOpts := []interpreter.AttrFactoryOption{