Function newProgram

cel/program.go:232–355

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 env's function bindings and shared dispatcher once (pure functions of the
	// env). The dispatcher holding the env's function bindings is identical across every
	// Program() built from it and read-only during planning — so assemble it once per env
	// and layer a thin child over it here for per-program Functions() isolation, rather than
	// re-indexing overloads on every Program() call.
	sharedDisp, hasAsync, err := e.initDispatcher()
	if err != nil {
		return nil, err
	}
	disp := interpreter.ExtendDispatcher(sharedDisp)

	// 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),
		hasAsync:       hasAsync,
	}

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

	// Set the attribute factory after the options have been set.
	var attrFactory interpreter.AttributeFactory
	attrFactorOpts := []interpreter.AttrFactoryOption{
		interpreter.EnableErrorOnBadPresenceTest(p.HasFeature(featureEnableErrorOnBadPresenceTest)),
	}
	if a.SourceInfo().HasExtension("json_name", ast.NewExtensionVersion(1, 1)) {
		if !e.HasFeature(featureJSONFieldNames) {
			return nil, errors.New("the AST extension 'json_name' requires the option cel.JSONFieldNames(true)")
		}
	}
	// Configure the type provider, considering whether the AST indicates whether it supports JSON field names
	if p.evalOpts&OptPartialEval == OptPartialEval {
		attrFactory = interpreter.NewPartialAttributeFactory(e.Container, e.adapter, e.provider, attrFactorOpts...)
	} else {
		attrFactory = interpreter.NewAttributeFactory(e.Container, e.adapter, e.provider, attrFactorOpts...)
	}
	interp := interpreter.NewInterpreter(disp, e.Container, e.provider, e.adapter, attrFactory)
	p.interpreter = interp

	// Translate the EvalOption flags into InterpretableDecorator instances.
	plannerOptions := make([]interpreter.PlannerOption, len(p.plannerOptions))
	copy(plannerOptions, p.plannerOptions)

	// Enable interrupt checking if there's a non-zero check frequency
	if p.interruptCheckFrequency > 0 {
		plannerOptions = append(plannerOptions, interpreter.InterruptableEval())
	}