Method Extend

cel/env.go:491–593

Extend the current environment with additional options to produce a new Env. Note, the extended Env value should not share memory with the original. It is possible, however, that a CustomTypeAdapter or CustomTypeProvider options could provide values which are mutable. To ensure separation of state

(opts ...EnvOption)

// TypeProvider are immutable, or that their underlying implementations are based on the
// ref.TypeRegistry which provides a Copy method which will be invoked by this method.
func (e *Env) Extend(opts ...EnvOption) (*Env, error) {
	chk, chkErr := e.getCheckerOrError()
	if chkErr != nil {
		return nil, chkErr
	}

	prsrOptsCopy := make([]parser.Option, len(e.prsrOpts))
	copy(prsrOptsCopy, e.prsrOpts)

	// The type-checker is configured with Declarations. The declarations may either be provided
	// as options which have not yet been validated, or may come from a previous checker instance
	// whose types have already been validated.
	chkOptsCopy := make([]checker.Option, len(e.chkOpts))
	copy(chkOptsCopy, e.chkOpts)

	// Copy the declarations if needed.
	if chk != nil {
		// If the type-checker has already been instantiated, then the e.declarations have been
		// validated within the chk instance.
		chkOptsCopy = append(chkOptsCopy, checker.ValidatedDeclarations(chk))
	}
	varsCopy := make([]*decls.VariableDecl, len(e.variables))
	copy(varsCopy, e.variables)

	// Copy macros and program options
	macsCopy := make([]parser.Macro, len(e.macros))
	progOptsCopy := make([]ProgramOption, len(e.progOpts))
	copy(macsCopy, e.macros)
	copy(progOptsCopy, e.progOpts)

	// Copy the adapter / provider if they appear to be mutable.
	adapter := e.adapter
	provider := e.provider
	adapterReg, isAdapterReg := e.adapter.(*types.Registry)
	providerReg, isProviderReg := e.provider.(*types.Registry)
	// In most cases the provider and adapter will be a ref.TypeRegistry;
	// however, in the rare cases where they are not, they are assumed to
	// be immutable. Since it is possible to set the TypeProvider separately
	// from the TypeAdapter, the possible configurations which could use a
	// TypeRegistry as the base implementation are captured below.
	if isAdapterReg && isProviderReg {
		reg := providerReg.Copy()
		provider = reg
		// If the adapter and provider are the same object, set the adapter
		// to the same ref.TypeRegistry as the provider.
		if adapterReg == providerReg {
			adapter = reg
		} else {
			// Otherwise, make a copy of the adapter.
			adapter = adapterReg.Copy()
		}
	} else if isProviderReg {
		provider = providerReg.Copy()
	} else if isAdapterReg {
		adapter = adapterReg.Copy()
	}

	featuresCopy := make(map[int]bool, len(e.features))