So far, CEL C++ always used only the generated descriptor pool (and message
factory). This means only protos that are compiled into the binary using CEL
can be used.

In our scenario, we have a database providing certain entities that can be
added in our system at run-time and which use proto to describe output data.
We want to use CEL to formulate expressions over this output. Since we know
only at run-time what protos these are, we need to create a hermtic descriptor
pool and dynamic message factory for that transitively closed file descriptor
set.

This CL adds the capability to CEL/C++ to use a custom descriptor poold and
message factory. From the users' perspective this is entirely optional and
the generated descriptor pool and message factory will be used if not
explicitly overridden.

PiperOrigin-RevId: 427701926

Allow users to register non-strict functions, which are functions that could
take `CelError` or `UnknownSet` as arguments.

- Add a field `is_strict` to `CelFunctionDescriptor`.
- Change `CelFunctionRegistry` so that it ensure if the function has any
  non-strict overload, it has only one overload.
- Modify `IsNonStrict` in `function_step.cc` to check `is_strict` field.

PiperOrigin-RevId: 427817399

PiperOrigin-RevId: 428042273

PiperOrigin-RevId: 428518876

PiperOrigin-RevId: 428531745

PiperOrigin-RevId: 428545658

PiperOrigin-RevId: 428639120

…nstead of directly using proto2::Arena api.

PiperOrigin-RevId: 429366046

PiperOrigin-RevId: 429395768

…sible.

This helps move toward making proto2::arena an optional dependency and enabling alternative memory management strategies.

PiperOrigin-RevId: 430473093

…traction. Update create map step to use builder allocated by the memory manager.

PiperOrigin-RevId: 431842547

PiperOrigin-RevId: 431990497

PiperOrigin-RevId: 432018873

PiperOrigin-RevId: 432468397

… for implementations of comparison operations.

PiperOrigin-RevId: 432540100

PiperOrigin-RevId: 433227593

…key lookups.

PiperOrigin-RevId: 433308944

PiperOrigin-RevId: 433349120

PiperOrigin-RevId: 433368987

PiperOrigin-RevId: 433487364

PiperOrigin-RevId: 433489389

AddStandardMessageTypesToDescriptorPool() cannot be called on descriptor pools
backed by a database. Yet users may need to add the relevant types. The new
function GetStandardMessageTypesFileDescriptorSet() gives a file descriptor
set of those types so that users can add those by themselves.

PiperOrigin-RevId: 433757758

The json_name field of the FieldDescriptorProto may be set differently (or not
at all) depending on the compiler used. We saw differences in just this field
leading to the differencer detecting a difference, but the messages would
still be compatible. Hence ignore this field.

PiperOrigin-RevId: 433757941

PiperOrigin-RevId: 433865216

PiperOrigin-RevId: 434537767

…onality to cel::Types. This introduces a transitional API to refactor the evaluator to be structurally compatible with new Type APIs without forcing a swap to the new type system.

PiperOrigin-RevId: 435127247

PiperOrigin-RevId: 435418602

… messages based on the configured descriptor pool.

PiperOrigin-RevId: 435544477

PiperOrigin-RevId: 446193337

PiperOrigin-RevId: 446214501

…example type provider and legacy type adapters.

PiperOrigin-RevId: 446302462

…pe adapters instead of directly consulting a proto DescriptorPool.

PiperOrigin-RevId: 446304673

PiperOrigin-RevId: 446304791

…ion steps.

PiperOrigin-RevId: 446304898

…sn't include any reflection utilities or assume that values are implementing the full message interface.

PiperOrigin-RevId: 446305046

PiperOrigin-RevId: 446484239

…tion adapter.

PiperOrigin-RevId: 446514900

PiperOrigin-RevId: 447089041

PiperOrigin-RevId: 448029301

PiperOrigin-RevId: 448302268

PiperOrigin-RevId: 448308815

PiperOrigin-RevId: 449819425

PiperOrigin-RevId: 450063543

PiperOrigin-RevId: 450776472

…ls when underlying std::unique_ptr<*> is unset.

PiperOrigin-RevId: 451211992

PiperOrigin-RevId: 451524495

… native type representations of the AST.

PiperOrigin-RevId: 452047564

PiperOrigin-RevId: 453225470

PiperOrigin-RevId: 453261653

PiperOrigin-RevId: 453272140

PiperOrigin-RevId: 453300107