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#ifndef UPB_UTIL_REQUIRED_FIELDS_H_
#define UPB_UTIL_REQUIRED_FIELDS_H_

#include "upb/def.h"
#include "upb/reflection.h"

/* Must be last. */
#include "upb/port_def.inc"

#ifdef __cplusplus
extern "C" {
#endif

// A FieldPath can be encoded as an array of upb_FieldPathEntry, in the
// following format:
//    { {.field = f1}, {.field = f2} }                      # f1.f2
//    { {.field = f1}, {.index = 5}, {.field = f2} }        # f1[5].f2
//    { {.field = f1}, {.key = "abc"}, {.field = f2} }      # f1["abc"].f2
//
// A user must look at the type of `f1` to know whether to expect an index or
// map key after it.
typedef union {
  const upb_fielddef* field;
  size_t index;
  upb_msgval key;
} upb_FieldPathEntry;

// Checks whether `msg` or any of its children has unset required fields,
// returning `true` if any are found.
//
// When this function returns true, `fields` is updated (if non-NULL) to point
// to a heap-allocated array encoding the field paths of the required fields
// that are missing.  Each path is terminated with {.field = NULL}, and a final
// {.field = NULL} terminates the list of paths.  The caller is responsible for
// freeing this array.
bool upb_util_HasUnsetRequired(const upb_msg* msg, const upb_msgdef* m,
                               const upb_symtab* ext_pool,
                               upb_FieldPathEntry** fields);

#ifdef __cplusplus
}  /* extern "C" */
#endif

#include "upb/port_undef.inc"

#endif  /* UPB_UTIL_REQUIRED_FIELDS_H_ */