generator/proto/nanopb.proto

// Custom options for defining:
// - Maximum size of string/bytes
// - Maximum number of elements in array
//
// These are used by nanopb to generate statically allocable structures
// for memory-limited environments.

syntax = "proto2";
import "google/protobuf/descriptor.proto";

option java_package = "fi.kapsi.koti.jpa.nanopb";

enum FieldType {
    FT_DEFAULT = 0; // Automatically decide field type, generate static field if possible.
    FT_CALLBACK = 1; // Always generate a callback field.
    FT_POINTER = 4; // Always generate a dynamically allocated field.
    FT_STATIC = 2; // Generate a static field or raise an exception if not possible.
    FT_IGNORE = 3; // Ignore the field completely.
    FT_INLINE = 5; // Legacy option, use the separate 'fixed_length' option instead
}

enum IntSize {
    IS_DEFAULT = 0; // Default, 32/64bit based on type in .proto
    IS_8 = 8;
    IS_16 = 16;
    IS_32 = 32;
    IS_64 = 64;
}

enum TypenameMangling {
    M_NONE = 0; // Default, no typename mangling
    M_STRIP_PACKAGE = 1; // Strip current package name
    M_FLATTEN = 2; // Only use last path component
    M_PACKAGE_INITIALS = 3; // Replace the package name by the initials
}

enum DescriptorSize {
    DS_AUTO = 0; // Select minimal size based on field type
    DS_1 = 1;    // 1 word; up to 15 byte fields, no arrays
    DS_2 = 2;    // 2 words; up to 4095 byte fields, 4095 entry arrays
    DS_4 = 4;    // 4 words; up to 2^32-1 byte fields, 2^16-1 entry arrays
    DS_8 = 8;    // 8 words; up to 2^32-1 entry arrays
}

// This is the inner options message, which basically defines options for
// a field. When it is used in message or file scope, it applies to all
// fields.
message NanoPBOptions {
  // Allocated size for 'bytes' and 'string' fields.
  // For string fields, this should include the space for null terminator.
  optional int32 max_size = 1;
  
  // Maximum length for 'string' fields. Setting this is equivalent
  // to setting max_size to a value of length+1.
  optional int32 max_length = 14;
  
  // Allocated number of entries in arrays ('repeated' fields)
  optional int32 max_count = 2;
  
  // Size of integer fields. Can save some memory if you don't need
  // full 32 bits for the value.
  optional IntSize int_size = 7 [default = IS_DEFAULT];

  // Force type of field (callback or static allocation)
  optional FieldType type = 3 [default = FT_DEFAULT];
  
  // Use long names for enums, i.e. EnumName_EnumValue.
  optional bool long_names = 4 [default = true];
  
  // Add 'packed' attribute to generated structs.
  // Note: this cannot be used on CPUs that break on unaligned
  // accesses to variables.
  optional bool packed_struct = 5 [default = false];
  
  // Add 'packed' attribute to generated enums.
  optional bool packed_enum = 10 [default = false];
  
  // Skip this message
  optional bool skip_message = 6 [default = false];

  // Generate oneof fields as normal optional fields instead of union.
  optional bool no_unions = 8 [default = false];

  // integer type tag for a message
  optional uint32 msgid = 9;

  // decode oneof as anonymous union
  optional bool anonymous_oneof = 11 [default = false];

  // Proto3 singular field does not generate a "has_" flag
  optional bool proto3 = 12 [default = false];
  
  // Force proto3 messages to have no "has_" flag.
  // This was default behavior until nanopb-0.4.0.
  optional bool proto3_singular_msgs = 21 [default = false];

  // Generate an enum->string mapping function (can take up lots of space).
  optional bool enum_to_string = 13 [default = false];

  // Generate bytes arrays with fixed length
  optional bool fixed_length = 15 [default = false];

  // Generate repeated field with fixed count
  optional bool fixed_count = 16 [default = false];

  // Generate message-level callback that is called before decoding submessages.
  // This can be used to set callback fields for submsgs inside oneofs.
  optional bool submsg_callback = 22 [default = false];

  // Shorten or remove package names from type names.
  // This option applies only on the file level.
  optional TypenameMangling mangle_names = 17 [default = M_NONE];

  // Data type for storage associated with callback fields.
  optional string callback_datatype = 18 [default = "pb_callback_t"];

  // Callback function used for encoding and decoding.
  // Prior to nanopb-0.4.0, the callback was specified in per-field pb_callback_t
  // structure. This is still supported, but does not work inside e.g. oneof or pointer
  // fields. Instead, a new method allows specifying a per-message callback that
  // will be called for all callback fields in a message type.
  optional string callback_function = 19 [default = "pb_default_field_callback"];

  // Select the size of field descriptors. This option has to be defined
  // for the whole message, not per-field. Usually automatic selection is
  // ok, but if it results in compilation errors you can increase the field
  // size here.
  optional DescriptorSize descriptorsize = 20 [default = DS_AUTO];

  // Set default value for has_ fields.
  optional bool default_has = 23 [default = false];

  // Extra files to include in generated `.pb.h`
  repeated string include = 24;

  // Automatic includes to exclude from generated `.pb.h`
  // Same as nanopb_generator.py command line flag -x.
  repeated string exclude = 26;

  // Package name that applies only for nanopb.
  optional string package = 25;
  
  // Override type of the field in generated C code. Only to be used with related field types
  optional google.protobuf.FieldDescriptorProto.Type type_override = 27;

  // Due to historical reasons, nanopb orders fields in structs by their tag number
  // instead of the order in .proto. Set this to false to keep the .proto order.
  // The default value will probably change to false in nanopb-0.5.0.
  optional bool sort_by_tag = 28 [default = true];

  // this affects the FT_DEFAULT (the default) field conversion strategy. A field
  // that can become a static member of a c struct (e.g. int, bool, etc) will be a
  // a static field. Fields with dynamic length are converted, to either a pointer or a callback.
  // this defines wether it becomes a pointer or a callback.
  optional FieldType fallback_type = 29 [default = FT_CALLBACK]; 
}

// Extensions to protoc 'Descriptor' type in order to define options
// inside a .proto file.
//
// Protocol Buffers extension number registry
// --------------------------------
// Project:  Nanopb
// Contact:  Petteri Aimonen <jpa@kapsi.fi>
// Web site: http://kapsi.fi/~jpa/nanopb
// Extensions: 1010 (all types)
// --------------------------------

extend google.protobuf.FileOptions {
    optional NanoPBOptions nanopb_fileopt = 1010;
}

extend google.protobuf.MessageOptions {
    optional NanoPBOptions nanopb_msgopt = 1010;
}

extend google.protobuf.EnumOptions {
    optional NanoPBOptions nanopb_enumopt = 1010;
}

extend google.protobuf.FieldOptions {
    optional NanoPBOptions nanopb = 1010;
}