This is a first cut at adding proto3 support.
As far as I understand protobuf-c already has pretty much everything
needed once it is built using a new version of protobuf itself.
The only missing thing is that in proto3 all fields are optional and
having to manually set has_foo is inconvenient.
This patch special cases the proto3 syntax files so that structs for the
bytes, enum and primitive fields do not emit the has_ field.
It also adds PROTOBUF_C_LABEL_NONE to the label enum that is used for
proto3 fields. When a fields has this label, the quantifier is not
consulted and instead the field is packed/unpacked depending on
whether it has a value different from NULL/0.
From https://developers.google.com/protocol-buffers/docs/proto#optional:
If the default value is not specified for an optional element, a
type-specific default value is used instead: for strings, the default
value is the empty string. For bools, the default value is false. For
numeric types, the default value is zero. For enums, the default value
is the first value listed in the enum's type definition. This means care
must be taken when adding a value to the beginning of an enum value
list.
Prior to this change, protoc-c set the default enum value to 0, whether
or not 0 was the first value listed in the enum's type definition (or if
it even was listed at all).
Adds support for the LITE_RUNTIME optimization option to the protobuf-c
compiler. Enabling this option would generate lighter weight message,
enum, and service descriptors that contain NO strings. As a result,
calls to lookup descriptors via the *_get_{field,value,method}_by_name
API will return NULL.
Default compiler behavior (when optimize_for is not specified or is not
set to LITE_RUNTIME) is unchanged.
Certain protobuf comments could generate invalid C comments
and inadvertently close the comment block. This commit removes '/'
signs in such comments.
One example of a .proto file containing such comments is a commonly
included descriptor.proto from the protobuf library.
identifiers that begin with an underscore are reserved. instead, use a
double underscore in the *middle* of the identifier to indicate that
it's an "internal" identifier.
exact version coupling between the compiler and the public headers is
too strict because some existing projects (such as collectd,
riemann-c-client, and nmsg) directly embed .pb-c.h files generated by
protoc-c into their exported headers. this would cause unnecessary build
failures in downstream clients of these libraries if a newer version of
the protobuf-c headers is installed.
however, it's still desireable to be able to explicitly declare when
compatibility is broken between the headers and the compiler, so
introduce new variables that allow independently setting the minimum
header version required by the compiler and the minimum compiler version
required by the header.
this follows the protobuf C++ implementation a little bit more closely,
though we don't have an analogous facility for verifying that the header
and *library* are compatible. (this seems like overkill for a C project;
in practice the headers and the library will be from the same version,
especially in downstream distributors like debian where the -dev package
has an exact versioned dependency on the shared library package.)
this adds a version guard like the protobuf C++ implementation. it
ensures that protoc-c and <protobuf-c.h> are from the exact same version
of protobuf-c.
rename PROTOBUF_C_FIELD_FLAGS_PACKED to PROTOBUF_C_FIELD_FLAG_PACKED.
rename ProtobufCFieldFlagType to ProtobufCFieldFlag.
wrap some particular long lines.
update documentation.
for clarity, use a "uint32_t" instead of "unsigned" for the 'flags'
field in _ProtobufCFieldDescriptor.
there is some confusion with regard to the use of lower case letters in
enum values. take the following message definition:
message LowerCase {
enum CaseEnum {
UPPER = 1;
lower = 2;
}
optional CaseEnum value = 1 [default = lower];
}
this generates the following C enum:
typedef enum _LowerCase__CaseEnum {
LOWER_CASE__CASE_ENUM__UPPER = 1,
LOWER_CASE__CASE_ENUM__lower = 2
_PROTOBUF_C_FORCE_ENUM_TO_BE_INT_SIZE(LOWER_CASE__CASE_ENUM)
} LowerCase__CaseEnum;
note that the case of the enum value 'lower' was preserved in the C
symbol name as 'LOWER_CASE__CASE_ENUM__lower', but that the _INIT macro
references the same enum value with the (non-existent) C symbol name
'LOWER_CASE__CASE_ENUM__LOWER':
#define LOWER_CASE__INIT \
{ PROTOBUF_C_MESSAGE_INIT (&lower_case__descriptor) \
, 0,LOWER_CASE__CASE_ENUM__LOWER }
additionally, the ProtobufCEnumValue array generated also refers to the
same enum value with the (non-existent) upper cased version:
const ProtobufCEnumValue lower_case__case_enum__enum_values_by_number[2] =
{
{ "UPPER", "LOWER_CASE__CASE_ENUM__UPPER", 1 },
{ "lower", "LOWER_CASE__CASE_ENUM__LOWER", 2 },
};
we should preserve the existing behavior of copying the case from the
enum values in the message definition and fix up the places where the
(non-existent) upper case version is used, rather than changing the enum
definition itself to match the case used in the _INIT macro and
enum_values_by_number array, because it's possible that there might be
existing working code that uses enum values with lower case letters that
would be affected by such a change.
incidentally, google's C++ protobuf implementation preserves case in
enum values. protoc --cpp_out generates the following enum declaration
for the message descriptor above:
enum LowerCase_CaseEnum {
LowerCase_CaseEnum_UPPER = 1,
LowerCase_CaseEnum_lower = 2
};
per https://code.google.com/p/protobuf/source/detail?r=50, the license
on google-originated protobuf code was switched from Apache-2.0 to
BSD-3-Clause (so-called "New BSD" license). update any of the google
license statements to use this new license.
per email with dave, drop the third clause on his BSD-3-Clause license,
so this now becomes BSD-2-Clause.
make sure to use consistent indentation and wrapping throughout.
