metadata.cpp
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#include "crucible/boba/metadata.hpp"
#include "crucible/core/assert.inl"
#include "crucible/parsing/bits.inl"
#include "crucible/parsing/combinators.inl"
#include <cstdint>
namespace crucible::boba::metadata {
namespace {
using namespace parsing::combinators::operators;
constexpr std::size_t FIELDS_PER_HEADER { 4 };
auto make_header_from_fields(std::vector<std::uint32_t> const &fields) -> Header {
constexpr std::uint32_t INTERNAL_MASK { 0x80000000 };
ASSERT_EQ(fields.size(), FIELDS_PER_HEADER);
Header h;
h.is_internal = (fields[0] & INTERNAL_MASK) == INTERNAL_MASK;
h.signature = fields[0] & ~INTERNAL_MASK;
h.data_size = fields[1];
h.user_data[0] = fields[2];
h.user_data[1] = fields[3];
return h;
}
auto const parse_one_header {
parsing::combinators::make_map<Header>(
make_header_from_fields,
parsing::combinators::make_sequence_of(
parsing::bits::BigEndianUnsignedInteger<std::uint32_t> {},
FIELDS_PER_HEADER
)
)
};
auto const parse_schema_header {
parsing::combinators::make_into<Schema>(
parse_one_header
)
};
template<typename T>
auto unpack_parsing_accept(parsing::errors::Accept<parsing::bits::BitsState, T> const &accept) -> T {
return accept.get_value();
};
auto wrap_parsing_error(parsing::errors::Reject<parsing::bits::BitsState> const &reject) -> errors::BobaError {
return errors::ParsingFailed { reject.get_error() };
}
auto parse_user_headers(std::size_t const user_header_count, parsing::bits::BitsState const &initial_state) -> errors::BobaResult<std::vector<Header>> {
auto const parser {
parsing::combinators::make_sequence_of(
parse_one_header,
user_header_count
)
};
auto const parser_result { parser(initial_state) };
auto const headers { parser_result.map_rhs(unpack_parsing_accept<std::vector<Header>>) };
return headers.map_lhs(wrap_parsing_error);
}
}
Schema::Schema(Header const &header) :
my_header { header } {
}
auto Schema::get_underlying_header() const -> Header {
return my_header;
}
auto Schema::get_full_header_count() const -> std::size_t {
constexpr std::uint32_t HEADER_COUNT_MASK { 0xff000000 };
constexpr std::size_t HEADER_COUNT_SHIFT { 24 };
return (my_header.user_data[0] & HEADER_COUNT_MASK) >> HEADER_COUNT_SHIFT;
}
auto Schema::get_user_header_count() const -> std::size_t {
return get_full_header_count() - 1;
}
auto Schema::get_header_size() const -> std::size_t {
constexpr std::uint32_t HEADER_SIZE_MASK { 0x00ff0000 };
constexpr std::size_t HEADER_SIZE_SHIFT { 16 };
return (my_header.user_data[0] & HEADER_SIZE_MASK) >> HEADER_SIZE_SHIFT;
}
auto Schema::get_entry_count() const -> std::size_t {
constexpr std::uint32_t ENTRY_COUNT_MASK { 0x0000ff00 };
constexpr std::size_t ENTRY_COUNT_SHIFT { 8 };
return (my_header.user_data[0] & ENTRY_COUNT_MASK) >> ENTRY_COUNT_SHIFT;
}
auto Schema::get_entry_size() const -> std::size_t {
constexpr std::uint32_t ENTRY_SIZE_MASK { 0x0000000ff };
constexpr std::size_t ENTRY_SIZE_SHIFT { 0 };
return (my_header.user_data[0] & ENTRY_SIZE_MASK) >> ENTRY_SIZE_SHIFT;
}
Container::Container(Schema const &schema) :
my_schema { schema } {
}
Container::Container(Schema const &schema, std::vector<Header> const &headers) :
my_schema { schema },
my_headers { headers } {
}
auto Container::get_schema() const -> Schema {
return my_schema;
}
auto Container::begin() const -> IteratorType {
return my_headers.begin();
}
auto Container::end() const -> IteratorType {
return my_headers.end();
}
auto from_bytes(std::span<std::byte const> bytes) -> errors::BobaResult<Container> {
parsing::bits::BitsState initial_state { bytes };
auto const schema_header_result { parse_one_header(initial_state) };
if (schema_header_result.has_lhs()) {
auto const &schema_header_reject { schema_header_result.get_lhs() };
return core::either::make_lhs<errors::BobaError>(errors::ParsingFailed { schema_header_reject.get_error() });
}
auto const &schema_header_accept { schema_header_result.get_rhs() };
Schema const schema { Header { schema_header_accept.get_value() } };
auto const user_headers_result { parse_user_headers(schema.get_user_header_count(), schema_header_accept.get_state()) };
if (user_headers_result.has_lhs()) {
return user_headers_result.forward_lhs();
}
auto headers { user_headers_result.get_rhs() };
std::size_t running_offset { schema.get_full_header_count() * schema.get_header_size() + schema.get_underlying_header().data_size };
for (auto &header : headers) {
header.offset = running_offset;
running_offset += header.data_size;
}
return core::either::make_rhs<Container>(schema, std::move(headers));
}
}