540 lines
20 KiB
C++
540 lines
20 KiB
C++
// Protocol Buffers - Google's data interchange format
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// Copyright 2008 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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// Author: kenton@google.com (Kenton Varda)
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// Based on original Protocol Buffers design by
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// Sanjay Ghemawat, Jeff Dean, and others.
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#ifndef GOOGLE_PROTOBUF_COMPILER_CPP_FIELD_H__
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#define GOOGLE_PROTOBUF_COMPILER_CPP_FIELD_H__
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#include <cstddef>
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#include <cstdint>
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#include <memory>
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#include <string>
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#include <vector>
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#include "absl/container/flat_hash_map.h"
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#include "absl/log/absl_check.h"
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#include "absl/strings/string_view.h"
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#include "absl/types/optional.h"
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#include "absl/types/span.h"
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#include "google/protobuf/compiler/cpp/helpers.h"
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#include "google/protobuf/compiler/cpp/options.h"
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#include "google/protobuf/descriptor.h"
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#include "google/protobuf/io/printer.h"
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namespace google {
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namespace protobuf {
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namespace compiler {
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namespace cpp {
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// Customization points for each field codegen type. See FieldGenerator to
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// see how each of these functions is used.
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//
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// TODO: Make every function except the dtor in this generator
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// non-pure-virtual. A generator with no implementation should be able to
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// automatically not contribute any code to the message it is part of, as a
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// matter of clean composability.
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class FieldGeneratorBase {
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public:
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// `GeneratorFunction` defines a subset of generator functions that may have
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// additional optimizations or requirements such as 'uses a local `arena`
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// variable instead of calling GetArena()'
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enum class GeneratorFunction { kMergeFrom };
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FieldGeneratorBase(const FieldDescriptor* field, const Options& options,
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MessageSCCAnalyzer* scc_analyzer);
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FieldGeneratorBase(const FieldGeneratorBase&) = delete;
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FieldGeneratorBase& operator=(const FieldGeneratorBase&) = delete;
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virtual ~FieldGeneratorBase() = 0;
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// Returns true if this field should be placed in the cold 'Split' section.
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bool should_split() const { return should_split_; }
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// Returns true if this field is trivial. (int, float, double, enum, bool)
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bool is_trivial() const { return is_trivial_; }
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// Returns true if the field value itself is trivial, i.e., the field is
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// trivial, or a (raw) pointer value to a singular, non lazy message.
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bool has_trivial_value() const { return has_trivial_value_; }
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// Returns true if the provided field has a trivial zero default.
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// I.e., the field can be initialized with `memset(&field, 0, sizeof(field))`
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bool has_trivial_zero_default() const { return has_trivial_zero_default_; }
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// Returns true if the provided field can be initialized with `= {}`.
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bool has_brace_default_assign() const { return has_brace_default_assign_; }
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// Returns true if the field is a singular or repeated message.
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// This includes group message types. To explicitly check if a message
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// type is a group type, use the `is_group()` function,
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bool is_message() const { return is_message_; }
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// Returns true if the field is a group message field (TYPE_GROUP).
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bool is_group() const { return is_group_; }
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// Returns true if the field is a weak message
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bool is_weak() const { return is_weak_; }
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// Returns true if the field is a lazy message.
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bool is_lazy() const { return is_lazy_; }
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// Returns true if the field is a foreign message field.
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bool is_foreign() const { return is_foreign_; }
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// Returns true if the field is a string field.
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bool is_string() const { return is_string_; }
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// Returns true if the field API uses bytes (void) instead of chars.
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bool is_bytes() const { return is_bytes_; }
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// Returns true if this field is part of a oneof field.
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bool is_oneof() const { return is_oneof_; }
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// Returns true if the field should be inlined instead of dynamically
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// allocated. Applies to string and message value.
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bool is_inlined() const { return is_inlined_; }
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// Returns true if this field has an appropriate default constexpr
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// constructor. i.e., there is no need for an explicit initializer.
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bool has_default_constexpr_constructor() const {
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return has_default_constexpr_constructor_;
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}
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// Returns true if this generator requires an 'arena' parameter on the
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// given generator function.
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virtual bool RequiresArena(GeneratorFunction) const { return false; }
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virtual std::vector<io::Printer::Sub> MakeVars() const { return {}; }
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virtual void GeneratePrivateMembers(io::Printer* p) const = 0;
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virtual void GenerateStaticMembers(io::Printer* p) const {}
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virtual void GenerateAccessorDeclarations(io::Printer* p) const = 0;
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virtual void GenerateInlineAccessorDefinitions(io::Printer* p) const = 0;
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virtual void GenerateNonInlineAccessorDefinitions(io::Printer* p) const {}
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virtual void GenerateClearingCode(io::Printer* p) const = 0;
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virtual void GenerateMessageClearingCode(io::Printer* p) const {
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GenerateClearingCode(p);
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}
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virtual void GenerateMergingCode(io::Printer* p) const = 0;
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virtual void GenerateCopyConstructorCode(io::Printer* p) const;
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virtual void GenerateSwappingCode(io::Printer* p) const = 0;
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virtual void GenerateConstructorCode(io::Printer* p) const = 0;
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virtual void GenerateDestructorCode(io::Printer* p) const {}
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virtual void GenerateArenaDestructorCode(io::Printer* p) const {
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ABSL_CHECK(NeedsArenaDestructor() == ArenaDtorNeeds::kNone)
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<< field_->cpp_type_name();
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}
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// Generates constexpr member initialization code, e.g.: `foo_{5}`.
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// The default implementation generates the following code:
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// - repeated fields and maps: `field_{}`
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// - all other fields: `field_{<default value>}`
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virtual void GenerateMemberConstexprConstructor(io::Printer* p) const;
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// Generates member initialization code, e.g.: `foo_(5)`.
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// The default implementation generates the following code:
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// - repeated fields and maps: `field_{visibility, arena}`
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// - split repeated fields (RawPtr): `field_{}`
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// - all other fields: `field_{<default value>}`
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virtual void GenerateMemberConstructor(io::Printer* p) const;
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// Generates member copy initialization code, e.g.: `foo_(5)`.
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// The default implementation generates the following code:
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// - repeated fields and maps: `field_{visibility, arena, from.field_}`
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// - all other fields: `field_{from.field_}`
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virtual void GenerateMemberCopyConstructor(io::Printer* p) const;
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// Generates 'placement new' copy construction code used to
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// explicitly copy initialize oneof field values.
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// The default implementation checks the current field to not be repeated,
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// an extension or a map, and generates the following code:
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// - `field_ = from.field_`
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virtual void GenerateOneofCopyConstruct(io::Printer* p) const;
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virtual void GenerateAggregateInitializer(io::Printer* p) const;
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virtual void GenerateConstexprAggregateInitializer(io::Printer* p) const;
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virtual void GenerateCopyAggregateInitializer(io::Printer* p) const;
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virtual void GenerateSerializeWithCachedSizesToArray(
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io::Printer* p) const = 0;
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virtual void GenerateByteSize(io::Printer* p) const = 0;
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virtual void GenerateIsInitialized(io::Printer* p) const {
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ABSL_CHECK(!NeedsIsInitialized());
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}
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virtual bool NeedsIsInitialized() const { return false; }
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virtual bool IsInlined() const { return false; }
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virtual ArenaDtorNeeds NeedsArenaDestructor() const {
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return ArenaDtorNeeds::kNone;
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}
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protected:
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const FieldDescriptor* field_;
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const Options& options_;
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MessageSCCAnalyzer* scc_;
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absl::flat_hash_map<absl::string_view, std::string> variables_;
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private:
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bool should_split_ = false;
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bool is_trivial_ = false;
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bool has_trivial_value_ = false;
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bool has_trivial_zero_default_ = false;
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bool has_brace_default_assign_ = false;
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bool is_message_ = false;
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bool is_group_ = false;
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bool is_string_ = false;
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bool is_bytes_ = false;
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bool is_inlined_ = false;
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bool is_foreign_ = false;
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bool is_lazy_ = false;
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bool is_weak_ = false;
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bool is_oneof_ = false;
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bool has_default_constexpr_constructor_ = false;
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};
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inline FieldGeneratorBase::~FieldGeneratorBase() = default;
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class FieldGenerator {
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private:
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// This function must be defined here so that the inline definitions below
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// can see it, which is required because it has deduced return type.
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auto PushVarsForCall(io::Printer* p) const {
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// NOTE: we use a struct here because:
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// * We want to ensure that order of evaluation below is well-defined,
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// which {...} guarantees but (...) does not.
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// * We do not require C++17 as of writing and therefore cannot use
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// std::tuple with CTAD.
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// * std::make_tuple uses (...), not {...}.
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struct Vars {
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decltype(p->WithVars(field_vars_)) cleanup1;
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decltype(p->WithVars(tracker_vars_)) cleanup2;
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decltype(p->WithVars(per_generator_vars_)) cleanup3;
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};
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return Vars{p->WithVars(field_vars_), p->WithVars(tracker_vars_),
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p->WithVars(per_generator_vars_)};
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}
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public:
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using GeneratorFunction = FieldGeneratorBase::GeneratorFunction;
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FieldGenerator(const FieldGenerator&) = delete;
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FieldGenerator& operator=(const FieldGenerator&) = delete;
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FieldGenerator(FieldGenerator&&) = default;
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FieldGenerator& operator=(FieldGenerator&&) = default;
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// Properties: see FieldGeneratorBase for documentation
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bool should_split() const { return impl_->should_split(); }
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bool is_trivial() const { return impl_->is_trivial(); }
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bool has_trivial_value() const { return impl_->has_trivial_value(); }
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bool has_trivial_zero_default() const {
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return impl_->has_trivial_zero_default();
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}
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bool has_brace_default_assign() const {
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return impl_->has_brace_default_assign();
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}
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bool is_message() const { return impl_->is_message(); }
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bool is_group() const { return impl_->is_group(); }
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bool is_weak() const { return impl_->is_weak(); }
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bool is_lazy() const { return impl_->is_lazy(); }
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bool is_foreign() const { return impl_->is_foreign(); }
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bool is_string() const { return impl_->is_string(); }
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bool is_bytes() const { return impl_->is_bytes(); }
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bool is_oneof() const { return impl_->is_oneof(); }
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bool is_inlined() const { return impl_->is_inlined(); }
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bool has_default_constexpr_constructor() const {
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return impl_->has_default_constexpr_constructor();
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}
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// Requirements: see FieldGeneratorBase for documentation
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bool RequiresArena(GeneratorFunction function) const {
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return impl_->RequiresArena(function);
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}
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// Prints private members needed to represent this field.
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//
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// These are placed inside the class definition.
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void GeneratePrivateMembers(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GeneratePrivateMembers(p);
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}
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// Prints static members needed to represent this field.
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//
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// These are placed inside the class definition.
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void GenerateStaticMembers(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateStaticMembers(p);
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}
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void GenerateMemberConstructor(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateMemberConstructor(p);
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}
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void GenerateMemberCopyConstructor(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateMemberCopyConstructor(p);
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}
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void GenerateOneofCopyConstruct(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateOneofCopyConstruct(p);
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}
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void GenerateMemberConstexprConstructor(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateMemberConstexprConstructor(p);
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}
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// Generates declarations for all of the accessor functions related to this
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// field.
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//
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// These are placed inside the class definition.
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void GenerateAccessorDeclarations(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateAccessorDeclarations(p);
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}
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// Generates inline definitions of accessor functions for this field.
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//
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// These are placed in namespace scope in the header after all class
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// definitions.
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void GenerateInlineAccessorDefinitions(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateInlineAccessorDefinitions(p);
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}
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// Generates definitions of accessors that aren't inlined.
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//
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// These are placed in namespace scope in the .cc file.
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void GenerateNonInlineAccessorDefinitions(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateNonInlineAccessorDefinitions(p);
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}
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// Generates statements which clear the field.
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//
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// This is used to define the clear_$name$() method.
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void GenerateClearingCode(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateClearingCode(p);
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}
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// Generates statements which clear the field as part of the Clear() method
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// for the whole message.
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//
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// For message types which have field presence bits,
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// MessageGenerator::GenerateClear will have already checked the presence
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// bits.
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void GenerateMessageClearingCode(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateMessageClearingCode(p);
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}
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// Generates statements which merge the contents of the field from the current
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// message to the target message, which is stored in the generated code
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// variable `from`.
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//
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// This is used to fill in the MergeFrom method for the whole message.
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//
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// Details of this usage can be found in message.cc under the
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// GenerateMergeFrom method.
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void GenerateMergingCode(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateMergingCode(p);
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}
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// Generates a copy constructor
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//
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// TODO: Document this properly.
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void GenerateCopyConstructorCode(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateCopyConstructorCode(p);
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}
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// Generates statements which swap this field and the corresponding field of
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// another message, which is stored in the generated code variable `other`.
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//
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// This is used to define the Swap method. Details of usage can be found in
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// message.cc under the GenerateSwap method.
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void GenerateSwappingCode(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateSwappingCode(p);
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}
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// Generates initialization code for private members declared by
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// GeneratePrivateMembers().
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//
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// These go into the message class's SharedCtor() method, invoked by each of
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// the generated constructors.
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void GenerateConstructorCode(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateConstructorCode(p);
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}
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// Generates any code that needs to go in the class's SharedDtor() method,
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// invoked by the destructor.
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void GenerateDestructorCode(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateDestructorCode(p);
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}
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// Generates a manual destructor invocation for use when the message is on an
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// arena.
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//
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// The code that this method generates will be executed inside a
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// shared-for-the-whole-message-class method registered with OwnDestructor().
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void GenerateArenaDestructorCode(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateArenaDestructorCode(p);
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}
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// Generates initialization code for private members declared by
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// GeneratePrivateMembers().
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//
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// These go into the SharedCtor's aggregate initialization of the _impl_
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// struct and must follow the syntax `decltype($field$){$default$}`.
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// Does not include `:` or `,` separators. Default values should be specified
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// here when possible.
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//
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// NOTE: We use `decltype($field$)` for both explicit construction and the
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// fact that it's self-documenting. Pre-C++17, copy elision isn't guaranteed
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// in aggregate initialization so a valid copy/move constructor must exist
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// (even though it's not used). Because of this, we need to comment out the
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// decltype and fallback to implicit construction.
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void GenerateAggregateInitializer(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateAggregateInitializer(p);
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}
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// Generates constinit initialization code for private members declared by
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// GeneratePrivateMembers().
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//
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// These go into the constexpr constructor's aggregate initialization of the
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// _impl_ struct and must follow the syntax `/*decltype($field$)*/{}` (see
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// above). Does not include `:` or `,` separators.
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void GenerateConstexprAggregateInitializer(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateConstexprAggregateInitializer(p);
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}
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// Generates copy initialization code for private members declared by
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// GeneratePrivateMembers().
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//
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// These go into the copy constructor's aggregate initialization of the _impl_
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// struct and must follow the syntax `decltype($field$){from.$field$}` (see
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// above). Does not include `:` or `,` separators.
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void GenerateCopyAggregateInitializer(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateCopyAggregateInitializer(p);
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}
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// Generates statements to serialize this field directly to the array
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// `target`, which are placed within the message's
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// SerializeWithCachedSizesToArray() method.
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//
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// This must also advance `target` past the written bytes.
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void GenerateSerializeWithCachedSizesToArray(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateSerializeWithCachedSizesToArray(p);
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}
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// Generates statements to compute the serialized size of this field, which
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// are placed in the message's ByteSize() method.
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void GenerateByteSize(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateByteSize(p);
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}
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// Generates lines to call IsInitialized() for eligible message fields. Non
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// message fields won't need to override this function.
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void GenerateIsInitialized(io::Printer* p) const {
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auto vars = PushVarsForCall(p);
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impl_->GenerateIsInitialized(p);
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}
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bool NeedsIsInitialized() const { return impl_->NeedsIsInitialized(); }
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// TODO: Document this properly.
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bool IsInlined() const { return impl_->IsInlined(); }
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// TODO: Document this properly.
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ArenaDtorNeeds NeedsArenaDestructor() const {
|
|
return impl_->NeedsArenaDestructor();
|
|
}
|
|
|
|
private:
|
|
friend class FieldGeneratorTable;
|
|
FieldGenerator(const FieldDescriptor* field, const Options& options,
|
|
MessageSCCAnalyzer* scc_analyzer,
|
|
absl::optional<uint32_t> hasbit_index,
|
|
absl::optional<uint32_t> inlined_string_index);
|
|
|
|
std::unique_ptr<FieldGeneratorBase> impl_;
|
|
std::vector<io::Printer::Sub> field_vars_;
|
|
std::vector<io::Printer::Sub> tracker_vars_;
|
|
std::vector<io::Printer::Sub> per_generator_vars_;
|
|
};
|
|
|
|
// Convenience class which constructs FieldGeneratorBases for a Descriptor.
|
|
class FieldGeneratorTable {
|
|
public:
|
|
explicit FieldGeneratorTable(const Descriptor* descriptor)
|
|
: descriptor_(descriptor) {}
|
|
|
|
FieldGeneratorTable(const FieldGeneratorTable&) = delete;
|
|
FieldGeneratorTable& operator=(const FieldGeneratorTable&) = delete;
|
|
|
|
void Build(const Options& options, MessageSCCAnalyzer* scc_analyzer,
|
|
absl::Span<const int32_t> has_bit_indices,
|
|
absl::Span<const int32_t> inlined_string_indices);
|
|
|
|
const FieldGenerator& get(const FieldDescriptor* field) const {
|
|
ABSL_CHECK_EQ(field->containing_type(), descriptor_);
|
|
ABSL_DCHECK_GE(field->index(), 0);
|
|
return fields_[static_cast<size_t>(field->index())];
|
|
}
|
|
|
|
private:
|
|
const Descriptor* descriptor_;
|
|
std::vector<FieldGenerator> fields_;
|
|
};
|
|
|
|
// Returns variables common to all fields.
|
|
//
|
|
// TODO: Make this function .cc-private.
|
|
std::vector<io::Printer::Sub> FieldVars(const FieldDescriptor* field,
|
|
const Options& opts);
|
|
} // namespace cpp
|
|
} // namespace compiler
|
|
} // namespace protobuf
|
|
} // namespace google
|
|
|
|
#endif // GOOGLE_PROTOBUF_COMPILER_CPP_FIELD_H__
|