cpp_enum.cc

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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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// modification, are permitted provided that the following conditions are
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//
//     * Redistributions of source code must retain the above copyright
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// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
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// contributors may be used to endorse or promote products derived from
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//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
// Author: kenton@google.com (Kenton Varda)
//  Based on original Protocol Buffers design by
//  Sanjay Ghemawat, Jeff Dean, and others.
 
#include <map>
 
#include <google/protobuf/compiler/cpp/cpp_enum.h>
#include <google/protobuf/compiler/cpp/cpp_helpers.h>
#include <google/protobuf/io/printer.h>
#include <google/protobuf/stubs/strutil.h>
 
namespace google {
namespace protobuf {
namespace compiler {
namespace cpp {
 
namespace {
// The GOOGLE_ARRAYSIZE constant is the max enum value plus 1. If the max enum value
// is kint32max, GOOGLE_ARRAYSIZE will overflow. In such cases we should omit the
// generation of the GOOGLE_ARRAYSIZE constant.
bool ShouldGenerateArraySize(const EnumDescriptor* descriptor) {
  int32 max_value = descriptor->value(0)->number();
  for (int i = 0; i < descriptor->value_count(); i++) {
    if (descriptor->value(i)->number() > max_value) {
      max_value = descriptor->value(i)->number();
    }
  }
  return max_value != kint32max;
}
 
// Returns the number of unique numeric enum values. This is less than
// descriptor->value_count() when there are aliased values.
int CountUniqueValues(const EnumDescriptor* descriptor) {
  std::set<int> values;
  for (int i = 0; i < descriptor->value_count(); ++i) {
    values.insert(descriptor->value(i)->number());
  }
  return values.size();
}
 
}  // namespace
 
EnumGenerator::EnumGenerator(const EnumDescriptor* descriptor,
                             const std::map<std::string, std::string>& vars,
                             const Options& options)
    : descriptor_(descriptor),
      classname_(ClassName(descriptor, false)),
      options_(options),
      generate_array_size_(ShouldGenerateArraySize(descriptor)),
      variables_(vars) {
  variables_["classname"] = classname_;
  variables_["classtype"] = QualifiedClassName(descriptor_, options);
  variables_["short_name"] = descriptor_->name();
  variables_["nested_name"] = descriptor_->name();
  variables_["resolved_name"] = ResolveKeyword(descriptor_->name());
  variables_["prefix"] =
      (descriptor_->containing_type() == NULL) ? "" : classname_ + "_";
}
 
EnumGenerator::~EnumGenerator() {}
 
void EnumGenerator::GenerateDefinition(io::Printer* printer) {
  Formatter format(printer, variables_);
  format("enum ${1$$classname$$}$ : int {\n", descriptor_);
  format.Indent();
 
  const EnumValueDescriptor* min_value = descriptor_->value(0);
  const EnumValueDescriptor* max_value = descriptor_->value(0);
 
  for (int i = 0; i < descriptor_->value_count(); i++) {
    auto format_value = format;
    format_value.Set("name", EnumValueName(descriptor_->value(i)));
    // In C++, an value of -2147483648 gets interpreted as the negative of
    // 2147483648, and since 2147483648 can't fit in an integer, this produces a
    // compiler warning.  This works around that issue.
    format_value.Set("number", Int32ToString(descriptor_->value(i)->number()));
    format_value.Set(
        "deprecation",
        DeprecatedAttribute(options_,
                            descriptor_->value(i)->options().deprecated()));
 
    if (i > 0) format_value(",\n");
    format_value("${1$$prefix$$name$$}$ $deprecation$= $number$",
                 descriptor_->value(i));
 
    if (descriptor_->value(i)->number() < min_value->number()) {
      min_value = descriptor_->value(i);
    }
    if (descriptor_->value(i)->number() > max_value->number()) {
      max_value = descriptor_->value(i);
    }
  }
 
  if (descriptor_->file()->syntax() == FileDescriptor::SYNTAX_PROTO3) {
    // For new enum semantics: generate min and max sentinel values equal to
    // INT32_MIN and INT32_MAX
    if (descriptor_->value_count() > 0) format(",\n");
    format(
        "$classname$_$prefix$INT_MIN_SENTINEL_DO_NOT_USE_ = "
        "std::numeric_limits<$int32$>::min(),\n"
        "$classname$_$prefix$INT_MAX_SENTINEL_DO_NOT_USE_ = "
        "std::numeric_limits<$int32$>::max()");
  }
 
  format.Outdent();
  format("\n};\n");
 
  format(
      "$dllexport_decl $bool $classname$_IsValid(int value);\n"
      "constexpr $classname$ ${1$$prefix$$short_name$_MIN$}$ = "
      "$prefix$$2$;\n"
      "constexpr $classname$ ${1$$prefix$$short_name$_MAX$}$ = "
      "$prefix$$3$;\n",
      descriptor_, EnumValueName(min_value), EnumValueName(max_value));
 
  if (generate_array_size_) {
    format(
        "constexpr int ${1$$prefix$$short_name$_ARRAYSIZE$}$ = "
        "$prefix$$short_name$_MAX + 1;\n\n",
        descriptor_);
  }
 
  if (HasDescriptorMethods(descriptor_->file(), options_)) {
    format(
        "$dllexport_decl $const ::$proto_ns$::EnumDescriptor* "
        "$classname$_descriptor();\n");
  }
 
  // The _Name and _Parse functions. The lite implementation is table-based, so
  // we make sure to keep the tables hidden in the .cc file.
  if (!HasDescriptorMethods(descriptor_->file(), options_)) {
    format("const std::string& $classname$_Name($classname$ value);\n");
  }
  // The _Name() function accepts the enum type itself but also any integral
  // type.
  format(
      "template<typename T>\n"
      "inline const std::string& $classname$_Name(T enum_t_value) {\n"
      "  static_assert(::std::is_same<T, $classname$>::value ||\n"
      "    ::std::is_integral<T>::value,\n"
      "    \"Incorrect type passed to function $classname$_Name.\");\n");
  if (HasDescriptorMethods(descriptor_->file(), options_)) {
    format(
        "  return ::$proto_ns$::internal::NameOfEnum(\n"
        "    $classname$_descriptor(), enum_t_value);\n");
  } else {
    format(
        "  return $classname$_Name(static_cast<$classname$>(enum_t_value));\n");
  }
  format("}\n");
 
  if (HasDescriptorMethods(descriptor_->file(), options_)) {
    format(
        "inline bool $classname$_Parse(\n"
        "    const std::string& name, $classname$* value) {\n"
        "  return ::$proto_ns$::internal::ParseNamedEnum<$classname$>(\n"
        "    $classname$_descriptor(), name, value);\n"
        "}\n");
  } else {
    format(
        "bool $classname$_Parse(\n"
        "    const std::string& name, $classname$* value);\n");
  }
}
 
void EnumGenerator::GenerateGetEnumDescriptorSpecializations(
    io::Printer* printer) {
  Formatter format(printer, variables_);
  format(
      "template <> struct is_proto_enum< $classtype$> : ::std::true_type "
      "{};\n");
  if (HasDescriptorMethods(descriptor_->file(), options_)) {
    format(
        "template <>\n"
        "inline const EnumDescriptor* GetEnumDescriptor< $classtype$>() {\n"
        "  return $classtype$_descriptor();\n"
        "}\n");
  }
}
 
void EnumGenerator::GenerateSymbolImports(io::Printer* printer) const {
  Formatter format(printer, variables_);
  format("typedef $classname$ $resolved_name$;\n");
 
  for (int j = 0; j < descriptor_->value_count(); j++) {
    std::string deprecated_attr = DeprecatedAttribute(
        options_, descriptor_->value(j)->options().deprecated());
    format(
        "$1$static constexpr $resolved_name$ ${2$$3$$}$ =\n"
        "  $classname$_$3$;\n",
        deprecated_attr, descriptor_->value(j),
        EnumValueName(descriptor_->value(j)));
  }
 
  format(
      "static inline bool $nested_name$_IsValid(int value) {\n"
      "  return $classname$_IsValid(value);\n"
      "}\n"
      "static constexpr $resolved_name$ ${1$$nested_name$_MIN$}$ =\n"
      "  $classname$_$nested_name$_MIN;\n"
      "static constexpr $resolved_name$ ${1$$nested_name$_MAX$}$ =\n"
      "  $classname$_$nested_name$_MAX;\n",
      descriptor_);
  if (generate_array_size_) {
    format(
        "static constexpr int ${1$$nested_name$_ARRAYSIZE$}$ =\n"
        "  $classname$_$nested_name$_ARRAYSIZE;\n",
        descriptor_);
  }
 
  if (HasDescriptorMethods(descriptor_->file(), options_)) {
    format(
        "static inline const ::$proto_ns$::EnumDescriptor*\n"
        "$nested_name$_descriptor() {\n"
        "  return $classname$_descriptor();\n"
        "}\n");
  }
 
  format(
      "template<typename T>\n"
      "static inline const std::string& $nested_name$_Name(T enum_t_value) {\n"
      "  static_assert(::std::is_same<T, $resolved_name$>::value ||\n"
      "    ::std::is_integral<T>::value,\n"
      "    \"Incorrect type passed to function $nested_name$_Name.\");\n"
      "  return $classname$_Name(enum_t_value);\n"
      "}\n");
  format(
      "static inline bool $nested_name$_Parse(const std::string& name,\n"
      "    $resolved_name$* value) {\n"
      "  return $classname$_Parse(name, value);\n"
      "}\n");
}
 
void EnumGenerator::GenerateMethods(int idx, io::Printer* printer) {
  Formatter format(printer, variables_);
  if (HasDescriptorMethods(descriptor_->file(), options_)) {
    format(
        "const ::$proto_ns$::EnumDescriptor* $classname$_descriptor() {\n"
        "  ::$proto_ns$::internal::AssignDescriptors(&$desc_table$);\n"
        "  return $file_level_enum_descriptors$[$1$];\n"
        "}\n",
        idx);
  }
 
  format(
      "bool $classname$_IsValid(int value) {\n"
      "  switch (value) {\n");
 
  // Multiple values may have the same number.  Make sure we only cover
  // each number once by first constructing a set containing all valid
  // numbers, then printing a case statement for each element.
 
  std::set<int> numbers;
  for (int j = 0; j < descriptor_->value_count(); j++) {
    const EnumValueDescriptor* value = descriptor_->value(j);
    numbers.insert(value->number());
  }
 
  for (std::set<int>::iterator iter = numbers.begin(); iter != numbers.end();
       ++iter) {
    format("    case $1$:\n", Int32ToString(*iter));
  }
 
  format(
      "      return true;\n"
      "    default:\n"
      "      return false;\n"
      "  }\n"
      "}\n"
      "\n");
 
  if (!HasDescriptorMethods(descriptor_->file(), options_)) {
    // In lite mode (where descriptors are unavailable), we generate separate
    // tables for mapping between enum names and numbers. The _entries table
    // contains the bulk of the data and is sorted by name, while
    // _entries_by_number is sorted by number and just contains pointers into
    // _entries. The two tables allow mapping from name to number and number to
    // name, both in time logarithmic in the number of enum entries. This could
    // probably be made faster, but for now the tables are intended to be simple
    // and compact.
    //
    // Enums with allow_alias = true support multiple entries with the same
    // numerical value. In cases where there are multiple names for the same
    // number, we treat the first name appearing in the .proto file as the
    // canonical one.
    std::map<std::string, int> name_to_number;
    std::map<int, std::string> number_to_canonical_name;
    for (int i = 0; i < descriptor_->value_count(); i++) {
      const EnumValueDescriptor* value = descriptor_->value(i);
      name_to_number.emplace(value->name(), value->number());
      // The same number may appear with multiple names, so we use emplace() to
      // let the first name win.
      number_to_canonical_name.emplace(value->number(), value->name());
    }
 
    format(
        "static ::$proto_ns$::internal::ExplicitlyConstructed<std::string> "
        "$classname$_strings[$1$] = {};\n\n",
        CountUniqueValues(descriptor_));
 
    // We concatenate all the names for a given enum into one big string
    // literal. If instead we store an array of string literals, the linker
    // seems to put all enum strings for a given .proto file in the same
    // section, which hinders its ability to strip out unused strings.
    format("static const char $classname$_names[] =");
    for (const auto& p : name_to_number) {
      format("\n  \"$1$\"", p.first);
    }
    format(";\n\n");
 
    format(
        "static const ::$proto_ns$::internal::EnumEntry $classname$_entries[] "
        "= {\n");
    int i = 0;
    std::map<int, int> number_to_index;
    int data_index = 0;
    for (const auto& p : name_to_number) {
      format("  { {$classname$_names + $1$, $2$}, $3$ },\n", data_index,
             p.first.size(), p.second);
      if (number_to_canonical_name[p.second] == p.first) {
        number_to_index.emplace(p.second, i);
      }
      ++i;
      data_index += p.first.size();
    }
 
    format(
        "};\n"
        "\n"
        "static const int $classname$_entries_by_number[] = {\n");
    for (const auto& p : number_to_index) {
      format("  $1$, // $2$ -> $3$\n", p.second, p.first,
             number_to_canonical_name[p.first]);
    }
    format(
        "};\n"
        "\n");
 
    format(
        "const std::string& $classname$_Name(\n"
        "    $classname$ value) {\n"
        "  static const bool dummy =\n"
        "      ::$proto_ns$::internal::InitializeEnumStrings(\n"
        "          $classname$_entries,\n"
        "          $classname$_entries_by_number,\n"
        "          $1$, $classname$_strings);\n"
        "  (void) dummy;\n"
        "  int idx = ::$proto_ns$::internal::LookUpEnumName(\n"
        "      $classname$_entries,\n"
        "      $classname$_entries_by_number,\n"
        "      $1$, value);\n"
        "  return idx == -1 ? ::$proto_ns$::internal::GetEmptyString() :\n"
        "                     $classname$_strings[idx].get();\n"
        "}\n",
        CountUniqueValues(descriptor_));
    format(
        "bool $classname$_Parse(\n"
        "    const std::string& name, $classname$* value) {\n"
        "  int int_value;\n"
        "  bool success = ::$proto_ns$::internal::LookUpEnumValue(\n"
        "      $classname$_entries, $1$, name, &int_value);\n"
        "  if (success) {\n"
        "    *value = static_cast<$classname$>(int_value);\n"
        "  }\n"
        "  return success;\n"
        "}\n",
        descriptor_->value_count());
  }
 
  if (descriptor_->containing_type() != NULL) {
    std::string parent = ClassName(descriptor_->containing_type(), false);
    // Before C++17, we must define the static constants which were
    // declared in the header, to give the linker a place to put them.
    // But pre-2015 MSVC++ insists that we not.
    format(
        "#if (__cplusplus < 201703) && "
        "(!defined(_MSC_VER) || _MSC_VER >= 1900)\n");
 
    for (int i = 0; i < descriptor_->value_count(); i++) {
      format("constexpr $classname$ $1$::$2$;\n", parent,
             EnumValueName(descriptor_->value(i)));
    }
    format(
        "constexpr $classname$ $1$::$nested_name$_MIN;\n"
        "constexpr $classname$ $1$::$nested_name$_MAX;\n",
        parent);
    if (generate_array_size_) {
      format("constexpr int $1$::$nested_name$_ARRAYSIZE;\n", parent);
    }
 
    format(
        "#endif  // (__cplusplus < 201703) && "
        "(!defined(_MSC_VER) || _MSC_VER >= 1900)\n");
  }
}
 
}  // namespace cpp
}  // namespace compiler
}  // namespace protobuf
}  // namespace google