object-introspection/types

Container Type Definition Format

This document describes the format of the container definition files contained in this directory.

info

• type_name

  The fully-qualified name of the container type. This is used to match against the names of types contained in an executable's debug information.

• ctype

  A reference to the enum ContainerTypeEnum in OI's source code.

• header

  The name of the C++ header file in which this container is defined.

• stub_template_params

  The indexes of template parameters which do not represent types stored within this container. These parameters will not be recursed into and measured by OI.

• underlying_container_index

  Only used for container adapters. Points OI to the template parameter representing the underlying container to be measured.

codegen

• decl

  C++ code for the declaration of a getSizeType function for this container.

• func

  C++ code for the definition of a getSizeType function for this container.

• handler

  C++ code for the definition of a TypeHandler class for this container. See further down for a description.

Changes introduced with Typed Data Segment

• decl and func fields are ignored when using -ftyped-data-segment and the handler field is used instead.

TypeHandler Classes

A TypeHandler class describes both what a type will write into the data segment and how to write it. It consists of two major parts:

• using type = ...; - describe what it will write into the data segment.
• static types::st::Unit<DB> getSizeType(...) - a function which takes a const reference to a container and a ::type by value and fills in the type.

Example:

template <typename DB, typename T0>
struct TypeHandler<DB, std::string<T0>> {
  using type =
      types::st::Pair<DB, types::st::VarInt<DB>, types::st::VarInt<DB>>;

  static types::st::Unit<DB> getSizeType(
      const std::string<T0> & container,
      typename TypeHandler<DB, std::string<T0>>::type returnArg) {
    bool sso = ((uintptr_t)container.data() <
                (uintptr_t)(&container + sizeof(std::string<T0>))) &&
               ((uintptr_t)container.data() >= (uintptr_t)&container);

    return returnArg.write(container.capacity()).write(container.size());
  }
};

Changes introduced with TypeGraph

• typeName and matcher fields have been merged into the single field type_name.
• ns namespace definition is no longer required.
• underlyingContainerIndex renamed to underlying_container_index
• The options for measuring / stubbing / removing template parameters have been reworked:
  • By default all parameters are now measured. This includes the tail parameters in a variadic template.
  • There is one option to specify template parameters which should not be measured: stub_template_params. The type graph code will automatically determine what type of stubbing to apply to each parameter in this list.

Deprecated Options

• numTemplateParams

  The first numTemplateParams template parameters for this container represent the types for the data we want to process. If this is not set, use all a container's template parameters. All of a container's parameters will still be enumerated and output in CodeGen, regardless of this setting.

• allocatorIndex

  Index of a template parameter representing an allocator. It will be not be used when CodeGenning this container.

• replaceTemplateParamIndex

  Indexes of template parameters to be stubbed out, i.e. replaced with dummy structs of a given size. Used for custom hashers and comparers.