You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
214 lines
7.6 KiB
214 lines
7.6 KiB
//
|
|
// Copyright 2019 The Abseil Authors.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// https://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
#ifndef ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
|
|
#define ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
|
|
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
|
|
#include <memory>
|
|
#include <string>
|
|
#include <typeinfo>
|
|
|
|
#include "absl/base/config.h"
|
|
#include "absl/base/macros.h"
|
|
#include "absl/flags/config.h"
|
|
#include "absl/flags/marshalling.h"
|
|
#include "absl/strings/string_view.h"
|
|
#include "absl/types/optional.h"
|
|
|
|
namespace absl {
|
|
ABSL_NAMESPACE_BEGIN
|
|
namespace flags_internal {
|
|
|
|
// An alias for flag static type id. Values of type identify the flag value type
|
|
// simialarly to typeid(T), but without relying on RTTI being available. In most
|
|
// cases this id is enough to uniquely identify the flag's value type. In a few
|
|
// cases we'll have to resort to using actual RTTI implementation if it is
|
|
// available.
|
|
using FlagStaticTypeId = void* (*)();
|
|
|
|
// Address of this function template is used in current implementation as a flag
|
|
// static type id.
|
|
template <typename T>
|
|
void* FlagStaticTypeIdGen() {
|
|
#if defined(ABSL_FLAGS_INTERNAL_HAS_RTTI)
|
|
return const_cast<std::type_info*>(&typeid(T));
|
|
#else
|
|
return nullptr;
|
|
#endif
|
|
}
|
|
|
|
// Options that control SetCommandLineOptionWithMode.
|
|
enum FlagSettingMode {
|
|
// update the flag's value unconditionally (can call this multiple times).
|
|
SET_FLAGS_VALUE,
|
|
// update the flag's value, but *only if* it has not yet been updated
|
|
// with SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef".
|
|
SET_FLAG_IF_DEFAULT,
|
|
// set the flag's default value to this. If the flag has not been updated
|
|
// yet (via SET_FLAGS_VALUE, SET_FLAG_IF_DEFAULT, or "FLAGS_xxx = nondef")
|
|
// change the flag's current value to the new default value as well.
|
|
SET_FLAGS_DEFAULT
|
|
};
|
|
|
|
// Options that control SetFromString: Source of a value.
|
|
enum ValueSource {
|
|
// Flag is being set by value specified on a command line.
|
|
kCommandLine,
|
|
// Flag is being set by value specified in the code.
|
|
kProgrammaticChange,
|
|
};
|
|
|
|
// Handle to FlagState objects. Specific flag state objects will restore state
|
|
// of a flag produced this flag state from method CommandLineFlag::SaveState().
|
|
class FlagStateInterface {
|
|
public:
|
|
virtual ~FlagStateInterface() {}
|
|
|
|
// Restores the flag originated this object to the saved state.
|
|
virtual void Restore() const = 0;
|
|
};
|
|
|
|
// Holds all information for a flag.
|
|
class CommandLineFlag {
|
|
public:
|
|
constexpr CommandLineFlag() = default;
|
|
|
|
// Not copyable/assignable.
|
|
CommandLineFlag(const CommandLineFlag&) = delete;
|
|
CommandLineFlag& operator=(const CommandLineFlag&) = delete;
|
|
|
|
// Non-polymorphic access methods.
|
|
|
|
// Return true iff flag has type T.
|
|
template <typename T>
|
|
inline bool IsOfType() const {
|
|
return TypeId() == &flags_internal::FlagStaticTypeIdGen<T>;
|
|
}
|
|
|
|
// Attempts to retrieve the flag value. Returns value on success,
|
|
// absl::nullopt otherwise.
|
|
template <typename T>
|
|
absl::optional<T> Get() const {
|
|
if (IsRetired() || !IsOfType<T>()) {
|
|
return absl::nullopt;
|
|
}
|
|
|
|
// Implementation notes:
|
|
//
|
|
// We are wrapping a union around the value of `T` to serve three purposes:
|
|
//
|
|
// 1. `U.value` has correct size and alignment for a value of type `T`
|
|
// 2. The `U.value` constructor is not invoked since U's constructor does
|
|
// not do it explicitly.
|
|
// 3. The `U.value` destructor is invoked since U's destructor does it
|
|
// explicitly. This makes `U` a kind of RAII wrapper around non default
|
|
// constructible value of T, which is destructed when we leave the
|
|
// scope. We do need to destroy U.value, which is constructed by
|
|
// CommandLineFlag::Read even though we left it in a moved-from state
|
|
// after std::move.
|
|
//
|
|
// All of this serves to avoid requiring `T` being default constructible.
|
|
union U {
|
|
T value;
|
|
U() {}
|
|
~U() { value.~T(); }
|
|
};
|
|
U u;
|
|
|
|
Read(&u.value);
|
|
return std::move(u.value);
|
|
}
|
|
|
|
// Polymorphic access methods
|
|
|
|
// Returns name of this flag.
|
|
virtual absl::string_view Name() const = 0;
|
|
// Returns name of the file where this flag is defined.
|
|
virtual std::string Filename() const = 0;
|
|
// Returns name of the flag's value type for some built-in types or empty
|
|
// std::string.
|
|
virtual absl::string_view Typename() const = 0;
|
|
// Returns help message associated with this flag.
|
|
virtual std::string Help() const = 0;
|
|
// Returns true iff this object corresponds to retired flag.
|
|
virtual bool IsRetired() const { return false; }
|
|
// Returns true iff this is a handle to an Abseil Flag.
|
|
virtual bool IsAbseilFlag() const { return true; }
|
|
// Returns id of the flag's value type.
|
|
virtual FlagStaticTypeId TypeId() const = 0;
|
|
virtual bool IsModified() const = 0;
|
|
virtual bool IsSpecifiedOnCommandLine() const = 0;
|
|
virtual std::string DefaultValue() const = 0;
|
|
virtual std::string CurrentValue() const = 0;
|
|
|
|
// Interfaces to operate on validators.
|
|
virtual bool ValidateInputValue(absl::string_view value) const = 0;
|
|
|
|
// Interface to save flag to some persistent state. Returns current flag state
|
|
// or nullptr if flag does not support saving and restoring a state.
|
|
virtual std::unique_ptr<FlagStateInterface> SaveState() = 0;
|
|
|
|
// Sets the value of the flag based on specified std::string `value`. If the flag
|
|
// was successfully set to new value, it returns true. Otherwise, sets `error`
|
|
// to indicate the error, leaves the flag unchanged, and returns false. There
|
|
// are three ways to set the flag's value:
|
|
// * Update the current flag value
|
|
// * Update the flag's default value
|
|
// * Update the current flag value if it was never set before
|
|
// The mode is selected based on `set_mode` parameter.
|
|
virtual bool SetFromString(absl::string_view value,
|
|
flags_internal::FlagSettingMode set_mode,
|
|
flags_internal::ValueSource source,
|
|
std::string* error) = 0;
|
|
|
|
// Checks that flags default value can be converted to std::string and back to the
|
|
// flag's value type.
|
|
virtual void CheckDefaultValueParsingRoundtrip() const = 0;
|
|
|
|
protected:
|
|
~CommandLineFlag() = default;
|
|
|
|
private:
|
|
// Copy-construct a new value of the flag's type in a memory referenced by
|
|
// the dst based on the current flag's value.
|
|
virtual void Read(void* dst) const = 0;
|
|
};
|
|
|
|
// This macro is the "source of truth" for the list of supported flag built-in
|
|
// types.
|
|
#define ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(A) \
|
|
A(bool) \
|
|
A(short) \
|
|
A(unsigned short) \
|
|
A(int) \
|
|
A(unsigned int) \
|
|
A(long) \
|
|
A(unsigned long) \
|
|
A(long long) \
|
|
A(unsigned long long) \
|
|
A(double) \
|
|
A(float) \
|
|
A(std::string) \
|
|
A(std::vector<std::string>)
|
|
|
|
} // namespace flags_internal
|
|
ABSL_NAMESPACE_END
|
|
} // namespace absl
|
|
|
|
#endif // ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
|