Files
allwpilib/wpilibc/shared/include/SmartDashboard/SendableChooser.inc
Tyler Veness e4a918850f Fixed return value of SendableChooser<T>::GetSelected() for non-pointer T's (#512)
Fixed undefined behavior when returning nullptr for T = std::string. Also added
support for smart pointers. T = std::unique_ptr<U> returns U* and T =
std::shared_ptr<U> returns std::weak_ptr<U>.
2017-06-30 15:37:22 -07:00

107 lines
3.1 KiB
C++

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2011-2017. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
/*----------------------------------------------------------------------------*/
#pragma once
#include <algorithm>
#include <memory>
#include <string>
#include <utility>
#include <vector>
namespace frc {
/**
* Adds the given object to the list of options.
*
* On the {@link SmartDashboard} on the desktop, the object will appear as the
* given name.
*
* @param name the name of the option
* @param object the option
*/
template <class T>
void SendableChooser<T>::AddObject(llvm::StringRef name, T object) {
m_choices[name] = std::move(object);
}
/**
* Add the given object to the list of options and marks it as the default.
*
* Functionally, this is very close to {@link SendableChooser#AddObject(const
* char *name, void *object) AddObject(...)} except that it will use this as
* the default option if none other is explicitly selected.
*
* @param name the name of the option
* @param object the option
*/
template <class T>
void SendableChooser<T>::AddDefault(llvm::StringRef name, T object) {
m_defaultChoice = name;
AddObject(name, std::move(object));
}
/**
* Returns a copy of the selected option (a raw pointer U* if T =
* std::unique_ptr<U> or a std::weak_ptr<U> if T = std::shared_ptr<U>).
*
* If there is none selected, it will return the default. If there is none
* selected and no default, then it will return a value-initialized instance.
* For integer types, this is 0. For container types like std::string, this is
* an empty string.
*
* @return the option selected
*/
template <class T>
auto SendableChooser<T>::GetSelected()
-> decltype(_unwrap_smart_ptr(m_choices[""])) {
std::string selected = m_table->GetString(kSelected, m_defaultChoice);
if (selected == "") {
return decltype(_unwrap_smart_ptr(m_choices[""])){};
} else {
return _unwrap_smart_ptr(m_choices[selected]);
}
}
template <class T>
void SendableChooser<T>::InitTable(std::shared_ptr<ITable> subtable) {
std::vector<std::string> keys;
m_table = subtable;
if (m_table != nullptr) {
for (const auto& choice : m_choices) {
keys.push_back(choice.first());
}
// Unlike std::map, llvm::StringMap elements are not sorted
std::sort(keys.begin(), keys.end());
m_table->PutValue(kOptions, nt::Value::MakeStringArray(std::move(keys)));
m_table->PutString(kDefault, m_defaultChoice);
}
}
template <class T>
template <class U>
U SendableChooser<T>::_unwrap_smart_ptr(const U& value) {
return value;
}
template <class T>
template <class U>
U* SendableChooser<T>::_unwrap_smart_ptr(const std::unique_ptr<U>& value) {
return value.get();
}
template <class T>
template <class U>
std::weak_ptr<U> SendableChooser<T>::_unwrap_smart_ptr(
const std::shared_ptr<U>& value) {
return value;
}
} // namespace frc