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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef REMOTING_HOST_LINUX_GVARIANT_REF_H_
#define REMOTING_HOST_LINUX_GVARIANT_REF_H_
#include <glib-object.h>
#include <glib.h>
#include <glibconfig.h>
#include <algorithm>
#include <array>
#include <compare>
#include <concepts>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <iterator>
#include <map>
#include <optional>
#include <ranges>
#include <string>
#include <string_view>
#include <tuple>
#include <type_traits>
#include <utility>
#include <variant>
#include <vector>
#include "base/check.h"
#include "base/check_op.h"
#include "base/compiler_specific.h"
#include "base/location.h"
#include "base/strings/strcat.h"
#include "base/strings/stringprintf.h"
#include "base/types/expected.h"
#include "remoting/host/base/loggable.h"
#include "remoting/host/base/pointer_utils.h"
#include "remoting/host/linux/gvariant_type.h"
// Provides a scoped wrapper, GVariantRef, around a GLib Variant to handle
// reference counting, conversion to and from other C++ types, and additional
// convenience methods when the GVariant's type is statically known.
//
// A good familiarity with the GVariant type system is recommended to use or
// read this code: https://docs.gtk.org/glib/struct.VariantType.html
namespace remoting {
namespace gvariant {
// A GVariantRef is a wrapper around a GLib Variant that handles scoped
// reference counting and convenient, typesafe conversion between GVariants and
// standard types.
//
// GVariants are logically immutable once created, and this class's only data
// member is a reference-counted pointer. Thus, instances can be copied and
// passed around cheaply.
//
// Sample usage:
//
// Creating a GVariantRef:
//
// // Creates a GVariantRef with a compile-time type of "*" (can hold any
// // value) and initialize it with a value of type "as" (array of strings)
// // constructed from the provided span.
// GVariantRef<> variant =
// GVariantRef<>::From(base::span{{"Bob", "Sally", "Alice"}});
//
// If a type string is provided as a template argument, the GVariantRef may only
// hold values that match that type string, which may be indefinite. E.g., a
// GVariantRef<"s"> may only strings, while a GVariantRef<"{?*}"> may hold any
// dictionary entry. The type may be narrowed using TryFrom:
//
// GVariantRef<> variant = ...;
// // expectedVariant will be a base::expected with either the requested
// // GVariantRef or an error message suitable for logging.
// auto expectedVariant = GVariantRef<"as">::TryFrom(variant);
// if (expectedVariant.has_value()) {
// // expectedVariant.value() is guaranteed to be an array of strings
// // and can be iterated through, infalibly converted to a
// // std::vector<std::string>, passed to functions expected GVariantRef
// // arrays, et cetera.
// }
//
// Conversion can combine narrowing and converting from C++ types:
//
// std::tuple<GVariantRef<>> tuple = ...;
// auto expectedVariant = GVariantRef<"(s)">::TryFrom(tuple);
//
// Getting values from a GVariantRef:
//
// GVariantRef<> variant = ...;
// // Returns a base::expected with the value or an error message.
// auto value = result.TryInto<std::vector<std::string>>();
//
// If the requested conversion is valid for all values of the GVariantRef's
// static type, you can use Into instead to get the value directly:
//
// GVariantRef<"s"> variant = ...;
// std::string value = variant.Into<std::string>();
//
// Like TryFrom, TryInto can also be used to attempt to narrow a GVariantRef's
// static type, and can be combined with conversions to C++ types:
//
// GVariantRef<> variant = ...; // Compile-time type string is "*";
// // Value will be returned if variant's run-time type is a subtype of
// // "a(s*)". Otherwise, an error string will be returned.
// auto result2 = variant.TryInto<std::vector<GVariantRef<"(s*)">>>();
//
// If the GVariantRef is known to be a container (that is, it's static type is
// a boxed value, an array, a maybe value, a tuple, or a dictionary entry), it
// can be used with range-based for:
//
// GVariantRef<"a(iu)"> variant1 = ...;
// for (auto item : variant1) { /* item is a GVariantRef<"(iu)"> */}
// GVariantRef<"r"> variant2 = ...;
// for (auto item : variant1) { /* item is a GVariantRef<"*"> */}
//
// If it is known to be a container of a fixed size (boxed value, fixed-size
// tuple (not "r"), or dictionary entry), it can be used with structured
// binding:
//
// GVariantRef<"(uba{sv})"> variant = ...;
// // Yields GVariantRef<"u">, GVariantRef<"b">, and GVariantRef<"a{sv}">
// auto [first, second, third] = variant;
//
// For convenience, GVariantRefs known to be a dictionary type (the compile-time
// type string is a subtype of "a{?*}") provide a LookUp() method to find the
// first value with a matching key.
//
// GVariantRef<"a{is}"> variant = ...;
// std::optional<GVariantRef<"s">> value = variant.LookUp(5);
//
// Finally, values can be extracted from containers using Destructure() and
// TryDestructure(). Destructure requires a known fixed-size container, while
// TryDestructure checks if the GVariantRef holds a matching container at
// runtime.
//
// GVariantRef<"(ii(ssssv))"> variant = ...;
// std::uint32_t i1, i2;
// std::string s1, s2, s3, s4;
// GVariantRef<> v;
// // Inner containers can be unpacked by passing (possibly nested) tuples
// // of lvalue references.
// variant.Destructure(i1, i2, std::forward_as_tuple(s1, s2, s3, s4,
// std::tie(v)));
//
// GVariantRef<"mb"> variant = ...;
// bool b;
// // result will contain an error if the maybe value is unexpectedly empty.
// base::expected<void, Loggable> result = variant.TryDestructure(b);
//
// Access to the underlying GVariant pointer can be obtained via raw() and
// release(). A GVariantRef can be created from a raw GVariant pointer via
// Ref(), RefSink(), and Take().
//
// For convenience, the GVariantRef class is exported to the remoting namespace.
//
// This header provides conversions to and from the following types. Additional
// support for additional types can be added by providing an appropriate
// specialization of gvariant::Mapping<T>.
//
// Basic fixed types:
//
// bool (type code "b")
// std::uint8_t (type code "y")
// std::int16_t (type code "n")
// std::uint16_t (type code "q")
// std::int32_t (type code "i")
// std::uint32_t (type code "u")
// std::int64_t (type code "x")
// std::uint64_t (type code "t")
// double (type code "d")
//
// Strings:
//
// std::string (type code "s")
// const char * ([Try]From() only, type code "s")
// std::string_view ([Try]From() only, type code "s")
//
// Note: Strings must be valid UTF-8. For convenience, both From() and TryFrom()
// are provided. If the string (or all strings in an aggregate type) are
// known to be valid UTF-8, From() may be used. Otherwise TryFrom() should be
// used. Calling From() with a string containing invalid UTF-8 will
// result in a crash.
//
// Containers:
//
// std::optional<T> (type code "mT") - To use with From(), the type string of T
// must be definite. E.g., it may not contain an unboxed heterogeneous
// std::variant or unconstrained GVariantRef. Otherwise, TryFrom() must be
// used. Alternatively, GVariantRef::FilledMaybe can be used for indefinite
// types that will never actually be absent. Note that maybe values are not
// currently supported by D-Bus.
// std::vector<T> (type code "aT") - To use with From(), the type string of T
// must be definite. Otherwise, TryFrom() must be used.
// std::map<K, T> (type code "a{KT}") - To use with From(), the type string of K
// and T must be definite. Otherwise, TryFrom() must be used.
// std::pair<K, T> (type code "{KT}")
// std::ranges::range<T> ([Try]From() only, type code "aE" where
// E = std::ranges::range_value_t<T>) - The type string of T must be
// definite to use with From(). Otherwise, TryFrom() must be used.
// std::tuple<...> (type code "(...)")
// std::variant<...> (type code "S", where S is the narrowest common supertype
// of all of the variant alternatives) - Despite the name, when used with
// From(), the type will be the type of the active variant, not "v". If the
// type should be "v", use a gvariant::Boxed<std::variant<...>>. When used
// with [Try]Into(), each variant alternative will be
// tried in turn until one succeeds or all are exhausted. Similarly to
// From(), if the type in the GVariant is expected to be "v" rather than a
// concrete type, use with gvariant::Boxed. From() and TryFrom() are
// provided if all of the alternatives provide the respected method.
// TryInto() is provided if provided by any of the alternatives. Into() is
// provided if the GVariantRef at hand can be infallibly converted to any
// of the variant's alternatives. E.g., the following is valid:
//
// GVariantRef<"i"> gvariant = ...;
// auto v = gvariant.Into<std::variant<std::int32, bool>>();
//
// Special types:
//
// GVariantRef<C> (type code "C") - GVariantRef can itself be used with
// [Try]From() or [Try]Into(). This can be used to widen or narrow the
// type or to hold inner values as nested GVariants. Like with
// std::variant, the type of the GVariantRef is used directly. If the
// expected/desired type is "v", wrap it in a gvariant::Boxed.
// gvariant::Ignored ([Try]Into() only, type code "*") - Discard the value at
// this position instead of decoding it.
// decltype(std::ignore) - Same as gvariant::Ignored. Allows passing std::ignore
// to [Try]Destructure().
// gvariant::Boxed<T> (type code "v") - Wrapper for a value that appears boxed
// inside a nested variant, rather than directly. A Boxed<T> is definite
// regardless of whether the contained type is. Provides [Try]From() and
// [Try]Into() if the inner type provides them for GVariantRef<"*">.
// gvariant::FilledMaybe<T> (type code "mT") - Wrapper for a value that
// appears inside a maybe, but will always be present. Presence of
// [Try]From() and TryInto() mirror the inner type. Into() is never
// provided.
// gvariant::EmptyArrayOf<C> (type code "aC") - Represents an empty array of
// the type C, which should be an instance of GVariantRef::Type. C must be
// definite to use with [Try]From(). Into() is never provided; TryInto()
// must be used to check if the array is, in fact, empty.
// gvariant::ObjectPath (type code "o") - Wrapper around a std::string that
// contains a DBus object path.
// gvariant::ObjectPathCStr ([Try]From() only, type code "o") - An owned object
// path that can be used as a function parameter (somewhat analogous to a
// string_view) or to hold a compile-time-verified object path constant.
// gvariant::TypeSignature (type code "g") - Wrapper around a std::string
// that contains a DBus type signature.
// gvariant::TypeSignatureCStr ([Try]From() only, type code "g") - An owned type
// signature that can be used as a function parameter (somewhat analogous to
// a string_view) or to hold a compile-time-verified type signature
// constant.
//
// Convenience functions:
//
// GVariantFrom(value) - Like GVariantRef<C>::From(), but infers C from value's
// type.
// gvariant::BoxedRef(value) - Returns a gvariant::Boxed that holds a const
// reference to value. (Whereas Boxed{value} would hold a copy of value.)
// gvariant::FilledMaybeRef(value) - Returns a gvariant::FilledMaybe that holds
// a const reference to value. (Whereas FilledMaybe{value} would hold a copy
// of value.)
template <Type C = Type("*")>
class GVariantRef;
// A struct specialized for each type supporting conversion to or from a
// GVariant.
//
// All specializations must provide a kType field, which should be in the form
// of a static constexpr Type. If the exact type can only be determined at
// runtime, an indefinite type can be used (e.g., "*").
//
// static constexpr Type kType{"i"};
//
// A given type may support conversion to a GVariant, from a GVariant, or
// both. An example of a type that only supports conversion to a GVariant is
// a C-style string (const char *). An example of a type that only supports
// conversion from a GVariant is GVariantRef::Ignored.
//
// To support conversion to a GVariant, the specialization should provide a
// static From or TryFrom method that takes a value of the type and returns a
// GVariantRef<kType>, e.g.,
//
// static GVariantRef<kType> From(const T&);
// static base::expected<GVariantRef<kType>, Loggable> TryFrom(const T&);
//
// Usually a specialization will provide one or the other.
//
// To support conversion from a GVariant, the specialization should provide a
// static Into or TryInto method that takes a GVariantRef<kType> and returns a
// value of the type, e.g.,
//
// static T Into(const GVariantRef<kType>&);
// static base::expected<T, Loggable> TryInto(const GVariantRef<kType>&);
//
// Usually a specialization will provide one or the other, with one exception:
// In the event that infallible conversion is possible for only some subtypes of
// kType, Into may be specified only for those subtypes. In that case, TryInto
// must also be specified. E.g., if a conversion can take an int or a string,
// the definition might look like this:
//
// static constexpr Type kType{"?"};
// static base::expected<T, Loggable> TryInto(const GVariantRef<kType>&);
// static T Into(const GVariantRef<"i">&);
// static T Into(const GVariantRef<"s">&);
//
// In the event a Try* conversion fails, the method should return an error
// string suitable for inclusion in a log message.
template <typename T>
struct Mapping;
// Common members of all GVariantRefs.
class GVariantBase {
public:
// Allows creating an owned reference given a reference to GVariantBase.
explicit operator GVariantRef<>() const;
// Returns the inner GVariant reference without incrementing the count. It is
// the caller's responsibility to increment the ref count if it is to be held
// longer than the containing remoting::GVariant instance. Otherwise, the
// caller should not call unref on it.
GVariant* raw() const;
// Takes owneriship of the inner GVariant, leaving this in a moved-from state.
// It is the caller's responsibility to call unref when they are done with it.
[[nodiscard]] GVariant* release() &&;
// Returns the type of the value currently held in the GVariant. Will always
// be definite.
Type<> GetType() const;
friend bool operator==(const GVariantBase& lhs, const GVariantBase& rhs);
protected:
using GVariantPtr = CRefCounted<GVariant,
g_variant_ref,
g_variant_unref,
g_variant_take_ref,
g_variant_ref_sink>;
GVariantBase();
explicit GVariantBase(GVariantPtr variant);
GVariantBase(const GVariantBase& other);
GVariantBase(GVariantBase&& other);
GVariantBase& operator=(const GVariantBase& other);
GVariantBase& operator=(GVariantBase&& other);
~GVariantBase();
private:
GVariantPtr variant_;
};
bool operator==(const GVariantBase& lhs, const GVariantBase& rhs);
template <Type C>
class GVariantRef : public GVariantBase {
public:
static constexpr auto kType = C;
// Default constructor constructs an empty GVariantRef in the same state as
// one that has been moved from. No operations are valid until a value has
// been assigned.
GVariantRef() = default;
// Copyable and movable. Copies are cheap, only bumping the reference count.
// The only valid operations for a moved-from instance are dropping it and
// assigning a new value.
GVariantRef(const GVariantRef& other) = default;
GVariantRef(GVariantRef&& other) = default;
GVariantRef& operator=(const GVariantRef& other) = default;
GVariantRef& operator=(GVariantRef&& other) = default;
~GVariantRef() = default;
// Allow implicit conversion from subtype to supertype.
template <Type D>
// NOLINTNEXTLINE(google-explicit-constructor)
GVariantRef(const GVariantRef<D>& other)
requires(D.IsSubtypeOf(C));
template <Type D>
// NOLINTNEXTLINE(google-explicit-constructor)
GVariantRef(GVariantRef<D>&& other)
requires(D.IsSubtypeOf(C));
// Type conversions
// Constructs a new GVariantRef from the provided value.
template <typename T>
static GVariantRef From(const T& value)
requires(Mapping<T>::kType.IsSubtypeOf(C) &&
requires { Mapping<T>::From(value); });
// Constructs a new GVariantRef from the provided value, if possible.
template <typename T>
static base::expected<GVariantRef, Loggable> TryFrom(const T& value)
requires(Mapping<T>::kType.HasCommonTypeWith(C) &&
(requires { Mapping<T>::TryFrom(value); } ||
requires { Mapping<T>::From(value); }));
// Builds a value of the provided type from the contents of the GVariant.
// Calls will only compile if they are guaranteed to succeed at runtime.
template <typename T>
T Into() const
requires(C.IsSubtypeOf(Mapping<T>::kType) &&
requires { Mapping<T>::Into(*this); });
// Builds a value of the provided type from the contents of the GVariant, if
// possible. Fails to compile if the conversion can statically be determined
// never to succeed.
template <typename T>
base::expected<T, Loggable> TryInto() const
requires(C.HasCommonTypeWith(Mapping<T>::kType) &&
(requires(GVariantRef<Mapping<T>::kType> v) {
Mapping<T>::TryInto(v);
} ||
requires(GVariantRef<Mapping<T>::kType> v) {
Mapping<T>::Into(v);
}));
// Unpacks a container GVariant into lvalue references. The GVariant must be a
// boxed value, a tuple, or a dictionary entry. Each argument must be a lvalue
// reference or a tuple to unpack a nested container. Each tuple should
// similarly consist of lvalue references and tuples. std::tie and
// std::forward_as_tuple can be useful for constructing such tuples. Calls to
// Destructure will only compile if it can be guaranteed at compile time that
// the operation will succeed.
template <typename... Types>
void Destructure(Types&&... refs) const;
// As above, but allows conversions that could fail at runtime. The GVariant
// must be a boxed value, a maybe value, a tuple, an array, or a dictionary
// entry. If the types or number of values don't match at runtime, an error
// message will be returned. In this case, the reference lvalues will be in an
// indeterminate state, as some values may have been read prior to the error
// occurring.
template <typename... Types>
base::expected<void, Loggable> TryDestructure(Types&&... refs) const;
// Iterate through the values of a container GVariant. The value type will be
// GVariant<TypeBase::ContainedType(C)>.
auto begin() const
requires(C.IsContainer());
auto end() const
requires(C.IsContainer());
std::size_t size() const
requires(C.IsContainer());
// Get the Ith element from a fixed-size container GVariant. Specializations
// of std::tuple_size and std::tuple_element are also provided to make fixed-
// size container GVariants tuple-like.
template <std::size_t I>
auto get() const
requires(C.IsFixedSizeContainer());
// Look up the provided key in a dictionary GVariant. The provided argument
// must be convertible to the key type via TryFrom. Returns a
// std::optional<GVariantRef<[value type]>> containing the found value, or
// nullopt if the key was not found. Note that this performs a linear search
// through the dictionary. If the dictionary is large and many lookups will be
// performed, it might be more efficient to convert to a std::map or another
// datastructure first.
template <typename T>
auto LookUp(const T& key)
requires(C.IsSubtypeOf(Type("a{?*}")) && requires {
decltype((*begin()).template get<0>())::TryFrom(key);
});
// Access the contained string without copying. C must be "s", "o", or "g".
std::string_view string_view() const
requires(C.IsStringType());
// Access the contained string without copying. C must be "s", "o", or "g".
const char* c_string() const
requires(C.IsStringType());
// Create from a raw GVariant*. Can only be used with GVariantRef<Type("*")>.
// To get a narrower GVariantRef, first create one with "*" and then use
// TryInto (or TryFrom) to convert to the narrower type.
// Takes ownership of the reference. If it is floating, it will be sunk. May
// not be null.
//
// This is the right method to call with a floating or caller-owned
// GVariant* when one wants to pass ownership to the new GVariantRef. Most
// GLib functions returning a GVariant* will return either a floating
// reference (e.g., `g_variant_new`) or a caller owned reference (e.g.,
// `get_child_value`), making their return value suitable to be passed to this
// method (after checking for null, if the function is falible).
static GVariantRef Take(GVariant* variant)
requires(C == Type("*"));
// Takes a new reference unconditionally. If object is floating, it will
// remain so. May not be null.
//
// This is the right method to call with a borrowed GVariant* (such as is
// returned by `raw()` or might be owned by a different class/struct) or a
// caller-owned GVariant* of which the caller wants to maintain ownership.
static GVariantRef Ref(GVariant* variant)
requires(C == Type("*"));
// If the reference count is floating, takes ownership and sinks it.
// Otherwise, takes a new reference. May not be null.
//
// This is usually the right method to call with a GVariant* that was passed
// into the caller as an argument. That gives the caller's caller the
// flexibility to pass in either a newly-constructed GVariant (in which case
// the reference will be floating, and GVariantRef will take ownership) or an
// existing GVariant* (in which case GVariantRef will take its own reference).
static GVariantRef RefSink(GVariant* variant)
requires(C == Type("*"));
// Same as above, but can be used with any GVariantRef type. The caller must
// ensure the passed pointer is actually of the appropriate type. Passing a
// pointer that does not match C can result in undefined behavior.
static GVariantRef TakeUnchecked(GVariant* variant);
static GVariantRef RefUnchecked(GVariant* variant);
static GVariantRef RefSinkUnchecked(GVariant* variant);
private:
using GVariantBase::GVariantBase;
};
// Constructs a new GVariantRef from the provided value, inferring the type
// string.
template <typename T>
static GVariantRef<Mapping<T>::kType> GVariantFrom(const T& value) {
return GVariantRef<Mapping<T>::kType>::From(value);
}
// Wrapper types and special types
// Can be used as a nested type in a call to [Try]Into() as a placeholder for a
// value the caller isn't interested in.
struct Ignored {};
// Wrapper for a value to specify that it will appear in the GVariant "boxed".
// That is, as a nested variant (type "v") holding the value, rather than the
// value directly.
template <typename T>
struct Boxed {
T value;
};
template <typename T, typename U>
bool operator==(const Boxed<T>& lhs, const Boxed<U>& rhs)
requires requires(T t, U u) { t == u; }
{
return lhs.value == rhs.value;
}
// Returns a gvariant::Boxed that holds a const reference to value. (Whereas
// Boxed{value} would hold a copy of value.) Useful to avoid making an extra
// copy when constructing a GVariantRef.
template <typename T>
Boxed<const T&> BoxedRef(const T& value LIFETIME_BOUND) {
return {value};
}
// Wrapper for a value that should appear inside a maybe, but will always be
// present.
template <typename T>
struct FilledMaybe {
T value;
};
template <typename T, typename U>
bool operator==(const FilledMaybe<T>& lhs, const FilledMaybe<U>& rhs)
requires requires(T t, U u) { t == u; }
{
return lhs.value == rhs.value;
}
// Returns a gvariant::FilledMaybe that holds a const reference to value.
// (Whereas FilledMaybe{value} would hold a copy of value.) Useful to avoid
// making an extra copy when constructing a GVariantRef.
template <typename T>
FilledMaybe<const T&> FilledMaybeRef(const T& value LIFETIME_BOUND) {
return {value};
}
// Represents an empty array of the given type.
template <Type C>
struct EmptyArrayOf {};
class ObjectPath;
// Holds an unowned pointer to a null-terminated string known to be a valid
// D-Bus object path.
class ObjectPathCStr {
public:
// Constructs from a compile-time constant. The passed string is checked at
// compile time to be a valid object path.
// Allows implicit construction so string constants can easily be passed to
// ObjectPathCStr parameters.
// NOLINTNEXTLINE(google-explicit-constructor)
consteval ObjectPathCStr(const char* path);
// Constructs from an ObjectPath object. The resulting ObjectPathCStr is only
// valid as long as the ObjectPath to which it refers.
// Allows explicit construction so ObjectPaths can easily be passed to
// ObjectPathCStr parameters.
// NOLINTNEXTLINE(google-explicit-constructor)
ObjectPathCStr(const ObjectPath& path LIFETIME_BOUND);
// Attempts to construct from an existing C string. Returns an error string
// if |path| is not a valid object path.
static base::expected<ObjectPathCStr, Loggable> TryFrom(
const char* path LIFETIME_BOUND);
// Gets the object path C string.
constexpr const char* c_str() const LIFETIME_BOUND;
friend constexpr bool operator==(const ObjectPathCStr& lhs,
const ObjectPathCStr& rhs);
private:
struct Checked {};
// Construct from already-checked path. Extra parameter to avoid conflicting
// with consteval constructor.
ObjectPathCStr(const char* path LIFETIME_BOUND, Checked);
const char* path_;
};
constexpr bool operator==(const ObjectPathCStr& lhs, const ObjectPathCStr& rhs);
// Represents an owned D-Bus object path.
class ObjectPath {
public:
// Constructs an instance of the root path "/"
ObjectPath();
// Constructs an owned copy of |path|.
explicit ObjectPath(ObjectPathCStr path);
// Attempts to construct from an existing std::string. Returns an error string
// if |path| is not a valid object path.
static base::expected<ObjectPath, Loggable> TryFrom(std::string path);
// Gets the object path.
const std::string& value() const LIFETIME_BOUND;
// Shorthand for .value().c_str()
const char* c_str() const LIFETIME_BOUND;
private:
// Construct from already-checked path.
explicit ObjectPath(std::string path);
std::string path_;
friend struct Mapping<ObjectPath>;
};
class TypeSignature;
// Holds an unowned pointer to a null-terminated string known to be a valid
// D-Bus type signature.
class TypeSignatureCStr {
public:
// Constructs from a compile-time constant. The passed string is checked at
// compile time to be a valid type signature.
// Allows implicit construction so string constants can easily be passed to
// TypeSignatureCStr parameters.
// NOLINTNEXTLINE(google-explicit-constructor)
consteval TypeSignatureCStr(const char* signature);
// Constructs from a TypeSignature object. The resulting TypeSignatureCStr is
// only valid as long as the TypeSignature to which it refers.
// Allows implicit construction so TypeSignatures can easily be passed to
// TypeSignatureCStr parameters.
// NOLINTNEXTLINE(google-explicit-constructor)
TypeSignatureCStr(const TypeSignature& signature LIFETIME_BOUND);
// Attempts to construct from an existing C string. Returns an error if
// |signature| is not a valid type signature.
static base::expected<TypeSignatureCStr, Loggable> TryFrom(
const char* signature LIFETIME_BOUND);
// Gets the type signature C string.
constexpr const char* c_str() const LIFETIME_BOUND;
friend constexpr bool operator==(const TypeSignatureCStr& lhs,
const TypeSignatureCStr& rhs);
private:
struct Checked {};
// Construct from already-checked path. Extra parameter to avoid conflicting
// with consteval constructor.
TypeSignatureCStr(const char* signature LIFETIME_BOUND, Checked);
const char* signature_;
};
constexpr bool operator==(const TypeSignatureCStr& lhs,
const TypeSignatureCStr& rhs);
// Represents an owned D-Bus type signature.
class TypeSignature {
public:
// Constructs an empty type signature.
TypeSignature();
// Constructs an owned copy of |signature|.
explicit TypeSignature(TypeSignatureCStr signature);
// Attempts to construct from an existing std::string. Returns an error if
// |signature| is not a valid type signature.
static base::expected<TypeSignature, Loggable> TryFrom(std::string signature);
// Gets the type signature.
const std::string& value() const LIFETIME_BOUND;
// Shorthand for .value().c_str()
const char* c_str() const LIFETIME_BOUND;
private:
// Construct from already-checked signature.
explicit TypeSignature(std::string);
std::string signature_;
friend struct Mapping<TypeSignature>;
};
// Iterator type for a container GVariant
template <Type C>
class Iterator;
template <Type C>
Iterator<C> operator+(std::ptrdiff_t n, const Iterator<C>& iter);
template <Type C>
class Iterator {
public:
Iterator() = default;
// Copyable and movable
Iterator(const Iterator& other) = default;
Iterator(Iterator&& other) = default;
Iterator& operator=(const Iterator& other) = default;
Iterator& operator=(Iterator&& other) = default;
// Iterator interface
// LegacyForwardIterator requires reference_type be &value_type or
// const &value_type, so this implementation is only a LegacyInputIterator.
using iterator_category = std::input_iterator_tag;
// The std::forward_iterator and higher concepts impose no such requirement,
// so this can be a full random-access iterator.
using iterator_concept = std::random_access_iterator_tag;
using value_type = GVariantRef<C>;
using reference_type = GVariantRef<C>;
using difference_type = std::ptrdiff_t;
// input iterator
value_type operator*() const;
Iterator& operator++();
Iterator operator++(int);
// forward iterator
bool operator==(const Iterator& other) const;
// bidirectional iterator
Iterator& operator--();
Iterator operator--(int);
// random access iterator
std::partial_ordering operator<=>(const Iterator& other) const;
difference_type operator-(const Iterator& other) const;
Iterator operator+(difference_type n) const;
friend Iterator operator+ <C>(difference_type n, const Iterator& iter);
Iterator operator-(difference_type n) const;
Iterator& operator+=(difference_type n);
Iterator& operator-=(difference_type n);
value_type operator[](difference_type i) const;
private:
Iterator(GVariantRef<> variant, std::size_t i);
std::size_t i_ = 0;
GVariantRef<> variant_;
template <Type D>
friend class GVariantRef;
};
// GVariantRef implementation
template <Type C>
template <Type D>
GVariantRef<C>::GVariantRef(const GVariantRef<D>& other)
requires(D.IsSubtypeOf(C))
: GVariantBase(other) {}
template <Type C>
template <Type D>
GVariantRef<C>::GVariantRef(GVariantRef<D>&& other)
requires(D.IsSubtypeOf(C))
: GVariantBase(std::move(other)) {}
// static
template <Type C>
template <typename T>
GVariantRef<C> GVariantRef<C>::From(const T& value)
requires(Mapping<T>::kType.IsSubtypeOf(C) &&
requires { Mapping<T>::From(value); })
{
return Mapping<T>::From(value);
}
// static
template <Type C>
template <typename T>
base::expected<GVariantRef<C>, Loggable> GVariantRef<C>::TryFrom(
const T& value)
requires(Mapping<T>::kType.HasCommonTypeWith(C) &&
(requires { Mapping<T>::TryFrom(value); } ||
requires { Mapping<T>::From(value); }))
{
if constexpr (requires { Mapping<T>::TryFrom(value); }) {
return Mapping<T>::TryFrom(value).and_then(
[](auto value) { return value.template TryInto<GVariantRef>(); });
} else {
return Mapping<T>::From(value).template TryInto<GVariantRef>();
}
}
template <Type C>
template <typename T>
T GVariantRef<C>::Into() const
requires(C.IsSubtypeOf(Mapping<T>::kType) &&
requires { Mapping<T>::Into(*this); })
{
return Mapping<T>::Into(*this);
}
template <Type C>
template <typename T>
base::expected<T, Loggable> GVariantRef<C>::TryInto() const
requires(C.HasCommonTypeWith(Mapping<T>::kType) &&
(requires(GVariantRef<Mapping<T>::kType> v) {
Mapping<T>::TryInto(v);
} ||
requires(GVariantRef<Mapping<T>::kType> v) {
Mapping<T>::Into(v);
}))
{
if constexpr (!C.IsSubtypeOf(Mapping<T>::kType)) {
if (GetType().IsSubtypeOf(Mapping<T>::kType)) {
return GVariantRef<Mapping<T>::kType>::RefUnchecked(raw())
.template TryInto<T>();
} else {
return base::unexpected(Loggable(
FROM_HERE,
base::StrCat({"Expected type: ", Mapping<T>::kType.string_view(),
" Found: ", GetType().string_view()})));
}
} else if constexpr (requires { Mapping<T>::TryInto(*this); }) {
return Mapping<T>::TryInto(*this);
} else {
return base::ok(Mapping<T>::Into(*this));
}
}
template <Type C>
template <typename... Types>
void GVariantRef<C>::Destructure(Types&&... refs) const {
static_assert((... && (std::is_lvalue_reference_v<Types> ||
requires { std::tuple_size_v<Types>; })));
constexpr auto contained_types = TypeBase::Unpack<C>();
static_assert(std::tuple_size_v<decltype(contained_types)> == sizeof...(refs),
"Incorrect number of elements.");
[&]<std::size_t... Is>(std::index_sequence<Is...>) {
(
[&]() {
auto inner_variant =
GVariantRef<std::get<Is>(contained_types)>::TakeUnchecked(
g_variant_get_child_value(raw(), Is));
if constexpr (std::is_lvalue_reference_v<Types>) {
refs =
inner_variant.template Into<std::remove_reference_t<Types>>();
} else {
std::apply(
[&]<typename... Ts>(Ts&&... subref) {
return inner_variant.Destructure(std::forward<Ts>(subref)...);
},
std::forward<Types>(refs));
}
}(),
...);
}(std::index_sequence_for<Types...>());
}
template <Type C>
template <typename... Types>
base::expected<void, Loggable> GVariantRef<C>::TryDestructure(
Types&&... refs) const {
static_assert((... && (std::is_lvalue_reference_v<Types> ||
requires { std::tuple_size_v<Types>; })));
if (!g_variant_is_container(raw())) {
return base::unexpected(
Loggable(FROM_HERE, "Destructured GVariant is not a container."));
}
if (std::size_t size = g_variant_n_children(raw()); size != sizeof...(refs)) {
return base::unexpected(Loggable(
FROM_HERE, base::StringPrintf(
"Incorrect number of elements. Expected: %zd Found: %zd",
sizeof...(refs), size)));
}
base::expected<void, Loggable> result;
[&]<std::size_t... Is>(std::index_sequence<Is...>) {
([&]() {
GVariantRef<> inner_variant =
GVariantRef<>::Take(g_variant_get_child_value(raw(), Is));
if constexpr (std::is_lvalue_reference_v<Types>) {
auto value = inner_variant.TryInto<std::remove_reference_t<Types>>();
if (!value.has_value()) {
result = std::move(value).error().UnexpectedWithContext(
FROM_HERE, "While destructuring container");
return false;
}
refs = value.value();
} else {
auto nested_result = std::apply(
[&]<typename... Ts>(Ts&&... subref) {
return inner_variant.TryDestructure(std::forward<Ts>(subref)...);
},
std::forward<Types>(refs));
if (!nested_result.has_value()) {
result = std::move(nested_result);
return false;
}
}
return true;
}() &&
...);
}(std::index_sequence_for<Types...>());
return result;
}
template <Type C>
auto GVariantRef<C>::begin() const
requires(C.IsContainer())
{
return Iterator<TypeBase::ContainedType<C>()>(*this, 0);
}
template <Type C>
auto GVariantRef<C>::end() const
requires(C.IsContainer())
{
return Iterator<TypeBase::ContainedType<C>()>(*this,
g_variant_n_children(raw()));
}
template <Type C>
std::size_t GVariantRef<C>::size() const
requires(C.IsContainer())
{
return g_variant_n_children(raw());
}
template <Type C>
template <std::size_t I>
auto GVariantRef<C>::get() const
requires(C.IsFixedSizeContainer())
{
return GVariantRef<std::get<I>(TypeBase::Unpack<C>())>::TakeUnchecked(
g_variant_get_child_value(raw(), I));
}
// Define free version as well for generic code that calls get(tuple_like) using
// argument-dependent lookup.
template <std::size_t I, Type C>
requires(C.IsFixedSizeContainer())
auto get(const GVariantRef<C>& variant) {
return variant.template get<I>();
}
template <Type C>
template <typename T>
auto GVariantRef<C>::LookUp(const T& needle)
requires(C.IsSubtypeOf(Type("a{?*}")) &&
requires {
decltype((*begin()).template get<0>())::TryFrom(needle);
})
{
using KeyType = decltype((*begin()).template get<0>());
using ValueType = decltype((*begin()).template get<1>());
auto needle_variant = KeyType::TryFrom(needle);
if (!needle_variant.has_value()) {
// If the value is something that can't be converted to a GVariant (e.g.,
// a non-UTF-8 string), it's probably safe to say it's not in the
// dictionary.
return std::optional<ValueType>();
}
for (auto [key, value] : *this) {
if (key == needle_variant.value()) {
return std::optional<ValueType>(std::move(value));
}
}
return std::optional<ValueType>();
}
template <Type C>
std::string_view GVariantRef<C>::string_view() const
requires(C.IsStringType())
{
gsize length;
const char* string = g_variant_get_string(raw(), &length);
return std::string_view(string, length);
}
template <Type C>
const char* GVariantRef<C>::c_string() const
requires(C.IsStringType())
{
return g_variant_get_string(raw(), nullptr);
}
// static
template <Type C>
GVariantRef<C> GVariantRef<C>::TakeUnchecked(GVariant* variant) {
DCHECK(g_variant_is_of_type(variant, C.gvariant_type()));
return GVariantRef<C>(GVariantPtr::Take(variant));
}
// static
template <Type C>
GVariantRef<C> GVariantRef<C>::RefUnchecked(GVariant* variant) {
DCHECK(g_variant_is_of_type(variant, C.gvariant_type()));
return GVariantRef<C>(GVariantPtr::Ref(variant));
}
// static
template <Type C>
GVariantRef<C> GVariantRef<C>::RefSinkUnchecked(GVariant* variant) {
DCHECK(g_variant_is_of_type(variant, C.gvariant_type()));
return GVariantRef<C>(GVariantPtr::RefSink(variant));
}
// Wrapper implementation
consteval ObjectPathCStr::ObjectPathCStr(const char* path) {
// SAFETY: Since this constructor is consteval, it can only execute at compile
// time. Thus, a read past the end triggered by a missing null terminator will
// result in a compile-time error, with no risk at runtime.
// TODO: bug 400761089 - Remove UNSAFE_BUFFERS annotations when Clang no
// longer flags consteval code.
// CHECKs cannot actually print messages at compile time, but a failed check
// will trigger a compiler error pointing to the failed check, allowing the
// message to be seen in the source code.
CHECK_EQ(*path, '/') << "Path must start with a '/'";
const char* prev_char = path;
const char* current_char = UNSAFE_BUFFERS(path + 1);
while (*current_char != '\0') {
CHECK((*current_char >= 'A' && *current_char <= 'Z') ||
(*current_char >= 'a' && *current_char <= 'z') ||
(*current_char >= '0' && *current_char <= '9') ||
*current_char == '_' || *current_char == '/')
<< "Path contains invalid character";
CHECK(*prev_char != '/' || *current_char != '/')
<< "Two '/' characters may not appear in a row";
UNSAFE_BUFFERS(++prev_char);
UNSAFE_BUFFERS(++current_char;)
}
CHECK(*prev_char != '/' || prev_char == path)
<< "Path may not end in '/' unless the whole path is only a single '/' "
"referring to the root path";
path_ = path;
}
constexpr const char* ObjectPathCStr::c_str() const {
return path_;
}
constexpr bool operator==(const ObjectPathCStr& lhs,
const ObjectPathCStr& rhs) {
if (std::is_constant_evaluated()) {
return std::string_view(lhs.c_str()) == std::string_view(rhs.c_str());
} else {
return UNSAFE_TODO(std::strcmp(lhs.c_str(), rhs.c_str())) == 0;
}
}
consteval TypeSignatureCStr::TypeSignatureCStr(const char* signature) {
// SAFETY: Since this constructor is consteval, it can only execute at compile
// time. Thus, a read past the end triggered by a missing null terminator will
// result in a compile-time error, with no risk at runtime.
// TODO: bug 400761089 - Remove UNSAFE_BUFFERS annotations when Clang no
// longer flags consteval code.
// CHECKs cannot actually print messages at compile time, but a failed check
// will trigger a compiler error pointing to the failed check, allowing the
// message to be seen in the source code.
CHECK(Type("(", signature, ")").IsValid()) << "Not a valid signature";
CHECK(Type("(", signature, ")").IsDefinite()) << "Signature must be definite";
char prev_char = '\0';
for (const char* current_char = signature; *current_char != '\0';
UNSAFE_BUFFERS(++current_char)) {
CHECK(*current_char != 'm') << "Maybe type not valid in D-Bus signature";
CHECK(*current_char != '{' || prev_char == 'a')
<< "Dict entry not part of a dictionary.";
prev_char = *current_char;
}
signature_ = signature;
}
constexpr const char* TypeSignatureCStr::c_str() const {
return signature_;
}
constexpr bool operator==(const TypeSignatureCStr& lhs,
const TypeSignatureCStr& rhs) {
if (std::is_constant_evaluated()) {
return std::string_view(lhs.c_str()) == std::string_view(rhs.c_str());
} else {
return UNSAFE_TODO(std::strcmp(lhs.c_str(), rhs.c_str())) == 0;
}
}
// Iterator implementation
template <Type C>
GVariantRef<C> Iterator<C>::operator*() const {
return GVariantRef<C>::TakeUnchecked(
g_variant_get_child_value(variant_.raw(), i_));
}
template <Type C>
Iterator<C>& Iterator<C>::operator++() {
++i_;
return *this;
}
template <Type C>
Iterator<C> Iterator<C>::operator++(int) {
return Iterator(variant_, i_++);
}
template <Type C>
bool Iterator<C>::operator==(const Iterator& other) const {
return variant_.raw() == other.variant_.raw() && i_ == other.i_;
}
template <Type C>
Iterator<C>& Iterator<C>::operator--() {
--i_;
return *this;
}
template <Type C>
Iterator<C> Iterator<C>::operator--(int) {
return Iterator(variant_, i_--);
}
template <Type C>
std::partial_ordering Iterator<C>::operator<=>(const Iterator& other) const {
if (variant_.raw() != other.variant_.raw()) {
return std::partial_ordering::unordered;
}
return i_ <=> other.i_;
}
template <Type C>
std::ptrdiff_t Iterator<C>::operator-(const Iterator& other) const {
return static_cast<std::ptrdiff_t>(i_) -
static_cast<std::ptrdiff_t>(other.i_);
}
template <Type C>
Iterator<C> Iterator<C>::operator+(std::ptrdiff_t n) const {
return Iterator(variant_, static_cast<std::ptrdiff_t>(i_) + n);
}
template <Type C>
Iterator<C> operator+(std::ptrdiff_t n, const Iterator<C>& iter) {
return Iterator<C>(iter.variant_, n + static_cast<std::ptrdiff_t>(iter.i_));
}
template <Type C>
Iterator<C> Iterator<C>::operator-(std::ptrdiff_t n) const {
return Iterator(variant_, static_cast<std::ptrdiff_t>(i_) - n);
}
template <Type C>
Iterator<C>& Iterator<C>::operator+=(std::ptrdiff_t n) {
i_ = static_cast<std::size_t>(static_cast<std::ptrdiff_t>(i_) + n);
return *this;
}
template <Type C>
Iterator<C>& Iterator<C>::operator-=(std::ptrdiff_t n) {
i_ = static_cast<std::size_t>(static_cast<std::ptrdiff_t>(i_) - n);
return *this;
}
template <Type C>
GVariantRef<C> Iterator<C>::operator[](std::ptrdiff_t i) const {
return GVariantRef<C>::TakeUnchecked(g_variant_get_child_value(
variant_.raw(),
static_cast<std::size_t>(static_cast<std::ptrdiff_t>(i_) + i)));
}
template <Type C>
Iterator<C>::Iterator(GVariantRef<> variant, std::size_t i)
: i_(i), variant_(variant) {}
// Mapping implementations
// Possibly cv-qualified reference can be used with *From() but not *Into().
template <typename T>
requires(!std::same_as<T, std::decay_t<T>>)
struct Mapping<T> {
static constexpr Type kType = Mapping<std::decay_t<const T&>>::kType;
static auto From(const T& value)
// Typically one wouldn't want a requires clause that just mirrors the
// function body. Unfortunately, it is necessary to allow other generic
// mappings to detect when From is absent, since requires expressions only
// care about what is valid according to the declaration, not whether the
// resulting instantiation would actually compile.
requires(requires {
GVariantRef<kType>::template From<std::decay_t<const T&>>(value);
})
{
return GVariantRef<kType>::template From<std::decay_t<const T&>>(value);
}
static auto TryFrom(const T& value)
requires(requires {
GVariantRef<kType>::template TryFrom<std::decay_t<const T&>>(value);
})
{
return GVariantRef<kType>::template TryFrom<std::decay_t<const T&>>(value);
}
};
// Basic fixed values.
template <>
struct Mapping<bool> {
static constexpr Type kType{"b"};
static GVariantRef<kType> From(bool value);
static bool Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<std::uint8_t> {
static constexpr Type kType{"y"};
static GVariantRef<kType> From(std::uint8_t value);
static std::uint8_t Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<std::int16_t> {
static constexpr Type kType{"n"};
static GVariantRef<kType> From(std::int16_t value);
static std::int16_t Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<std::uint16_t> {
static constexpr Type kType{"q"};
static GVariantRef<kType> From(std::uint16_t value);
static std::uint16_t Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<std::int32_t> {
static constexpr Type kType{"i"};
static GVariantRef<kType> From(std::int32_t value);
static std::int32_t Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<std::uint32_t> {
static constexpr Type kType{"u"};
static GVariantRef<kType> From(std::uint32_t value);
static std::uint32_t Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<std::int64_t> {
static constexpr Type kType{"x"};
static GVariantRef<kType> From(std::int64_t value);
static std::int64_t Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<std::uint64_t> {
static constexpr Type kType{"t"};
static GVariantRef<kType> From(std::uint64_t value);
static std::uint64_t Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<double> {
static constexpr Type kType{"d"};
static GVariantRef<kType> From(double value);
static double Into(const GVariantRef<kType>& variant);
};
// Strings.
template <>
struct Mapping<std::string> {
static constexpr Type kType{"s"};
// Crashes if string is not valid UTF-8.
static GVariantRef<kType> From(const std::string& value);
// Fails if string is not valid UTF-8.
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const std::string& value);
static std::string Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<std::string_view> {
static constexpr Type kType{"s"};
// Crashes if string is not valid UTF-8.
static GVariantRef<kType> From(std::string_view value);
// Fails if string is not valid UTF-8.
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
std::string_view value);
};
template <>
struct Mapping<const char*> {
static constexpr Type kType{"s"};
// Crashes if string is not valid UTF-8.
static GVariantRef<kType> From(const char* value);
// Fails if string is not valid UTF-8.
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const char* value);
};
// Containers
template <typename T>
struct Mapping<std::optional<T>> {
static constexpr Type kInnerType = Mapping<T>::kType;
static constexpr Type kType{"m", kInnerType};
static GVariantRef<kType> From(const std::optional<T>& value)
requires(kInnerType.IsDefinite() &&
requires(T v) { GVariantRef<kInnerType>::From(v); })
{
std::optional<GVariantRef<kInnerType>> variant;
GVariant* child = nullptr;
if (value) {
variant = GVariantRef<kInnerType>::From(*value);
child = variant->raw();
}
return GVariantRef<kType>::TakeUnchecked(
g_variant_new_maybe(kInnerType.gvariant_type(), child));
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const std::optional<T>& value)
requires(requires(T v) { GVariantRef<kInnerType>::TryFrom(v); })
{
if (value.has_value()) {
auto result = GVariantRef<kInnerType>::TryFrom(*value);
if (!result.has_value()) {
return base::unexpected(std::move(result).error());
}
return base::ok(GVariantRef<kType>::From(FilledMaybe{result.value()}));
} else if constexpr (kInnerType.IsDefinite()) {
return base::ok(
GVariantRef<kType>::From(std::optional<GVariantRef<kInnerType>>()));
} else {
return base::unexpected(Loggable(
FROM_HERE, "Can't convert indefinite optional with no value."));
}
}
static std::optional<T> Into(const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kInnerType> v) { v.template Into<T>(); })
{
GVariant* child = g_variant_get_maybe(variant.raw());
if (child) {
return GVariantRef<kInnerType>::TakeUnchecked(child).template Into<T>();
} else {
return std::nullopt;
}
}
static base::expected<std::optional<T>, Loggable> TryInto(
const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kInnerType> v) { v.template TryInto<T>(); })
{
auto optional =
variant.template Into<std::optional<GVariantRef<kInnerType>>>();
if (optional.has_value()) {
return optional->template TryInto<T>();
} else {
return base::ok(std::nullopt);
}
}
};
namespace internal {
template <Type kType, Type kInnerType, typename R>
GVariantRef<kType> FromRange(const R& value)
requires(kInnerType.IsDefinite())
{
GVariantBuilder builder;
g_variant_builder_init(&builder, kType.gvariant_type());
for (const auto& item : value) {
g_variant_builder_add_value(&builder,
GVariantRef<kInnerType>::From(item).raw());
}
return GVariantRef<kType>::TakeUnchecked(g_variant_builder_end(&builder));
}
template <Type kType, Type kInnerType, typename R>
static base::expected<GVariantRef<kType>, Loggable> TryFromRange(
const R& value) {
if (!kInnerType.IsDefinite() && value.empty()) {
return base::unexpected(
Loggable(FROM_HERE, "Can't convert empty indefinite array"));
}
std::optional<Type<>> inner_type;
GVariantBuilder builder;
g_variant_builder_init(&builder, kType.gvariant_type());
for (const auto& item : value) {
auto converted = GVariantRef<kInnerType>::TryFrom(item);
if (!converted.has_value()) {
g_variant_builder_clear(&builder);
return base::unexpected(std::move(converted).error());
}
if constexpr (!kInnerType.IsDefinite()) {
if (!inner_type.has_value()) {
inner_type = converted->GetType();
} else if (!converted->GetType().IsSubtypeOf(inner_type.value())) {
g_variant_builder_clear(&builder);
return base::unexpected(
Loggable(FROM_HERE, "Mismatched types in array"));
}
}
g_variant_builder_add_value(&builder, converted->raw());
}
return base::ok(
GVariantRef<kType>::TakeUnchecked(g_variant_builder_end(&builder)));
}
} // namespace internal
// If needed, a further specialization could be added for vectors and
// contiguous ranges of fixed basic types (bools, bytes, ints, and doubles)
// to use g_variant_{new,get}_fixed_array() rather than processing each
// element individually. This would make handling, e.g., large blobs of binary
// data much more efficient.
template <typename T>
struct Mapping<std::vector<T>> {
static constexpr Type kInnerType = Mapping<T>::kType;
static constexpr Type kType{"a", kInnerType};
static GVariantRef<kType> From(const std::vector<T>& value)
requires(kInnerType.IsDefinite() &&
requires(T v) { GVariantRef<kInnerType>::From(v); })
{
return internal::FromRange<kType, kInnerType>(value);
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const std::vector<T>& value)
requires(requires(T v) { GVariantRef<kInnerType>::TryFrom(v); })
{
return internal::TryFromRange<kType, kInnerType>(value);
}
static std::vector<T> Into(const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kInnerType> v) { v.template Into<T>(); })
{
std::vector<T> result;
GVariantIter iter;
g_variant_iter_init(&iter, variant.raw());
result.reserve(g_variant_iter_n_children(&iter));
while (GVariant* next = g_variant_iter_next_value(&iter)) {
auto item_gvariant = GVariantRef<kInnerType>::TakeUnchecked(next);
result.push_back(item_gvariant.template Into<T>());
}
return result;
}
static base::expected<std::vector<T>, Loggable> TryInto(
const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kInnerType> v) { v.template TryInto<T>(); })
{
std::vector<T> result;
GVariantIter iter;
g_variant_iter_init(&iter, variant.raw());
result.reserve(g_variant_iter_n_children(&iter));
while (GVariant* next = g_variant_iter_next_value(&iter)) {
auto item_gvariant = GVariantRef<>::Take(next);
auto item_result = item_gvariant.TryInto<T>();
if (item_result.has_value()) {
result.push_back(std::move(item_result).value());
} else {
return base::unexpected(std::move(item_result).error());
}
}
return result;
}
};
template <typename K, typename T>
requires(Mapping<K>::kType.IsBasic())
struct Mapping<std::map<K, T>> {
static constexpr Type kKeyType = Mapping<K>::kType;
static constexpr Type kValueType = Mapping<T>::kType;
static constexpr Type kInnerType{"{", kKeyType, kValueType, "}"};
static constexpr Type kType{"a", kInnerType};
static GVariantRef<kType> From(const std::map<K, T>& value)
requires(kInnerType.IsDefinite() &&
requires(std::pair<K, T> v) { GVariantRef<kInnerType>::From(v); })
{
return internal::FromRange<kType, kInnerType>(value);
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const std::map<K, T>& value)
requires(requires(std::pair<K, T> v) {
GVariantRef<kInnerType>::TryFrom(v);
})
{
return internal::TryFromRange<kType, kInnerType>(value);
}
static std::map<K, T> Into(const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kInnerType> v) {
v.template Into<std::pair<K, T>>();
})
{
std::map<K, T> result;
GVariantIter iter;
g_variant_iter_init(&iter, variant.raw());
while (GVariant* next = g_variant_iter_next_value(&iter)) {
auto item_gvariant = GVariantRef<kInnerType>::TakeUnchecked(next);
result.insert(item_gvariant.template Into<std::pair<K, T>>());
}
return result;
}
static base::expected<std::map<K, T>, Loggable> TryInto(
const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kInnerType> v) {
v.template TryInto<std::pair<K, T>>();
})
{
std::map<K, T> result;
GVariantIter iter;
g_variant_iter_init(&iter, variant.raw());
while (GVariant* next = g_variant_iter_next_value(&iter)) {
auto item_gvariant = GVariantRef<>::Take(next);
auto item_result = item_gvariant.TryInto<std::pair<K, T>>();
if (item_result.has_value()) {
result.insert(std::move(item_result).value());
} else {
return base::unexpected(std::move(item_result).error());
}
}
return result;
}
};
template <typename K, typename T>
requires(Mapping<K>::kType.IsBasic())
struct Mapping<std::pair<K, T>> {
static constexpr Type kKeyType = Mapping<K>::kType;
static constexpr Type kValueType = Mapping<T>::kType;
static constexpr Type kType{"{", kKeyType, kValueType, "}"};
static GVariantRef<kType> From(const std::pair<K, T>& pair)
requires(requires(K k, T v) {
GVariantRef<kKeyType>::From(k);
GVariantRef<kValueType>::From(v);
})
{
auto key = GVariantRef<kKeyType>::From(pair.first);
auto value = GVariantRef<kValueType>::From(pair.second);
return GVariantRef<kType>::TakeUnchecked(
g_variant_new_dict_entry(key.raw(), value.raw()));
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const std::pair<K, T>& pair)
requires(requires(K k, T v) {
GVariantRef<kKeyType>::TryFrom(k);
GVariantRef<kValueType>::TryFrom(v);
})
{
auto key = GVariantRef<kKeyType>::TryFrom(pair.first);
if (!key.has_value()) {
return base::unexpected(std::move(key).error());
}
auto value = GVariantRef<kValueType>::TryFrom(pair.second);
if (!value.has_value()) {
return base::unexpected(std::move(value).error());
}
return GVariantRef<kType>::From(std::pair(key.value(), value.value()));
}
static std::pair<K, T> Into(const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kKeyType> k, GVariantRef<kValueType> v) {
k.template Into<K>();
v.template Into<T>();
})
{
GVariantIter iter;
g_variant_iter_init(&iter, variant.raw());
auto key_gvariant =
GVariantRef<kKeyType>::TakeUnchecked(g_variant_iter_next_value(&iter));
auto value_gvariant = GVariantRef<kValueType>::TakeUnchecked(
g_variant_iter_next_value(&iter));
return std::pair(key_gvariant.template Into<K>(),
value_gvariant.template Into<T>());
}
static base::expected<std::pair<K, T>, Loggable> TryInto(
const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kKeyType> k, GVariantRef<kValueType> v) {
k.template TryInto<K>();
v.template TryInto<T>();
})
{
auto gvariants = variant.template Into<
std::pair<GVariantRef<kKeyType>, GVariantRef<kValueType>>>();
auto key_result = gvariants.first.template TryInto<K>();
if (!key_result.has_value()) {
return base::unexpected(std::move(key_result).error());
}
auto value_result = gvariants.second.template TryInto<T>();
if (!value_result.has_value()) {
return base::unexpected(std::move(value_result).error());
}
return std::pair(std::move(key_result).value(),
std::move(value_result).value());
}
};
template <typename R>
// If the type can decay, let that happen first to avoid ambiguities.
// E.g., a std::vector<double>& could either be used as a range directly or
// decayed into a std::vector<double>. Resolving in favor of decay is
// desirable so that string constants decay into a const char* and are treated
// as a C string rather than a range of chars.
requires(std::ranges::range<R> && std::same_as<R, std::decay_t<R>>)
struct Mapping<R> {
static constexpr Type kInnerType =
Mapping<std::ranges::range_value_t<R>>::kType;
static constexpr Type kType{"a", kInnerType};
static GVariantRef<kType> From(const R& value)
requires(kInnerType.IsDefinite() &&
requires(std::ranges::range_value_t<R> v) {
GVariantRef<kInnerType>::From(v);
})
{
return internal::FromRange<kType, kInnerType>(value);
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(const R& value)
requires(requires(std::ranges::range_value_t<R> v) {
GVariantRef<kInnerType>::TryFrom(v);
})
{
return internal::TryFromRange<kType, kInnerType>(value);
}
};
template <typename... Types>
struct Mapping<std::tuple<Types...>> {
static constexpr Type kType{"(", Mapping<Types>::kType..., ")"};
static GVariantRef<kType> From(const std::tuple<Types...>& value)
requires(requires(Types... v) {
(GVariantRef<Mapping<Types>::kType>::From(v), ...);
})
{
GVariantBuilder builder;
g_variant_builder_init(&builder, kType.gvariant_type());
std::apply(
[&](const Types&... values) {
(g_variant_builder_add_value(
&builder,
GVariantRef<Mapping<Types>::kType>::From(values).raw()),
...);
},
value);
return GVariantRef<kType>::TakeUnchecked(g_variant_builder_end(&builder));
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const std::tuple<Types...>& value)
requires(requires(Types... v) {
(GVariantRef<Mapping<Types>::kType>::TryFrom(v), ...);
})
{
auto conversion_result = std::apply(
[](const Types&... item) { return TupleTryFrom<Types...>(item...); },
value);
if (!conversion_result.has_value()) {
return base::unexpected(std::move(conversion_result).error());
}
return GVariantRef<kType>::From(conversion_result.value());
}
static std::tuple<Types...> Into(const GVariantRef<kType>& variant)
requires(requires(GVariantRef<Mapping<Types>::kType>... v) {
(v.template Into<Types>(), ...);
})
{
GVariantIter iter;
g_variant_iter_init(&iter, variant.raw());
// Must use uniform-initialization syntax since (in contrast to
// function-call syntax) it is specified to evalulate values in order.
auto gvariant_items =
std::tuple{GVariantRef<Mapping<Types>::kType>::TakeUnchecked(
g_variant_iter_next_value(&iter))...};
return std::apply(
[](const GVariantRef<Mapping<Types>::kType>&... items) {
return std::tuple(items.template Into<Types>()...);
},
gvariant_items);
}
static base::expected<std::tuple<Types...>, Loggable> TryInto(
const GVariantRef<kType>& variant)
requires(requires(GVariantRef<Mapping<Types>::kType>... v) {
(v.template TryInto<Types>(), ...);
})
{
auto gvariant_items =
variant
.template Into<std::tuple<GVariantRef<Mapping<Types>::kType>...>>();
return std::apply(
[](const GVariantRef<Mapping<Types>::kType>&... items) {
return TupleTryInto<Types...>(items...);
},
gvariant_items);
}
private:
// Attempt to turn a tuple of Ts into a tuple of GVariantRefs
template <typename T = void>
static base::expected<std::tuple<>, Loggable> TupleTryFrom() {
return base::ok(std::tuple());
}
template <typename T, typename... Ts>
static base::expected<std::tuple<GVariantRef<Mapping<T>::kType>,
GVariantRef<Mapping<Ts>::kType>...>,
Loggable>
TupleTryFrom(const T& first, const Ts&... rest) {
auto first_result = GVariantRef<Mapping<T>::kType>::TryFrom(first);
if (!first_result.has_value()) {
return base::unexpected(std::move(first_result).error());
}
auto rest_result = TupleTryFrom<Ts...>(rest...);
if (!rest_result.has_value()) {
return base::unexpected(std::move(first_result).error());
}
return std::tuple_cat(std::tuple(first_result.value()),
rest_result.value());
}
// Attempt to turn a tuple of GVariantRefs into a tuple of Ts
template <typename T = void>
static base::expected<std::tuple<>, Loggable> TupleTryInto() {
return base::ok(std::tuple());
}
template <typename T, typename... Ts>
static base::expected<std::tuple<T, Ts...>, Loggable> TupleTryInto(
const GVariantRef<Mapping<T>::kType>& first,
const GVariantRef<Mapping<Ts>::kType>&... rest) {
auto first_result = first.template TryInto<T>();
if (!first_result.has_value()) {
return base::unexpected(std::move(first_result).error());
}
auto rest_result = TupleTryInto<Ts...>(rest...);
if (!rest_result.has_value()) {
return base::unexpected(std::move(first_result).error());
}
return std::tuple_cat(std::tuple(first_result.value()),
rest_result.value());
}
};
template <typename... Types>
requires(sizeof...(Types) > 0)
struct Mapping<std::variant<Types...>> {
static constexpr Type kType =
TypeBase::CommonSuperTypeOf<Mapping<Types>::kType...>();
static GVariantRef<kType> From(const std::variant<Types...>& value)
requires(requires(Types... v) { (GVariantRef<kType>::From(v), ...); })
{
return [&]<std::size_t... Is>(std::index_sequence<Is...>) {
std::optional<GVariantRef<kType>> result;
((std::ignore =
value.index() == Is &&
(result.emplace(GVariantRef<kType>::From(std::get<Is>(value))),
false)),
...);
return std::move(*result);
}(std::index_sequence_for<Types...>());
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const std::variant<Types...>& value)
requires(requires(Types... v) { (GVariantRef<kType>::TryFrom(v), ...); })
{
return [&]<std::size_t... Is>(std::index_sequence<Is...>) {
std::optional<base::expected<GVariantRef<kType>, Loggable>> result;
((std::ignore =
value.index() == Is &&
(result.emplace(GVariantRef<kType>::TryFrom(std::get<Is>(value))),
false)),
...);
return std::move(*result);
}(std::index_sequence_for<Types...>());
}
template <Type C>
static std::variant<Types...> Into(const GVariantRef<C>& variant)
// Infallible Into is provided if at least one alternative provides an
// infallible Into for the provided type.
requires(... || requires { variant.template Into<Types>(); })
{
// Try TryInto() first so where possible Into and TryInto produce the same
// variant.
auto result = VariantTryInto<0, Types...>(variant);
if (result.has_value()) {
return std::move(result).value();
}
// To get here, one of the types must provide both a fallible and infallible
// conversion, and the fallible version failed. Loop through again and call
// the infallible version to get a value to return.
return VariantInto<C, 0, Types...>(variant);
}
static base::expected<std::variant<Types...>, Loggable> TryInto(
const GVariantRef<kType>& variant)
// TryInto is only provided if it is provided by at least one alternative.
requires(... || requires { variant.template TryInto<Types>(); })
{
return VariantTryInto<0, Types...>(variant);
}
private:
template <std::size_t I>
static base::expected<std::variant<Types...>, Loggable> VariantTryInto(
const GVariantRef<kType>& variant) {
return base::unexpected(
Loggable(FROM_HERE, "No variant alternative could decode value"));
}
template <std::size_t I, typename T, typename... Ts>
static base::expected<std::variant<Types...>, Loggable> VariantTryInto(
const GVariantRef<kType>& variant) {
if constexpr (requires { variant.template TryInto<T>(); }) {
auto alternative_result = variant.template TryInto<T>();
if (alternative_result.has_value()) {
return base::ok(std::variant<Types...>(
std::in_place_index<I>, std::move(alternative_result).value()));
}
}
return VariantTryInto<I + 1, Ts...>(variant);
}
// No base case needed, as at least one type is guaranteed to provide an
// infallible conversion.
template <Type C, std::size_t I, typename T, typename... Ts>
static std::variant<Types...> VariantInto(const GVariantRef<C>& variant) {
if constexpr (requires { variant.template Into<T>(); }) {
return std::variant<Types...>(std::in_place_index<I>,
variant.template Into<T>());
} else {
return VariantInto<C, I + 1, Ts...>(variant);
}
}
};
// Special Types
template <Type C>
struct Mapping<GVariantRef<C>> {
static constexpr Type kType = C;
static GVariantRef<kType> From(GVariantRef<kType> value) { return value; }
static GVariantRef<kType> Into(GVariantRef<kType> value) { return value; }
};
template <>
struct Mapping<Ignored> {
static constexpr Type kType{"*"};
static Ignored Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<decltype(std::ignore)> {
static constexpr Type kType{"*"};
static decltype(std::ignore) Into(const GVariantRef<kType>& variant);
};
template <typename T>
struct Mapping<Boxed<T>> {
static constexpr Type kType{"v"};
static GVariantRef<kType> From(const Boxed<T>& value)
requires(requires(T v) { GVariantRef<>::From(v); })
{
return GVariantRef<kType>::TakeUnchecked(
g_variant_new_variant(GVariantRef<>::From(value.value).raw()));
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const Boxed<T>& value)
requires(requires(T v) { GVariantRef<>::TryFrom(v); })
{
auto result = GVariantRef<>::TryFrom(value.value);
if (!result.has_value()) {
return base::unexpected(std::move(result).error());
}
return base::ok(GVariantRef<kType>::From(Boxed{result.value()}));
}
static Boxed<T> Into(const GVariantRef<kType>& variant)
requires(requires(GVariantRef<> v) { v.Into<T>(); })
{
return Boxed{
GVariantRef<>::Take(g_variant_get_variant(variant.raw())).Into<T>()};
}
static base::expected<Boxed<T>, Loggable> TryInto(
const GVariantRef<kType>& variant)
requires(requires(GVariantRef<> v) { v.TryInto<T>(); })
{
return variant.Into<Boxed<GVariantRef<>>>().value.TryInto<T>().transform(
[](auto v) { return Boxed{std::move(v)}; });
}
};
template <typename T>
struct Mapping<FilledMaybe<T>> {
static constexpr Type kInnerType = Mapping<T>::kType;
static constexpr Type kType{"m", kInnerType};
static GVariantRef<kType> From(const FilledMaybe<T>& value)
requires(requires(T v) { GVariantRef<kInnerType>::From(v); })
{
return GVariantRef<kType>::TakeUnchecked(g_variant_new_maybe(
nullptr, GVariantRef<kInnerType>::From(value.value).raw()));
}
static base::expected<GVariantRef<kType>, Loggable> TryFrom(
const FilledMaybe<T>& value)
requires(requires(T v) { GVariantRef<kInnerType>::TryFrom(v); })
{
auto result = GVariantRef<kInnerType>::TryFrom(value.value);
if (!result.has_value()) {
return base::unexpected(std::move(result).error());
}
return base::ok(GVariantRef<kType>::From(FilledMaybe{result.value()}));
}
static base::expected<FilledMaybe<T>, Loggable> TryInto(
const GVariantRef<kType>& variant)
requires(requires(GVariantRef<kInnerType> v) { v.template TryInto<T>(); })
{
GVariant* contents = g_variant_get_maybe(variant.raw());
if (!contents) {
return base::unexpected(
Loggable(FROM_HERE, "Maybe value unexpectedly empty"));
}
return GVariantRef<kInnerType>::TakeUnchecked(contents)
.template TryInto<T>()
.transform([](auto v) { return FilledMaybe{std::move(v)}; });
}
};
template <Type C>
struct Mapping<EmptyArrayOf<C>> {
static constexpr Type kType{"a", C};
static GVariantRef<kType> From(const EmptyArrayOf<C>& value)
requires(C.IsDefinite())
{
return GVariantRef<kType>::TakeUnchecked(
g_variant_new_array(C.gvariant_type(), nullptr, 0));
}
static base::expected<EmptyArrayOf<C>, Loggable> TryInto(
const GVariantRef<kType>& variant) {
if (auto size = g_variant_n_children(variant.raw()); size != 0) {
return base::unexpected(
Loggable(FROM_HERE, "Array unexpectedly not empty."));
}
return EmptyArrayOf<C>{};
}
};
template <>
struct Mapping<ObjectPathCStr> {
static constexpr Type kType{"o"};
static GVariantRef<kType> From(const ObjectPathCStr& value);
};
template <>
struct Mapping<ObjectPath> {
static constexpr Type kType{"o"};
static GVariantRef<kType> From(const ObjectPath& value);
static ObjectPath Into(const GVariantRef<kType>& variant);
};
template <>
struct Mapping<TypeSignatureCStr> {
static constexpr Type kType{"g"};
static GVariantRef<kType> From(const TypeSignatureCStr& value);
};
template <>
struct Mapping<TypeSignature> {
static constexpr Type kType{"g"};
static GVariantRef<kType> From(const TypeSignature& value);
static TypeSignature Into(const GVariantRef<kType>& variant);
};
} // namespace gvariant
using gvariant::GVariantFrom;
using gvariant::GVariantRef;
} // namespace remoting
// Make tuple-like
template <remoting::gvariant::Type C>
requires(C.IsFixedSizeContainer())
struct std::tuple_size<remoting::GVariantRef<C>>
: public std::tuple_size<
decltype(remoting::gvariant::TypeBase::Unpack<C>())> {};
template <std::size_t I, remoting::gvariant::Type C>
requires(C.IsFixedSizeContainer())
struct std::tuple_element<I, remoting::GVariantRef<C>> {
using type = remoting::GVariantRef<std::get<I>(
remoting::gvariant::TypeBase::Unpack<C>())>;
};
#endif // REMOTING_HOST_LINUX_GVARIANT_REF_H_
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