summaryrefslogtreecommitdiffstats
path: root/security/sandbox/chromium/base/tuple.h
blob: e5872cc4fa8b90904554ed45f26b93800446a946 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// A Tuple is a generic templatized container, similar in concept to std::pair
// and std::tuple.  The convenient MakeTuple() function takes any number of
// arguments and will construct and return the appropriate Tuple object.  The
// functions DispatchToMethod and DispatchToFunction take a function pointer or
// instance and method pointer, and unpack a tuple into arguments to the call.
//
// Tuple elements are copied by value, and stored in the tuple.  See the unit
// tests for more details of how/when the values are copied.
//
// Example usage:
//   // These two methods of creating a Tuple are identical.
//   Tuple<int, const char*> tuple_a(1, "wee");
//   Tuple<int, const char*> tuple_b = MakeTuple(1, "wee");
//
//   void SomeFunc(int a, const char* b) { }
//   DispatchToFunction(&SomeFunc, tuple_a);  // SomeFunc(1, "wee")
//   DispatchToFunction(
//       &SomeFunc, MakeTuple(10, "foo"));    // SomeFunc(10, "foo")
//
//   struct { void SomeMeth(int a, int b, int c) { } } foo;
//   DispatchToMethod(&foo, &Foo::SomeMeth, MakeTuple(1, 2, 3));
//   // foo->SomeMeth(1, 2, 3);

#ifndef BASE_TUPLE_H_
#define BASE_TUPLE_H_

#include <stddef.h>

#include "base/bind_helpers.h"
#include "build/build_config.h"

namespace base {

// Index sequences
//
// Minimal clone of the similarly-named C++14 functionality.

template <size_t...>
struct IndexSequence {};

template <size_t... Ns>
struct MakeIndexSequenceImpl;

#if defined(_PREFAST_) && defined(OS_WIN)

// Work around VC++ 2013 /analyze internal compiler error:
// https://connect.microsoft.com/VisualStudio/feedback/details/1053626

template <> struct MakeIndexSequenceImpl<0> {
  using Type = IndexSequence<>;
};
template <> struct MakeIndexSequenceImpl<1> {
  using Type = IndexSequence<0>;
};
template <> struct MakeIndexSequenceImpl<2> {
  using Type = IndexSequence<0,1>;
};
template <> struct MakeIndexSequenceImpl<3> {
  using Type = IndexSequence<0,1,2>;
};
template <> struct MakeIndexSequenceImpl<4> {
  using Type = IndexSequence<0,1,2,3>;
};
template <> struct MakeIndexSequenceImpl<5> {
  using Type = IndexSequence<0,1,2,3,4>;
};
template <> struct MakeIndexSequenceImpl<6> {
  using Type = IndexSequence<0,1,2,3,4,5>;
};
template <> struct MakeIndexSequenceImpl<7> {
  using Type = IndexSequence<0,1,2,3,4,5,6>;
};
template <> struct MakeIndexSequenceImpl<8> {
  using Type = IndexSequence<0,1,2,3,4,5,6,7>;
};
template <> struct MakeIndexSequenceImpl<9> {
  using Type = IndexSequence<0,1,2,3,4,5,6,7,8>;
};
template <> struct MakeIndexSequenceImpl<10> {
  using Type = IndexSequence<0,1,2,3,4,5,6,7,8,9>;
};
template <> struct MakeIndexSequenceImpl<11> {
  using Type = IndexSequence<0,1,2,3,4,5,6,7,8,9,10>;
};
template <> struct MakeIndexSequenceImpl<12> {
  using Type = IndexSequence<0,1,2,3,4,5,6,7,8,9,10,11>;
};
template <> struct MakeIndexSequenceImpl<13> {
  using Type = IndexSequence<0,1,2,3,4,5,6,7,8,9,10,11,12>;
};

#else  // defined(WIN) && defined(_PREFAST_)

template <size_t... Ns>
struct MakeIndexSequenceImpl<0, Ns...> {
  using Type = IndexSequence<Ns...>;
};

template <size_t N, size_t... Ns>
struct MakeIndexSequenceImpl<N, Ns...>
    : MakeIndexSequenceImpl<N - 1, N - 1, Ns...> {};

#endif  // defined(WIN) && defined(_PREFAST_)

template <size_t N>
using MakeIndexSequence = typename MakeIndexSequenceImpl<N>::Type;

// Traits ----------------------------------------------------------------------
//
// A simple traits class for tuple arguments.
//
// ValueType: the bare, nonref version of a type (same as the type for nonrefs).
// RefType: the ref version of a type (same as the type for refs).
// ParamType: what type to pass to functions (refs should not be constified).

template <class P>
struct TupleTraits {
  typedef P ValueType;
  typedef P& RefType;
  typedef const P& ParamType;
};

template <class P>
struct TupleTraits<P&> {
  typedef P ValueType;
  typedef P& RefType;
  typedef P& ParamType;
};

// Tuple -----------------------------------------------------------------------
//
// This set of classes is useful for bundling 0 or more heterogeneous data types
// into a single variable.  The advantage of this is that it greatly simplifies
// function objects that need to take an arbitrary number of parameters; see
// RunnableMethod and IPC::MessageWithTuple.
//
// Tuple<> is supplied to act as a 'void' type.  It can be used, for example,
// when dispatching to a function that accepts no arguments (see the
// Dispatchers below).
// Tuple<A> is rarely useful.  One such use is when A is non-const ref that you
// want filled by the dispatchee, and the tuple is merely a container for that
// output (a "tier").  See MakeRefTuple and its usages.

template <typename IxSeq, typename... Ts>
struct TupleBaseImpl;
template <typename... Ts>
using TupleBase = TupleBaseImpl<MakeIndexSequence<sizeof...(Ts)>, Ts...>;
template <size_t N, typename T>
struct TupleLeaf;

template <typename... Ts>
struct Tuple final : TupleBase<Ts...> {
  Tuple() : TupleBase<Ts...>() {}
  explicit Tuple(typename TupleTraits<Ts>::ParamType... args)
      : TupleBase<Ts...>(args...) {}
};

// Avoids ambiguity between Tuple's two constructors.
template <>
struct Tuple<> final {};

template <size_t... Ns, typename... Ts>
struct TupleBaseImpl<IndexSequence<Ns...>, Ts...> : TupleLeaf<Ns, Ts>... {
  TupleBaseImpl() : TupleLeaf<Ns, Ts>()... {}
  explicit TupleBaseImpl(typename TupleTraits<Ts>::ParamType... args)
      : TupleLeaf<Ns, Ts>(args)... {}
};

template <size_t N, typename T>
struct TupleLeaf {
  TupleLeaf() {}
  explicit TupleLeaf(typename TupleTraits<T>::ParamType x) : x(x) {}

  T& get() { return x; }
  const T& get() const { return x; }

  T x;
};

// Tuple getters --------------------------------------------------------------
//
// Allows accessing an arbitrary tuple element by index.
//
// Example usage:
//   base::Tuple<int, double> t2;
//   base::get<0>(t2) = 42;
//   base::get<1>(t2) = 3.14;

template <size_t I, typename T>
T& get(TupleLeaf<I, T>& leaf) {
  return leaf.get();
}

template <size_t I, typename T>
const T& get(const TupleLeaf<I, T>& leaf) {
  return leaf.get();
}

// Tuple types ----------------------------------------------------------------
//
// Allows for selection of ValueTuple/RefTuple/ParamTuple without needing the
// definitions of class types the tuple takes as parameters.

template <typename T>
struct TupleTypes;

template <typename... Ts>
struct TupleTypes<Tuple<Ts...>> {
  using ValueTuple = Tuple<typename TupleTraits<Ts>::ValueType...>;
  using RefTuple = Tuple<typename TupleTraits<Ts>::RefType...>;
  using ParamTuple = Tuple<typename TupleTraits<Ts>::ParamType...>;
};

// Tuple creators -------------------------------------------------------------
//
// Helper functions for constructing tuples while inferring the template
// argument types.

template <typename... Ts>
inline Tuple<Ts...> MakeTuple(const Ts&... arg) {
  return Tuple<Ts...>(arg...);
}

// The following set of helpers make what Boost refers to as "Tiers" - a tuple
// of references.

template <typename... Ts>
inline Tuple<Ts&...> MakeRefTuple(Ts&... arg) {
  return Tuple<Ts&...>(arg...);
}

// Dispatchers ----------------------------------------------------------------
//
// Helper functions that call the given method on an object, with the unpacked
// tuple arguments.  Notice that they all have the same number of arguments,
// so you need only write:
//   DispatchToMethod(object, &Object::method, args);
// This is very useful for templated dispatchers, since they don't need to know
// what type |args| is.

// Non-Static Dispatchers with no out params.

template <typename ObjT, typename Method, typename... Ts, size_t... Ns>
inline void DispatchToMethodImpl(ObjT* obj,
                                 Method method,
                                 const Tuple<Ts...>& arg,
                                 IndexSequence<Ns...>) {
  (obj->*method)(base::internal::UnwrapTraits<Ts>::Unwrap(get<Ns>(arg))...);
}

template <typename ObjT, typename Method, typename... Ts>
inline void DispatchToMethod(ObjT* obj,
                             Method method,
                             const Tuple<Ts...>& arg) {
  DispatchToMethodImpl(obj, method, arg, MakeIndexSequence<sizeof...(Ts)>());
}

// Static Dispatchers with no out params.

template <typename Function, typename... Ts, size_t... Ns>
inline void DispatchToFunctionImpl(Function function,
                                   const Tuple<Ts...>& arg,
                                   IndexSequence<Ns...>) {
  (*function)(base::internal::UnwrapTraits<Ts>::Unwrap(get<Ns>(arg))...);
}

template <typename Function, typename... Ts>
inline void DispatchToFunction(Function function, const Tuple<Ts...>& arg) {
  DispatchToFunctionImpl(function, arg, MakeIndexSequence<sizeof...(Ts)>());
}

// Dispatchers with out parameters.

template <typename ObjT,
          typename Method,
          typename... InTs,
          typename... OutTs,
          size_t... InNs,
          size_t... OutNs>
inline void DispatchToMethodImpl(ObjT* obj,
                                 Method method,
                                 const Tuple<InTs...>& in,
                                 Tuple<OutTs...>* out,
                                 IndexSequence<InNs...>,
                                 IndexSequence<OutNs...>) {
  (obj->*method)(base::internal::UnwrapTraits<InTs>::Unwrap(get<InNs>(in))...,
                 &get<OutNs>(*out)...);
}

template <typename ObjT, typename Method, typename... InTs, typename... OutTs>
inline void DispatchToMethod(ObjT* obj,
                             Method method,
                             const Tuple<InTs...>& in,
                             Tuple<OutTs...>* out) {
  DispatchToMethodImpl(obj, method, in, out,
                       MakeIndexSequence<sizeof...(InTs)>(),
                       MakeIndexSequence<sizeof...(OutTs)>());
}

}  // namespace base

#endif  // BASE_TUPLE_H_