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
|
//===--- WitnessIndex.h - Index into a witness table ------------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file defines the WitnessIndex type, used for drilling into a
// protocol witness table or value witness table.
//
//===----------------------------------------------------------------------===//
#ifndef SWIFT_IRGEN_WITNESSINDEX_H
#define SWIFT_IRGEN_WITNESSINDEX_H
#include "swift/ABI/MetadataValues.h"
#include "swift/IRGen/ValueWitness.h"
namespace swift {
namespace irgen {
/// A class which encapsulates an index into a witness table.
class WitnessIndex {
// Negative values are indexing into the private area of a protocol witness
// table.
int Value : 31;
unsigned IsPrefix : 1;
public:
WitnessIndex() = default;
explicit WitnessIndex(int index, bool isPrefix)
: Value(index), IsPrefix(isPrefix) {}
int getValue() const { return Value; }
bool isPrefix() const { return IsPrefix; }
/// Adjust the index to refer into a protocol witness table (rather than
/// a value witness table).
WitnessIndex forProtocolWitnessTable() const {
int NewValue = Value < 0
? Value
: Value + WitnessTableFirstRequirementOffset;
return WitnessIndex(NewValue, IsPrefix);
}
};
} // end namespace irgen
} // end namespace swift
#endif
|
