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
|
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2016 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file implements implicit derivation of the CaseIterable protocol.
//
//===----------------------------------------------------------------------===//
#include "TypeChecker.h"
#include "swift/AST/Decl.h"
#include "swift/AST/Stmt.h"
#include "swift/AST/Expr.h"
#include "swift/AST/Types.h"
#include "llvm/Support/raw_ostream.h"
#include "DerivedConformances.h"
using namespace swift;
/// Common preconditions for CaseIterable.
static bool canDeriveConformance(NominalTypeDecl *type) {
// The type must be an enum.
auto enumDecl = dyn_cast<EnumDecl>(type);
if (!enumDecl)
return false;
// "Simple" enums without availability attributes can derive
// a CaseIterable conformance.
//
// FIXME: Lift the availability restriction.
return !enumDecl->hasPotentiallyUnavailableCaseValue()
&& enumDecl->hasOnlyCasesWithoutAssociatedValues();
}
/// Derive the implementation of allCases for a "simple" no-payload enum.
std::pair<BraceStmt *, bool>
deriveCaseIterable_enum_getter(AbstractFunctionDecl *funcDecl, void *) {
auto *parentDC = funcDecl->getDeclContext();
auto *parentEnum = parentDC->getSelfEnumDecl();
auto enumTy = parentDC->getDeclaredTypeInContext();
auto &C = parentDC->getASTContext();
SmallVector<Expr *, 8> elExprs;
for (EnumElementDecl *elt : parentEnum->getAllElements()) {
auto *base = TypeExpr::createImplicit(enumTy, C);
auto *apply = new (C) MemberRefExpr(base, SourceLoc(),
elt, DeclNameLoc(), /*implicit*/true);
elExprs.push_back(apply);
}
auto *arrayExpr = ArrayExpr::create(C, SourceLoc(), elExprs, {}, SourceLoc());
auto *returnStmt = ReturnStmt::createImplicit(C, arrayExpr);
auto *body = BraceStmt::create(C, SourceLoc(), ASTNode(returnStmt),
SourceLoc());
return { body, /*isTypeChecked=*/false };
}
static ArraySliceType *computeAllCasesType(NominalTypeDecl *enumDecl) {
auto enumType = enumDecl->getDeclaredInterfaceType();
if (!enumType || enumType->hasError())
return nullptr;
return ArraySliceType::get(enumType);
}
static Type deriveCaseIterable_AllCases(DerivedConformance &derived) {
// enum SomeEnum : CaseIterable {
// @derived
// typealias AllCases = [SomeEnum]
// }
auto *rawInterfaceType = computeAllCasesType(cast<EnumDecl>(derived.Nominal));
return derived.getConformanceContext()->mapTypeIntoContext(rawInterfaceType);
}
ValueDecl *DerivedConformance::deriveCaseIterable(ValueDecl *requirement) {
auto &C = requirement->getASTContext();
// Conformance can't be synthesized in an extension.
if (checkAndDiagnoseDisallowedContext(requirement))
return nullptr;
// Check that we can actually derive CaseIterable for this type.
if (!canDeriveConformance(Nominal))
return nullptr;
// Build the necessary decl.
if (requirement->getBaseName() != Context.Id_allCases) {
requirement->diagnose(diag::broken_case_iterable_requirement);
return nullptr;
}
// Define the property.
auto *returnTy = computeAllCasesType(Nominal);
VarDecl *propDecl;
PatternBindingDecl *pbDecl;
std::tie(propDecl, pbDecl) = declareDerivedProperty(
SynthesizedIntroducer::Var, Context.Id_allCases, returnTy, returnTy,
/*isStatic=*/true, /*isFinal=*/true);
propDecl->getAttrs().add(
new (C) NonisolatedAttr(/*unsafe=*/false, /*implicit=*/true));
// Define the getter.
auto *getterDecl = addGetterToReadOnlyDerivedProperty(propDecl, returnTy);
getterDecl->setBodySynthesizer(&deriveCaseIterable_enum_getter);
addMembersToConformanceContext({propDecl, pbDecl});
return propDecl;
}
Type DerivedConformance::deriveCaseIterable(AssociatedTypeDecl *assocType) {
// Check that we can actually derive CaseIterable for this type.
if (!canDeriveConformance(Nominal))
return nullptr;
if (assocType->getName() == Context.Id_AllCases) {
return deriveCaseIterable_AllCases(*this);
}
Context.Diags.diagnose(assocType->getLoc(),
diag::broken_case_iterable_requirement);
return nullptr;
}
|
