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| 1 | +//===--- InFlightSubstitution.h - In-flight substitution data ---*- C++ -*-===// |
| 2 | +// |
| 3 | +// This source file is part of the Swift.org open source project |
| 4 | +// |
| 5 | +// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors |
| 6 | +// Licensed under Apache License v2.0 with Runtime Library Exception |
| 7 | +// |
| 8 | +// See https://swift.org/LICENSE.txt for license information |
| 9 | +// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| 10 | +// |
| 11 | +//===----------------------------------------------------------------------===// |
| 12 | +// |
| 13 | +// This file defines the InFlightSubstitution structure, which captures |
| 14 | +// all the information about a type substitution that's currently in |
| 15 | +// progress. For now, this is meant to be an internal implementation |
| 16 | +// detail of the substitution system, and other systems should not use |
| 17 | +// it (unless they are part of the extended substitution system, such as |
| 18 | +// the SIL type substituter) |
| 19 | +// |
| 20 | +//===----------------------------------------------------------------------===// |
| 21 | + |
| 22 | +#ifndef SWIFT_AST_INFLIGHTSUBSTITUTION_H |
| 23 | +#define SWIFT_AST_INFLIGHTSUBSTITUTION_H |
| 24 | + |
| 25 | +#include "swift/AST/SubstitutionMap.h" |
| 26 | + |
| 27 | +namespace swift { |
| 28 | +class SubstitutionMap; |
| 29 | + |
| 30 | +class InFlightSubstitution { |
| 31 | + SubstOptions Options; |
| 32 | + TypeSubstitutionFn BaselineSubstType; |
| 33 | + LookupConformanceFn BaselineLookupConformance; |
| 34 | + |
| 35 | + struct ActivePackExpansion { |
| 36 | + bool isSubstExpansion = false; |
| 37 | + unsigned expansionIndex = 0; |
| 38 | + }; |
| 39 | + SmallVector<ActivePackExpansion, 4> ActivePackExpansions; |
| 40 | + |
| 41 | +public: |
| 42 | + InFlightSubstitution(TypeSubstitutionFn substType, |
| 43 | + LookupConformanceFn lookupConformance, |
| 44 | + SubstOptions options) |
| 45 | + : Options(options), |
| 46 | + BaselineSubstType(substType), |
| 47 | + BaselineLookupConformance(lookupConformance) {} |
| 48 | + |
| 49 | + InFlightSubstitution(const InFlightSubstitution &) = delete; |
| 50 | + InFlightSubstitution &operator=(const InFlightSubstitution &) = delete; |
| 51 | + |
| 52 | + // TODO: when we add PackElementType, we should recognize it during |
| 53 | + // substitution and either call different methods on this class or |
| 54 | + // pass an extra argument for the pack-expansion depth D. We should |
| 55 | + // be able to rely on that to mark a pack-element reference instead |
| 56 | + // of checking whether the original type was a pack. Substitution |
| 57 | + // should use the D'th entry from the end of ActivePackExpansions to |
| 58 | + // guide the element substitution: |
| 59 | + // - project the given index of the pack substitution |
| 60 | + // - wrap it in a PackElementType if it's a subst expansion |
| 61 | + // - the depth of that PackElementType is the number of subst |
| 62 | + // expansions between the depth entry and the end of |
| 63 | + // ActivePackExpansions |
| 64 | + |
| 65 | + /// Perform primitive substitution on the given type. Returns Type() |
| 66 | + /// if the type should not be substituted as a whole. |
| 67 | + Type substType(SubstitutableType *origType); |
| 68 | + |
| 69 | + /// Perform primitive conformance lookup on the given type. |
| 70 | + ProtocolConformanceRef lookupConformance(CanType dependentType, |
| 71 | + Type conformingReplacementType, |
| 72 | + ProtocolDecl *conformedProtocol); |
| 73 | + |
| 74 | + /// Given the shape type of a pack expansion, invoke the given callback |
| 75 | + /// for each expanded component of it. If the substituted component |
| 76 | + /// is an expansion component, the desired shape of that expansion |
| 77 | + /// is passed as the argument; otherwise, the argument is Type(). |
| 78 | + /// In either case, an active expansion is entered on this IFS for |
| 79 | + /// the duration of the call to handleComponent, and subsequent |
| 80 | + /// pack-element type references will substitute to the corresponding |
| 81 | + /// element of the substitution of the pack. |
| 82 | + void expandPackExpansionShape(Type origShape, |
| 83 | + llvm::function_ref<void(Type substComponentShape)> handleComponent); |
| 84 | + |
| 85 | + /// Call the given function for each expanded component type of the |
| 86 | + /// given pack expansion type. The function will be invoked with the |
| 87 | + /// active expansion still active. |
| 88 | + void expandPackExpansionType(PackExpansionType *origExpansionType, |
| 89 | + llvm::function_ref<void(Type substType)> handleComponentType) { |
| 90 | + expandPackExpansionShape(origExpansionType->getCountType(), |
| 91 | + [&](Type substComponentShape) { |
| 92 | + auto origPatternType = origExpansionType->getPatternType(); |
| 93 | + auto substEltType = origPatternType.subst(*this); |
| 94 | + |
| 95 | + auto substComponentType = |
| 96 | + (substComponentShape |
| 97 | + ? PackExpansionType::get(substEltType, substComponentShape) |
| 98 | + : substEltType); |
| 99 | + handleComponentType(substComponentType); |
| 100 | + }); |
| 101 | + } |
| 102 | + |
| 103 | + /// Return a list of component types that the pack expansion expands to. |
| 104 | + SmallVector<Type, 8> |
| 105 | + expandPackExpansionType(PackExpansionType *origExpansionType) { |
| 106 | + SmallVector<Type, 8> substComponentTypes; |
| 107 | + expandPackExpansionType(origExpansionType, substComponentTypes); |
| 108 | + return substComponentTypes; |
| 109 | + } |
| 110 | + |
| 111 | + /// Expand the list of component types that the pack expansion expands |
| 112 | + /// to into the given array. |
| 113 | + void expandPackExpansionType(PackExpansionType *origExpansionType, |
| 114 | + SmallVectorImpl<Type> &substComponentTypes) { |
| 115 | + expandPackExpansionType(origExpansionType, [&](Type substComponentType) { |
| 116 | + substComponentTypes.push_back(substComponentType); |
| 117 | + }); |
| 118 | + } |
| 119 | + |
| 120 | + class OptionsAdjustmentScope { |
| 121 | + InFlightSubstitution &IFS; |
| 122 | + SubstOptions SavedOptions; |
| 123 | + |
| 124 | + public: |
| 125 | + OptionsAdjustmentScope(InFlightSubstitution &IFS, SubstOptions newOptions) |
| 126 | + : IFS(IFS), SavedOptions(IFS.Options) { |
| 127 | + IFS.Options = newOptions; |
| 128 | + } |
| 129 | + |
| 130 | + OptionsAdjustmentScope(const OptionsAdjustmentScope &) = delete; |
| 131 | + OptionsAdjustmentScope &operator=(const OptionsAdjustmentScope &) = delete; |
| 132 | + |
| 133 | + ~OptionsAdjustmentScope() { |
| 134 | + IFS.Options = SavedOptions; |
| 135 | + } |
| 136 | + }; |
| 137 | + |
| 138 | + template <class Fn> |
| 139 | + auto withNewOptions(SubstOptions options, Fn &&fn) |
| 140 | + -> decltype(std::forward<Fn>(fn)()) { |
| 141 | + OptionsAdjustmentScope scope(*this, options); |
| 142 | + return std::forward<Fn>(fn)(); |
| 143 | + } |
| 144 | + |
| 145 | + SubstOptions getOptions() const { |
| 146 | + return Options; |
| 147 | + } |
| 148 | + |
| 149 | + bool shouldSubstituteOpaqueArchetypes() const { |
| 150 | + return Options.contains(SubstFlags::SubstituteOpaqueArchetypes); |
| 151 | + } |
| 152 | + |
| 153 | + /// Is the given type invariant to substitution? |
| 154 | + bool isInvariant(Type type) const; |
| 155 | +}; |
| 156 | + |
| 157 | +/// A helper classes that provides stable storage for the query |
| 158 | +/// functions against a SubstitutionMap. |
| 159 | +struct InFlightSubstitutionViaSubMapHelper { |
| 160 | + QuerySubstitutionMap QueryType; |
| 161 | + LookUpConformanceInSubstitutionMap QueryConformance; |
| 162 | + |
| 163 | + InFlightSubstitutionViaSubMapHelper(SubstitutionMap subMap) |
| 164 | + : QueryType{subMap}, QueryConformance(subMap) {} |
| 165 | +}; |
| 166 | +class InFlightSubstitutionViaSubMap : |
| 167 | + private InFlightSubstitutionViaSubMapHelper, |
| 168 | + public InFlightSubstitution { |
| 169 | + |
| 170 | +public: |
| 171 | + InFlightSubstitutionViaSubMap(SubstitutionMap subMap, |
| 172 | + SubstOptions options) |
| 173 | + : InFlightSubstitutionViaSubMapHelper(subMap), |
| 174 | + InFlightSubstitution(QueryType, QueryConformance, options) {} |
| 175 | +}; |
| 176 | + |
| 177 | +} // end namespace swift |
| 178 | + |
| 179 | +#endif |
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