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121 lines
4.0 KiB
C++
121 lines
4.0 KiB
C++
//===--- SILWitnessVisitor.h - Witness method table visitor -----*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the SILWitnessVisitor class, which is used to generate and
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// perform lookups in witness method tables for protocols and protocol
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// conformances.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_SIL_SILWITNESSVISITOR_H
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#define SWIFT_SIL_SILWITNESSVISITOR_H
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#include "swift/AST/ASTVisitor.h"
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#include "swift/AST/Decl.h"
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#include "swift/AST/Types.h"
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#include "swift/SIL/TypeLowering.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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namespace swift {
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/// A CRTP class for visiting the witnesses of a protocol.
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///
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/// The design here is that each entry (or small group of entries)
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/// gets turned into a call to the implementation class describing
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/// the exact variant of witness. For example, for member
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/// variables, there should be separate callbacks for adding a
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/// getter/setter pair, for just adding a getter, and for adding a
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/// physical projection (if we decide to support that).
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///
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/// You must override the following methods:
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/// - addOutOfLineBaseProtocol()
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/// - addMethod()
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/// - addConstructor()
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/// - addAssociatedType()
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template <class T> class SILWitnessVisitor : public ASTVisitor<T> {
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T &asDerived() { return *static_cast<T*>(this); }
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public:
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void visitProtocolDecl(ProtocolDecl *protocol) {
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// Visit inherited protocols.
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// TODO: We need to figure out all the guarantees we want here.
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// It would be abstractly good to allow conversion to a base
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// protocol to be trivial, but it's not clear that there's
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// really a structural guarantee we can rely on here.
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for (auto baseProto : protocol->getInheritedProtocols(nullptr)) {
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// ObjC protocols do not have witnesses.
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if (!Lowering::TypeConverter::protocolRequiresWitnessTable(baseProto))
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continue;
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asDerived().addOutOfLineBaseProtocol(baseProto);
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}
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/// Visit the witnesses for the direct members of a protocol.
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for (Decl *member : protocol->getMembers())
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ASTVisitor<T>::visit(member);
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}
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/// Fallback for unexpected protocol requirements.
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void visitDecl(Decl *d) {
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d->print(llvm::errs());
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llvm_unreachable("unhandled protocol requirement");
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}
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void visitAbstractStorageDecl(AbstractStorageDecl *sd) {
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asDerived().addMethod(sd->getGetter());
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if (sd->isSettable(sd->getDeclContext())) {
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asDerived().addMethod(sd->getSetter());
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if (sd->getMaterializeForSetFunc())
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asDerived().addMethod(sd->getMaterializeForSetFunc());
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}
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}
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void visitConstructorDecl(ConstructorDecl *cd) {
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asDerived().addConstructor(cd);
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}
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void visitFuncDecl(FuncDecl *func) {
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// Accessors are emitted by their var/subscript declaration.
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if (func->isAccessor())
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return;
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asDerived().addMethod(func);
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}
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void visitAssociatedTypeDecl(AssociatedTypeDecl *td) {
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SmallVector<ProtocolDecl *, 4> protos;
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for (auto p : td->getConformingProtocols())
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protos.push_back(p);
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ProtocolType::canonicalizeProtocols(protos);
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asDerived().addAssociatedType(td, protos);
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}
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void visitTypeAliasDecl(TypeAliasDecl *tad) {
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// We don't care about these by themselves for witnesses.
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}
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void visitPatternBindingDecl(PatternBindingDecl *pbd) {
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// We only care about the contained VarDecls.
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}
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void visitIfConfigDecl(IfConfigDecl *icd) {
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// We only care about the active members, which were already subsumed by the
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// enclosing type.
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}
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};
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} // end namespace swift
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#endif
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