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Allow a protocol requirement for a function or property to declare a function builder. A witness to such a protocol requirement will infer that function builder when all of the following are two: * The witness does not explicitly adopt a function builder * The witness is declared within the same context that conforms to the protocol requirement (e.g., same extension or primary type declaration) * The witness's body does not contain a "return" statement (since those disable the function builder transform).
1712 lines
60 KiB
C++
1712 lines
60 KiB
C++
//===--- BuilderTransform.cpp - Function-builder transformation -----------===//
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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 - 2018 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 implements routines associated with the function-builder
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// transformation.
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//
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//===----------------------------------------------------------------------===//
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#include "ConstraintSystem.h"
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#include "MiscDiagnostics.h"
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#include "SolutionResult.h"
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#include "TypeChecker.h"
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#include "swift/AST/ASTVisitor.h"
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#include "swift/AST/ASTWalker.h"
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#include "swift/AST/NameLookup.h"
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#include "swift/AST/NameLookupRequests.h"
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#include "swift/AST/ParameterList.h"
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#include "swift/AST/TypeCheckRequests.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallVector.h"
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#include <iterator>
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#include <map>
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#include <memory>
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#include <utility>
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#include <tuple>
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using namespace swift;
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using namespace constraints;
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namespace {
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/// Visitor to classify the contents of the given closure.
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class BuilderClosureVisitor
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: private StmtVisitor<BuilderClosureVisitor, VarDecl *> {
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friend StmtVisitor<BuilderClosureVisitor, VarDecl *>;
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ConstraintSystem *cs;
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DeclContext *dc;
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ASTContext &ctx;
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Type builderType;
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NominalTypeDecl *builder = nullptr;
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Identifier buildOptionalId;
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llvm::SmallDenseMap<Identifier, bool> supportedOps;
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SkipUnhandledConstructInFunctionBuilder::UnhandledNode unhandledNode;
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/// Whether an error occurred during application of the builder closure,
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/// e.g., during constraint generation.
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bool hadError = false;
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/// Counter used to give unique names to the variables that are
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/// created implicitly.
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unsigned varCounter = 0;
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/// The record of what happened when we applied the builder transform.
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AppliedBuilderTransform applied;
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/// Produce a builder call to the given named function with the given
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/// arguments.
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Expr *buildCallIfWanted(SourceLoc loc,
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Identifier fnName, ArrayRef<Expr *> args,
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ArrayRef<Identifier> argLabels) {
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if (!cs)
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return nullptr;
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// FIXME: Setting a base on this expression is necessary in order
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// to get diagnostics if something about this builder call fails,
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// e.g. if there isn't a matching overload for `buildBlock`.
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TypeExpr *typeExpr;
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auto simplifiedTy = cs->simplifyType(builderType);
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if (!simplifiedTy->hasTypeVariable()) {
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typeExpr = TypeExpr::createImplicitHack(loc, simplifiedTy, ctx);
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} else {
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// HACK: If there's not enough information in the constraint system,
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// create a garbage base type to force it to diagnose
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// this as an ambiguous expression.
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typeExpr = TypeExpr::createImplicitHack(loc, ErrorType::get(ctx), ctx);
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}
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cs->setType(typeExpr, MetatypeType::get(builderType));
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SmallVector<SourceLoc, 4> argLabelLocs;
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for (auto i : indices(argLabels)) {
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argLabelLocs.push_back(args[i]->getStartLoc());
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}
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auto memberRef = new (ctx) UnresolvedDotExpr(
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typeExpr, loc, DeclNameRef(fnName), DeclNameLoc(loc),
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/*implicit=*/true);
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memberRef->setFunctionRefKind(FunctionRefKind::SingleApply);
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SourceLoc openLoc = args.empty() ? loc : args.front()->getStartLoc();
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SourceLoc closeLoc = args.empty() ? loc : args.back()->getEndLoc();
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Expr *result = CallExpr::create(ctx, memberRef, openLoc, args,
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argLabels, argLabelLocs, closeLoc,
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/*trailing closures*/{},
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/*implicit*/true);
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return result;
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}
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/// Check whether the builder supports the given operation.
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bool builderSupports(Identifier fnName,
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ArrayRef<Identifier> argLabels = {}) {
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auto known = supportedOps.find(fnName);
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if (known != supportedOps.end()) {
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return known->second;
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}
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bool found = false;
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for (auto decl : builder->lookupDirect(fnName)) {
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if (auto func = dyn_cast<FuncDecl>(decl)) {
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// Function must be static.
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if (!func->isStatic())
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continue;
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// Function must have the right argument labels, if provided.
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if (!argLabels.empty()) {
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auto funcLabels = func->getName().getArgumentNames();
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if (argLabels.size() > funcLabels.size() ||
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funcLabels.slice(0, argLabels.size()) != argLabels)
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continue;
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}
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// Okay, it's a good-enough match.
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found = true;
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break;
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}
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}
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return supportedOps[fnName] = found;
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}
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/// Build an implicit variable in this context.
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VarDecl *buildVar(SourceLoc loc) {
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// Create the implicit variable.
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Identifier name = ctx.getIdentifier(
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("$__builder" + Twine(varCounter++)).str());
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auto var = new (ctx) VarDecl(/*isStatic=*/false, VarDecl::Introducer::Var,
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/*isCaptureList=*/false, loc, name, dc);
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var->setImplicit();
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return var;
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}
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/// Capture the given expression into an implicitly-generated variable.
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VarDecl *captureExpr(Expr *expr, bool oneWay,
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llvm::PointerUnion<Stmt *, Expr *> forEntity = nullptr) {
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if (!cs)
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return nullptr;
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Expr *origExpr = expr;
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if (oneWay) {
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// Form a one-way constraint to prevent backward propagation.
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expr = new (ctx) OneWayExpr(expr);
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}
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// Generate constraints for this expression.
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expr = cs->generateConstraints(expr, dc);
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if (!expr) {
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hadError = true;
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return nullptr;
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}
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// Create the implicit variable.
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auto var = buildVar(expr->getStartLoc());
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// Record the new variable and its corresponding expression & statement.
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if (auto forStmt = forEntity.dyn_cast<Stmt *>()) {
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applied.capturedStmts.insert({forStmt, { var, { expr } }});
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} else {
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if (auto forExpr = forEntity.dyn_cast<Expr *>())
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origExpr = forExpr;
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applied.capturedExprs.insert({origExpr, {var, expr}});
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}
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cs->setType(var, cs->getType(expr));
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return var;
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}
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/// Build an implicit reference to the given variable.
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DeclRefExpr *buildVarRef(VarDecl *var, SourceLoc loc) {
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return new (ctx) DeclRefExpr(var, DeclNameLoc(loc), /*Implicit=*/true);
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}
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public:
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BuilderClosureVisitor(ASTContext &ctx, ConstraintSystem *cs,
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DeclContext *dc, Type builderType,
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Type bodyResultType)
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: cs(cs), dc(dc), ctx(ctx), builderType(builderType) {
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assert((cs || !builderType->hasTypeVariable()) &&
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"cannot handle builder type with type variables without "
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"constraint system");
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builder = builderType->getAnyNominal();
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applied.builderType = builderType;
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applied.bodyResultType = bodyResultType;
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// Use buildOptional(_:) if available, otherwise fall back to buildIf
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// when available.
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if (builderSupports(ctx.Id_buildOptional) ||
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!builderSupports(ctx.Id_buildIf))
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buildOptionalId = ctx.Id_buildOptional;
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else
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buildOptionalId = ctx.Id_buildIf;
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}
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/// Apply the builder transform to the given statement.
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Optional<AppliedBuilderTransform> apply(Stmt *stmt) {
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VarDecl *bodyVar = visit(stmt);
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if (!bodyVar)
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return None;
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applied.returnExpr = buildVarRef(bodyVar, stmt->getEndLoc());
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// If there is a buildFinalResult(_:), call it.
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ASTContext &ctx = cs->getASTContext();
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if (builderSupports(ctx.Id_buildFinalResult, { Identifier() })) {
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applied.returnExpr = buildCallIfWanted(
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applied.returnExpr->getLoc(), ctx.Id_buildFinalResult,
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{ applied.returnExpr }, { Identifier() });
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}
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applied.returnExpr = cs->buildTypeErasedExpr(applied.returnExpr,
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dc, applied.bodyResultType,
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CTP_ReturnStmt);
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applied.returnExpr = cs->generateConstraints(applied.returnExpr, dc);
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if (!applied.returnExpr) {
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hadError = true;
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return None;
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}
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return std::move(applied);
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}
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/// Check whether the function builder can be applied to this statement.
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/// \returns the node that cannot be handled by this builder on failure.
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SkipUnhandledConstructInFunctionBuilder::UnhandledNode check(Stmt *stmt) {
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(void)visit(stmt);
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return unhandledNode;
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}
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protected:
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#define CONTROL_FLOW_STMT(StmtClass) \
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VarDecl *visit##StmtClass##Stmt(StmtClass##Stmt *stmt) { \
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if (!unhandledNode) \
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unhandledNode = stmt; \
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\
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return nullptr; \
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}
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void visitPatternBindingDecl(PatternBindingDecl *patternBinding) {
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// If any of the entries lacks an initializer, don't handle this node.
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if (!llvm::all_of(range(patternBinding->getNumPatternEntries()),
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[&](unsigned index) {
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return patternBinding->isExplicitlyInitialized(index);
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})) {
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if (!unhandledNode)
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unhandledNode = patternBinding;
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return;
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}
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// If we aren't generating constraints, there's nothing to do.
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if (!cs)
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return;
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/// Generate constraints for each pattern binding entry
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for (unsigned index : range(patternBinding->getNumPatternEntries())) {
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// Type check the pattern.
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auto pattern = patternBinding->getPattern(index);
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auto contextualPattern = ContextualPattern::forRawPattern(pattern, dc);
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Type patternType = TypeChecker::typeCheckPattern(contextualPattern);
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// Generate constraints for the initialization.
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auto target = SolutionApplicationTarget::forInitialization(
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patternBinding->getInit(index), dc, patternType, pattern,
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/*bindPatternVarsOneWay=*/true);
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if (cs->generateConstraints(target, FreeTypeVariableBinding::Disallow))
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continue;
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// Keep track of this binding entry.
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applied.patternBindingEntries.insert({{patternBinding, index}, target});
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}
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}
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VarDecl *visitBraceStmt(BraceStmt *braceStmt) {
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SmallVector<Expr *, 4> expressions;
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auto addChild = [&](VarDecl *childVar) {
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if (!childVar)
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return;
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expressions.push_back(buildVarRef(childVar, childVar->getLoc()));
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};
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for (auto node : braceStmt->getElements()) {
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// Implicit returns in single-expression function bodies are treated
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// as the expression.
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if (auto returnStmt =
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dyn_cast_or_null<ReturnStmt>(node.dyn_cast<Stmt *>())) {
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assert(returnStmt->isImplicit());
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node = returnStmt->getResult();
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}
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if (auto stmt = node.dyn_cast<Stmt *>()) {
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addChild(visit(stmt));
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continue;
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}
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if (auto decl = node.dyn_cast<Decl *>()) {
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// Just ignore #if; the chosen children should appear in the
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// surrounding context. This isn't good for source tools but it
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// at least works.
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if (isa<IfConfigDecl>(decl))
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continue;
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// Skip #warning/#error; we'll handle them when applying the builder.
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if (isa<PoundDiagnosticDecl>(decl)) {
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continue;
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}
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// Pattern bindings are okay so long as all of the entries are
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// initialized.
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if (auto patternBinding = dyn_cast<PatternBindingDecl>(decl)) {
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visitPatternBindingDecl(patternBinding);
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continue;
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}
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// Ignore variable declarations, because they're always handled within
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// their enclosing pattern bindings.
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if (isa<VarDecl>(decl))
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continue;
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if (!unhandledNode)
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unhandledNode = decl;
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continue;
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}
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auto expr = node.get<Expr *>();
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if (cs && builderSupports(ctx.Id_buildExpression)) {
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expr = buildCallIfWanted(expr->getLoc(), ctx.Id_buildExpression,
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{ expr }, { Identifier() });
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}
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addChild(captureExpr(expr, /*oneWay=*/true, node.get<Expr *>()));
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}
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if (!cs || hadError)
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return nullptr;
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// Call Builder.buildBlock(... args ...)
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auto call = buildCallIfWanted(braceStmt->getStartLoc(),
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ctx.Id_buildBlock, expressions,
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/*argLabels=*/{ });
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if (!call)
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return nullptr;
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return captureExpr(call, /*oneWay=*/true, braceStmt);
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}
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VarDecl *visitReturnStmt(ReturnStmt *stmt) {
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if (!unhandledNode)
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unhandledNode = stmt;
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return nullptr;
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}
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VarDecl *visitDoStmt(DoStmt *doStmt) {
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if (!builderSupports(ctx.Id_buildDo)) {
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if (!unhandledNode)
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unhandledNode = doStmt;
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return nullptr;
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}
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auto childVar = visit(doStmt->getBody());
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if (!childVar)
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return nullptr;
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auto childRef = buildVarRef(childVar, doStmt->getEndLoc());
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auto call = buildCallIfWanted(doStmt->getStartLoc(), ctx.Id_buildDo,
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childRef, /*argLabels=*/{ });
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if (!call)
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return nullptr;
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return captureExpr(call, /*oneWay=*/true, doStmt);
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}
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CONTROL_FLOW_STMT(Yield)
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CONTROL_FLOW_STMT(Defer)
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static bool isBuildableIfChainRecursive(IfStmt *ifStmt,
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unsigned &numPayloads,
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bool &isOptional) {
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// The 'then' clause contributes a payload.
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numPayloads++;
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// If there's an 'else' clause, it contributes payloads:
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if (auto elseStmt = ifStmt->getElseStmt()) {
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// If it's 'else if', it contributes payloads recursively.
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if (auto elseIfStmt = dyn_cast<IfStmt>(elseStmt)) {
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return isBuildableIfChainRecursive(elseIfStmt, numPayloads,
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isOptional);
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// Otherwise it's just the one.
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} else {
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numPayloads++;
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}
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// If not, the chain result is at least optional.
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} else {
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isOptional = true;
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}
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return true;
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}
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bool isBuildableIfChain(IfStmt *ifStmt, unsigned &numPayloads,
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bool &isOptional) {
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if (!isBuildableIfChainRecursive(ifStmt, numPayloads, isOptional))
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return false;
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// If there's a missing 'else', we need 'buildOptional' to exist.
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if (isOptional && !builderSupports(buildOptionalId))
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return false;
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// If there are multiple clauses, we need 'buildEither(first:)' and
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// 'buildEither(second:)' to both exist.
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if (numPayloads > 1) {
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if (!builderSupports(ctx.Id_buildEither, {ctx.Id_first}) ||
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!builderSupports(ctx.Id_buildEither, {ctx.Id_second}))
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return false;
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}
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return true;
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}
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VarDecl *visitIfStmt(IfStmt *ifStmt) {
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// Check whether the chain is buildable and whether it terminates
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// without an `else`.
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bool isOptional = false;
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unsigned numPayloads = 0;
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if (!isBuildableIfChain(ifStmt, numPayloads, isOptional)) {
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if (!unhandledNode)
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unhandledNode = ifStmt;
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return nullptr;
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}
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// Attempt to build the chain, propagating short-circuits, which
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// might arise either do to error or not wanting an expression.
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return buildIfChainRecursive(ifStmt, 0, numPayloads, isOptional,
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/*isTopLevel=*/true);
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}
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/// Recursively build an if-chain: build an expression which will have
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/// a value of the chain result type before any call to `buildIf`.
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/// The expression will perform any necessary calls to `buildEither`,
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/// and the result will have optional type if `isOptional` is true.
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VarDecl *buildIfChainRecursive(IfStmt *ifStmt, unsigned payloadIndex,
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unsigned numPayloads, bool isOptional,
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bool isTopLevel = false) {
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assert(payloadIndex < numPayloads);
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// First generate constraints for the conditions. This can introduce
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// variable bindings that will be used within the "then" branch.
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if (cs && cs->generateConstraints(ifStmt->getCond(), dc)) {
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hadError = true;
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return nullptr;
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}
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// Make sure we recursively visit both sides even if we're not
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// building expressions.
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// Build the then clause. This will have the corresponding payload
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// type (i.e. not wrapped in any way).
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VarDecl *thenVar = visit(ifStmt->getThenStmt());
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// Build the else clause, if present. If this is from an else-if,
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// this will be fully wrapped; otherwise it will have the corresponding
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// payload type (at index `payloadIndex + 1`).
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assert(ifStmt->getElseStmt() || isOptional);
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bool isElseIf = false;
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Optional<VarDecl *> elseChainVar;
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if (auto elseStmt = ifStmt->getElseStmt()) {
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if (auto elseIfStmt = dyn_cast<IfStmt>(elseStmt)) {
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isElseIf = true;
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elseChainVar = buildIfChainRecursive(elseIfStmt, payloadIndex + 1,
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numPayloads, isOptional);
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} else {
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elseChainVar = visit(elseStmt);
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}
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}
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// Short-circuit if appropriate.
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if (!cs || !thenVar || (elseChainVar && !*elseChainVar))
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return nullptr;
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// Prepare the `then` operand by wrapping it to produce a chain result.
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Expr *thenExpr = buildWrappedChainPayload(
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buildVarRef(thenVar, ifStmt->getThenStmt()->getEndLoc()),
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payloadIndex, numPayloads, isOptional);
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// Prepare the `else operand:
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Expr *elseExpr;
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SourceLoc elseLoc;
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// - If there's no `else` clause, use `Optional.none`.
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if (!elseChainVar) {
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assert(isOptional);
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elseLoc = ifStmt->getEndLoc();
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elseExpr = buildNoneExpr(elseLoc);
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|
|
// - If there's an `else if`, the chain expression from that
|
|
// should already be producing a chain result.
|
|
} else if (isElseIf) {
|
|
elseExpr = buildVarRef(*elseChainVar, ifStmt->getEndLoc());
|
|
elseLoc = ifStmt->getElseLoc();
|
|
|
|
// - Otherwise, wrap it to produce a chain result.
|
|
} else {
|
|
elseLoc = ifStmt->getElseLoc();
|
|
elseExpr = buildWrappedChainPayload(
|
|
buildVarRef(*elseChainVar, ifStmt->getEndLoc()),
|
|
payloadIndex + 1, numPayloads, isOptional);
|
|
}
|
|
|
|
// The operand should have optional type if we had optional results,
|
|
// so we just need to call `buildIf` now, since we're at the top level.
|
|
if (isOptional && isTopLevel) {
|
|
thenExpr = buildCallIfWanted(ifStmt->getEndLoc(), buildOptionalId,
|
|
thenExpr, /*argLabels=*/{ });
|
|
elseExpr = buildCallIfWanted(ifStmt->getEndLoc(), buildOptionalId,
|
|
elseExpr, /*argLabels=*/{ });
|
|
}
|
|
|
|
thenExpr = cs->generateConstraints(thenExpr, dc);
|
|
if (!thenExpr) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
elseExpr = cs->generateConstraints(elseExpr, dc);
|
|
if (!elseExpr) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
Type resultType = cs->addJoinConstraint(cs->getConstraintLocator(ifStmt),
|
|
{
|
|
{ cs->getType(thenExpr), cs->getConstraintLocator(thenExpr) },
|
|
{ cs->getType(elseExpr), cs->getConstraintLocator(elseExpr) }
|
|
});
|
|
if (!resultType) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
// Create a variable to capture the result of this expression.
|
|
auto ifVar = buildVar(ifStmt->getStartLoc());
|
|
cs->setType(ifVar, resultType);
|
|
applied.capturedStmts.insert({ifStmt, { ifVar, { thenExpr, elseExpr }}});
|
|
return ifVar;
|
|
}
|
|
|
|
/// Wrap a payload value in an expression which will produce a chain
|
|
/// result (without `buildIf`).
|
|
Expr *buildWrappedChainPayload(Expr *operand, unsigned payloadIndex,
|
|
unsigned numPayloads, bool isOptional) {
|
|
assert(payloadIndex < numPayloads);
|
|
|
|
// Inject into the appropriate chain position.
|
|
//
|
|
// We produce a (left-biased) balanced binary tree of Eithers in order
|
|
// to prevent requiring a linear number of injections in the worst case.
|
|
// That is, if we have 13 clauses, we want to produce:
|
|
//
|
|
// /------------------Either------------\
|
|
// /-------Either-------\ /--Either--\
|
|
// /--Either--\ /--Either--\ /--Either--\ \
|
|
// /-E-\ /-E-\ /-E-\ /-E-\ /-E-\ /-E-\ \
|
|
// 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100
|
|
//
|
|
// Note that a prefix of length D of the payload index acts as a path
|
|
// through the tree to the node at depth D. On the rightmost path
|
|
// through the tree (when this prefix is equal to the corresponding
|
|
// prefix of the maximum payload index), the bits of the index mark
|
|
// where Eithers are required.
|
|
//
|
|
// Since we naturally want to build from the innermost Either out, and
|
|
// therefore work with progressively shorter prefixes, we can do it all
|
|
// with right-shifts.
|
|
for (auto path = payloadIndex, maxPath = numPayloads - 1;
|
|
maxPath != 0; path >>= 1, maxPath >>= 1) {
|
|
// Skip making Eithers on the rightmost path where they aren't required.
|
|
// This isn't just an optimization: adding spurious Eithers could
|
|
// leave us with unresolvable type variables if `buildEither` has
|
|
// a signature like:
|
|
// static func buildEither<T,U>(first value: T) -> Either<T,U>
|
|
// which relies on unification to work.
|
|
if (path == maxPath && !(maxPath & 1)) continue;
|
|
|
|
bool isSecond = (path & 1);
|
|
operand = buildCallIfWanted(operand->getStartLoc(),
|
|
ctx.Id_buildEither, operand,
|
|
{isSecond ? ctx.Id_second : ctx.Id_first});
|
|
}
|
|
|
|
// Inject into Optional if required. We'll be adding the call to
|
|
// `buildIf` after all the recursive calls are complete.
|
|
if (isOptional) {
|
|
operand = buildSomeExpr(operand);
|
|
}
|
|
|
|
return operand;
|
|
}
|
|
|
|
Expr *buildSomeExpr(Expr *arg) {
|
|
auto optionalDecl = ctx.getOptionalDecl();
|
|
auto optionalType = optionalDecl->getDeclaredType();
|
|
|
|
auto loc = arg->getStartLoc();
|
|
auto optionalTypeExpr =
|
|
TypeExpr::createImplicitHack(loc, optionalType, ctx);
|
|
auto someRef = new (ctx) UnresolvedDotExpr(
|
|
optionalTypeExpr, loc, DeclNameRef(ctx.getIdentifier("some")),
|
|
DeclNameLoc(loc), /*implicit=*/true);
|
|
return CallExpr::createImplicit(ctx, someRef, arg, { });
|
|
}
|
|
|
|
Expr *buildNoneExpr(SourceLoc endLoc) {
|
|
auto optionalDecl = ctx.getOptionalDecl();
|
|
auto optionalType = optionalDecl->getDeclaredType();
|
|
|
|
auto optionalTypeExpr =
|
|
TypeExpr::createImplicitHack(endLoc, optionalType, ctx);
|
|
return new (ctx) UnresolvedDotExpr(
|
|
optionalTypeExpr, endLoc, DeclNameRef(ctx.getIdentifier("none")),
|
|
DeclNameLoc(endLoc), /*implicit=*/true);
|
|
}
|
|
|
|
VarDecl *visitSwitchStmt(SwitchStmt *switchStmt) {
|
|
// Generate constraints for the subject expression, and capture its
|
|
// type for use in matching the various patterns.
|
|
Expr *subjectExpr = switchStmt->getSubjectExpr();
|
|
if (cs) {
|
|
// Form a one-way constraint to prevent backward propagation.
|
|
subjectExpr = new (ctx) OneWayExpr(subjectExpr);
|
|
|
|
// FIXME: Add contextual type purpose for switch subjects?
|
|
SolutionApplicationTarget target(subjectExpr, dc, CTP_Unused, Type(),
|
|
/*isDiscarded=*/false);
|
|
if (cs->generateConstraints(target, FreeTypeVariableBinding::Disallow)) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
cs->setSolutionApplicationTarget(switchStmt, target);
|
|
subjectExpr = target.getAsExpr();
|
|
assert(subjectExpr && "Must have a subject expression here");
|
|
}
|
|
|
|
// Generate constraints and capture variables for all of the cases.
|
|
SmallVector<std::pair<CaseStmt *, VarDecl *>, 4> capturedCaseVars;
|
|
for (auto *caseStmt : switchStmt->getCases()) {
|
|
if (auto capturedCaseVar = visitCaseStmt(caseStmt, subjectExpr)) {
|
|
capturedCaseVars.push_back({caseStmt, capturedCaseVar});
|
|
}
|
|
}
|
|
|
|
if (!cs)
|
|
return nullptr;
|
|
|
|
// Form the expressions that inject the result of each case into the
|
|
// appropriate
|
|
llvm::TinyPtrVector<Expr *> injectedCaseExprs;
|
|
SmallVector<std::pair<Type, ConstraintLocator *>, 4> injectedCaseTerms;
|
|
for (unsigned idx : indices(capturedCaseVars)) {
|
|
auto caseStmt = capturedCaseVars[idx].first;
|
|
auto caseVar = capturedCaseVars[idx].second;
|
|
|
|
// Build the expression that injects the case variable into appropriate
|
|
// buildEither(first:)/buildEither(second:) chain.
|
|
Expr *caseVarRef = buildVarRef(caseVar, caseStmt->getEndLoc());
|
|
Expr *injectedCaseExpr = buildWrappedChainPayload(
|
|
caseVarRef, idx, capturedCaseVars.size(), /*isOptional=*/false);
|
|
|
|
// Generate constraints for this injected case result.
|
|
injectedCaseExpr = cs->generateConstraints(injectedCaseExpr, dc);
|
|
if (!injectedCaseExpr) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
// Record this injected case expression.
|
|
injectedCaseExprs.push_back(injectedCaseExpr);
|
|
|
|
// Record the type and locator for this injected case expression, to be
|
|
// used in the "join" constraint later.
|
|
injectedCaseTerms.push_back(
|
|
{ cs->getType(injectedCaseExpr)->getRValueType(),
|
|
cs->getConstraintLocator(injectedCaseExpr) });
|
|
}
|
|
|
|
// Form the type of the switch itself.
|
|
Type resultType = cs->addJoinConstraint(
|
|
cs->getConstraintLocator(switchStmt), injectedCaseTerms);
|
|
if (!resultType) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
// Create a variable to capture the result of evaluating the switch.
|
|
auto switchVar = buildVar(switchStmt->getStartLoc());
|
|
cs->setType(switchVar, resultType);
|
|
applied.capturedStmts.insert(
|
|
{switchStmt, { switchVar, std::move(injectedCaseExprs) } });
|
|
return switchVar;
|
|
}
|
|
|
|
VarDecl *visitCaseStmt(CaseStmt *caseStmt, Expr *subjectExpr) {
|
|
// If needed, generate constraints for everything in the case statement.
|
|
if (cs) {
|
|
auto locator = cs->getConstraintLocator(
|
|
subjectExpr, LocatorPathElt::ContextualType());
|
|
Type subjectType = cs->getType(subjectExpr);
|
|
|
|
if (cs->generateConstraints(caseStmt, dc, subjectType, locator)) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
}
|
|
|
|
// Translate the body.
|
|
return visit(caseStmt->getBody());
|
|
}
|
|
|
|
VarDecl *visitForEachStmt(ForEachStmt *forEachStmt) {
|
|
// for...in statements are handled via buildArray(_:); bail out if the
|
|
// builder does not support it.
|
|
if (!builderSupports(ctx.Id_buildArray)) {
|
|
if (!unhandledNode)
|
|
unhandledNode = forEachStmt;
|
|
return nullptr;
|
|
}
|
|
|
|
// For-each statements require the Sequence protocol. If we don't have
|
|
// it (which generally means the standard library isn't loaded), fall
|
|
// out of the function-builder path entirely to let normal type checking
|
|
// take care of this.
|
|
auto sequenceProto = TypeChecker::getProtocol(
|
|
dc->getASTContext(), forEachStmt->getForLoc(),
|
|
KnownProtocolKind::Sequence);
|
|
if (!sequenceProto) {
|
|
if (!unhandledNode)
|
|
unhandledNode = forEachStmt;
|
|
return nullptr;
|
|
}
|
|
|
|
// Generate constraints for the loop header. This also wires up the
|
|
// types for the patterns.
|
|
auto target = SolutionApplicationTarget::forForEachStmt(
|
|
forEachStmt, sequenceProto, dc, /*bindPatternVarsOneWay=*/true);
|
|
if (cs) {
|
|
if (cs->generateConstraints(target, FreeTypeVariableBinding::Disallow)) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
cs->setSolutionApplicationTarget(forEachStmt, target);
|
|
}
|
|
|
|
// Visit the loop body itself.
|
|
VarDecl *bodyVar = visit(forEachStmt->getBody());
|
|
if (!bodyVar)
|
|
return nullptr;
|
|
|
|
// If there's no constraint system, there is nothing left to visit.
|
|
if (!cs)
|
|
return nullptr;
|
|
|
|
// Form a variable of array type that will capture the result of each
|
|
// iteration of the loop. We need a fresh type variable to remove the
|
|
// lvalue-ness of the array variable.
|
|
SourceLoc loc = forEachStmt->getForLoc();
|
|
VarDecl *arrayVar = buildVar(loc);
|
|
Type arrayElementType = cs->createTypeVariable(
|
|
cs->getConstraintLocator(forEachStmt), 0);
|
|
cs->addConstraint(
|
|
ConstraintKind::Equal, cs->getType(bodyVar), arrayElementType,
|
|
cs->getConstraintLocator(
|
|
forEachStmt, ConstraintLocator::RValueAdjustment));
|
|
Type arrayType = ArraySliceType::get(arrayElementType);
|
|
cs->setType(arrayVar, arrayType);
|
|
|
|
// Form an initialization of the array to an empty array literal.
|
|
Expr *arrayInitExpr = ArrayExpr::create(ctx, loc, { }, { }, loc);
|
|
cs->setContextualType(
|
|
arrayInitExpr, TypeLoc::withoutLoc(arrayType), CTP_CannotFail);
|
|
arrayInitExpr = cs->generateConstraints(arrayInitExpr, dc);
|
|
if (!arrayInitExpr) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
cs->addConstraint(
|
|
ConstraintKind::Equal, cs->getType(arrayInitExpr), arrayType,
|
|
cs->getConstraintLocator(
|
|
arrayInitExpr, LocatorPathElt::ContextualType()));
|
|
|
|
// Form a call to Array.append(_:) to add the result of executing each
|
|
// iteration of the loop body to the array formed above.
|
|
SourceLoc endLoc = forEachStmt->getEndLoc();
|
|
auto arrayVarRef = buildVarRef(arrayVar, endLoc);
|
|
auto arrayAppendRef = new (ctx) UnresolvedDotExpr(
|
|
arrayVarRef, endLoc, DeclNameRef(ctx.getIdentifier("append")),
|
|
DeclNameLoc(endLoc), /*implicit=*/true);
|
|
arrayAppendRef->setFunctionRefKind(FunctionRefKind::SingleApply);
|
|
auto bodyVarRef = buildVarRef(bodyVar, endLoc);
|
|
Expr *arrayAppendCall = CallExpr::create(
|
|
ctx, arrayAppendRef, endLoc, { bodyVarRef } , { Identifier() },
|
|
{ endLoc }, endLoc, /*trailingClosures=*/{}, /*implicit=*/true);
|
|
arrayAppendCall = cs->generateConstraints(arrayAppendCall, dc);
|
|
if (!arrayAppendCall) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
// Form the final call to buildArray(arrayVar) to allow the function
|
|
// builder to reshape the array into whatever it wants as the result of
|
|
// the for-each loop.
|
|
auto finalArrayVarRef = buildVarRef(arrayVar, endLoc);
|
|
auto buildArrayCall = buildCallIfWanted(
|
|
endLoc, ctx.Id_buildArray, { finalArrayVarRef }, { Identifier() });
|
|
assert(buildArrayCall);
|
|
buildArrayCall = cs->generateConstraints(buildArrayCall, dc);
|
|
if (!buildArrayCall) {
|
|
hadError = true;
|
|
return nullptr;
|
|
}
|
|
|
|
// Form a final variable for the for-each expression itself, which will
|
|
// be initialized with the call to the function builder's buildArray(_:).
|
|
auto finalForEachVar = buildVar(loc);
|
|
cs->setType(finalForEachVar, cs->getType(buildArrayCall));
|
|
applied.capturedStmts.insert(
|
|
{forEachStmt, {
|
|
finalForEachVar,
|
|
{ arrayVarRef, arrayInitExpr, arrayAppendCall, buildArrayCall }}});
|
|
|
|
return finalForEachVar;
|
|
}
|
|
|
|
CONTROL_FLOW_STMT(Guard)
|
|
CONTROL_FLOW_STMT(While)
|
|
CONTROL_FLOW_STMT(DoCatch)
|
|
CONTROL_FLOW_STMT(RepeatWhile)
|
|
CONTROL_FLOW_STMT(Case)
|
|
CONTROL_FLOW_STMT(Break)
|
|
CONTROL_FLOW_STMT(Continue)
|
|
CONTROL_FLOW_STMT(Fallthrough)
|
|
CONTROL_FLOW_STMT(Fail)
|
|
CONTROL_FLOW_STMT(Throw)
|
|
CONTROL_FLOW_STMT(PoundAssert)
|
|
|
|
#undef CONTROL_FLOW_STMT
|
|
};
|
|
|
|
/// Describes the target into which the result of a particular statement in
|
|
/// a closure involving a function builder should be written.
|
|
struct FunctionBuilderTarget {
|
|
enum Kind {
|
|
/// The resulting value is returned from the closure.
|
|
ReturnValue,
|
|
/// The temporary variable into which the result should be assigned.
|
|
TemporaryVar,
|
|
/// An expression to evaluate at the end of the block, allowing the update
|
|
/// of some state from an outer scope.
|
|
Expression,
|
|
} kind;
|
|
|
|
/// Captured variable information.
|
|
std::pair<VarDecl *, llvm::TinyPtrVector<Expr *>> captured;
|
|
|
|
static FunctionBuilderTarget forReturn(Expr *expr) {
|
|
return FunctionBuilderTarget{ReturnValue, {nullptr, {expr}}};
|
|
}
|
|
|
|
static FunctionBuilderTarget forAssign(VarDecl *temporaryVar,
|
|
llvm::TinyPtrVector<Expr *> exprs) {
|
|
return FunctionBuilderTarget{TemporaryVar, {temporaryVar, exprs}};
|
|
}
|
|
|
|
static FunctionBuilderTarget forExpression(Expr *expr) {
|
|
return FunctionBuilderTarget{Expression, { nullptr, { expr }}};
|
|
}
|
|
};
|
|
|
|
/// Handles the rewrite of the body of a closure to which a function builder
|
|
/// has been applied.
|
|
class BuilderClosureRewriter
|
|
: public StmtVisitor<BuilderClosureRewriter, Stmt *, FunctionBuilderTarget> {
|
|
ASTContext &ctx;
|
|
const Solution &solution;
|
|
DeclContext *dc;
|
|
AppliedBuilderTransform builderTransform;
|
|
std::function<
|
|
Optional<SolutionApplicationTarget> (SolutionApplicationTarget)>
|
|
rewriteTarget;
|
|
|
|
/// Retrieve the temporary variable that will be used to capture the
|
|
/// value of the given expression.
|
|
AppliedBuilderTransform::RecordedExpr takeCapturedExpr(Expr *expr) {
|
|
auto found = builderTransform.capturedExprs.find(expr);
|
|
assert(found != builderTransform.capturedExprs.end());
|
|
|
|
// Set the type of the temporary variable.
|
|
auto recorded = found->second;
|
|
if (auto temporaryVar = recorded.temporaryVar) {
|
|
Type type = solution.simplifyType(solution.getType(temporaryVar));
|
|
temporaryVar->setInterfaceType(type->mapTypeOutOfContext());
|
|
}
|
|
|
|
// Erase the captured expression, so we're sure we never do this twice.
|
|
builderTransform.capturedExprs.erase(found);
|
|
return recorded;
|
|
}
|
|
|
|
/// Rewrite an expression without any particularly special context.
|
|
Expr *rewriteExpr(Expr *expr) {
|
|
auto result = rewriteTarget(
|
|
SolutionApplicationTarget(expr, dc, CTP_Unused, Type(),
|
|
/*isDiscarded=*/false));
|
|
if (result)
|
|
return result->getAsExpr();
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
public:
|
|
/// Retrieve information about a captured statement.
|
|
std::pair<VarDecl *, llvm::TinyPtrVector<Expr *>>
|
|
takeCapturedStmt(Stmt *stmt) {
|
|
auto found = builderTransform.capturedStmts.find(stmt);
|
|
assert(found != builderTransform.capturedStmts.end());
|
|
|
|
// Set the type of the temporary variable.
|
|
auto temporaryVar = found->second.first;
|
|
Type type = solution.simplifyType(solution.getType(temporaryVar));
|
|
temporaryVar->setInterfaceType(type->mapTypeOutOfContext());
|
|
|
|
// Take the expressions.
|
|
auto exprs = std::move(found->second.second);
|
|
|
|
// Erase the statement, so we're sure we never do this twice.
|
|
builderTransform.capturedStmts.erase(found);
|
|
return std::make_pair(temporaryVar, std::move(exprs));
|
|
}
|
|
|
|
private:
|
|
/// Build the statement or expression to initialize the target.
|
|
ASTNode initializeTarget(FunctionBuilderTarget target) {
|
|
assert(target.captured.second.size() == 1);
|
|
auto capturedExpr = target.captured.second.front();
|
|
SourceLoc implicitLoc = capturedExpr->getEndLoc();
|
|
switch (target.kind) {
|
|
case FunctionBuilderTarget::ReturnValue: {
|
|
// Return the expression.
|
|
Type bodyResultType =
|
|
solution.simplifyType(builderTransform.bodyResultType);
|
|
|
|
SolutionApplicationTarget returnTarget(
|
|
capturedExpr, dc, CTP_ReturnStmt, bodyResultType,
|
|
/*isDiscarded=*/false);
|
|
Expr *resultExpr = nullptr;
|
|
if (auto resultTarget = rewriteTarget(returnTarget))
|
|
resultExpr = resultTarget->getAsExpr();
|
|
|
|
return new (ctx) ReturnStmt(implicitLoc, resultExpr);
|
|
}
|
|
|
|
case FunctionBuilderTarget::TemporaryVar: {
|
|
// Assign the expression into a variable.
|
|
auto temporaryVar = target.captured.first;
|
|
auto declRef = new (ctx) DeclRefExpr(
|
|
temporaryVar, DeclNameLoc(implicitLoc), /*implicit=*/true);
|
|
declRef->setType(LValueType::get(temporaryVar->getType()));
|
|
|
|
// Load the right-hand side if needed.
|
|
auto finalCapturedExpr = rewriteExpr(capturedExpr);
|
|
if (finalCapturedExpr->getType()->hasLValueType()) {
|
|
finalCapturedExpr =
|
|
TypeChecker::addImplicitLoadExpr(ctx, finalCapturedExpr);
|
|
}
|
|
|
|
auto assign = new (ctx) AssignExpr(
|
|
declRef, implicitLoc, finalCapturedExpr, /*implicit=*/true);
|
|
assign->setType(TupleType::getEmpty(ctx));
|
|
return assign;
|
|
}
|
|
|
|
case FunctionBuilderTarget::Expression:
|
|
// Execute the expression.
|
|
return rewriteExpr(capturedExpr);
|
|
}
|
|
llvm_unreachable("invalid function builder target");
|
|
}
|
|
|
|
/// Declare the given temporary variable, adding the appropriate
|
|
/// entries to the elements of a brace stmt.
|
|
void declareTemporaryVariable(VarDecl *temporaryVar,
|
|
std::vector<ASTNode> &elements,
|
|
Expr *initExpr = nullptr) {
|
|
if (!temporaryVar)
|
|
return;
|
|
|
|
// Form a new pattern binding to bind the temporary variable to the
|
|
// transformed expression.
|
|
auto pattern = NamedPattern::createImplicit(ctx, temporaryVar);
|
|
pattern->setType(temporaryVar->getType());
|
|
|
|
auto pbd = PatternBindingDecl::create(
|
|
ctx, SourceLoc(), StaticSpellingKind::None, temporaryVar->getLoc(),
|
|
pattern, SourceLoc(), initExpr, dc);
|
|
elements.push_back(temporaryVar);
|
|
elements.push_back(pbd);
|
|
}
|
|
|
|
/// Produce a final type-checked pattern binding.
|
|
void finishPatternBindingDecl(PatternBindingDecl *patternBinding) {
|
|
for (unsigned index : range(patternBinding->getNumPatternEntries())) {
|
|
// Find the solution application target for this.
|
|
auto knownTarget =
|
|
builderTransform.patternBindingEntries.find({patternBinding, index});
|
|
assert(knownTarget != builderTransform.patternBindingEntries.end());
|
|
|
|
// Rewrite the target.
|
|
auto resultTarget = rewriteTarget(knownTarget->second);
|
|
if (!resultTarget)
|
|
continue;
|
|
|
|
patternBinding->setPattern(
|
|
index, resultTarget->getInitializationPattern(),
|
|
resultTarget->getDeclContext());
|
|
patternBinding->setInit(index, resultTarget->getAsExpr());
|
|
}
|
|
}
|
|
|
|
public:
|
|
BuilderClosureRewriter(
|
|
const Solution &solution,
|
|
DeclContext *dc,
|
|
const AppliedBuilderTransform &builderTransform,
|
|
std::function<
|
|
Optional<SolutionApplicationTarget> (SolutionApplicationTarget)>
|
|
rewriteTarget
|
|
) : ctx(solution.getConstraintSystem().getASTContext()),
|
|
solution(solution), dc(dc), builderTransform(builderTransform),
|
|
rewriteTarget(rewriteTarget) { }
|
|
|
|
Stmt *visitBraceStmt(BraceStmt *braceStmt, FunctionBuilderTarget target,
|
|
Optional<FunctionBuilderTarget> innerTarget = None) {
|
|
std::vector<ASTNode> newElements;
|
|
|
|
// If there is an "inner" target corresponding to this brace, declare
|
|
// it's temporary variable if needed.
|
|
if (innerTarget) {
|
|
declareTemporaryVariable(innerTarget->captured.first, newElements);
|
|
}
|
|
|
|
for (auto node : braceStmt->getElements()) {
|
|
// Implicit returns in single-expression function bodies are treated
|
|
// as the expression.
|
|
if (auto returnStmt =
|
|
dyn_cast_or_null<ReturnStmt>(node.dyn_cast<Stmt *>())) {
|
|
assert(returnStmt->isImplicit());
|
|
node = returnStmt->getResult();
|
|
}
|
|
|
|
if (auto expr = node.dyn_cast<Expr *>()) {
|
|
// Skip error expressions.
|
|
if (isa<ErrorExpr>(expr))
|
|
continue;
|
|
|
|
// Each expression turns into a 'let' that captures the value of
|
|
// the expression.
|
|
auto recorded = takeCapturedExpr(expr);
|
|
|
|
// Rewrite the expression
|
|
Expr *finalExpr = rewriteExpr(recorded.generatedExpr);
|
|
|
|
// Form a new pattern binding to bind the temporary variable to the
|
|
// transformed expression.
|
|
declareTemporaryVariable(recorded.temporaryVar, newElements, finalExpr);
|
|
continue;
|
|
}
|
|
|
|
if (auto stmt = node.dyn_cast<Stmt *>()) {
|
|
// Each statement turns into a (potential) temporary variable
|
|
// binding followed by the statement itself.
|
|
auto captured = takeCapturedStmt(stmt);
|
|
|
|
declareTemporaryVariable(captured.first, newElements);
|
|
|
|
Stmt *finalStmt = visit(
|
|
stmt,
|
|
FunctionBuilderTarget{FunctionBuilderTarget::TemporaryVar,
|
|
std::move(captured)});
|
|
newElements.push_back(finalStmt);
|
|
continue;
|
|
}
|
|
|
|
auto decl = node.get<Decl *>();
|
|
|
|
// Skip #if declarations.
|
|
if (isa<IfConfigDecl>(decl)) {
|
|
newElements.push_back(decl);
|
|
continue;
|
|
}
|
|
|
|
// Diagnose #warning / #error during application.
|
|
if (auto poundDiag = dyn_cast<PoundDiagnosticDecl>(decl)) {
|
|
TypeChecker::typeCheckDecl(poundDiag);
|
|
newElements.push_back(decl);
|
|
continue;
|
|
}
|
|
|
|
// Skip variable declarations; they're always part of a pattern
|
|
// binding.
|
|
if (isa<VarDecl>(decl)) {
|
|
newElements.push_back(decl);
|
|
continue;
|
|
}
|
|
|
|
// Handle pattern bindings.
|
|
if (auto patternBinding = dyn_cast<PatternBindingDecl>(decl)) {
|
|
finishPatternBindingDecl(patternBinding);
|
|
newElements.push_back(decl);
|
|
continue;
|
|
}
|
|
|
|
llvm_unreachable("Cannot yet handle declarations");
|
|
}
|
|
|
|
// If there is an "inner" target corresponding to this brace, initialize
|
|
// it.
|
|
if (innerTarget) {
|
|
newElements.push_back(initializeTarget(*innerTarget));
|
|
}
|
|
|
|
// Capture the result of the buildBlock() call in the manner requested
|
|
// by the caller.
|
|
newElements.push_back(initializeTarget(target));
|
|
|
|
return BraceStmt::create(ctx, braceStmt->getLBraceLoc(), newElements,
|
|
braceStmt->getRBraceLoc());
|
|
}
|
|
|
|
Stmt *visitIfStmt(IfStmt *ifStmt, FunctionBuilderTarget target) {
|
|
// Rewrite the condition.
|
|
if (auto condition = rewriteTarget(
|
|
SolutionApplicationTarget(ifStmt->getCond(), dc)))
|
|
ifStmt->setCond(*condition->getAsStmtCondition());
|
|
|
|
assert(target.kind == FunctionBuilderTarget::TemporaryVar);
|
|
auto temporaryVar = target.captured.first;
|
|
|
|
// Translate the "then" branch.
|
|
auto capturedThen = takeCapturedStmt(ifStmt->getThenStmt());
|
|
auto newThen = visitBraceStmt(cast<BraceStmt>(ifStmt->getThenStmt()),
|
|
FunctionBuilderTarget::forAssign(
|
|
temporaryVar, {target.captured.second[0]}),
|
|
FunctionBuilderTarget::forAssign(
|
|
capturedThen.first, {capturedThen.second.front()}));
|
|
ifStmt->setThenStmt(newThen);
|
|
|
|
if (auto elseBraceStmt =
|
|
dyn_cast_or_null<BraceStmt>(ifStmt->getElseStmt())) {
|
|
// Translate the "else" branch when it's a stmt-brace.
|
|
auto capturedElse = takeCapturedStmt(elseBraceStmt);
|
|
Stmt *newElse = visitBraceStmt(
|
|
elseBraceStmt,
|
|
FunctionBuilderTarget::forAssign(
|
|
temporaryVar, {target.captured.second[1]}),
|
|
FunctionBuilderTarget::forAssign(
|
|
capturedElse.first, {capturedElse.second.front()}));
|
|
ifStmt->setElseStmt(newElse);
|
|
} else if (auto elseIfStmt = cast_or_null<IfStmt>(ifStmt->getElseStmt())){
|
|
// Translate the "else" branch when it's an else-if.
|
|
auto capturedElse = takeCapturedStmt(elseIfStmt);
|
|
std::vector<ASTNode> newElseElements;
|
|
declareTemporaryVariable(capturedElse.first, newElseElements);
|
|
newElseElements.push_back(
|
|
visitIfStmt(
|
|
elseIfStmt,
|
|
FunctionBuilderTarget::forAssign(
|
|
capturedElse.first, capturedElse.second)));
|
|
newElseElements.push_back(
|
|
initializeTarget(
|
|
FunctionBuilderTarget::forAssign(
|
|
temporaryVar, {target.captured.second[1]})));
|
|
|
|
Stmt *newElse = BraceStmt::create(
|
|
ctx, elseIfStmt->getStartLoc(), newElseElements,
|
|
elseIfStmt->getEndLoc());
|
|
ifStmt->setElseStmt(newElse);
|
|
} else {
|
|
// Form an "else" brace containing an assignment to the temporary
|
|
// variable.
|
|
auto init = initializeTarget(
|
|
FunctionBuilderTarget::forAssign(
|
|
temporaryVar, {target.captured.second[1]}));
|
|
auto newElse = BraceStmt::create(
|
|
ctx, ifStmt->getEndLoc(), { init }, ifStmt->getEndLoc());
|
|
ifStmt->setElseStmt(newElse);
|
|
}
|
|
|
|
return ifStmt;
|
|
}
|
|
|
|
Stmt *visitDoStmt(DoStmt *doStmt, FunctionBuilderTarget target) {
|
|
// Each statement turns into a (potential) temporary variable
|
|
// binding followed by the statement itself.
|
|
auto body = cast<BraceStmt>(doStmt->getBody());
|
|
auto captured = takeCapturedStmt(body);
|
|
|
|
auto newInnerBody = cast<BraceStmt>(
|
|
visitBraceStmt(
|
|
body,
|
|
target,
|
|
FunctionBuilderTarget::forAssign(
|
|
captured.first, {captured.second.front()})));
|
|
doStmt->setBody(newInnerBody);
|
|
return doStmt;
|
|
}
|
|
|
|
Stmt *visitSwitchStmt(SwitchStmt *switchStmt, FunctionBuilderTarget target) {
|
|
// Translate the subject expression.
|
|
ConstraintSystem &cs = solution.getConstraintSystem();
|
|
auto subjectTarget =
|
|
rewriteTarget(*cs.getSolutionApplicationTarget(switchStmt));
|
|
if (!subjectTarget)
|
|
return nullptr;
|
|
|
|
switchStmt->setSubjectExpr(subjectTarget->getAsExpr());
|
|
|
|
// Handle any declaration nodes within the case list first; we'll
|
|
// handle the cases in a second pass.
|
|
for (auto child : switchStmt->getRawCases()) {
|
|
if (auto decl = child.dyn_cast<Decl *>()) {
|
|
TypeChecker::typeCheckDecl(decl);
|
|
}
|
|
}
|
|
|
|
// Translate all of the cases.
|
|
bool limitExhaustivityChecks = false;
|
|
assert(target.kind == FunctionBuilderTarget::TemporaryVar);
|
|
auto temporaryVar = target.captured.first;
|
|
unsigned caseIndex = 0;
|
|
for (auto caseStmt : switchStmt->getCases()) {
|
|
if (!visitCaseStmt(
|
|
caseStmt,
|
|
FunctionBuilderTarget::forAssign(
|
|
temporaryVar, {target.captured.second[caseIndex]})))
|
|
return nullptr;
|
|
|
|
// Check restrictions on '@unknown'.
|
|
if (caseStmt->hasUnknownAttr()) {
|
|
checkUnknownAttrRestrictions(
|
|
cs.getASTContext(), caseStmt, /*fallthroughDest=*/nullptr,
|
|
limitExhaustivityChecks);
|
|
}
|
|
|
|
++caseIndex;
|
|
}
|
|
|
|
TypeChecker::checkSwitchExhaustiveness(
|
|
switchStmt, dc, limitExhaustivityChecks);
|
|
|
|
return switchStmt;
|
|
}
|
|
|
|
Stmt *visitCaseStmt(CaseStmt *caseStmt, FunctionBuilderTarget target) {
|
|
// Translate the patterns and guard expressions for each case label item.
|
|
for (auto &caseLabelItem : caseStmt->getMutableCaseLabelItems()) {
|
|
SolutionApplicationTarget caseLabelTarget(&caseLabelItem, dc);
|
|
if (!rewriteTarget(caseLabelTarget))
|
|
return nullptr;
|
|
}
|
|
|
|
// Transform the body of the case.
|
|
auto body = cast<BraceStmt>(caseStmt->getBody());
|
|
auto captured = takeCapturedStmt(body);
|
|
auto newInnerBody = cast<BraceStmt>(
|
|
visitBraceStmt(
|
|
body,
|
|
target,
|
|
FunctionBuilderTarget::forAssign(
|
|
captured.first, {captured.second.front()})));
|
|
caseStmt->setBody(newInnerBody);
|
|
|
|
return caseStmt;
|
|
}
|
|
|
|
Stmt *visitForEachStmt(
|
|
ForEachStmt *forEachStmt, FunctionBuilderTarget target) {
|
|
// Translate the for-each loop header.
|
|
ConstraintSystem &cs = solution.getConstraintSystem();
|
|
auto forEachTarget =
|
|
rewriteTarget(*cs.getSolutionApplicationTarget(forEachStmt));
|
|
if (!forEachTarget)
|
|
return nullptr;
|
|
|
|
const auto &captured = target.captured;
|
|
auto finalForEachVar = captured.first;
|
|
auto arrayVarRef = captured.second[0];
|
|
auto arrayVar = cast<VarDecl>(cast<DeclRefExpr>(arrayVarRef)->getDecl());
|
|
auto arrayInitExpr = captured.second[1];
|
|
auto arrayAppendCall = captured.second[2];
|
|
auto buildArrayCall = captured.second[3];
|
|
|
|
// Collect the three steps to initialize the array variable to an
|
|
// empty array, execute the loop to collect the results of each iteration,
|
|
// then form the buildArray() call to the write the result.
|
|
std::vector<ASTNode> outerBodySteps;
|
|
|
|
// Step 1: Declare and initialize the array variable.
|
|
arrayVar->setInterfaceType(solution.simplifyType(cs.getType(arrayVar)));
|
|
arrayInitExpr = rewriteExpr(arrayInitExpr);
|
|
declareTemporaryVariable(arrayVar, outerBodySteps, arrayInitExpr);
|
|
|
|
// Step 2. Transform the body of the for-each statement. Each iteration
|
|
// will append the result of executing the loop body to the array.
|
|
auto body = forEachStmt->getBody();
|
|
auto capturedBody = takeCapturedStmt(body);
|
|
auto newBody = cast<BraceStmt>(
|
|
visitBraceStmt(
|
|
body,
|
|
FunctionBuilderTarget::forExpression(arrayAppendCall),
|
|
FunctionBuilderTarget::forAssign(
|
|
capturedBody.first, {capturedBody.second.front()})));
|
|
forEachStmt->setBody(newBody);
|
|
outerBodySteps.push_back(forEachStmt);
|
|
|
|
// Step 3. Perform the buildArray() call to turn the array of results
|
|
// collected from the iterations into a single value under the control of
|
|
// the function builder.
|
|
outerBodySteps.push_back(
|
|
initializeTarget(
|
|
FunctionBuilderTarget::forAssign(finalForEachVar, {buildArrayCall})));
|
|
|
|
// Form a brace statement to put together the three main steps for the
|
|
// for-each loop translation outlined above.
|
|
return BraceStmt::create(
|
|
ctx, forEachStmt->getStartLoc(), outerBodySteps, newBody->getEndLoc());
|
|
}
|
|
|
|
#define UNHANDLED_FUNCTION_BUILDER_STMT(STMT) \
|
|
Stmt *visit##STMT##Stmt(STMT##Stmt *stmt, FunctionBuilderTarget target) { \
|
|
llvm_unreachable("Function builders do not allow statement of kind " \
|
|
#STMT); \
|
|
}
|
|
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Return)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Yield)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Guard)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(While)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Defer)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(DoCatch)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(RepeatWhile)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Break)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Continue)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Fallthrough)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Fail)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(Throw)
|
|
UNHANDLED_FUNCTION_BUILDER_STMT(PoundAssert)
|
|
#undef UNHANDLED_FUNCTION_BUILDER_STMT
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
BraceStmt *swift::applyFunctionBuilderTransform(
|
|
const Solution &solution,
|
|
AppliedBuilderTransform applied,
|
|
BraceStmt *body,
|
|
DeclContext *dc,
|
|
std::function<
|
|
Optional<SolutionApplicationTarget> (SolutionApplicationTarget)>
|
|
rewriteTarget) {
|
|
BuilderClosureRewriter rewriter(solution, dc, applied, rewriteTarget);
|
|
auto captured = rewriter.takeCapturedStmt(body);
|
|
return cast<BraceStmt>(
|
|
rewriter.visitBraceStmt(
|
|
body,
|
|
FunctionBuilderTarget::forReturn(applied.returnExpr),
|
|
FunctionBuilderTarget::forAssign(
|
|
captured.first, captured.second)));
|
|
}
|
|
|
|
Optional<BraceStmt *> TypeChecker::applyFunctionBuilderBodyTransform(
|
|
FuncDecl *func, Type builderType) {
|
|
// Pre-check the body: pre-check any expressions in it and look
|
|
// for return statements.
|
|
//
|
|
// If we encountered an error or there was an explicit result type,
|
|
// bail out and report that to the caller.
|
|
auto &ctx = func->getASTContext();
|
|
auto request = PreCheckFunctionBuilderRequest{func};
|
|
switch (evaluateOrDefault(
|
|
ctx.evaluator, request, FunctionBuilderBodyPreCheck::Error)) {
|
|
case FunctionBuilderBodyPreCheck::Okay:
|
|
// If the pre-check was okay, apply the function-builder transform.
|
|
break;
|
|
|
|
case FunctionBuilderBodyPreCheck::Error:
|
|
return nullptr;
|
|
|
|
case FunctionBuilderBodyPreCheck::HasReturnStmt: {
|
|
// One or more explicit 'return' statements were encountered, which
|
|
// disables the function builder transform. Warn when we do this.
|
|
auto returnStmts = findReturnStatements(func);
|
|
assert(!returnStmts.empty());
|
|
|
|
ctx.Diags.diagnose(
|
|
returnStmts.front()->getReturnLoc(),
|
|
diag::function_builder_disabled_by_return, builderType);
|
|
|
|
// Note that one can remove the function builder attribute.
|
|
auto attr = func->getAttachedFunctionBuilder();
|
|
if (!attr) {
|
|
if (auto accessor = dyn_cast<AccessorDecl>(func)) {
|
|
attr = accessor->getStorage()->getAttachedFunctionBuilder();
|
|
}
|
|
}
|
|
|
|
if (attr) {
|
|
ctx.Diags.diagnose(
|
|
attr->getLocation(), diag::function_builder_remove_attr)
|
|
.fixItRemove(attr->getRangeWithAt());
|
|
attr->setInvalid();
|
|
}
|
|
|
|
// Note that one can remove all of the return statements.
|
|
{
|
|
auto diag = ctx.Diags.diagnose(
|
|
returnStmts.front()->getReturnLoc(),
|
|
diag::function_builder_remove_returns);
|
|
for (auto returnStmt : returnStmts) {
|
|
diag.fixItRemove(returnStmt->getReturnLoc());
|
|
}
|
|
}
|
|
|
|
return None;
|
|
}
|
|
}
|
|
|
|
ConstraintSystemOptions options = ConstraintSystemFlags::AllowFixes;
|
|
auto resultInterfaceTy = func->getResultInterfaceType();
|
|
auto resultContextType = func->mapTypeIntoContext(resultInterfaceTy);
|
|
|
|
// Determine whether we're inferring the underlying type for the opaque
|
|
// result type of this function.
|
|
ConstraintKind resultConstraintKind = ConstraintKind::Conversion;
|
|
if (auto opaque = resultContextType->getAs<OpaqueTypeArchetypeType>()) {
|
|
if (opaque->getDecl()->isOpaqueReturnTypeOfFunction(func)) {
|
|
resultConstraintKind = ConstraintKind::OpaqueUnderlyingType;
|
|
}
|
|
}
|
|
|
|
// Build a constraint system in which we can check the body of the function.
|
|
ConstraintSystem cs(func, options);
|
|
|
|
if (auto result = cs.matchFunctionBuilder(
|
|
func, builderType, resultContextType, resultConstraintKind,
|
|
cs.getConstraintLocator(func->getBody()),
|
|
cs.getConstraintLocator(func->getBody()))) {
|
|
if (result->isFailure())
|
|
return nullptr;
|
|
}
|
|
|
|
// Solve the constraint system.
|
|
SmallVector<Solution, 4> solutions;
|
|
if (cs.solve(solutions) || solutions.size() != 1) {
|
|
// Try to fix the system or provide a decent diagnostic.
|
|
auto salvagedResult = cs.salvage();
|
|
switch (salvagedResult.getKind()) {
|
|
case SolutionResult::Kind::Success:
|
|
solutions.clear();
|
|
solutions.push_back(std::move(salvagedResult).takeSolution());
|
|
break;
|
|
|
|
case SolutionResult::Kind::Error:
|
|
case SolutionResult::Kind::Ambiguous:
|
|
return nullptr;
|
|
|
|
case SolutionResult::Kind::UndiagnosedError:
|
|
cs.diagnoseFailureFor(SolutionApplicationTarget(func));
|
|
salvagedResult.markAsDiagnosed();
|
|
return nullptr;
|
|
|
|
case SolutionResult::Kind::TooComplex:
|
|
func->diagnose(diag::expression_too_complex)
|
|
.highlight(func->getBodySourceRange());
|
|
salvagedResult.markAsDiagnosed();
|
|
return nullptr;
|
|
}
|
|
|
|
// The system was salvaged; continue on as if nothing happened.
|
|
}
|
|
|
|
// FIXME: Shouldn't need to do this.
|
|
cs.applySolution(solutions.front());
|
|
|
|
// Apply the solution to the function body.
|
|
if (auto result = cs.applySolution(
|
|
solutions.front(),
|
|
SolutionApplicationTarget(func))) {
|
|
return result->getFunctionBody();
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Optional<ConstraintSystem::TypeMatchResult>
|
|
ConstraintSystem::matchFunctionBuilder(
|
|
AnyFunctionRef fn, Type builderType, Type bodyResultType,
|
|
ConstraintKind bodyResultConstraintKind,
|
|
ConstraintLocator *calleeLocator, ConstraintLocatorBuilder locator) {
|
|
auto builder = builderType->getAnyNominal();
|
|
assert(builder && "Bad function builder type");
|
|
assert(builder->getAttrs().hasAttribute<FunctionBuilderAttr>());
|
|
|
|
// Pre-check the body: pre-check any expressions in it and look
|
|
// for return statements.
|
|
auto request = PreCheckFunctionBuilderRequest{fn};
|
|
switch (evaluateOrDefault(getASTContext().evaluator, request,
|
|
FunctionBuilderBodyPreCheck::Error)) {
|
|
case FunctionBuilderBodyPreCheck::Okay:
|
|
// If the pre-check was okay, apply the function-builder transform.
|
|
break;
|
|
|
|
case FunctionBuilderBodyPreCheck::Error:
|
|
// If the pre-check had an error, flag that.
|
|
return getTypeMatchFailure(locator);
|
|
|
|
case FunctionBuilderBodyPreCheck::HasReturnStmt:
|
|
// If the body has a return statement, suppress the transform but
|
|
// continue solving the constraint system.
|
|
return None;
|
|
}
|
|
|
|
// Check the form of this body to see if we can apply the
|
|
// function-builder translation at all.
|
|
auto dc = fn.getAsDeclContext();
|
|
{
|
|
// Check whether we can apply this specific function builder.
|
|
BuilderClosureVisitor visitor(getASTContext(), nullptr, dc, builderType,
|
|
bodyResultType);
|
|
|
|
// If we saw a control-flow statement or declaration that the builder
|
|
// cannot handle, we don't have a well-formed function builder application.
|
|
if (auto unhandledNode = visitor.check(fn.getBody())) {
|
|
// If we aren't supposed to attempt fixes, fail.
|
|
if (!shouldAttemptFixes()) {
|
|
return getTypeMatchFailure(locator);
|
|
}
|
|
|
|
// Record the first unhandled construct as a fix.
|
|
if (recordFix(
|
|
SkipUnhandledConstructInFunctionBuilder::create(
|
|
*this, unhandledNode, builder,
|
|
getConstraintLocator(locator)))) {
|
|
return getTypeMatchFailure(locator);
|
|
}
|
|
}
|
|
}
|
|
|
|
// If the builder type has a type parameter, substitute in the type
|
|
// variables.
|
|
if (builderType->hasTypeParameter()) {
|
|
// Find the opened type for this callee and substitute in the type
|
|
// parametes.
|
|
for (const auto &opened : OpenedTypes) {
|
|
if (opened.first == calleeLocator) {
|
|
OpenedTypeMap replacements(opened.second.begin(),
|
|
opened.second.end());
|
|
builderType = openType(builderType, replacements);
|
|
break;
|
|
}
|
|
}
|
|
assert(!builderType->hasTypeParameter());
|
|
}
|
|
|
|
BuilderClosureVisitor visitor(getASTContext(), this, dc, builderType,
|
|
bodyResultType);
|
|
|
|
auto applied = visitor.apply(fn.getBody());
|
|
if (!applied)
|
|
return getTypeMatchFailure(locator);
|
|
|
|
Type transformedType = getType(applied->returnExpr);
|
|
assert(transformedType && "Missing type");
|
|
|
|
// Record the transformation.
|
|
assert(std::find_if(
|
|
functionBuilderTransformed.begin(),
|
|
functionBuilderTransformed.end(),
|
|
[&](const std::pair<AnyFunctionRef, AppliedBuilderTransform> &elt) {
|
|
return elt.first == fn;
|
|
}) == functionBuilderTransformed.end() &&
|
|
"already transformed this body along this path!?!");
|
|
functionBuilderTransformed.push_back(
|
|
std::make_pair(fn, std::move(*applied)));
|
|
|
|
// If builder is applied to the closure expression then
|
|
// `closure body` to `closure result` matching should
|
|
// use special locator.
|
|
if (auto *closure = fn.getAbstractClosureExpr())
|
|
locator = getConstraintLocator(closure, ConstraintLocator::ClosureResult);
|
|
|
|
// Bind the body result type to the type of the transformed expression.
|
|
addConstraint(bodyResultConstraintKind, transformedType, bodyResultType,
|
|
locator);
|
|
return getTypeMatchSuccess();
|
|
}
|
|
|
|
namespace {
|
|
|
|
/// Pre-check all the expressions in the body.
|
|
class PreCheckFunctionBuilderApplication : public ASTWalker {
|
|
AnyFunctionRef Fn;
|
|
bool SkipPrecheck = false;
|
|
std::vector<ReturnStmt *> ReturnStmts;
|
|
bool HasError = false;
|
|
|
|
bool hasReturnStmt() const { return !ReturnStmts.empty(); }
|
|
|
|
public:
|
|
PreCheckFunctionBuilderApplication(AnyFunctionRef fn, bool skipPrecheck)
|
|
: Fn(fn), SkipPrecheck(skipPrecheck) {}
|
|
|
|
const std::vector<ReturnStmt *> getReturnStmts() const { return ReturnStmts; }
|
|
|
|
FunctionBuilderBodyPreCheck run() {
|
|
Stmt *oldBody = Fn.getBody();
|
|
|
|
Stmt *newBody = oldBody->walk(*this);
|
|
|
|
// If the walk was aborted, it was because we had a problem of some kind.
|
|
assert((newBody == nullptr) == HasError &&
|
|
"unexpected short-circuit while walking body");
|
|
if (HasError)
|
|
return FunctionBuilderBodyPreCheck::Error;
|
|
|
|
if (hasReturnStmt())
|
|
return FunctionBuilderBodyPreCheck::HasReturnStmt;
|
|
|
|
assert(oldBody == newBody && "pre-check walk wasn't in-place?");
|
|
|
|
return FunctionBuilderBodyPreCheck::Okay;
|
|
}
|
|
|
|
std::pair<bool, Expr *> walkToExprPre(Expr *E) override {
|
|
// Pre-check the expression. If this fails, abort the walk immediately.
|
|
// Otherwise, replace the expression with the result of pre-checking.
|
|
// In either case, don't recurse into the expression.
|
|
if (!SkipPrecheck &&
|
|
ConstraintSystem::preCheckExpression(E, /*DC*/ Fn.getAsDeclContext())) {
|
|
HasError = true;
|
|
return std::make_pair(false, nullptr);
|
|
}
|
|
|
|
return std::make_pair(false, E);
|
|
}
|
|
|
|
std::pair<bool, Stmt *> walkToStmtPre(Stmt *S) override {
|
|
// If we see a return statement, note it..
|
|
if (auto returnStmt = dyn_cast<ReturnStmt>(S)) {
|
|
if (!returnStmt->isImplicit()) {
|
|
ReturnStmts.push_back(returnStmt);
|
|
return std::make_pair(false, S);
|
|
}
|
|
}
|
|
|
|
// Otherwise, recurse into the statement normally.
|
|
return std::make_pair(true, S);
|
|
}
|
|
|
|
/// Ignore patterns.
|
|
std::pair<bool, Pattern*> walkToPatternPre(Pattern *pat) override {
|
|
return { false, pat };
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
FunctionBuilderBodyPreCheck
|
|
PreCheckFunctionBuilderRequest::evaluate(Evaluator &eval,
|
|
AnyFunctionRef fn) const {
|
|
return PreCheckFunctionBuilderApplication(fn, false).run();
|
|
}
|
|
|
|
std::vector<ReturnStmt *> TypeChecker::findReturnStatements(AnyFunctionRef fn) {
|
|
PreCheckFunctionBuilderApplication precheck(fn, true);
|
|
(void)precheck.run();
|
|
return precheck.getReturnStmts();
|
|
}
|