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[CodeSynthesis] Improve synthesized Decodable.init(from:) for enums #41674

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Merged
merged 1 commit into from
Mar 11, 2022
Merged

[CodeSynthesis] Improve synthesized Decodable.init(from:) for enums #41674

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3 changes: 2 additions & 1 deletion include/swift/AST/KnownIdentifiers.def
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Original file line number Diff line number Diff line change
Expand Up @@ -109,6 +109,7 @@ IDENTIFIER(keyPath)
IDENTIFIER(makeIterator)
IDENTIFIER(makeAsyncIterator)
IDENTIFIER(nestedContainer)
IDENTIFIER(isEmpty)
IDENTIFIER(Iterator)
IDENTIFIER(AsyncIterator)
IDENTIFIER(load)
Expand All @@ -124,6 +125,7 @@ IDENTIFIER(oldValue)
IDENTIFIER(Optional)
IDENTIFIER_(OptionalNilComparisonType)
IDENTIFIER(parameter)
IDENTIFIER(popFirst)
IDENTIFIER(projected)
IDENTIFIER(projectedValue)
IDENTIFIER(Protocol)
Expand All @@ -149,7 +151,6 @@ IDENTIFIER(Type)
IDENTIFIER(type)
IDENTIFIER(typeMismatch)
IDENTIFIER(underlyingError)
IDENTIFIER(unsafelyUnwrapped)
IDENTIFIER(Value)
IDENTIFIER(value)
IDENTIFIER_WITH_NAME(value_, "_value")
Expand Down
1 change: 1 addition & 0 deletions include/swift/AST/KnownStdlibTypes.def
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Expand Up @@ -49,6 +49,7 @@ KNOWN_STDLIB_TYPE_DECL(String, NominalTypeDecl, 0)
KNOWN_STDLIB_TYPE_DECL(StaticString, NominalTypeDecl, 0)
KNOWN_STDLIB_TYPE_DECL(Substring, NominalTypeDecl, 0)
KNOWN_STDLIB_TYPE_DECL(Array, NominalTypeDecl, 1)
KNOWN_STDLIB_TYPE_DECL(ArraySlice, NominalTypeDecl, 1)
KNOWN_STDLIB_TYPE_DECL(_ContiguousArrayStorage, ClassDecl, 1)
KNOWN_STDLIB_TYPE_DECL(Set, NominalTypeDecl, 1)
KNOWN_STDLIB_TYPE_DECL(Sequence, NominalTypeDecl, 1)
Expand Down
30 changes: 16 additions & 14 deletions lib/AST/ASTPrinter.cpp
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Expand Up @@ -4917,20 +4917,22 @@ void PrintAST::visitRepeatWhileStmt(RepeatWhileStmt *stmt) {
visit(stmt->getCond());
}

void PrintAST::printStmtCondition(StmtCondition stmt) {
for (auto elt : stmt) {
if (auto pattern = elt.getPatternOrNull()) {
printPattern(pattern);
auto initializer = elt.getInitializer();
if (initializer) {
Printer << " = ";
visit(initializer);
}
}
else if (auto boolean = elt.getBooleanOrNull()) {
visit(boolean);
}
}
void PrintAST::printStmtCondition(StmtCondition condition) {
interleave(
condition,
[&](StmtConditionElement &elt) {
if (auto pattern = elt.getPatternOrNull()) {
printPattern(pattern);
auto initializer = elt.getInitializer();
if (initializer) {
Printer << " = ";
visit(initializer);
}
} else if (auto boolean = elt.getBooleanOrNull()) {
visit(boolean);
}
},
[&] { Printer << ", "; });
}

void PrintAST::visitDoStmt(DoStmt *stmt) {
Expand Down
98 changes: 64 additions & 34 deletions lib/Sema/DerivedConformanceCodable.cpp
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Expand Up @@ -1552,13 +1552,14 @@ deriveBodyDecodable_enum_init(AbstractFunctionDecl *initDecl, void *) {
//
// @derived init(from decoder: Decoder) throws {
// let container = try decoder.container(keyedBy: CodingKeys.self)
// if container.allKeys.count != 1 {
// var allKeys = ArraySlice(container.allKeys)
// guard let onlyKey = allKeys.popFirst(), allKeys.isEmpty else {
// let context = DecodingError.Context(
// codingPath: container.codingPath,
// debugDescription: "Invalid number of keys found, expected one.")
// throw DecodingError.typeMismatch(Foo.self, context)
// }
// switch container.allKeys.first {
// switch onlyKey {
// case .bar:
// let nestedContainer = try container.nestedContainer(
// keyedBy: BarCodingKeys.self, forKey: .bar)
Expand Down Expand Up @@ -1597,15 +1598,67 @@ deriveBodyDecodable_enum_init(AbstractFunctionDecl *initDecl, void *) {
initDecl->getParameters()->get(0), codingKeysEnum, statements,
/*throws*/ true);

// generate: var allKeys = ArraySlice(container.allKeys);
auto *allKeysDecl =
new (C) VarDecl(/*IsStatic=*/false, VarDecl::Introducer::Var,
SourceLoc(), C.Id_allKeys, funcDC);
allKeysDecl->setImplicit();
allKeysDecl->setSynthesized();
{
auto *arraySliceRef =
new (C) DeclRefExpr(ConcreteDeclRef(C.getArraySliceDecl()),
DeclNameLoc(), /*Implicit=*/true);
auto *containerAllKeys =
UnresolvedDotExpr::createImplicit(C, containerExpr, C.Id_allKeys);
auto *argList = ArgumentList::createImplicit(
C, {Argument::unlabeled(containerAllKeys)});
auto *init = CallExpr::createImplicit(C, arraySliceRef, argList);

auto *allKeysPattern = NamedPattern::createImplicit(C, allKeysDecl);
auto *allKeysBindingDecl = PatternBindingDecl::createImplicit(
C, StaticSpellingKind::None, allKeysPattern, init, funcDC);

statements.push_back(allKeysBindingDecl);
statements.push_back(allKeysDecl);
}

// generate:
//
// if container.allKeys.count != 1 {
// guard let onlyKey = allKeys.popFirst(), allKeys.isEmpty else {
// let context = DecodingError.Context(
// codingPath: container.codingPath,
// debugDescription: "Invalid number of keys found, expected
// one.")
// throw DecodingError.typeMismatch(Foo.self, context)
// }
auto *theKeyDecl =
new (C) VarDecl(/*IsStatic=*/false, VarDecl::Introducer::Let,
SourceLoc(), C.getIdentifier("onlyKey"), funcDC);
theKeyDecl->setImplicit();
theKeyDecl->setSynthesized();

SmallVector<StmtConditionElement, 2> guardElements;
{
auto *allKeysExpr =
new (C) DeclRefExpr(ConcreteDeclRef(allKeysDecl), DeclNameLoc(),
/*Implicit=*/true);

// generate: let onlyKey = allKeys.popFirst;
auto *allKeysPopFisrtCallExpr = CallExpr::createImplicitEmpty(
C, UnresolvedDotExpr::createImplicit(C, allKeysExpr, C.Id_popFirst));

auto *theKeyPattern = BindingPattern::createImplicit(
C, /*isLet=*/true, NamedPattern::createImplicit(C, theKeyDecl));

guardElements.emplace_back(SourceLoc(), theKeyPattern,
allKeysPopFisrtCallExpr);

// generate: allKeys.isEmpty;
auto *allKeysIsEmptyExpr =
UnresolvedDotExpr::createImplicit(C, allKeysExpr, C.Id_isEmpty);

guardElements.emplace_back(allKeysIsEmptyExpr);
}

auto *targetType = TypeExpr::createImplicit(
funcDC->mapTypeIntoContext(targetEnum->getDeclaredInterfaceType()), C);
auto *targetTypeExpr =
Expand All @@ -1615,44 +1668,21 @@ deriveBodyDecodable_enum_init(AbstractFunctionDecl *initDecl, void *) {
C, containerExpr, C.getDecodingErrorDecl(), C.Id_typeMismatch,
targetTypeExpr, "Invalid number of keys found, expected one.");

// container.allKeys
auto *allKeysExpr =
UnresolvedDotExpr::createImplicit(C, containerExpr, C.Id_allKeys);

// container.allKeys.count
auto *keysCountExpr =
UnresolvedDotExpr::createImplicit(C, allKeysExpr, C.Id_count);

// container.allKeys.count == 1
auto *cmpFunc = C.getEqualIntDecl();
auto *fnType = cmpFunc->getInterfaceType()->castTo<FunctionType>();
auto *cmpFuncExpr = new (C)
DeclRefExpr(cmpFunc, DeclNameLoc(),
/*implicit*/ true, AccessSemantics::Ordinary, fnType);
auto *oneExpr = IntegerLiteralExpr::createFromUnsigned(C, 1);

auto *cmpExpr = BinaryExpr::create(C, keysCountExpr, cmpFuncExpr, oneExpr,
/*implicit*/ true);
cmpExpr->setThrows(false);

auto *guardBody = BraceStmt::create(C, SourceLoc(), {throwStmt},
SourceLoc(), /* Implicit */ true);

auto *guardStmt = new (C)
GuardStmt(SourceLoc(), cmpExpr, guardBody, /* Implicit */ true, C);
auto *guardStmt =
new (C) GuardStmt(SourceLoc(), C.AllocateCopy(guardElements), guardBody,
/* Implicit */ true);

statements.push_back(guardStmt);

// generate: switch container.allKeys.first { }
auto *firstExpr =
UnresolvedDotExpr::createImplicit(C, allKeysExpr, C.Id_first);

// generate: switch container.allKeys.first.unsafelyUnwrapped { }
auto *unwrapped =
UnresolvedDotExpr::createImplicit(C, firstExpr, C.Id_unsafelyUnwrapped);
// generate: switch onlyKey { }
auto *theKeyExpr = new (C) DeclRefExpr(ConcreteDeclRef(theKeyDecl),
DeclNameLoc(), /*Implicit=*/true);

auto switchStmt = createEnumSwitch(
C, funcDC, unwrapped, targetEnum, codingKeysEnum,
C, funcDC, theKeyExpr, targetEnum, codingKeysEnum,
/*createSubpattern*/ false,
[&](auto *elt, auto *codingKeyCase,
auto payloadVars) -> std::tuple<EnumElementDecl *, BraceStmt *> {
Expand Down
6 changes: 4 additions & 2 deletions test/refactoring/AddCodableImplementation/Outputs/enum/codable.swift.expected
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Expand Up @@ -18,10 +18,12 @@ enum Payload: Codable {
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: Payload.CodingKeys.self)

guard container.allKeys.count == 1 else {
var allKeys = ArraySlice(container.allKeys)

guard let onlyKey = allKeys.popFirst(), allKeys.isEmpty else {
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@louisdh louisdh Mar 5, 2022 •
edited
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Perfect!

I was confused at first seeing allKeys.isEmpty. Then I realized it's mutating allKeys with the popFirst() (I initially just read it as accessing the first key, not removing it from the array).

Seems like a much more efficient (and safe) way for checking that's there's only 1 key. 😃

throw DecodingError.typeMismatch(Payload.self, DecodingError.Context.init(codingPath: container.codingPath, debugDescription: "Invalid number of keys found, expected one.", underlyingError: nil))
}
switch container.allKeys.first.unsafelyUnwrapped {
switch onlyKey {
case .plain:

let nestedContainer = try container.nestedContainer(keyedBy: Payload.PlainCodingKeys.self, forKey: Payload.CodingKeys.plain)
Expand Down
6 changes: 4 additions & 2 deletions test/refactoring/AddCodableImplementation/Outputs/enum/decodable.swift.expected
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Expand Up @@ -23,10 +23,12 @@ enum Payload_D: Decodable {
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: Payload_D.CodingKeys.self)

guard container.allKeys.count == 1 else {
var allKeys = ArraySlice(container.allKeys)

guard let onlyKey = allKeys.popFirst(), allKeys.isEmpty else {
throw DecodingError.typeMismatch(Payload_D.self, DecodingError.Context.init(codingPath: container.codingPath, debugDescription: "Invalid number of keys found, expected one.", underlyingError: nil))
}
switch container.allKeys.first.unsafelyUnwrapped {
switch onlyKey {
case .plain:

let nestedContainer = try container.nestedContainer(keyedBy: Payload_D.PlainCodingKeys.self, forKey: Payload_D.CodingKeys.plain)
Expand Down