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Merged
merged 1 commit into from
Sep 11, 2018
Merged

Allow ByteTree deserialisation functions to throw #2

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49 changes: 31 additions & 18 deletions Sources/SwiftSyntax/ByteTreeDeserialization.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,17 @@ struct ByteTreeUserInfoKey: Hashable {
}
}

public enum ByteTreeDecodingError: Error, CustomStringConvertible {
case invalidEnumRawValue(type: String, value: Int)

public var description: String {
switch self {
case .invalidEnumRawValue(let type, let value):
return "Invalid raw value \"\(value)\" for \(type)"
}
}
}

/// A type that can be deserialized from ByteTree into a scalar value that
/// doesn't have any child nodes
protocol ByteTreeScalarDecodable {
Expand All @@ -32,7 +43,8 @@ protocol ByteTreeScalarDecodable {
/// - size: The length of the serialized data in bytes
/// - Returns: The deserialized value
static func read(from pointer: UnsafeRawPointer, size: Int,
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>) -> Self
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>
) throws -> Self
}

/// A type that can be deserialized from ByteTree into an object with child
Expand All @@ -50,7 +62,8 @@ protocol ByteTreeObjectDecodable {
/// - Returns: The deserialized object
static func read(from reader: UnsafeMutablePointer<ByteTreeObjectReader>,
numFields: Int,
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>) -> Self
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>
) throws -> Self
}

// MARK: - Reader objects
Expand Down Expand Up @@ -92,9 +105,9 @@ struct ByteTreeObjectReader {
/// - Returns: The decoded field
mutating func readField<FieldType: ByteTreeScalarDecodable>(
_ objectType: FieldType.Type, index: Int
) -> FieldType {
) throws -> FieldType {
advanceAndValidateIndex(index)
return reader.pointee.read(objectType)
return try reader.pointee.read(objectType)
}

/// Read the field at the given index as the specified type. All indicies must
Expand All @@ -107,9 +120,9 @@ struct ByteTreeObjectReader {
/// - Returns: The decoded field
mutating func readField<FieldType: ByteTreeObjectDecodable>(
_ objectType: FieldType.Type, index: Int
) -> FieldType {
) throws -> FieldType {
advanceAndValidateIndex(index)
return reader.pointee.read(objectType)
return try reader.pointee.read(objectType)
}

/// Read and immediately discard the field at the specified index. This
Expand Down Expand Up @@ -178,7 +191,7 @@ struct ByteTreeReader {
) throws -> T {
var reader = ByteTreeReader(pointer: pointer, userInfo: userInfo)
try reader.readAndValidateProtocolVersion(protocolVersionValidation)
return reader.read(rootObjectType)
return try reader.read(rootObjectType)
}

/// Deserialize an object tree from the ByteTree data at the given memory
Expand Down Expand Up @@ -266,15 +279,15 @@ struct ByteTreeReader {
/// - Returns: The deserialized object
fileprivate mutating func read<T: ByteTreeObjectDecodable>(
_ objectType: T.Type
) -> T {
) throws -> T {
let numFields = readObjectLength()
var objectReader = ByteTreeObjectReader(reader: &self,
numFields: numFields)
defer {
objectReader.finalize()
}
return T.read(from: &objectReader, numFields: numFields,
userInfo: userInfo)
return try T.read(from: &objectReader, numFields: numFields,
userInfo: userInfo)
}

/// Read the next field in the tree as a scalar of the specified type.
Expand All @@ -283,12 +296,12 @@ struct ByteTreeReader {
/// - Returns: The deserialized scalar
fileprivate mutating func read<T: ByteTreeScalarDecodable>(
_ scalarType: T.Type
) -> T {
) throws -> T {
let fieldSize = readScalarLength()
defer {
pointer = pointer.advanced(by: fieldSize)
}
return T.read(from: pointer, size: fieldSize, userInfo: userInfo)
return try T.read(from: pointer, size: fieldSize, userInfo: userInfo)
}

/// Discard the next scalar field, advancing the pointer to the next field
Expand Down Expand Up @@ -338,12 +351,12 @@ extension Optional: ByteTreeObjectDecodable
static func read(from reader: UnsafeMutablePointer<ByteTreeObjectReader>,
numFields: Int,
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>
) -> Optional<Wrapped> {
) throws -> Optional<Wrapped> {
if numFields == 0 {
return nil
} else {
return Wrapped.read(from: reader, numFields: numFields,
userInfo: userInfo)
return try Wrapped.read(from: reader, numFields: numFields,
userInfo: userInfo)
}
}
}
Expand All @@ -354,9 +367,9 @@ extension Array: ByteTreeObjectDecodable
static func read(from reader: UnsafeMutablePointer<ByteTreeObjectReader>,
numFields: Int,
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>
) -> Array<Element> {
return (0..<numFields).map {
return reader.pointee.readField(Element.self, index: $0)
) throws -> Array<Element> {
return try (0..<numFields).map {
return try reader.pointee.readField(Element.self, index: $0)
}
}
}
25 changes: 12 additions & 13 deletions Sources/SwiftSyntax/RawSyntax.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -409,33 +409,32 @@ extension RawSyntax: ByteTreeObjectDecodable {
static func read(from reader: UnsafeMutablePointer<ByteTreeObjectReader>,
numFields: Int,
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>
) -> RawSyntax {
) throws -> RawSyntax {
let syntaxNode: RawSyntax
let type = reader.pointee.readField(SyntaxType.self, index: 0)
let id = reader.pointee.readField(SyntaxNodeId.self, index: 1)
let type = try reader.pointee.readField(SyntaxType.self, index: 0)
let id = try reader.pointee.readField(SyntaxNodeId.self, index: 1)
switch type {
case .token:
let presence = reader.pointee.readField(SourcePresence.self, index: 2)
let kind = reader.pointee.readField(TokenKind.self, index: 3)
let leadingTrivia = reader.pointee.readField(Trivia.self, index: 4)
let trailingTrivia = reader.pointee.readField(Trivia.self, index: 5)
let presence = try reader.pointee.readField(SourcePresence.self, index: 2)
let kind = try reader.pointee.readField(TokenKind.self, index: 3)
let leadingTrivia = try reader.pointee.readField(Trivia.self, index: 4)
let trailingTrivia = try reader.pointee.readField(Trivia.self, index: 5)
syntaxNode = RawSyntax(kind: kind, leadingTrivia: leadingTrivia,
trailingTrivia: trailingTrivia,
presence: presence, id: id)
case .layout:
let presence = reader.pointee.readField(SourcePresence.self, index: 2)
let kind = reader.pointee.readField(SyntaxKind.self, index: 3)
let layout = reader.pointee.readField([RawSyntax?].self, index: 4)
let presence = try reader.pointee.readField(SourcePresence.self, index: 2)
let kind = try reader.pointee.readField(SyntaxKind.self, index: 3)
let layout = try reader.pointee.readField([RawSyntax?].self, index: 4)
syntaxNode = RawSyntax(kind: kind, layout: layout, presence: presence,
id: id)
case .omitted:
guard let lookupFunc = userInfo.pointee[.omittedNodeLookupFunction] as?
(SyntaxNodeId) -> RawSyntax? else {
fatalError("omittedNodeLookupFunction is required when decoding an " +
"incrementally transferred syntax tree")
throw IncrementalDecodingError.noLookupFunctionPassed
}
guard let lookupNode = lookupFunc(id) else {
fatalError("Node lookup for id \(id) failed")
throw IncrementalDecodingError.nodeLookupFailed(id)
}
syntaxNode = lookupNode
}
Expand Down
11 changes: 6 additions & 5 deletions Sources/SwiftSyntax/TokenKind.swift.gyb
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Original file line number Diff line number Diff line change
Expand Up @@ -114,31 +114,32 @@ extension TokenKind: ByteTreeObjectDecodable {
static func read(from reader: UnsafeMutablePointer<ByteTreeObjectReader>,
numFields: Int,
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>
) -> TokenKind {
) throws -> TokenKind {
// Explicitly spell out all TokenKinds to keep the serialized value stable
// even if its members get reordered or members get removed
let kind = reader.pointee.readField(UInt8.self, index: 0)
let kind = try reader.pointee.readField(UInt8.self, index: 0)
switch kind {
case 0: return .eof
% for token in SYNTAX_TOKENS:
case ${token.serialization_code}:
% if token.text: # The token does not have text associated with it
return .${token.swift_kind()}
% else:
let text = reader.pointee.readField(String.self, index: 1)
let text = try reader.pointee.readField(String.self, index: 1)
return .${token.swift_kind()}(text)
% end
% end
default:
if numFields > 1 {
// Default to an unknown token with the passed text if we don't know
// its kind.
let text = reader.pointee.readField(String.self, index: 1)
let text = try reader.pointee.readField(String.self, index: 1)
return .unknown(text)
} else {
// If we were not passed the token's text, we cannot recover since we
// would lose roundtripness.
fatalError("Unknown TokenKind \(kind)")
throw ByteTreeDecodingError.invalidEnumRawValue(type: "\(self)",
value: Int(kind))
}
}
}
Expand Down
17 changes: 9 additions & 8 deletions Sources/SwiftSyntax/Trivia.swift.gyb
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Original file line number Diff line number Diff line change
Expand Up @@ -224,9 +224,9 @@ extension Trivia: ByteTreeObjectDecodable {
static func read(from reader: UnsafeMutablePointer<ByteTreeObjectReader>,
numFields: Int,
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>
) -> Trivia {
let pieces = [TriviaPiece].read(from: reader, numFields: numFields,
userInfo: userInfo)
) throws -> Trivia {
let pieces = try [TriviaPiece].read(from: reader, numFields: numFields,
userInfo: userInfo)
return Trivia(pieces: pieces)
}
}
Expand All @@ -235,21 +235,22 @@ extension TriviaPiece: ByteTreeObjectDecodable {
static func read(from reader: UnsafeMutablePointer<ByteTreeObjectReader>,
numFields: Int,
userInfo: UnsafePointer<[ByteTreeUserInfoKey: Any]>
) -> TriviaPiece {
let kind = reader.pointee.readField(UInt8.self, index: 0)
) throws -> TriviaPiece {
let kind = try reader.pointee.readField(UInt8.self, index: 0)
switch kind {
% for trivia in TRIVIAS:
case ${trivia.serialization_code}:
% if trivia.is_collection():
let count = Int(reader.pointee.readField(UInt32.self, index: 1))
let count = Int(try reader.pointee.readField(UInt32.self, index: 1))
return .${trivia.lower_name}s(count)
% else:
let text = reader.pointee.readField(String.self, index: 1)
let text = try reader.pointee.readField(String.self, index: 1)
return .${trivia.lower_name}(text)
% end
% end
default:
fatalError("Unknown trivia piece kind \(kind)")
throw ByteTreeDecodingError.invalidEnumRawValue(type: "\(self)",
value: Int(kind))
}
}
}