Files
swift-mirror/stdlib/public/core/OutputStream.swift

404 lines
13 KiB
Swift

//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import SwiftShims
//===----------------------------------------------------------------------===//
// Input/Output interfaces
//===----------------------------------------------------------------------===//
/// A target of text streaming operations.
public protocol OutputStream {
mutating func _lock()
mutating func _unlock()
/// Append the given `string` to this stream.
mutating func write(string: String)
}
extension OutputStream {
public mutating func _lock() {}
public mutating func _unlock() {}
}
/// A source of text streaming operations. `Streamable` instances can
/// be written to any *output stream*.
///
/// For example: `String`, `Character`, `UnicodeScalar`.
public protocol Streamable {
/// Write a textual representation of `self` into `target`.
func write<Target : OutputStream>(to target: inout Target)
}
/// A type with a customized textual representation.
///
/// This textual representation is used when values are written to an
/// *output stream*, for example, by `print`.
///
/// - Note: `String(instance)` will work for an `instance` of *any*
/// type, returning its `description` if the `instance` happens to be
/// `CustomStringConvertible`. Using `CustomStringConvertible` as a
/// generic constraint, or accessing a conforming type's `description`
/// directly, is therefore discouraged.
///
/// - SeeAlso: `String.init<T>(T)`, `CustomDebugStringConvertible`
public protocol CustomStringConvertible {
/// A textual representation of `self`.
var description: String { get }
}
/// A type with a customized textual representation suitable for
/// debugging purposes.
///
/// This textual representation is used when values are written to an
/// *output stream* by `debugPrint`, and is
/// typically more verbose than the text provided by a
/// `CustomStringConvertible`'s `description` property.
///
/// - Note: `String(reflecting: instance)` will work for an `instance`
/// of *any* type, returning its `debugDescription` if the `instance`
/// happens to be `CustomDebugStringConvertible`. Using
/// `CustomDebugStringConvertible` as a generic constraint, or
/// accessing a conforming type's `debugDescription` directly, is
/// therefore discouraged.
///
/// - SeeAlso: `String.init<T>(reflecting: T)`,
/// `CustomStringConvertible`
public protocol CustomDebugStringConvertible {
/// A textual representation of `self`, suitable for debugging.
var debugDescription: String { get }
}
//===----------------------------------------------------------------------===//
// Default (ad-hoc) printing
//===----------------------------------------------------------------------===//
@_silgen_name("swift_EnumCaseName")
func _getEnumCaseName<T>(value: T) -> UnsafePointer<CChar>
@_silgen_name("swift_OpaqueSummary")
func _opaqueSummary(metadata: Any.Type) -> UnsafePointer<CChar>
/// Do our best to print a value that cannot be printed directly.
internal func _adHocPrint_unlocked<T, TargetStream : OutputStream>(
value: T, _ mirror: Mirror, _ target: inout TargetStream,
isDebugPrint: Bool
) {
func printTypeName(type: Any.Type) {
// Print type names without qualification, unless we're debugPrint'ing.
target.write(_typeName(type, qualified: isDebugPrint))
}
if let displayStyle = mirror.displayStyle {
switch displayStyle {
case .optional:
if let child = mirror.children.first {
_debugPrint_unlocked(child.1, &target)
} else {
_debugPrint_unlocked("nil", &target)
}
case .tuple:
target.write("(")
var first = true
for (_, value) in mirror.children {
if first {
first = false
} else {
target.write(", ")
}
_debugPrint_unlocked(value, &target)
}
target.write(")")
case .`struct`:
printTypeName(mirror.subjectType)
target.write("(")
var first = true
for (label, value) in mirror.children {
if let label = label {
if first {
first = false
} else {
target.write(", ")
}
target.write(label)
target.write(": ")
_debugPrint_unlocked(value, &target)
}
}
target.write(")")
case .`enum`:
let cString = _getEnumCaseName(value)
if cString != nil, let caseName = String(validatingUTF8: cString) {
// Write the qualified type name in debugPrint.
if isDebugPrint {
printTypeName(mirror.subjectType)
target.write(".")
}
target.write(caseName)
} else {
// If the case name is garbage, just print the type name.
printTypeName(mirror.subjectType)
}
if let (_, value) = mirror.children.first {
if (Mirror(reflecting: value).displayStyle == .tuple) {
_debugPrint_unlocked(value, &target)
} else {
target.write("(")
_debugPrint_unlocked(value, &target)
target.write(")")
}
}
default:
target.write(_typeName(mirror.subjectType))
}
} else if let metatypeValue = value as? Any.Type {
// Metatype
printTypeName(metatypeValue)
} else {
// Fall back to the type or an opaque summary of the kind
let cString = _opaqueSummary(mirror.subjectType)
if cString != nil, let opaqueSummary = String(validatingUTF8: cString) {
target.write(opaqueSummary)
} else {
target.write(_typeName(mirror.subjectType, qualified: true))
}
}
}
@inline(never)
@_semantics("stdlib_binary_only")
internal func _print_unlocked<T, TargetStream : OutputStream>(
value: T, _ target: inout TargetStream
) {
// Optional has no representation suitable for display; therefore,
// values of optional type should be printed as a debug
// string. Check for Optional first, before checking protocol
// conformance below, because an Optional value is convertible to a
// protocol if its wrapped type conforms to that protocol.
if _isOptional(value.dynamicType) {
let debugPrintable = value as! CustomDebugStringConvertible
debugPrintable.debugDescription.write(to: &target)
return
}
if case let streamableObject as Streamable = value {
streamableObject.write(to: &target)
return
}
if case let printableObject as CustomStringConvertible = value {
printableObject.description.write(to: &target)
return
}
if case let debugPrintableObject as CustomDebugStringConvertible = value {
debugPrintableObject.debugDescription.write(to: &target)
return
}
let mirror = Mirror(reflecting: value)
_adHocPrint_unlocked(value, mirror, &target, isDebugPrint: false)
}
/// Returns the result of `print`'ing `x` into a `String`.
///
/// Exactly the same as `String`, but annotated 'readonly' to allow
/// the optimizer to remove calls where results are unused.
///
/// This function is forbidden from being inlined because when building the
/// standard library inlining makes us drop the special semantics.
@inline(never) @effects(readonly)
func _toStringReadOnlyStreamable<T : Streamable>(x: T) -> String {
var result = ""
x.write(to: &result)
return result
}
@inline(never) @effects(readonly)
func _toStringReadOnlyPrintable<T : CustomStringConvertible>(x: T) -> String {
return x.description
}
//===----------------------------------------------------------------------===//
// `debugPrint`
//===----------------------------------------------------------------------===//
@inline(never)
public func _debugPrint_unlocked<T, TargetStream : OutputStream>(
value: T, _ target: inout TargetStream
) {
if let debugPrintableObject = value as? CustomDebugStringConvertible {
debugPrintableObject.debugDescription.write(to: &target)
return
}
if let printableObject = value as? CustomStringConvertible {
printableObject.description.write(to: &target)
return
}
if let streamableObject = value as? Streamable {
streamableObject.write(to: &target)
return
}
let mirror = Mirror(reflecting: value)
_adHocPrint_unlocked(value, mirror, &target, isDebugPrint: true)
}
internal func _dumpPrint_unlocked<T, TargetStream : OutputStream>(
value: T, _ mirror: Mirror, _ target: inout TargetStream
) {
if let displayStyle = mirror.displayStyle {
// Containers and tuples are always displayed in terms of their element count
switch displayStyle {
case .tuple:
let count = mirror.children.count
target.write(count == 1 ? "(1 element)" : "(\(count) elements)")
return
case .collection:
let count = mirror.children.count
target.write(count == 1 ? "1 element" : "\(count) elements")
return
case .dictionary:
let count = mirror.children.count
target.write(count == 1 ? "1 key/value pair" : "\(count) key/value pairs")
return
case .`set`:
let count = mirror.children.count
target.write(count == 1 ? "1 member" : "\(count) members")
return
default:
break
}
}
if let debugPrintableObject = value as? CustomDebugStringConvertible {
debugPrintableObject.debugDescription.write(to: &target)
return
}
if let printableObject = value as? CustomStringConvertible {
printableObject.description.write(to: &target)
return
}
if let streamableObject = value as? Streamable {
streamableObject.write(to: &target)
return
}
if let displayStyle = mirror.displayStyle {
switch displayStyle {
case .`class`, .`struct`:
// Classes and structs without custom representations are displayed as
// their fully qualified type name
target.write(_typeName(mirror.subjectType, qualified: true))
return
case .`enum`:
target.write(_typeName(mirror.subjectType, qualified: true))
let cString = _getEnumCaseName(value)
if cString != nil, let caseName = String(validatingUTF8: cString) {
target.write(".")
target.write(caseName)
}
return
default:
break
}
}
_adHocPrint_unlocked(value, mirror, &target, isDebugPrint: true)
}
//===----------------------------------------------------------------------===//
// OutputStreams
//===----------------------------------------------------------------------===//
internal struct _Stdout : OutputStream {
mutating func _lock() {
_swift_stdlib_flockfile_stdout()
}
mutating func _unlock() {
_swift_stdlib_funlockfile_stdout()
}
mutating func write(string: String) {
if string.isEmpty { return }
if string._core.isASCII {
defer { _fixLifetime(string) }
_swift_stdlib_fwrite_stdout(UnsafePointer(string._core.startASCII),
string._core.count, 1)
return
}
for c in string.utf8 {
_swift_stdlib_putchar_unlocked(Int32(c))
}
}
}
extension String : OutputStream {
/// Append `other` to this stream.
public mutating func write(other: String) {
self += other
}
}
//===----------------------------------------------------------------------===//
// Streamables
//===----------------------------------------------------------------------===//
extension String : Streamable {
/// Write a textual representation of `self` into `target`.
public func write<Target : OutputStream>(to target: inout Target) {
target.write(self)
}
}
extension Character : Streamable {
/// Write a textual representation of `self` into `target`.
public func write<Target : OutputStream>(to target: inout Target) {
target.write(String(self))
}
}
extension UnicodeScalar : Streamable {
/// Write a textual representation of `self` into `target`.
public func write<Target : OutputStream>(to target: inout Target) {
target.write(String(Character(self)))
}
}
/// A hook for playgrounds to print through.
public var _playgroundPrintHook : ((String) -> Void)? = {_ in () }
internal struct _TeeStream<
L : OutputStream,
R : OutputStream
> : OutputStream {
var left: L
var right: R
/// Append the given `string` to this stream.
mutating func write(string: String)
{ left.write(string); right.write(string) }
mutating func _lock() { left._lock(); right._lock() }
mutating func _unlock() { right._unlock(); left._unlock() }
}
@available(*, unavailable, renamed="OutputStream")
public typealias OutputStreamType = OutputStream