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335 lines
11 KiB
Swift
335 lines
11 KiB
Swift
//===----------------------------------------------------------------------===//
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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 - 2015 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 http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SwiftShims // for putchar
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//===----------------------------------------------------------------------===//
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// Input/Output interfaces
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//===----------------------------------------------------------------------===//
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/// A target of text streaming operations.
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public protocol OutputStreamType {
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/// Append the given `string` to this stream.
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mutating func write(string: String)
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}
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/// A source of text streaming operations. `Streamable` instances can
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/// be written to any *output stream*.
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///
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/// For example: `String`, `Character`, `UnicodeScalar`.
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public protocol Streamable {
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/// Write a textual representation of `self` into `target`
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func writeTo<Target : OutputStreamType>(inout target: Target)
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}
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/// A type with a customized textual representation.
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///
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/// This textual representation is used when objects are written to an
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/// *output stream*, for example, by `print` and `println`.
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///
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/// In order to generate a textual representation for an instance of any
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/// type (which might or might not conform to `Printable`), use `toString`.
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public protocol Printable {
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/// A textual representation of `self`.
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var description: String { get }
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}
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/// A type with a customized textual representation for debugging
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/// purposes.
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///
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/// This textual representation is used when objects are written to an
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/// *output stream* by `debugPrint` and `debugPrintln`, and is
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/// typically more verbose than the text provided by a `Printable`\ 's
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/// `description` property.
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///
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/// In order to generate a textual representation for an instance of any
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/// type (which might or might not conform to `DebugPrintable`), use
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/// `toDebugString`.
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public protocol DebugPrintable {
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/// A textual representation of `self`, suitable for debugging.
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var debugDescription: String { get }
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}
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//===----------------------------------------------------------------------===//
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// `print`
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//===----------------------------------------------------------------------===//
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/// Do our best to print a value that can not be printed directly, using one of
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/// its conformances to `Streamable`, `Printable` or `DebugPrintable`.
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func _adHocPrint<T, TargetStream : OutputStreamType>(
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object: T, inout target: TargetStream
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) {
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var mirror = reflect(object)
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// Checking the mirror kind is not a good way to implement this, but we don't
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// have a more expressive reflection API now.
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if mirror is _TupleMirror {
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print("(", &target)
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var first = true
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for i in 0..<mirror.count {
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if first {
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first = false
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} else {
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print(", ", &target)
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}
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var (label, elementMirror) = mirror[i]
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var elt = elementMirror.value
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// FIXME: uncomment for a compiler crash:
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//_adHocPrint(elt, &target)
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// workaround:
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print(elt, &target)
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}
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print(")", &target)
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return
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}
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print(mirror.summary, &target)
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}
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/// Writes the textual representation of `object` into the stream `target`.
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///
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/// The textual representation is obtained from the `object` using its protocol
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/// conformances, in the following order of preference: `Streamable`,
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/// `Printable`, `DebugPrintable`.
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///
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/// Do not overload this function for your type. Instead, adopt one of the
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/// protocols mentioned above.
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public func print<T, TargetStream : OutputStreamType>(
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object: T, inout target: TargetStream
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) {
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if let streamableObject = object as? Streamable {
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streamableObject.writeTo(&target)
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return
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}
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if var printableObject = object as? Printable {
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printableObject.description.writeTo(&target)
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return
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}
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if let debugPrintableObject = object as? DebugPrintable {
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debugPrintableObject.debugDescription.writeTo(&target)
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return
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}
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_adHocPrint(object, &target)
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}
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/// Writes the textual representation of `object` and a newline character into
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/// the stream `target`.
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///
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/// The textual representation is obtained from the `object` using its protocol
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/// conformances, in the following order of preference: `Streamable`,
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/// `Printable`, `DebugPrintable`.
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///
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/// Do not overload this function for your type. Instead, adopt one of the
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/// protocols mentioned above.
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public func println<T, TargetStream : OutputStreamType>(
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object: T, inout target: TargetStream
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) {
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print(object, &target)
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target.write("\n")
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}
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/// Writes the textual representation of `object` into the standard output.
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///
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/// The textual representation is obtained from the `object` using its protocol
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/// conformances, in the following order of preference: `Streamable`,
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/// `Printable`, `DebugPrintable`.
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///
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/// Do not overload this function for your type. Instead, adopt one of the
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/// protocols mentioned above.
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public func print<T>(object: T) {
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var stdoutStream = _Stdout()
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print(object, &stdoutStream)
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}
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/// Writes the textual representation of `object` and a newline character into
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/// the standard output.
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///
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/// The textual representation is obtained from the `object` using its protocol
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/// conformances, in the following order of preference: `Streamable`,
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/// `Printable`, `DebugPrintable`.
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///
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/// Do not overload this function for your type. Instead, adopt one of the
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/// protocols mentioned above.
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public func println<T>(object: T) {
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var stdoutStream = _Stdout()
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print(object, &stdoutStream)
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stdoutStream.write("\n")
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}
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/// Writes a single newline character into the standard output.
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public func println() {
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var stdoutStream = _Stdout()
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stdoutStream.write("\n")
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}
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/// Returns the result of `print`\ 'ing `x` into a `String`
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public func toString<T>(x: T) -> String {
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var result = ""
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print(x, &result)
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return result
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}
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/// Returns the result of `print`\ 'ing `x` into a `String`
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///
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/// Exactly the same as `toString`, but annotated 'readonly' to allow the optimizer
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/// to remove calls where results are unused.
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///
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/// This function is forbidden from being inlined because when building the
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/// standard library inlining makes us drop the special semantics.
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@inline(never) @effects(readonly)
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func _toStringReadOnlyStreamable<T : Streamable>(x: T) -> String {
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var result = ""
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x.writeTo(&result)
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return result
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}
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@inline(never) @effects(readonly)
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func _toStringReadOnlyPrintable<T : Printable>(x: T) -> String {
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return x.description
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}
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/// Returns the result of `debugPrint`\ 'ing `x` into a `String`
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public func toDebugString<T>(x: T) -> String {
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var result = ""
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debugPrint(x, &result)
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return result
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}
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//===----------------------------------------------------------------------===//
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// `debugPrint`
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//===----------------------------------------------------------------------===//
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/// Write to `target` the textual representation of `x` most suitable
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/// for debugging.
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///
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/// * If `T` conforms to `DebugPrintable`, write `x.debugDescription`
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/// * Otherwise, if `T` conforms to `Printable`, write `x.description`
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/// * Otherwise, if `T` conforms to `Stramable`, write `x`
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/// * Otherwise, fall back to a default textual representation.
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///
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/// See also: `debugPrintln(x, &target)`
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public func debugPrint<T, TargetStream : OutputStreamType>(
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object: T, inout target: TargetStream
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) {
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if let debugPrintableObject = object as? DebugPrintable {
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debugPrintableObject.debugDescription.writeTo(&target)
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return
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}
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if var printableObject = object as? Printable {
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printableObject.description.writeTo(&target)
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return
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}
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if let streamableObject = object as? Streamable {
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streamableObject.writeTo(&target)
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return
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}
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_adHocPrint(object, &target)
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}
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/// Write to `target` the textual representation of `x` most suitable
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/// for debugging, followed by a newline.
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///
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/// * If `T` conforms to `DebugPrintable`, write `x.debugDescription`
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/// * Otherwise, if `T` conforms to `Printable`, write `x.description`
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/// * Otherwise, if `T` conforms to `Stramable`, write `x`
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/// * Otherwise, fall back to a default textual representation.
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///
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/// See also: `debugPrint(x, &target)`
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public func debugPrintln<T, TargetStream : OutputStreamType>(
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x: T, inout target: TargetStream
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) {
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debugPrint(x, &target)
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target.write("\n")
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}
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/// Write to the console the textual representation of `x` most suitable
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/// for debugging.
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///
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/// * If `T` conforms to `DebugPrintable`, write `x.debugDescription`
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/// * Otherwise, if `T` conforms to `Printable`, write `x.description`
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/// * Otherwise, if `T` conforms to `Stramable`, write `x`
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/// * Otherwise, fall back to a default textual representation.
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///
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/// See also: `debugPrintln(x)`
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public func debugPrint<T>(x: T) {
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var stdoutStream = _Stdout()
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debugPrint(x, &stdoutStream)
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}
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/// Write to the console the textual representation of `x` most suitable
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/// for debugging, followed by a newline.
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///
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/// * If `T` conforms to `DebugPrintable`, write `x.debugDescription`
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/// * Otherwise, if `T` conforms to `Printable`, write `x.description`
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/// * Otherwise, if `T` conforms to `Stramable`, write `x`
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/// * Otherwise, fall back to a default textual representation.
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///
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/// See also: `debugPrint(x)`
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public func debugPrintln<T>(x: T) {
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var stdoutStream = _Stdout()
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debugPrint(x, &stdoutStream)
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stdoutStream.write("\n")
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}
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//===----------------------------------------------------------------------===//
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// OutputStreams
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//===----------------------------------------------------------------------===//
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internal struct _Stdout : OutputStreamType {
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mutating func write(string: String) {
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// FIXME: buffering?
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// It is important that we use stdio routines in order to correctly
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// interoperate with stdio buffering.
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for c in string.utf8 {
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putchar(Int32(c))
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}
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}
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}
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extension String : OutputStreamType {
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public mutating
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/// Append `other` to this stream.
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func write(other: String) {
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self += other
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}
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}
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//===----------------------------------------------------------------------===//
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// Streamables
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//===----------------------------------------------------------------------===//
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extension String : Streamable {
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/// Write a textual representation of `self` into `target`
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public func writeTo<Target : OutputStreamType>(inout target: Target) {
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target.write(self)
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}
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}
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extension Character : Streamable {
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/// Write a textual representation of `self` into `target`
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public func writeTo<Target : OutputStreamType>(inout target: Target) {
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target.write(String(self))
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}
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}
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extension UnicodeScalar : Streamable {
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/// Write a textual representation of `self` into `target`
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public func writeTo<Target : OutputStreamType>(inout target: Target) {
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target.write(String(Character(self)))
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}
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}
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