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August 29, 2015 14:02
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C++-style stream output for Swift. (For fun only: Never, ever use this.)
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| import Foundation | |
| // Swift's << operator is not left-associative, so we'll use <<< instead | |
| operator infix <<< { associativity left } | |
| // Output operator for Streamable objects | |
| func <<< (var outputStream: OutputStream, streamable: Streamable) -> OutputStream { | |
| // Note: It seems like streamable.writeTo(&outputStream) should work, but playground crashes, | |
| // so we write to a string and then output the string | |
| var outputString = "" | |
| streamable.writeTo(&outputString) | |
| outputStream.write(outputString) | |
| return outputStream | |
| } | |
| // Output operator for Printable objects | |
| func <<< (var outputStream: OutputStream, printable: Printable) -> OutputStream { | |
| outputStream.write(printable.description) | |
| return outputStream | |
| } | |
| // Output operator for functions, e.g. endl() | |
| func <<< (var outputStream:OutputStream, f: OutputStream -> OutputStream) -> OutputStream { | |
| return f(outputStream) | |
| } | |
| // Write newline to a stream | |
| func endl(var outputStream: OutputStream) -> OutputStream { | |
| outputStream.write("\n") | |
| return outputStream | |
| } | |
| // Swift Strings are OutputStreams, so no need for a StringBuilder/StringOutputStream | |
| let myString = "" | |
| myString <<< 1 <<< " + " <<< 2 <<< " = " <<< (1 + 2) <<< endl | |
| print(myString) // "1 + 2 = 3\n" | |
| class ConsoleOutputStream: OutputStream { | |
| func write(string: String) { | |
| print(string) | |
| } | |
| } | |
| let cout = ConsoleOutputStream() | |
| cout <<< "Hello, world!" <<< endl |
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