Add 'open' functions for reading files.

SwiftShell/Files.swift

@@ -14,3 +14,24 @@ public let Files = NSFileManager.defaultManager()
 public func / (leftpath: NSURL, rightpath: String) -> NSURL {
 	return leftpath.URLByAppendingPathComponent(rightpath)
 }
+
+/** Run a function which takes a NSErrorPointer. If an NSError occurs, throw it, otherwise return result. */
+func makeThrowable <T> (nserrorfunc: (NSErrorPointer) -> T) throws -> T {
+	var maybeerror: NSError?
+	let result = nserrorfunc(&maybeerror)
+	if let actualerror = maybeerror {
+		throw actualerror
+	}
+	return result
+}
+
+/** Open a file for reading, throw if an error occurs. */
+public func open (path: String, encoding: NSStringEncoding = main.encoding) throws -> ReadableStream {
+	return try open(NSURL(fileURLWithPath: path, isDirectory: false), encoding: encoding)
+}
+
+/** Open a file for reading, throw if an error occurs. */
+public func open (path: NSURL, encoding: NSStringEncoding = main.encoding) throws -> ReadableStream {
+	try makeThrowable(path.checkResourceIsReachableAndReturnError)
+	return ReadableStream(try NSFileHandle(forReadingFromURL: path), encoding: encoding)
+}

SwiftShellTests/Files_Tests.swift

@@ -17,3 +17,24 @@ class UrlAppendationOperator: XCTestCase {
 		XCTAssertEqual( NSURL(string: "dir")! / "file.txt", NSURL(string: "dir/file.txt"))
 	}
 }
+
+class Open: XCTestCase {
+
+	func testReadFile () {
+		let shorttextpath = pathForTestResource("shorttext", type: "txt")
+
+		AssertNoThrow {
+			let file = try open(shorttextpath)
+			XCTAssert(file.read().hasPrefix("Lorem ipsum dolor"))
+		}
+	}
+
+	func testReadFileWhichDoesNotExist () {
+		do {
+			let _ = try open("/nonexistingfile.txt")
+			XCTFail("Creating stream from non-existing file did not throw error")
+		} catch {
+
+		}
+	}
+}