| 1 | /* -*-scala-*- |
| 2 | * |
| 3 | * Miscellaneous utilities |
| 4 | * |
| 5 | * (c) 2018 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of the Trivial IP Encryption (TrIPE) Android app. |
| 11 | * |
| 12 | * TrIPE is free software: you can redistribute it and/or modify it under |
| 13 | * the terms of the GNU General Public License as published by the Free |
| 14 | * Software Foundation; either version 3 of the License, or (at your |
| 15 | * option) any later version. |
| 16 | * |
| 17 | * TrIPE is distributed in the hope that it will be useful, but WITHOUT |
| 18 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 19 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 20 | * for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU General Public License |
| 23 | * along with TrIPE. If not, see <https://www.gnu.org/licenses/>. |
| 24 | */ |
| 25 | |
| 26 | package uk.org.distorted; package object tripe { |
| 27 | |
| 28 | /*----- Imports -----------------------------------------------------------*/ |
| 29 | |
| 30 | import scala.language.{existentials, implicitConversions}; |
| 31 | |
| 32 | import scala.collection.mutable.{HashSet, WeakHashMap}; |
| 33 | import scala.concurrent.duration.{Deadline, Duration}; |
| 34 | import scala.util.control.{Breaks, ControlThrowable}; |
| 35 | |
| 36 | import java.io.{BufferedReader, Closeable, File, InputStream, Reader}; |
| 37 | import java.net.{HttpURLConnection, URL, URLConnection}; |
| 38 | import java.nio.{ByteBuffer, CharBuffer}; |
| 39 | import java.nio.channels.{SelectionKey, Selector}; |
| 40 | import java.nio.channels.spi.{AbstractSelector, AbstractSelectableChannel}; |
| 41 | import java.nio.charset.Charset; |
| 42 | import java.text.SimpleDateFormat; |
| 43 | import java.util.{Set => JSet}; |
| 44 | import java.util.concurrent.locks.{Lock, ReentrantLock}; |
| 45 | |
| 46 | /*----- Miscellaneous useful things ---------------------------------------*/ |
| 47 | |
| 48 | val rng = new java.security.SecureRandom; |
| 49 | |
| 50 | def unreachable(msg: String): Nothing = throw new AssertionError(msg); |
| 51 | def unreachable(): Nothing = unreachable("unreachable"); |
| 52 | final val ok = (); |
| 53 | class Brand(val what: String) { |
| 54 | override def toString(): String = s"<${getClass.getName} $what>"; |
| 55 | } |
| 56 | |
| 57 | /*----- Various pieces of implicit magic ----------------------------------*/ |
| 58 | |
| 59 | class InvalidCStringException(msg: String) extends Exception(msg); |
| 60 | |
| 61 | object Implicits { |
| 62 | |
| 63 | /* --- Syntactic sugar for locks --- */ |
| 64 | |
| 65 | implicit class LockOps(lk: Lock) { |
| 66 | /* LK withLock { BODY } |
| 67 | * LK.withLock(INTERRUPT) { BODY } |
| 68 | * LK.withLock(DUR, [INTERRUPT]) { BODY } orElse { ALT } |
| 69 | * LK.withLock(DL, [INTERRUPT]) { BODY } orElse { ALT } |
| 70 | * |
| 71 | * Acquire a lock while executing a BODY. If a duration or deadline is |
| 72 | * given then wait so long for the lock, and then give up and run ALT |
| 73 | * instead. |
| 74 | */ |
| 75 | |
| 76 | def withLock[T](dur: Duration, interrupt: Boolean) |
| 77 | (body: => T): PendingLock[T] = |
| 78 | new PendingLock(lk, if (dur > Duration.Zero) dur else Duration.Zero, |
| 79 | interrupt, body); |
| 80 | def withLock[T](dur: Duration)(body: => T): PendingLock[T] = |
| 81 | withLock(dur, true)(body); |
| 82 | def withLock[T](dl: Deadline, interrupt: Boolean) |
| 83 | (body: => T): PendingLock[T] = |
| 84 | new PendingLock(lk, dl.timeLeft, interrupt, body); |
| 85 | def withLock[T](dl: Deadline)(body: => T): PendingLock[T] = |
| 86 | withLock(dl, true)(body); |
| 87 | def withLock[T](interrupt: Boolean)(body: => T): T = { |
| 88 | if (interrupt) lk.lockInterruptibly(); |
| 89 | else lk.lock(); |
| 90 | try { body; } finally lk.unlock(); |
| 91 | } |
| 92 | def withLock[T](body: => T): T = withLock(true)(body); |
| 93 | } |
| 94 | |
| 95 | class PendingLock[T] private[Implicits] |
| 96 | (val lk: Lock, val dur: Duration, |
| 97 | val interrupt: Boolean, body: => T) { |
| 98 | /* An auxiliary class for LockOps; provides the `orElse' qualifier. */ |
| 99 | |
| 100 | def orElse(alt: => T): T = { |
| 101 | val locked = (dur, interrupt) match { |
| 102 | case (Duration.Inf, true) => lk.lockInterruptibly(); true |
| 103 | case (Duration.Inf, false) => lk.lock(); true |
| 104 | case (Duration.Zero, false) => lk.tryLock() |
| 105 | case (_, true) => lk.tryLock(dur.length, dur.unit) |
| 106 | case _ => unreachable("timed wait is always interruptible"); |
| 107 | } |
| 108 | if (!locked) alt; |
| 109 | else try { body; } finally lk.unlock(); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | /* Implicit conversions to `Boolean'. I miss the way C integers and |
| 114 | * pointers convert to boolean, so let's do that here. |
| 115 | * |
| 116 | * Numeric zero, null, and empty containers are all false; other objects |
| 117 | * are true. |
| 118 | */ |
| 119 | implicit def truish(n: Byte): Boolean = n != 0; |
| 120 | implicit def truish(n: Char): Boolean = n != 0; |
| 121 | implicit def truish(n: Short): Boolean = n != 0; |
| 122 | implicit def truish(n: Int): Boolean = n != 0; |
| 123 | implicit def truish(n: Long): Boolean = n != 0; |
| 124 | implicit def truish(n: Float): Boolean = n != 0; |
| 125 | implicit def truish(n: Double): Boolean = n != 0; |
| 126 | implicit def truish(x: AnyRef): Boolean = x != null; |
| 127 | implicit def truish(s: String): Boolean = s != null && s != ""; |
| 128 | implicit def truish(o: Option[_]): Boolean = o != None; |
| 129 | implicit def truish(i: Iterator[_]): Boolean = i != null && i.hasNext; |
| 130 | implicit def truish(c: Traversable[_]): Boolean = |
| 131 | c != null && c.nonEmpty; |
| 132 | |
| 133 | /* Some additional bitwise operators. |
| 134 | * |
| 135 | * For now, just the `bic' operator `&~', because typing `& ~' is |
| 136 | * inconsistent with my current style. |
| 137 | */ |
| 138 | class BitwiseIntImplicits(x: Int) { |
| 139 | def &~(y: Byte): Int = x & ~y; |
| 140 | def &~(y: Char): Int = x & ~y; |
| 141 | def &~(y: Short): Int = x & ~y; |
| 142 | def &~(y: Int): Int = x & ~y; |
| 143 | def &~(y: Long): Long = x & ~y; |
| 144 | } |
| 145 | class BitwiseLongImplicits(x: Long) { |
| 146 | def &~(y: Byte): Long = x & ~y; |
| 147 | def &~(y: Char): Long = x & ~y; |
| 148 | def &~(y: Short): Long = x & ~y; |
| 149 | def &~(y: Int): Long = x & ~y; |
| 150 | def &~(y: Long): Long = x & ~y; |
| 151 | } |
| 152 | implicit def bitwiseImplicits(x: Byte) = new BitwiseIntImplicits(x); |
| 153 | implicit def bitwiseImplicits(x: Char) = new BitwiseIntImplicits(x); |
| 154 | implicit def bitwiseImplicits(x: Short) = new BitwiseIntImplicits(x); |
| 155 | implicit def bitwiseImplicits(x: Int) = new BitwiseIntImplicits(x); |
| 156 | implicit def bitwiseImplicits(x: Long) = new BitwiseLongImplicits(x); |
| 157 | } |
| 158 | |
| 159 | import Implicits.truish; |
| 160 | |
| 161 | /*----- Cleanup assistant -------------------------------------------------*/ |
| 162 | |
| 163 | class Cleaner { |
| 164 | /* A helper class for avoiding deep nests of `try'/`finally'. |
| 165 | * |
| 166 | * Make a `Cleaner' instance CL at the start of your operation. Apply it |
| 167 | * to blocks of code -- as CL { ACTION } -- as you proceed, to accumulate |
| 168 | * cleanup actions. Finally, call CL.cleanup() to invoke the accumulated |
| 169 | * actions, in reverse order. |
| 170 | */ |
| 171 | |
| 172 | var cleanups: List[() => Unit] = Nil; |
| 173 | def apply(cleanup: => Unit) { cleanups +:= { () => cleanup; } } |
| 174 | def cleanup() { cleanups foreach { _() } } |
| 175 | } |
| 176 | |
| 177 | def withCleaner[T](body: Cleaner => T): T = { |
| 178 | /* An easier way to use the `Cleaner' class. Just |
| 179 | * |
| 180 | * withCleaner { CL => BODY } |
| 181 | * |
| 182 | * The BODY can attach cleanup actions to the cleaner CL by saying |
| 183 | * CL { ACTION } as usual. When the BODY exits, normally or otherwise, the |
| 184 | * cleanup actions are invoked in reverse order. |
| 185 | */ |
| 186 | |
| 187 | val cleaner = new Cleaner; |
| 188 | try { body(cleaner) } |
| 189 | finally { cleaner.cleanup(); } |
| 190 | } |
| 191 | |
| 192 | def closing[T, U <: Closeable](thing: U)(body: U => T): T = |
| 193 | try { body(thing) } |
| 194 | finally { thing.close(); } |
| 195 | |
| 196 | /*----- Control structures ------------------------------------------------*/ |
| 197 | |
| 198 | private case class ExitBlock[T](brand: Brand, result: T) |
| 199 | extends ControlThrowable; |
| 200 | |
| 201 | def block[T](body: (T => Nothing) => T): T = { |
| 202 | /* block { exit[T] => ...; exit(x); ... } |
| 203 | * |
| 204 | * Execute the body until it calls the `exit' function or finishes. |
| 205 | * Annoyingly, Scala isn't clever enough to infer the return type, so |
| 206 | * you'll have to write it explicitly. |
| 207 | */ |
| 208 | |
| 209 | val mybrand = new Brand("block-exit"); |
| 210 | try { body { result => throw new ExitBlock(mybrand, result) } } |
| 211 | catch { |
| 212 | case ExitBlock(brand, result) if brand eq mybrand => |
| 213 | result.asInstanceOf[T] |
| 214 | } |
| 215 | } |
| 216 | |
| 217 | def blockUnit(body: (=> Nothing) => Unit) { |
| 218 | /* blockUnit { exit => ...; exit; ... } |
| 219 | * |
| 220 | * Like `block'; it just saves you having to write `exit[Unit] => ...; |
| 221 | * exit(ok); ...'. |
| 222 | */ |
| 223 | |
| 224 | val mybrand = new Brand("block-exit"); |
| 225 | try { body { throw new ExitBlock(mybrand, null) }; } |
| 226 | catch { case ExitBlock(brand, result) if brand eq mybrand => ok; } |
| 227 | } |
| 228 | |
| 229 | def loop[T](body: (T => Nothing) => Unit): T = { |
| 230 | /* loop { exit[T] => ...; exit(x); ... } |
| 231 | * |
| 232 | * Repeatedly execute the body until it calls the `exit' function. |
| 233 | * Annoyingly, Scala isn't clever enough to infer the return type, so |
| 234 | * you'll have to write it explicitly. |
| 235 | */ |
| 236 | |
| 237 | block { exit => while (true) body(exit); unreachable } |
| 238 | } |
| 239 | |
| 240 | def loopUnit(body: (=> Nothing) => Unit): Unit = { |
| 241 | /* loopUnit { exit => ...; exit; ... } |
| 242 | * |
| 243 | * Like `loop'; it just saves you having to write `exit[Unit] => ...; |
| 244 | * exit(()); ...'. |
| 245 | */ |
| 246 | |
| 247 | blockUnit { exit => while (true) body(exit); } |
| 248 | } |
| 249 | |
| 250 | val BREAKS = new Breaks; |
| 251 | import BREAKS.{breakable, break}; |
| 252 | |
| 253 | /*----- Interruptably doing things ----------------------------------------*/ |
| 254 | |
| 255 | private class InterruptCatcher[T](body: => T, onWakeup: => Unit) |
| 256 | extends AbstractSelector(null) { |
| 257 | /* Hook onto the VM's thread interruption machinery. |
| 258 | * |
| 259 | * The `run' method is the only really interesting one. It will run the |
| 260 | * BODY, returning its result; if the thread is interrupted during this |
| 261 | * time, ONWAKEUP is invoked for effect. The expectation is that ONWAKEUP |
| 262 | * will somehow cause BODY to stop early. |
| 263 | * |
| 264 | * Credit for this hack goes to Nicholas Wilson: see |
| 265 | * <https://github.com/NWilson/javaInterruptHook>. |
| 266 | */ |
| 267 | |
| 268 | private def nope: Nothing = |
| 269 | { throw new UnsupportedOperationException("can't do that"); } |
| 270 | protected def implCloseSelector() { } |
| 271 | protected def register(chan: AbstractSelectableChannel, |
| 272 | ops: Int, att: Any): SelectionKey = nope; |
| 273 | def keys(): JSet[SelectionKey] = nope; |
| 274 | def selectedKeys(): JSet[SelectionKey] = nope; |
| 275 | def select(): Int = nope; |
| 276 | def select(millis: Long): Int = nope; |
| 277 | def selectNow(): Int = nope; |
| 278 | |
| 279 | def run(): T = try { |
| 280 | begin(); |
| 281 | val ret = body; |
| 282 | if (Thread.interrupted()) throw new InterruptedException; |
| 283 | ret |
| 284 | } finally { |
| 285 | end(); |
| 286 | } |
| 287 | def wakeup(): Selector = { onWakeup; this } |
| 288 | } |
| 289 | |
| 290 | class PendingInterruptable[T] private[tripe](body: => T) { |
| 291 | /* This class exists to provide the `onInterrupt THUNK' syntax. */ |
| 292 | |
| 293 | def onInterrupt(thunk: => Unit): T = |
| 294 | new InterruptCatcher(body, thunk).run(); |
| 295 | } |
| 296 | def interruptably[T](body: => T) = { |
| 297 | /* interruptably { BODY } onInterrupt { THUNK } |
| 298 | * |
| 299 | * Execute BODY and return its result. If the thread receives an |
| 300 | * interrupt -- or is already in an interrupted state -- execute THUNK for |
| 301 | * effect; it is expected to cause BODY to return expeditiously, and when |
| 302 | * the BODY completes, an `InterruptedException' is thrown. |
| 303 | */ |
| 304 | |
| 305 | new PendingInterruptable(body); |
| 306 | } |
| 307 | |
| 308 | /*----- A gadget for fetching URLs ----------------------------------------*/ |
| 309 | |
| 310 | class URLFetchException(msg: String) extends Exception(msg); |
| 311 | |
| 312 | trait URLFetchCallbacks { |
| 313 | def preflight(conn: URLConnection) { } |
| 314 | def write(buf: Array[Byte], n: Int, len: Long): Unit; |
| 315 | def done(win: Boolean) { } |
| 316 | } |
| 317 | |
| 318 | def fetchURL(url: URL, cb: URLFetchCallbacks) { |
| 319 | /* Fetch the URL, feeding the data through the callbacks CB. */ |
| 320 | |
| 321 | withCleaner { clean => |
| 322 | var win: Boolean = false; clean { cb.done(win); } |
| 323 | |
| 324 | /* Set up the connection. This isn't going to block, I think, and we |
| 325 | * need to use it in the interrupt handler. |
| 326 | */ |
| 327 | val c = url.openConnection(); |
| 328 | |
| 329 | /* Java's default URL handlers don't respond to interrupts, so we have to |
| 330 | * take over this duty. |
| 331 | */ |
| 332 | interruptably { |
| 333 | /* Run the caller's preflight check. This must be done here, since it |
| 334 | * might well block while it discovers things like the content length. |
| 335 | */ |
| 336 | cb.preflight(c); |
| 337 | |
| 338 | /* Start fetching data. */ |
| 339 | val in = c.getInputStream; clean { in.close(); } |
| 340 | val explen = c.getContentLength; |
| 341 | |
| 342 | /* Read a buffer at a time, and give it to the callback. Maintain a |
| 343 | * running total. |
| 344 | */ |
| 345 | var len: Long = 0; |
| 346 | blockUnit { exit => |
| 347 | for ((buf, n) <- blocks(in)) { |
| 348 | cb.write(buf, n, len); |
| 349 | len += n; |
| 350 | if (explen != -1 && len > explen) exit; |
| 351 | } |
| 352 | } |
| 353 | |
| 354 | /* I can't find it documented anywhere that the existing machinery |
| 355 | * checks the received stream against the advertised content length. |
| 356 | * It doesn't hurt to check again, anyway. |
| 357 | */ |
| 358 | if (explen != -1 && explen != len) { |
| 359 | throw new URLFetchException( |
| 360 | s"received $len /= $explen bytes from `$url'"); |
| 361 | } |
| 362 | |
| 363 | /* Glorious success is ours. */ |
| 364 | win = true; |
| 365 | } onInterrupt { |
| 366 | /* Oh. How do we do this? */ |
| 367 | |
| 368 | c match { |
| 369 | case c: HttpURLConnection => |
| 370 | /* It's an HTTP connection (what happened to the case here?). |
| 371 | * HTTPS connections match too because they're a subclass. Getting |
| 372 | * the input stream will block, but there's an easier way. |
| 373 | */ |
| 374 | c.disconnect(); |
| 375 | |
| 376 | case _ => |
| 377 | /* It's something else. Let's hope that getting the input stream |
| 378 | * doesn't block. |
| 379 | */ |
| 380 | c.getInputStream.close(); |
| 381 | } |
| 382 | } |
| 383 | } |
| 384 | } |
| 385 | |
| 386 | /*----- Threading things --------------------------------------------------*/ |
| 387 | |
| 388 | def thread(name: String, run: Boolean = true, daemon: Boolean = true) |
| 389 | (f: => Unit): Thread = { |
| 390 | /* Make a thread with a given name, and maybe start running it. */ |
| 391 | |
| 392 | val t = new Thread(new Runnable { def run() { f; } }, name); |
| 393 | if (daemon) t.setDaemon(true); |
| 394 | if (run) t.start(); |
| 395 | t |
| 396 | } |
| 397 | |
| 398 | class ValueThread[T](name: String, group: ThreadGroup = null, |
| 399 | stacksz: Long = 0)(body: => T) |
| 400 | extends Thread(group, null, name, stacksz) { |
| 401 | private[this] var exc: Throwable = _; |
| 402 | private[this] var ret: T = _; |
| 403 | |
| 404 | override def run() { |
| 405 | try { ret = body; } |
| 406 | catch { case e: Throwable => exc = e; } |
| 407 | } |
| 408 | def get: T = |
| 409 | if (isAlive) throw new IllegalArgumentException("still running"); |
| 410 | else if (exc != null) throw exc; |
| 411 | else ret; |
| 412 | } |
| 413 | def valueThread[T](name: String, run: Boolean = true) |
| 414 | (body: => T): ValueThread[T] = { |
| 415 | val t = new ValueThread(name)(body); |
| 416 | if (run) t.start(); |
| 417 | t |
| 418 | } |
| 419 | |
| 420 | /*----- Quoting and parsing tokens ----------------------------------------*/ |
| 421 | |
| 422 | def quoteTokens(v: Seq[String]): String = { |
| 423 | /* Return a string representing the token sequence V. |
| 424 | * |
| 425 | * The tokens are quoted as necessary. |
| 426 | */ |
| 427 | |
| 428 | val b = new StringBuilder; |
| 429 | var sep = false; |
| 430 | for (s <- v) { |
| 431 | |
| 432 | /* If this isn't the first word, then write a separating space. */ |
| 433 | if (!sep) sep = true; |
| 434 | else b += ' '; |
| 435 | |
| 436 | /* Decide how to handle this token. */ |
| 437 | if (s.length > 0 && |
| 438 | (s forall { ch => (ch != ''' && ch != '"' && ch != '\\' && |
| 439 | !ch.isWhitespace) })) { |
| 440 | /* If this word is nonempty and contains no problematic characters, |
| 441 | * we can write it literally. |
| 442 | */ |
| 443 | |
| 444 | b ++= s; |
| 445 | } else { |
| 446 | /* Otherwise, we shall have to do this the hard way. We could be |
| 447 | * cleverer about this, but it's not worth the effort. |
| 448 | */ |
| 449 | |
| 450 | b += '"'; |
| 451 | s foreach { ch => |
| 452 | if (ch == '"' || ch == '\\') b += '\\'; |
| 453 | b += ch; |
| 454 | } |
| 455 | b += '"'; |
| 456 | } |
| 457 | } |
| 458 | b.result |
| 459 | } |
| 460 | |
| 461 | class InvalidQuotingException(msg: String) extends Exception(msg); |
| 462 | |
| 463 | def nextToken(s: String, pos: Int = 0): Option[(String, Int)] = { |
| 464 | /* Parse the next token from a string S. |
| 465 | * |
| 466 | * If there is a token in S starting at or after index POS, then return |
| 467 | * it, and the index for the following token; otherwise return `None'. |
| 468 | */ |
| 469 | |
| 470 | val b = new StringBuilder; |
| 471 | val n = s.length; |
| 472 | var i = pos; |
| 473 | var q = 0; |
| 474 | |
| 475 | /* Skip whitespace while we find the next token. */ |
| 476 | while (i < n && s(i).isWhitespace) i += 1; |
| 477 | |
| 478 | /* Maybe there just isn't anything to find. */ |
| 479 | if (i >= n) return None; |
| 480 | |
| 481 | /* There is something there. Unpick the quoting and escaping. */ |
| 482 | while (i < n && (q || !s(i).isWhitespace)) { |
| 483 | s(i) match { |
| 484 | case '\\' => |
| 485 | if (i + 1 >= n) throw new InvalidQuotingException("trailing `\\'"); |
| 486 | b += s(i + 1); i += 2; |
| 487 | case ch@('"' | ''') => |
| 488 | if (!q) q = ch; |
| 489 | else if (q == ch) q = 0; |
| 490 | else b += ch; |
| 491 | i += 1; |
| 492 | case ch => |
| 493 | b += ch; |
| 494 | i += 1; |
| 495 | } |
| 496 | } |
| 497 | |
| 498 | /* Check that the quoting was valid. */ |
| 499 | if (q) throw new InvalidQuotingException(s"unmatched `$q'"); |
| 500 | |
| 501 | /* Skip whitespace before the next token. */ |
| 502 | while (i < n && s(i).isWhitespace) i += 1; |
| 503 | |
| 504 | /* We're done. */ |
| 505 | Some((b.result, i)) |
| 506 | } |
| 507 | |
| 508 | def splitTokens(s: String, pos: Int = 0): Seq[String] = { |
| 509 | /* Return all of the tokens in string S into tokens, starting at POS. */ |
| 510 | |
| 511 | val b = List.newBuilder[String]; |
| 512 | var i = pos; |
| 513 | |
| 514 | loopUnit { exit => nextToken(s, i) match { |
| 515 | case Some((w, j)) => b += w; i = j; |
| 516 | case None => exit; |
| 517 | } } |
| 518 | b.result |
| 519 | } |
| 520 | |
| 521 | /*----- Hooks -------------------------------------------------------------*/ |
| 522 | |
| 523 | /* This is a really simple publisher/subscriber system. The only slight |
| 524 | * tweak -- and the reason I'm not just using the Scala machinery -- is that |
| 525 | * being attached to a hook doesn't prevent the client from being garbage |
| 526 | * collected. |
| 527 | */ |
| 528 | |
| 529 | trait BaseHookClient[E] { |
| 530 | /* The minimal requirements for a hook client. Honestly you should be |
| 531 | * using `HookClient' instead. |
| 532 | */ |
| 533 | |
| 534 | type H = Hook[E]; // the type of hook we attach to |
| 535 | def hook(hk: H, evt: E); // called with events from the hook |
| 536 | } |
| 537 | |
| 538 | trait HookClient[E] extends BaseHookClient[E] { |
| 539 | /* The properly cooked hook client. This keeps track of which hooks we're |
| 540 | * attached to so we can release them all easily. |
| 541 | */ |
| 542 | |
| 543 | private val hooks = new HashSet[H]; |
| 544 | protected def attachHook(hk: H) { hk.addHookClient(this); hooks += hk; } |
| 545 | protected def detachHook(hk: H) { hk.rmHookClient(this); hooks -= hk; } |
| 546 | protected def detachAllHooks() |
| 547 | { for (hk <- hooks) hk.rmHookClient(this); hooks.clear(); } |
| 548 | } |
| 549 | |
| 550 | trait Hook[E] { |
| 551 | type C = BaseHookClient[E]; |
| 552 | private val clients = new WeakHashMap[C, Unit]; |
| 553 | def addHookClient(c: C) { clients(c) = (); } |
| 554 | def rmHookClient(c: C) { clients -= c; } |
| 555 | protected def callHook(evt: E) |
| 556 | { for (c <- clients.keys) c.hook(this, evt); } |
| 557 | } |
| 558 | |
| 559 | /*----- Fluid variables ---------------------------------------------------*/ |
| 560 | |
| 561 | object BaseFluid { |
| 562 | /* The multi-fluid `let' form is defined here so that it can access the |
| 563 | * `capture' method of individual fluids, but users should use the |
| 564 | * package-level veneer. |
| 565 | */ |
| 566 | |
| 567 | private[tripe] def let[U](fxs: (BaseFluid[T], T) forSome { type T }*) |
| 568 | (body: => U): U = { |
| 569 | /* See the package-level `let' for details. */ |
| 570 | val binds = for ((f, _) <- fxs) yield f.capture; |
| 571 | try { for ((f, x) <- fxs) f.v = x; body } |
| 572 | finally { for (b <- binds) b.restore(); } |
| 573 | } |
| 574 | } |
| 575 | def let[U](fxs: (BaseFluid[T], T) forSome { type T }*)(body: => U): U = { |
| 576 | /* let(F -> X, ...) { BODY } |
| 577 | * |
| 578 | * Evaluate BODY in a dynamic context where each fluid F is bound to the |
| 579 | * corresponding value X. |
| 580 | */ |
| 581 | |
| 582 | BaseFluid.let(fxs: _*)(body); |
| 583 | } |
| 584 | |
| 585 | trait BaseFluid[T] { |
| 586 | /* The basic fluid protocol. */ |
| 587 | |
| 588 | override def toString(): String = |
| 589 | f"${getClass.getName}%s@${hashCode}%x($v%s)"; |
| 590 | |
| 591 | protected trait Binding { |
| 592 | /* A captured binding which can be restored later. Implementing this is |
| 593 | * a subclass responsibility. |
| 594 | */ |
| 595 | |
| 596 | def restore(); |
| 597 | /* Restore the fluid's state to the state captured here. */ |
| 598 | } |
| 599 | |
| 600 | /* Fetch and modify the current binding. */ |
| 601 | def v: T; |
| 602 | def v_=(x: T); |
| 603 | |
| 604 | protected def capture: Binding; |
| 605 | /* Capture and the current state of the fluid. */ |
| 606 | |
| 607 | def let[U](x: T)(body: => U): U = { |
| 608 | /* let(X) { BODY } |
| 609 | * |
| 610 | * Evaluate BODY in a dynamic context where the fluid is bound to the |
| 611 | * value X. |
| 612 | */ |
| 613 | |
| 614 | val b = capture; |
| 615 | try { v = x; body } finally { b.restore(); } |
| 616 | } |
| 617 | } |
| 618 | |
| 619 | class SharedFluid[T](init: T) extends BaseFluid[T] { |
| 620 | /* A simple global fluid. It's probably a mistake to try to access a |
| 621 | * `SharedFluid' from multiple threads without serious synchronization. |
| 622 | */ |
| 623 | |
| 624 | var v: T = init; |
| 625 | private class Binding(old: T) extends super.Binding |
| 626 | { def restore() { v = old; } } |
| 627 | protected def capture: super.Binding = new Binding(v); |
| 628 | } |
| 629 | |
| 630 | class ThreadFluid[T](init: T) extends BaseFluid[T] { |
| 631 | /* A thread-aware fluid. The top-level binding is truly global, shared by |
| 632 | * all threads, but `let'-bindings are thread-local. |
| 633 | */ |
| 634 | |
| 635 | private[this] var global: T = init; |
| 636 | private[this] var bound: ThreadLocal[Option[T]] = new ThreadLocal; |
| 637 | bound.set(None); |
| 638 | |
| 639 | def v: T = bound.get match { case None => global; case Some(x) => x; }; |
| 640 | def v_=(x: T) { bound.get match { |
| 641 | case None => global = x; |
| 642 | case _ => bound.set(Some(x)); |
| 643 | } } |
| 644 | |
| 645 | private class Binding(old: Option[T]) extends super.Binding |
| 646 | { def restore() { bound.set(old); } } |
| 647 | protected def capture: super.Binding = new Binding(bound.get); |
| 648 | } |
| 649 | |
| 650 | /*----- Other random things -----------------------------------------------*/ |
| 651 | |
| 652 | trait LookaheadIterator[T] extends BufferedIterator[T] { |
| 653 | /* An iterator in terms of a single `maybe there's another item' function. |
| 654 | * |
| 655 | * It seems like every time I write an iterator in Scala, the only way to |
| 656 | * find out whether there's a next item, for `hasNext', is to actually try |
| 657 | * to fetch it. So here's an iterator in terms of a function which goes |
| 658 | * off and maybe returns a next thing. It turns out to be easy to satisfy |
| 659 | * the additional requirements for `BufferedIterator', so why not? |
| 660 | */ |
| 661 | |
| 662 | /* Subclass responsibility. */ |
| 663 | protected def fetch(): Option[T]; |
| 664 | |
| 665 | /* The machinery. `st' is `None' if there's no current item, null if we've |
| 666 | * actually hit the end, or `Some(x)' if the current item is x. |
| 667 | */ |
| 668 | private[this] var st: Option[T] = None; |
| 669 | private[this] def peek() { |
| 670 | /* Arrange to have a current item. */ |
| 671 | if (st == None) fetch() match { |
| 672 | case None => st = null; |
| 673 | case x@Some(_) => st = x; |
| 674 | } |
| 675 | } |
| 676 | |
| 677 | /* The `BufferedIterator' protocol. */ |
| 678 | override def hasNext: Boolean = { peek(); st != null } |
| 679 | override def head: T = |
| 680 | { peek(); if (st == null) throw new NoSuchElementException; st.get } |
| 681 | override def next(): T = { val it = head; st = None; it } |
| 682 | } |
| 683 | |
| 684 | def bufferedReader(r: Reader): BufferedReader = r match { |
| 685 | case br: BufferedReader => br |
| 686 | case _ => new BufferedReader(r) |
| 687 | } |
| 688 | |
| 689 | def lines(r: BufferedReader): BufferedIterator[String] = |
| 690 | new LookaheadIterator[String] { |
| 691 | /* Iterates over the lines of text in a `Reader' object. */ |
| 692 | override protected def fetch() = Option(r.readLine()); |
| 693 | } |
| 694 | def lines(r: Reader): BufferedIterator[String] = lines(bufferedReader(r)); |
| 695 | |
| 696 | def blocks(in: InputStream, blksz: Int): |
| 697 | BufferedIterator[(Array[Byte], Int)] = |
| 698 | /* Iterates over (possibly irregularly sized) blocks in a stream. */ |
| 699 | new LookaheadIterator[(Array[Byte], Int)] { |
| 700 | val buf = new Array[Byte](blksz) |
| 701 | override protected def fetch() = { |
| 702 | val n = in.read(buf); |
| 703 | if (n < 0) None |
| 704 | else Some((buf, n)) |
| 705 | } |
| 706 | } |
| 707 | def blocks(in: InputStream): |
| 708 | BufferedIterator[(Array[Byte], Int)] = blocks(in, 65536); |
| 709 | |
| 710 | def blocks(in: BufferedReader, blksz: Int): |
| 711 | BufferedIterator[(Array[Char], Int)] = |
| 712 | /* Iterates over (possibly irregularly sized) blocks in a reader. */ |
| 713 | new LookaheadIterator[(Array[Char], Int)] { |
| 714 | val buf = new Array[Char](blksz) |
| 715 | override protected def fetch() = { |
| 716 | val n = in.read(buf); |
| 717 | if (n < 0) None |
| 718 | else Some((buf, n)) |
| 719 | } |
| 720 | } |
| 721 | def blocks(in: BufferedReader): |
| 722 | BufferedIterator[(Array[Char], Int)] = blocks(in, 65536); |
| 723 | def blocks(r: Reader, blksz: Int): BufferedIterator[(Array[Char], Int)] = |
| 724 | blocks(bufferedReader(r), blksz); |
| 725 | def blocks(r: Reader): BufferedIterator[(Array[Char], Int)] = |
| 726 | blocks(bufferedReader(r)); |
| 727 | |
| 728 | def oxford(conj: String, things: Seq[String]): String = things match { |
| 729 | case Seq() => "<nothing>" |
| 730 | case Seq(a) => a |
| 731 | case Seq(a, b) => s"$a $conj $b" |
| 732 | case Seq(a, tail@_*) => |
| 733 | val sb = new StringBuilder; |
| 734 | sb ++= a; sb ++= ", "; |
| 735 | def iter(rest: Seq[String]) { |
| 736 | rest match { |
| 737 | case Seq() => unreachable; |
| 738 | case Seq(a) => sb ++= conj; sb += ' '; sb ++= a; |
| 739 | case Seq(a, tail@_*) => sb ++= a; sb ++= ", "; iter(tail); |
| 740 | } |
| 741 | } |
| 742 | iter(tail); |
| 743 | sb.result |
| 744 | } |
| 745 | |
| 746 | val datefmt = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss Z"); |
| 747 | |
| 748 | def formatDuration(t: Int): String = |
| 749 | if (t < -1) "???" |
| 750 | else { |
| 751 | val (s, t1) = (t%60, t/60); |
| 752 | val (m, h) = (t1%60, t1/60); |
| 753 | if (h > 0) f"$h%d:$m%02d:$s%02d" |
| 754 | else f"$m%02d:$s%02d" |
| 755 | } |
| 756 | |
| 757 | /*----- That's all, folks -------------------------------------------------*/ |
| 758 | |
| 759 | } |