1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
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   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
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  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
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  25 
  26 /* @test
  27  * @bug 8139885
  28  * @bug 8150635
  29  * @run testng/othervm -ea -esa test.java.lang.invoke.LoopCombinatorTest
  30  */
  31 
  32 package test.java.lang.invoke;
  33 
  34 import java.lang.invoke.MethodHandle;
  35 import java.lang.invoke.MethodHandles;
  36 import java.lang.invoke.MethodHandles.Lookup;
  37 import java.lang.invoke.MethodType;
  38 import java.util.*;
  39 
  40 import static java.lang.invoke.MethodType.methodType;
  41 
  42 import static org.testng.AssertJUnit.*;
  43 
  44 import org.testng.annotations.*;
  45 
  46 /**
  47  * Tests for the loop combinators introduced in JEP 274.
  48  */
  49 public class LoopCombinatorTest {
  50 
  51     static final Lookup LOOKUP = MethodHandles.lookup();
  52 
  53     @Test
  54     public static void testLoopFac() throws Throwable {
  55         MethodHandle[] counterClause = new MethodHandle[]{Fac.MH_zero, Fac.MH_inc};
  56         MethodHandle[] accumulatorClause = new MethodHandle[]{Fac.MH_one, Fac.MH_mult, Fac.MH_pred, Fac.MH_fin};
  57         MethodHandle loop = MethodHandles.loop(counterClause, accumulatorClause);
  58         assertEquals(Fac.MT_fac, loop.type());
  59         assertEquals(120, loop.invoke(5));
  60     }
  61 
  62     @Test
  63     public static void testLoopFacNullInit() throws Throwable {
  64         // null initializer for counter, should initialize to 0
  65         MethodHandle[] counterClause = new MethodHandle[]{null, Fac.MH_inc};
  66         MethodHandle[] accumulatorClause = new MethodHandle[]{Fac.MH_one, Fac.MH_mult, Fac.MH_pred, Fac.MH_fin};
  67         MethodHandle loop = MethodHandles.loop(counterClause, accumulatorClause);
  68         assertEquals(Fac.MT_fac, loop.type());
  69         assertEquals(120, loop.invoke(5));
  70     }
  71 
  72     @Test
  73     public static void testLoopNullInit() throws Throwable {
  74         // null initializer for counter, should initialize to 0, one-clause loop
  75         MethodHandle[] counterClause = new MethodHandle[]{null, Loop.MH_inc, Loop.MH_pred, Loop.MH_fin};
  76         MethodHandle loop = MethodHandles.loop(counterClause);
  77         assertEquals(Loop.MT_loop, loop.type());
  78         assertEquals(10, loop.invoke(10));
  79     }
  80 
  81     @Test
  82     public static void testLoopVoid1() throws Throwable {
  83         // construct a post-checked loop that only does one iteration and has a void body and void local state
  84         MethodHandle loop = MethodHandles.loop(new MethodHandle[]{Empty.MH_f, Empty.MH_f, Empty.MH_pred, null});
  85         assertEquals(MethodType.methodType(void.class), loop.type());
  86         loop.invoke();
  87     }
  88 
  89     @Test
  90     public static void testLoopVoid2() throws Throwable {
  91         // construct a post-checked loop that only does one iteration and has a void body and void local state,
  92         // initialized implicitly from the step type
  93         MethodHandle loop = MethodHandles.loop(new MethodHandle[]{null, Empty.MH_f, Empty.MH_pred, null});
  94         assertEquals(MethodType.methodType(void.class), loop.type());
  95         loop.invoke();
  96     }
  97 
  98     @Test
  99     public static void testLoopVoid3() throws Throwable {
 100         // construct a post-checked loop that only does one iteration and has a void body and void local state,
 101         // and that has a void finalizer
 102         MethodHandle loop = MethodHandles.loop(new MethodHandle[]{null, Empty.MH_f, Empty.MH_pred, Empty.MH_f});
 103         assertEquals(MethodType.methodType(void.class), loop.type());
 104         loop.invoke();
 105     }
 106 
 107     @Test
 108     public static void testLoopFacWithVoidState() throws Throwable {
 109         // like testLoopFac, but with additional void state that outputs a dot
 110         MethodHandle[] counterClause = new MethodHandle[]{Fac.MH_zero, Fac.MH_inc};
 111         MethodHandle[] accumulatorClause = new MethodHandle[]{Fac.MH_one, Fac.MH_mult, Fac.MH_pred, Fac.MH_fin};
 112         MethodHandle[] dotClause = new MethodHandle[]{null, Fac.MH_dot};
 113         MethodHandle loop = MethodHandles.loop(counterClause, accumulatorClause, dotClause);
 114         assertEquals(Fac.MT_fac, loop.type());
 115         assertEquals(120, loop.invoke(5));
 116     }
 117 
 118     @Test
 119     public static void testLoopVoidInt() throws Throwable {
 120         // construct a post-checked loop that only does one iteration and has a void body and void local state,
 121         // and that returns a constant
 122         MethodHandle loop = MethodHandles.loop(new MethodHandle[]{null, Empty.MH_f, Empty.MH_pred, Empty.MH_c});
 123         assertEquals(MethodType.methodType(int.class), loop.type());
 124         assertEquals(23, loop.invoke());
 125     }
 126 
 127     @Test
 128     public static void testLoopWithVirtuals() throws Throwable {
 129         // construct a loop (to calculate factorial) that uses a mix of static and virtual methods
 130         MethodHandle[] counterClause = new MethodHandle[]{null, LoopWithVirtuals.permute(LoopWithVirtuals.MH_inc)};
 131         MethodHandle[] accumulatorClause = new MethodHandle[]{
 132                 // init function must indicate the loop arguments (there is no other means to determine them)
 133                 MethodHandles.dropArguments(LoopWithVirtuals.MH_one, 0, LoopWithVirtuals.class),
 134                 LoopWithVirtuals.permute(LoopWithVirtuals.MH_mult),
 135                 LoopWithVirtuals.permute(LoopWithVirtuals.MH_pred),
 136                 LoopWithVirtuals.permute(LoopWithVirtuals.MH_fin)
 137         };
 138         MethodHandle loop = MethodHandles.loop(counterClause, accumulatorClause);
 139         assertEquals(LoopWithVirtuals.MT_loop, loop.type());
 140         assertEquals(120, loop.invoke(new LoopWithVirtuals(), 5));
 141     }
 142 
 143     @DataProvider
 144     static Object[][] negativeTestData() {
 145         MethodHandle i0 = MethodHandles.constant(int.class, 0);
 146         MethodHandle ii = MethodHandles.dropArguments(i0, 0, int.class, int.class);
 147         MethodHandle id = MethodHandles.dropArguments(i0, 0, int.class, double.class);
 148         MethodHandle i3 = MethodHandles.dropArguments(i0, 0, int.class, int.class, int.class);
 149         List<MethodHandle> inits = Arrays.asList(ii, id, i3);
 150         List<Class<?>> ints = Arrays.asList(int.class, int.class, int.class);
 151         List<MethodHandle> finis = Arrays.asList(Fac.MH_fin, Fac.MH_inc, Counted.MH_step);
 152         List<MethodHandle> preds1 = Arrays.asList(null, null, null);
 153         List<MethodHandle> preds2 = Arrays.asList(null, Fac.MH_fin, null);
 154         MethodHandle eek = MethodHandles.dropArguments(i0, 0, int.class, int.class, double.class);
 155         List<MethodHandle> nesteps = Arrays.asList(Fac.MH_inc, eek, Fac.MH_dot);
 156         List<MethodHandle> nepreds = Arrays.asList(null, Fac.MH_pred, null);
 157         List<MethodHandle> nefinis = Arrays.asList(null, Fac.MH_fin, null);
 158         List<MethodHandle> lvsteps = Arrays.asList(LoopWithVirtuals.MH_inc, LoopWithVirtuals.MH_mult);
 159         List<MethodHandle> lvpreds = Arrays.asList(null, LoopWithVirtuals.MH_pred);
 160         List<MethodHandle> lvfinis = Arrays.asList(null, LoopWithVirtuals.MH_fin);
 161         return new Object[][] {
 162                 {null, "null or no clauses passed"},
 163                 {new MethodHandle[][]{}, "null or no clauses passed"},
 164                 {new MethodHandle[][]{{null, Fac.MH_inc}, {Fac.MH_one, null, Fac.MH_mult, Fac.MH_pred, Fac.MH_fin}},
 165                         "All loop clauses must be represented as MethodHandle arrays with at most 4 elements."},
 166                 {new MethodHandle[][]{{null, Fac.MH_inc}, null}, "null clauses are not allowed"},
 167                 {new MethodHandle[][]{{Fac.MH_zero, Fac.MH_dot}},
 168                         "clause 0: init and step return types must match: int != void"},
 169                 {new MethodHandle[][]{{ii}, {id}, {i3}},
 170                         "found non-effectively identical init parameter type lists: " + inits +
 171                                 " (common suffix: " + ints + ")"},
 172                 {new MethodHandle[][]{{null, Fac.MH_inc, null, Fac.MH_fin}, {null, Fac.MH_inc, null, Fac.MH_inc},
 173                         {null, Counted.MH_start, null, Counted.MH_step}},
 174                         "found non-identical finalizer return types: " + finis + " (return type: int)"},
 175                 {new MethodHandle[][]{{Fac.MH_zero, Fac.MH_inc}, {Fac.MH_one, Fac.MH_mult, null, Fac.MH_fin},
 176                         {null, Fac.MH_dot}}, "no predicate found: " + preds1},
 177                 {new MethodHandle[][]{{Fac.MH_zero, Fac.MH_inc}, {Fac.MH_one, Fac.MH_mult, Fac.MH_fin, Fac.MH_fin},
 178                         {null, Fac.MH_dot}}, "predicates must have boolean return type: " + preds2},
 179                 {new MethodHandle[][]{{Fac.MH_zero, Fac.MH_inc}, {Fac.MH_one, eek, Fac.MH_pred, Fac.MH_fin},
 180                         {null, Fac.MH_dot}},
 181                         "found non-effectively identical parameter type lists:\nstep: " + nesteps +
 182                                 "\npred: " + nepreds + "\nfini: " + nefinis + " (common parameter sequence: " + ints + ")"},
 183                 {new MethodHandle[][]{{null, LoopWithVirtuals.MH_inc},
 184                         {LoopWithVirtuals.MH_one, LoopWithVirtuals.MH_mult, LoopWithVirtuals.MH_pred, LoopWithVirtuals.MH_fin}},
 185                         "found non-effectively identical parameter type lists:\nstep: " + lvsteps +
 186                                 "\npred: " + lvpreds + "\nfini: " + lvfinis + " (common parameter sequence: " + ints + ")"}
 187         };
 188     }
 189 
 190     static final MethodHandle MH_loop;
 191 
 192     static {
 193         try {
 194             MH_loop = LOOKUP.findStatic(MethodHandles.class, "loop", methodType(MethodHandle.class, MethodHandle[][].class));
 195         } catch (NoSuchMethodException | IllegalAccessException e) {
 196             throw new ExceptionInInitializerError(e);
 197         }
 198     }
 199 
 200     @Test(dataProvider = "negativeTestData")
 201     public static void testLoopNegative(MethodHandle[][] clauses, String expectedMessage) throws Throwable {
 202         boolean caught = false;
 203         try {
 204             MH_loop.invokeWithArguments(clauses);
 205         } catch (IllegalArgumentException iae) {
 206             assertEquals(expectedMessage, iae.getMessage());
 207             caught = true;
 208         }
 209         assertTrue(caught);
 210     }
 211 
 212     @Test
 213     public static void testWhileLoop() throws Throwable {
 214         // int i = 0; while (i < limit) { ++i; } return i; => limit
 215         MethodHandle loop = MethodHandles.whileLoop(While.MH_zero, While.MH_pred, While.MH_step);
 216         assertEquals(While.MT_while, loop.type());
 217         assertEquals(23, loop.invoke(23));
 218     }
 219 
 220     @Test
 221     public static void testWhileLoopNoIteration() throws Throwable {
 222         // a while loop that never executes its body because the predicate evaluates to false immediately
 223         MethodHandle loop = MethodHandles.whileLoop(While.MH_initString, While.MH_predString, While.MH_stepString);
 224         assertEquals(While.MT_string, loop.type());
 225         assertEquals("a", loop.invoke());
 226     }
 227 
 228     @Test
 229     public static void testDoWhileLoop() throws Throwable {
 230         // int i = 0; do { ++i; } while (i < limit); return i; => limit
 231         MethodHandle loop = MethodHandles.doWhileLoop(While.MH_zero, While.MH_step, While.MH_pred);
 232         assertEquals(While.MT_while, loop.type());
 233         assertEquals(23, loop.invoke(23));
 234     }
 235 
 236     @Test
 237     public static void testDoWhileNullInit() throws Throwable {
 238         While w = new While();
 239         int v = 5;
 240         MethodHandle loop = MethodHandles.doWhileLoop(null, While.MH_voidBody.bindTo(w), While.MH_voidPred.bindTo(w));
 241         assertEquals(While.MT_void, loop.type());
 242         loop.invoke(v);
 243         assertEquals(v, w.i);
 244     }
 245 
 246     @Test
 247     public static void testWhileZip() throws Throwable {
 248         MethodHandle loop = MethodHandles.doWhileLoop(While.MH_zipInitZip, While.MH_zipStep, While.MH_zipPred);
 249         assertEquals(While.MT_zip, loop.type());
 250         List<String> a = Arrays.asList("a", "b", "c", "d");
 251         List<String> b = Arrays.asList("e", "f", "g", "h");
 252         List<String> zipped = Arrays.asList("a", "e", "b", "f", "c", "g", "d", "h");
 253         assertEquals(zipped, (List<String>) loop.invoke(a.iterator(), b.iterator()));
 254     }
 255 
 256     @Test
 257     public static void testWhileNullInit() throws Throwable {
 258         While w = new While();
 259         int v = 5;
 260         MethodHandle loop = MethodHandles.whileLoop(null, While.MH_voidPred.bindTo(w), While.MH_voidBody.bindTo(w));
 261         assertEquals(While.MT_void, loop.type());
 262         loop.invoke(v);
 263         assertEquals(v, w.i);
 264     }
 265 
 266     @Test
 267     public static void testCountedLoop() throws Throwable {
 268         // String s = "Lambdaman!"; for (int i = 0; i < 13; ++i) { s = "na " + s; } return s; => a variation on a well known theme
 269         MethodHandle fit13 = MethodHandles.constant(int.class, 13);
 270         MethodHandle loop = MethodHandles.countedLoop(fit13, Counted.MH_start, Counted.MH_step);
 271         assertEquals(Counted.MT_counted, loop.type());
 272         assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke("Lambdaman!"));
 273     }
 274 
 275     @Test
 276     public static void testCountedArrayLoop() throws Throwable {
 277         // int[] a = new int[]{0}; for (int i = 0; i < 13; ++i) { ++a[0]; } => a[0] == 13
 278         MethodHandle fit13 = MethodHandles.dropArguments(MethodHandles.constant(int.class, 13), 0, int[].class);
 279         MethodHandle loop = MethodHandles.countedLoop(fit13, null, Counted.MH_stepUpdateArray);
 280         assertEquals(Counted.MT_arrayCounted, loop.type());
 281         int[] a = new int[]{0};
 282         loop.invoke(a);
 283         assertEquals(13, a[0]);
 284     }
 285 
 286     @Test
 287     public static void testCountedPrintingLoop() throws Throwable {
 288         MethodHandle fit5 = MethodHandles.constant(int.class, 5);
 289         MethodHandle loop = MethodHandles.countedLoop(fit5, null, Counted.MH_printHello);
 290         assertEquals(Counted.MT_countedPrinting, loop.type());
 291         loop.invoke();
 292     }
 293 
 294     @Test
 295     public static void testCountedRangeLoop() throws Throwable {
 296         // String s = "Lambdaman!"; for (int i = -5; i < 8; ++i) { s = "na " + s; } return s; => a well known theme
 297         MethodHandle fitm5 = MethodHandles.dropArguments(Counted.MH_m5, 0, String.class);
 298         MethodHandle fit8 = MethodHandles.dropArguments(Counted.MH_8, 0, String.class);
 299         MethodHandle loop = MethodHandles.countedLoop(fitm5, fit8, Counted.MH_start, Counted.MH_step);
 300         assertEquals(Counted.MT_counted, loop.type());
 301         assertEquals("na na na na na na na na na na na na na Lambdaman!", loop.invoke("Lambdaman!"));
 302     }
 303 
 304     @Test
 305     public static void testIterateSum() throws Throwable {
 306         // Integer[] a = new Integer[]{1,2,3,4,5,6}; int sum = 0; for (int e : a) { sum += e; } return sum; => 21
 307         MethodHandle loop = MethodHandles.iteratedLoop(Iterate.MH_sumIterator, Iterate.MH_sumInit, Iterate.MH_sumStep);
 308         assertEquals(Iterate.MT_sum, loop.type());
 309         assertEquals(21, loop.invoke(new Integer[]{1, 2, 3, 4, 5, 6}));
 310     }
 311 
 312     @Test
 313     public static void testIterateReverse() throws Throwable {
 314         MethodHandle loop = MethodHandles.iteratedLoop(null, Iterate.MH_reverseInit, Iterate.MH_reverseStep);
 315         assertEquals(Iterate.MT_reverse, loop.type());
 316         List<String> list = Arrays.asList("a", "b", "c", "d", "e");
 317         List<String> reversedList = Arrays.asList("e", "d", "c", "b", "a");
 318         assertEquals(reversedList, (List<String>) loop.invoke(list));
 319     }
 320 
 321     @Test
 322     public static void testIterateLength() throws Throwable {
 323         MethodHandle loop = MethodHandles.iteratedLoop(null, Iterate.MH_lengthInit, Iterate.MH_lengthStep);
 324         assertEquals(Iterate.MT_length, loop.type());
 325         List<Double> list = Arrays.asList(23.0, 148.0, 42.0);
 326         assertEquals(list.size(), (int) loop.invoke(list));
 327     }
 328 
 329     @Test
 330     public static void testIterateMap() throws Throwable {
 331         MethodHandle loop = MethodHandles.iteratedLoop(null, Iterate.MH_mapInit, Iterate.MH_mapStep);
 332         assertEquals(Iterate.MT_map, loop.type());
 333         List<String> list = Arrays.asList("Hello", "world", "!");
 334         List<String> upList = Arrays.asList("HELLO", "WORLD", "!");
 335         assertEquals(upList, (List<String>) loop.invoke(list));
 336     }
 337 
 338     @Test
 339     public static void testIteratePrint() throws Throwable {
 340         MethodHandle loop = MethodHandles.iteratedLoop(null, null, Iterate.MH_printStep);
 341         assertEquals(Iterate.MT_print, loop.type());
 342         loop.invoke(Arrays.asList("hello", "world"));
 343     }
 344 
 345     @Test
 346     public static void testIterateNullBody() {
 347         boolean caught = false;
 348         try {
 349             MethodHandles.iteratedLoop(MethodHandles.identity(int.class), MethodHandles.identity(int.class), null);
 350         } catch (IllegalArgumentException iae) {
 351             assertEquals("iterated loop body must not be null", iae.getMessage());
 352             caught = true;
 353         }
 354         assertTrue(caught);
 355     }
 356 
 357     static class Empty {
 358 
 359         static void f() { }
 360 
 361         static boolean pred() {
 362             return false;
 363         }
 364 
 365         static int c() {
 366             return 23;
 367         }
 368 
 369         static final Class<Empty> EMPTY = Empty.class;
 370 
 371         static final MethodType MT_f = methodType(void.class);
 372         static final MethodType MT_pred = methodType(boolean.class);
 373         static final MethodType MT_c = methodType(int.class);
 374 
 375         static final MethodHandle MH_f;
 376         static final MethodHandle MH_pred;
 377         static final MethodHandle MH_c;
 378 
 379         static {
 380             try {
 381                 MH_f = LOOKUP.findStatic(EMPTY, "f", MT_f);
 382                 MH_pred = LOOKUP.findStatic(EMPTY, "pred", MT_pred);
 383                 MH_c = LOOKUP.findStatic(EMPTY, "c", MT_c);
 384             } catch (Exception e) {
 385                 throw new ExceptionInInitializerError(e);
 386             }
 387         }
 388     }
 389 
 390     static class Fac {
 391 
 392         static int zero(int k) {
 393             return 0;
 394         }
 395 
 396         static int one(int k) {
 397             return 1;
 398         }
 399 
 400         static boolean pred(int i, int acc, int k) {
 401             return i < k;
 402         }
 403 
 404         static int inc(int i, int acc, int k) {
 405             return i + 1;
 406         }
 407 
 408         static int mult(int i, int acc, int k) {
 409             return i * acc;
 410         }
 411 
 412         static void dot(int i, int acc, int k) {
 413             System.out.print('.');
 414         }
 415 
 416         static int fin(int i, int acc, int k) {
 417             return acc;
 418         }
 419 
 420         static final Class<Fac> FAC = Fac.class;
 421 
 422         static final MethodType MT_init = methodType(int.class, int.class);
 423         static final MethodType MT_fn = methodType(int.class, int.class, int.class, int.class);
 424         static final MethodType MT_dot = methodType(void.class, int.class, int.class, int.class);
 425         static final MethodType MT_pred = methodType(boolean.class, int.class, int.class, int.class);
 426 
 427         static final MethodHandle MH_zero;
 428         static final MethodHandle MH_one;
 429         static final MethodHandle MH_pred;
 430         static final MethodHandle MH_inc;
 431         static final MethodHandle MH_mult;
 432         static final MethodHandle MH_dot;
 433         static final MethodHandle MH_fin;
 434 
 435         static final MethodType MT_fac = methodType(int.class, int.class);
 436 
 437         static {
 438             try {
 439                 MH_zero = LOOKUP.findStatic(FAC, "zero", MT_init);
 440                 MH_one = LOOKUP.findStatic(FAC, "one", MT_init);
 441                 MH_pred = LOOKUP.findStatic(FAC, "pred", MT_pred);
 442                 MH_inc = LOOKUP.findStatic(FAC, "inc", MT_fn);
 443                 MH_mult = LOOKUP.findStatic(FAC, "mult", MT_fn);
 444                 MH_dot = LOOKUP.findStatic(FAC, "dot", MT_dot);
 445                 MH_fin = LOOKUP.findStatic(FAC, "fin", MT_fn);
 446             } catch (Exception e) {
 447                 throw new ExceptionInInitializerError(e);
 448             }
 449         }
 450 
 451     }
 452 
 453     static class Loop {
 454 
 455         static int inc(int i, int k) {
 456             return i + 1;
 457         }
 458 
 459         static boolean pred(int i, int k) {
 460             return i < k;
 461         }
 462 
 463         static int fin(int i, int k) {
 464             return k;
 465         }
 466 
 467         static final Class<Loop> LOOP = Loop.class;
 468 
 469         static final MethodType MT_inc = methodType(int.class, int.class, int.class);
 470         static final MethodType MT_pred = methodType(boolean.class, int.class, int.class);
 471         static final MethodType MT_fin = methodType(int.class, int.class, int.class);
 472 
 473         static final MethodHandle MH_inc;
 474         static final MethodHandle MH_pred;
 475         static final MethodHandle MH_fin;
 476 
 477         static final MethodType MT_loop = methodType(int.class, int.class);
 478 
 479         static {
 480             try {
 481                 MH_inc = LOOKUP.findStatic(LOOP, "inc", MT_inc);
 482                 MH_pred = LOOKUP.findStatic(LOOP, "pred", MT_pred);
 483                 MH_fin = LOOKUP.findStatic(LOOP, "fin", MT_fin);
 484             } catch (Exception e) {
 485                 throw new ExceptionInInitializerError(e);
 486             }
 487         }
 488 
 489     }
 490 
 491     static class LoopWithVirtuals {
 492 
 493         static int one(int k) {
 494             return 1;
 495         }
 496 
 497         int inc(int i, int acc, int k) {
 498             return i + 1;
 499         }
 500 
 501         int mult(int i, int acc, int k) {
 502             return i * acc;
 503         }
 504 
 505         boolean pred(int i, int acc, int k) {
 506             return i < k;
 507         }
 508 
 509         int fin(int i, int acc, int k) {
 510             return acc;
 511         }
 512 
 513         static final Class<LoopWithVirtuals> LOOP_WITH_VIRTUALS = LoopWithVirtuals.class;
 514 
 515         static final MethodType MT_one = methodType(int.class, int.class);
 516         static final MethodType MT_inc = methodType(int.class, int.class, int.class, int.class);
 517         static final MethodType MT_mult = methodType(int.class, int.class, int.class, int.class);
 518         static final MethodType MT_pred = methodType(boolean.class, int.class, int.class, int.class);
 519         static final MethodType MT_fin = methodType(int.class, int.class, int.class, int.class);
 520 
 521         static final MethodHandle MH_one;
 522         static final MethodHandle MH_inc;
 523         static final MethodHandle MH_mult;
 524         static final MethodHandle MH_pred;
 525         static final MethodHandle MH_fin;
 526 
 527         static final MethodType MT_loop = methodType(int.class, LOOP_WITH_VIRTUALS, int.class);
 528 
 529         static {
 530             try {
 531                 MH_one = LOOKUP.findStatic(LOOP_WITH_VIRTUALS, "one", MT_one);
 532                 MH_inc = LOOKUP.findVirtual(LOOP_WITH_VIRTUALS, "inc", MT_inc);
 533                 MH_mult = LOOKUP.findVirtual(LOOP_WITH_VIRTUALS, "mult", MT_mult);
 534                 MH_pred = LOOKUP.findVirtual(LOOP_WITH_VIRTUALS, "pred", MT_pred);
 535                 MH_fin = LOOKUP.findVirtual(LOOP_WITH_VIRTUALS, "fin", MT_fin);
 536             } catch (Exception e) {
 537                 throw new ExceptionInInitializerError(e);
 538             }
 539         }
 540 
 541         static MethodHandle permute(MethodHandle h) {
 542             // The handles representing virtual methods need to be rearranged to match the required order of arguments
 543             // (loop-local state comes first, then loop arguments). As the receiver comes first in the signature but is
 544             // a loop argument, it must be moved to the appropriate position in the signature.
 545             return MethodHandles.permuteArguments(h,
 546                     methodType(h.type().returnType(), int.class, int.class, LOOP_WITH_VIRTUALS, int.class), 2, 0, 1, 3);
 547         }
 548 
 549     }
 550 
 551     static class While {
 552 
 553         static int zero(int limit) {
 554             return 0;
 555         }
 556 
 557         static boolean pred(int i, int limit) {
 558             return i < limit;
 559         }
 560 
 561         static int step(int i, int limit) {
 562             return i + 1;
 563         }
 564 
 565         static String initString() {
 566             return "a";
 567         }
 568 
 569         static boolean predString(String s) {
 570             return s.length() != 1;
 571         }
 572 
 573         static String stepString(String s) {
 574             return s + "a";
 575         }
 576 
 577         static List<String> zipInitZip(Iterator<String> a, Iterator<String> b) {
 578             return new ArrayList<>();
 579         }
 580 
 581         static boolean zipPred(List<String> zip, Iterator<String> a, Iterator<String> b) {
 582             return a.hasNext() && b.hasNext();
 583         }
 584 
 585         static List<String> zipStep(List<String> zip, Iterator<String> a, Iterator<String> b) {
 586             zip.add(a.next());
 587             zip.add(b.next());
 588             return zip;
 589         }
 590 
 591         private int i = 0;
 592 
 593         void voidBody(int k) {
 594             ++i;
 595         }
 596 
 597         boolean voidPred(int k) {
 598             return i < k;
 599         }
 600 
 601         static final Class<While> WHILE = While.class;
 602 
 603         static final MethodType MT_zero = methodType(int.class, int.class);
 604         static final MethodType MT_pred = methodType(boolean.class, int.class, int.class);
 605         static final MethodType MT_fn = methodType(int.class, int.class, int.class);
 606         static final MethodType MT_initString = methodType(String.class);
 607         static final MethodType MT_predString = methodType(boolean.class, String.class);
 608         static final MethodType MT_stepString = methodType(String.class, String.class);
 609         static final MethodType MT_zipInitZip = methodType(List.class, Iterator.class, Iterator.class);
 610         static final MethodType MT_zipPred = methodType(boolean.class, List.class, Iterator.class, Iterator.class);
 611         static final MethodType MT_zipStep = methodType(List.class, List.class, Iterator.class, Iterator.class);
 612         static final MethodType MT_voidBody = methodType(void.class, int.class);
 613         static final MethodType MT_voidPred = methodType(boolean.class, int.class);
 614 
 615         static final MethodHandle MH_zero;
 616         static final MethodHandle MH_pred;
 617         static final MethodHandle MH_step;
 618         static final MethodHandle MH_initString;
 619         static final MethodHandle MH_predString;
 620         static final MethodHandle MH_stepString;
 621         static final MethodHandle MH_zipInitZip;
 622         static final MethodHandle MH_zipPred;
 623         static final MethodHandle MH_zipStep;
 624         static final MethodHandle MH_voidBody;
 625         static final MethodHandle MH_voidPred;
 626 
 627         static final MethodType MT_while = methodType(int.class, int.class);
 628         static final MethodType MT_string = methodType(String.class);
 629         static final MethodType MT_zip = methodType(List.class, Iterator.class, Iterator.class);
 630         static final MethodType MT_void = methodType(void.class, int.class);
 631 
 632         static {
 633             try {
 634                 MH_zero = LOOKUP.findStatic(WHILE, "zero", MT_zero);
 635                 MH_pred = LOOKUP.findStatic(WHILE, "pred", MT_pred);
 636                 MH_step = LOOKUP.findStatic(WHILE, "step", MT_fn);
 637                 MH_initString = LOOKUP.findStatic(WHILE, "initString", MT_initString);
 638                 MH_predString = LOOKUP.findStatic(WHILE, "predString", MT_predString);
 639                 MH_stepString = LOOKUP.findStatic(WHILE, "stepString", MT_stepString);
 640                 MH_zipInitZip = LOOKUP.findStatic(WHILE, "zipInitZip", MT_zipInitZip);
 641                 MH_zipPred = LOOKUP.findStatic(WHILE, "zipPred", MT_zipPred);
 642                 MH_zipStep = LOOKUP.findStatic(WHILE, "zipStep", MT_zipStep);
 643                 MH_voidBody = LOOKUP.findVirtual(WHILE, "voidBody", MT_voidBody);
 644                 MH_voidPred = LOOKUP.findVirtual(WHILE, "voidPred", MT_voidPred);
 645             } catch (Exception e) {
 646                 throw new ExceptionInInitializerError(e);
 647             }
 648         }
 649 
 650     }
 651 
 652     static class Counted {
 653 
 654         static String start(String arg) {
 655             return arg;
 656         }
 657 
 658         static String step(int counter, String v, String arg) {
 659             return "na " + v;
 660         }
 661 
 662         static void stepUpdateArray(int counter, int[] a) {
 663             ++a[0];
 664         }
 665 
 666         static void printHello(int counter) {
 667             System.out.print("hello");
 668         }
 669 
 670         static final Class<Counted> COUNTED = Counted.class;
 671 
 672         static final MethodType MT_start = methodType(String.class, String.class);
 673         static final MethodType MT_step = methodType(String.class, int.class, String.class, String.class);
 674         static final MethodType MT_stepUpdateArray = methodType(void.class, int.class, int[].class);
 675         static final MethodType MT_printHello = methodType(void.class, int.class);
 676 
 677         static final MethodHandle MH_13;
 678         static final MethodHandle MH_m5;
 679         static final MethodHandle MH_8;
 680         static final MethodHandle MH_start;
 681         static final MethodHandle MH_step;
 682         static final MethodHandle MH_stepUpdateArray;
 683         static final MethodHandle MH_printHello;
 684 
 685         static final MethodType MT_counted = methodType(String.class, String.class);
 686         static final MethodType MT_arrayCounted = methodType(void.class, int[].class);
 687         static final MethodType MT_countedPrinting = methodType(void.class);
 688 
 689         static {
 690             try {
 691                 MH_13 = MethodHandles.constant(int.class, 13);
 692                 MH_m5 = MethodHandles.constant(int.class, -5);
 693                 MH_8 = MethodHandles.constant(int.class, 8);
 694                 MH_start = LOOKUP.findStatic(COUNTED, "start", MT_start);
 695                 MH_step = LOOKUP.findStatic(COUNTED, "step", MT_step);
 696                 MH_stepUpdateArray = LOOKUP.findStatic(COUNTED, "stepUpdateArray", MT_stepUpdateArray);
 697                 MH_printHello = LOOKUP.findStatic(COUNTED, "printHello", MT_printHello);
 698             } catch (Exception e) {
 699                 throw new ExceptionInInitializerError(e);
 700             }
 701         }
 702 
 703     }
 704 
 705     static class Iterate {
 706 
 707         static Iterator<Integer> sumIterator(Integer[] a) {
 708             return Arrays.asList(a).iterator();
 709         }
 710 
 711         static int sumInit(Integer[] a) {
 712             return 0;
 713         }
 714 
 715         static int sumStep(int s, int e, Integer[] a) {
 716             return s + e;
 717         }
 718 
 719         static List<String> reverseInit(List<String> l) {
 720             return new ArrayList<>();
 721         }
 722 
 723         static List<String> reverseStep(String e, List<String> r, List<String> l) {
 724             r.add(0, e);
 725             return r;
 726         }
 727 
 728         static int lengthInit(List<Double> l) {
 729             return 0;
 730         }
 731 
 732         static int lengthStep(Object o, int len, List<Double> l) {
 733             return len + 1;
 734         }
 735 
 736         static List<String> mapInit(List<String> l) {
 737             return new ArrayList<>();
 738         }
 739 
 740         static List<String> mapStep(String e, List<String> r, List<String> l) {
 741             r.add(e.toUpperCase());
 742             return r;
 743         }
 744 
 745         static void printStep(String s, List<String> l) {
 746             System.out.print(s);
 747         }
 748 
 749         static final Class<Iterate> ITERATE = Iterate.class;
 750 
 751         static final MethodType MT_sumIterator = methodType(Iterator.class, Integer[].class);
 752 
 753         static final MethodType MT_sumInit = methodType(int.class, Integer[].class);
 754         static final MethodType MT_reverseInit = methodType(List.class, List.class);
 755         static final MethodType MT_lenghInit = methodType(int.class, List.class);
 756         static final MethodType MT_mapInit = methodType(List.class, List.class);
 757 
 758         static final MethodType MT_sumStep = methodType(int.class, int.class, int.class, Integer[].class);
 759         static final MethodType MT_reverseStep = methodType(List.class, String.class, List.class, List.class);
 760         static final MethodType MT_lengthStep = methodType(int.class, Object.class, int.class, List.class);
 761         static final MethodType MT_mapStep = methodType(List.class, String.class, List.class, List.class);
 762         static final MethodType MT_printStep = methodType(void.class, String.class, List.class);
 763 
 764         static final MethodHandle MH_sumIterator;
 765         static final MethodHandle MH_sumInit;
 766         static final MethodHandle MH_sumStep;
 767         static final MethodHandle MH_printStep;
 768 
 769         static final MethodHandle MH_reverseInit;
 770         static final MethodHandle MH_reverseStep;
 771 
 772         static final MethodHandle MH_lengthInit;
 773         static final MethodHandle MH_lengthStep;
 774 
 775         static final MethodHandle MH_mapInit;
 776         static final MethodHandle MH_mapStep;
 777 
 778         static final MethodType MT_sum = methodType(int.class, Integer[].class);
 779         static final MethodType MT_reverse = methodType(List.class, List.class);
 780         static final MethodType MT_length = methodType(int.class, List.class);
 781         static final MethodType MT_map = methodType(List.class, List.class);
 782         static final MethodType MT_print = methodType(void.class, List.class);
 783 
 784         static {
 785             try {
 786                 MH_sumIterator = LOOKUP.findStatic(ITERATE, "sumIterator", MT_sumIterator);
 787                 MH_sumInit = LOOKUP.findStatic(ITERATE, "sumInit", MT_sumInit);
 788                 MH_sumStep = LOOKUP.findStatic(ITERATE, "sumStep", MT_sumStep);
 789                 MH_reverseInit = LOOKUP.findStatic(ITERATE, "reverseInit", MT_reverseInit);
 790                 MH_reverseStep = LOOKUP.findStatic(ITERATE, "reverseStep", MT_reverseStep);
 791                 MH_lengthInit = LOOKUP.findStatic(ITERATE, "lengthInit", MT_lenghInit);
 792                 MH_lengthStep = LOOKUP.findStatic(ITERATE, "lengthStep", MT_lengthStep);
 793                 MH_mapInit = LOOKUP.findStatic(ITERATE, "mapInit", MT_mapInit);
 794                 MH_mapStep = LOOKUP.findStatic(ITERATE, "mapStep", MT_mapStep);
 795                 MH_printStep = LOOKUP.findStatic(ITERATE, "printStep", MT_printStep);
 796             } catch (Exception e) {
 797                 throw new ExceptionInInitializerError(e);
 798             }
 799         }
 800 
 801     }
 802 
 803 }